Impending Storm Still On the Table

The latest information has come out from the 06z GFS model which indicates that a potential snowfall is possible for the area next week. At the current time, the models disagree widely on the track of the storm. In the more northerly track,

the Euro has the storm system's center moving through the region and northeast into Detroit, which would bring us initially rain, but then changing over to snow. In the southerly camp, the GFS has the storm system's center tracking through Southern Ohio (it has trended northward by quite a bit and is coming into agreement with the Euro), bringing our area initially periods of a wintry mix next Monday night and Tuesday, then causing wintry mix to change over to a moderate or at times *heavy* snowfall. That is the 06z GFS for us.

At this time, I'm not going with any model solution, and given what happened last year, I'm EXTREMELY skeptical of a snowstorm hitting the region next week. BUT, the possibility still remains that that a winter weather event remains on the table for the area.

Here is the 06z GFS snowfall forecast for next Monday and Tuesday. It is forecasting the potential of 6-12 inches of snow from Monday night through Wednesday!

DISCLAIMER: AGAIN, I DO NOT BELIEVE THAT THIS WILL HAPPEN. IT IS JUST ONE OF THE MANY POSSIBILITIES.

 

 

Impending Pattern Change on the Horizon

*IMPENDING PATTERN CHANGE ON THE HORIZON*

If you haven't heard yet, meteorologists are now looking at the possibility of an impending weather pattern change across a large portion of the United States. In fact, winter could begin impacting the United States rather quickly, especially after Thanksgiving (including shots of Arctic air).

Here's what's going to happen. Next weekend (after Black Friday), models generally agree that a strong upper level disturbance will move along the Canadian border and deepen. This will draw very cold arctic air southward as the low begins to close off. The cold Arctic air will drain southward into Iowa and Illinois on Friday and Saturday, before shifting eastward Saturday and Sunday into the Ohio Valley and East. Thermal profiles will favorable enough for the potential for a lake effect snow event along Lake Michigan, Lake Erie and Lake Ontario. The heaviest lake effect (of a few inches or so) will occur in the Eastern Great Lakes region, where the coldest air will likely reside over the Lakes. This Arctic wave will only be transient, and only a sign of things to come.

Next week, there is a general agreement between the ensembles and operational models that a more substantial and robust pattern could be taking shape. Currently, models disagree considerably on the magnitude, strength and track of this storm, which reveals the uselessness of model forecasts at this point in time. Based on the data I have seen, it's looking more and more likely that a strong Midwestern low will develop in the Central Plains, and move east-northeast into the Great Lakes. At this point, it is very difficult to determine the exact track of this low, or even if this low will occur, but what could and is the most likely to happen at this point is that the storm pulls extremely cold Arctic air southward behind the storm. This could in fact come into contact with moisture wrapping around the intense low pressure system, bringing a potential "blizzard" from Iowa, to Nebraska and Minnesota.

AT this point, it is not all that likely that this occurs, due to the model variability, BUT given the current signals, it is a possibility. Needless to say, behind this system's *massive* cold front, very cold air will settle into a very large portion of the Midwest, and East. In fact, at this point, due to several unfavorable signals, the worst of the below normal temperature anomalies will stay north in the Great Lakes and Midwest regions.

For our area, here's what's likely to happen: This weekend, a cold front will quickly pass through the region, dropping temperatures back into the mid and upper 30's and possibly colder if the Euro's forecast were to verify. This would likely spark numerous lake effect snow showers immediately downwind of Lake Michigan. This could in fact lead to a few snow flurries around the region by Saturday night. In everything though, this cold blast will not last long. In fact, it will last only a couple of days before getting pushed out of the region. After that, model uncertainty has lead to an uncertain forecast, and all I can say is that the pattern is likely to get a lot colder soon.
Again, this is not a forecast that is set in stone, only the most likely scenario.

Since we won't have to deal with this for about a week, have a great Thanksgiving! 

December 2012 Long-range Forecast

And here begins the December long-range forecast released by Northwest Ohio Storm Prediction Center!

I'm not going to go into detail about the long-range factors going into this forecast, as I well know that only true "weather geeks" really care about them. So for this, I will only make mention of the truly important factors.

Currently, the Equatorial Pacific is in the neutral ENSO phase, which us "weather geeks" like to sometimes call, "La Nada", which just references the fact that Neutral winters tend to have less affect on North American weather than do other variables. SST anomalies have been fluctuating, but have generally averaged just slightly above normal in the Equatorial Pacific. Current MJO forecasts (Madden Julian Oscillation, a weather pattern or frequency that occurs in the tropics, but can affect weather across the Pacific, as far away as the United States) suggest that in the next few weeks it will be going through phases 8,1, and 2. Phase 8 generally favors the strengthening of an El Nino, while phases 1 and 2 favor "La Nada's" and La Nina's. Another variable that I look at is the NAO, as well as the AO. The NAO stands for North Atlantic Oscillation, which is related to atmospheric pressure across the North Atlantic, and the AO stands for the Arctic Oscillation which is related to pressure anomalies across the Arctic (and including the stratospheric circulations). Both of these have been in the negative phase for nearly the ENTIRE fall. Last year, it was hard to keep the two negative. A negative AO/NAO couplet suggests a greater potential for cold weather to invade the Northern and Eastern United States, including the Midwest. Using a forecast of persistence, I can see the NAO staying near neutral or negative for the month of December (including the AO as well). Other variables related to my forecast include snow cover across Canada, the PDO index, the PNA index, solar cycle variation, etc. I will not go into detail on these.

As for the forecast, I'll start with the lower Great Lakes forecast. For the last few days of November and very beginning of December, long-range forecast models indicate that the pattern will become very "changeable", and is likely to go through a "pattern change" around the same time. In fact, it is all-together likely that this pattern change is marked by a major Arctic blast into the Great Lakes, which would usher in the first major lake effect snow event of the season. In the same time frame, both the NAO and AO are expected to go at least slightly negative, which supports the development of blocking across the North Atlantic, and thus a "stopped" and unchanging pattern. This could in fact allow arctic air intrusions to become more likely in December. At this point I do NOT believe that the December 2012 trough/ridge pattern will be very "blocked". This means that I do expect the pattern to still be rather "changing", but more likely to yield arctic air intrusions. In all, for the lower Great Lakes, expect slightly below normal temperatures, due to the Arctic air masses, but averaging in any "sustained" warm ups as well. As for precipitation, I expect near normal precipitation, as the storm track will favor Alberta Clippers into the region, but most "wet" storms will likely head south of the area. Areas downwind of the Great Lakes will likely see above normal precipitation and snowfall. For the rest of the Great Lakes and Ohio Valley, I think it will be definitely possible to see one decent snowstorm, but in light of recent events, most storm systems will likely feature a mix of ice/snow or heavy rainfall.

For the rest of the United States, expect below normal temperatures from the Northern Plains to the East Coast, with the core of the Arctic air still existing across Western Canada. An active southeastward storm track from the Northern Plains into the Ohio Valley and along the East Coast, will favor above normal precipitation in coastal cities, with near to below normal precipitation across the Southern Plains and Southwest United States. In the Great Lakes, precipitation will be near normal except for the Lake effect "belts". The Northern Plains will likely see near to above normal precipitation due to the storm track. This pattern I can see happening about two or three times during the month of December, each lasting about three or four days before a more transient trough/ridge pattern sets in, between these periods of Arctic cold. These will be the times when Midwestern storms make their way in, and a Great Lakes Cutter results, a storm that travels from the Central Plains into the Great Lakes region, bringing warmer conditions and heavy rains to the Ohio Valley and much of the East.

I will not yet release a Christmas Day forecast until December begins.

One point I would like to make and that is this: Once again, because of the fragile state of the ENSO phase especially, and the way the PDO has been trending, I can see that it is possible, that we see a storm track through the Ohio Valley, with near to above normal temperatures, but well above normal precipitation and potentially snowfall. This could in fact happen if a Western trough develops, which will eject disturbances into the Midwest region. I will keep an eye on this.

Here's the official forecast map:

 

Temperature Anomaly Forecast Map.

And here is the snow cover maps.. Comparing this year to last year:

Snow cover for November 2011

Snow cover November 2012, well above what last year saw.

European Ensemble Forecasts Support Pattern Change

Last Wednesday, Northwest Ohio Storm Prediction Center released a long range forecast, explaining that the ensembles were predicting a more transient and "potentially" stormier long range pattern. As you can see, this past week, we saw a major West Coast storm move into the Midwest, and slam the Upper Midwest with as much as four feet of snow, high winds throughout the Central Plains, and heavy rains to a widespread area. Not only that, but it brought along with it the first true Arctic blast of the season, with the lake effect snow affecting a large area of Michigan.

Global models are now expecting that this pattern be disrupted until Thanksgiving Week (next week). The disruption will occur as a major Gulf of Alaskan low becomes prevalent. It will cause the jet stream to "split", indicating that the pattern will be rather dry and inactive, with no major storms expected to hit any part of the United States until late next week. NOW, Global models as well as the ensembles are forecasting a potential pattern change at the end of Thanksgiving week (that could potentially screw up my entire winter forecast). In fact, the ensembles are forecasting that the Aleutian/Gulf of Alaskan low will begin to "dig" into the West Coast. In response, a strong elongated jet streak will begin to form across the Northern Plains, which will allow the PV (Polar Vortex) to begin shifting southward again. At the same time, ridging (North Atlantic blocking) will build into Greenland, forcing a trough to form in the East, with a flat ridge developing over the West. In fact, this could be the beginning of more widespread arctic air into the United States.

The storm that could bring these changes could either be a Midwest storm system, a Northeast coastal low, or both. In fact, both of these possibilities have been suggested by the global models. In my opinion, here is what will happen. A large storm will drop southeastward in the Midwest, drawing an Arctic air mass into the East. On the edge of the cold front, a secondary low could develop and move along the East Coast. Currently, there are too many differences to in fact make an accurate forecast of what will happen. In any case, this change will occur on Thanksgiving Day or the few days afterward.

More Details of the Winter Outlook

A preview of the winter forecast that is to be released later this week. It could get quite interesting this winter.
 

One thing I would like to mention is this: There are two VERY different scenarios (in my mind) that could play out. In one scenario, it becomes very similar to a hybrid El Nino winter, one in which a western ridge prevails over the Rocky Mountains and Western states, with a mean trough over the Central and Eastern United States. This would create a storm track across the Deep South and into the Western Atlantic, at which point some storms will travel up the coast and some will move out to sea. IF this scenario were true, then this would be the most common path of storm systems. This is already supported by what has happened this fall. What this would mean for the Midwest and Ohio Valley is a very cold and DRY winter, with a few periods of warmth as the Western ridge ejects eastward.  Areas along the Great Lakes would see above normal lake effect snowfall. Anywhere else in the Ohio Valley and Midwest would likely see a lack of precipitation and thus snowfall.

In Scenario TWO, this winter turns out similar to a La Nina winter hybrid. A strong Pacific jet stream sets up across the United States, with the development of a strong South-eastern ridge, while a cold Arctic air mass exists across the West and Western Canada. This would indicate a winter with near normal temperatures for the area (lower Great Lakes region), but above normal precipitation and near normal snowfall. Let me state this though: In this scenario, the first part of December will likely feature a split flow regime, indicating that the Lower Great Lakes and Midwest will probably be devoid of storm systems, but due to shallow arctic air masses, temperatures will likely be kept near to below normal. By very late December, the pattern transitions to a very strong Pacific jet, with a weak mean trough in the West, with a ridge of high pressure over the Northern Gulf of Mexico. This would put the storm track across the Midwest and through the North-eastern states. I believe that this has a likelihood of occurring due to the rapidly expanding snowpack across Western Canada and the Northern Plains. In that case, well below normal temperatures will prevail across the Northern Plains and the West, with near normal temperatures across our area, but with above normal precipitation. The East would feature near to above normal temperatures, but generally wetter conditions. I believe, if this scenario occurred, that this will last through mid-January or so, before transitioning to deeper Arctic pattern, in which the NAO/AO go strongly negative, and a backloaded winter would be the case for a good chunk of the East. February, in this scenario would be the best case for Nor'easters and monster snowstorms.

At this point, I really do not have much confidence in either of these. Either one may occur.

IN any case, I do believe this winter will likely be worse towards the end of the winter. At this point, its likely that once the winter turns for the worse over the area (cold arctic air), it will stay cold and dry. If Scenario two plays out (this is based off of the forecast that a Neutral ENSO will persist and could possibly become a weak La Nina by the end of the winter), then expect a warm, but possibly wet December through January, before colder weather builds into the region.

This is the less likely scenario in which a strong Pacific Jet stream works its way across North America.

The scenario in which the NAO/AO goes strongly negative during the months of January and February, leading to a back loaded winter.

Final Winter Outlook Being Released.

Either tonight or tomorrow I will be releasing Northwest Ohio Storm Prediction Center's official and FINAL winter outlook for the winter of 2012-2013. Even though this forecast center mainly focuses on weather across the region, this forecast will deal with EACH region of the United States.

This forecast will be primarily based off of long term climate signals, including the ENSO (El Nino/La Nina Southern Oscillation) phase, atmospheric blocking across the North Atlantic, SST anomaly patterns across the North Pacific and North Atlantic, the current storm track and jet stream pattern, and the solar cycle. Many other factors MUST be taken into consideration. A few of these variables are very hard to forecast more than two weeks out, mainly including the atmospheric blocking signals, which will be determined in the next few weeks.

I will also include in part of my forecast about what the climate models are forecasting for the upcoming winter as well. Some of these models differ considerably from my forecast, and several of them coincide rather well.

This forecast should be done sometime this week.

As for a sneak peek into the forecast here's a few things of what I expect:

• Quite possibly a slow start to winter
  (December could end up being very warm across a good majority of the United States, except for the Northern Plains and Pacific Northwest).
• NO past years match up quite well with this year
• Data points to a back-loaded winter regardless of winter's start (This means that a harsh January and February is likely).
• Periods of record warmth, are just as likely this winter as brutal cold, making it a very VERY changeable winter.

New Long Range Pattern Setting Up

After reviewing the ensemble runs of the GFS and Euro model, as well as looking at teleconnection forecasts, I can see that there is going to be a MAJOR shift in the storm track over the next several weeks.

First of all, the NAO, which is the North Atlantic Oscillation, will transition to its positive phase this week, after being strongly negative for almost two months. This is a significant trend, and may not be a good trend for a cold winter across the area. The positive phase features a ridge centered on, or just off of the East Coast. "Coupling" with this positive phase of the NAO, will be the PNA, which is the Pacific North American index. The PNA will likely be in its negative phase at the same time the NAO will be in its positive phase, likely resulting in a strong West Coast trough. Another teleconnection I am watching is the AO, which is very similar to the NAO, but it is determined by the arctic stratospheric circulation. In this case, when the AO is in its positive phase, which it will be for the next few weeks, a strong jet stream results over North America, especially in occurence with a negative PNA and positive NAO pattern. Last winter, a positive NAO in combination with a neutral AO allowed for a split flow jet stream. With this upcoming weather pattern for most of November, a strong jet stream will be in place across the country, allowing for occasional strong storm systems to traverse the nation, the first one being this weekend and early next week, which will bring a wave of showers and thunderstorms to the area. Most of these storm systems will likely cause brief warm ups, which will bring periods of rain to the area. After these storm systems pass through, transient cold waves will move into the area, bringing periods of well below normal temperatures. This type of a weather pattern most reflects November 2010. In fact, I believe that this could be a positive factor in cold, snowy conditions across the U.S. this year (unlike last year).

In my opinion, this indicates that the Midwest is about to get quite a bit stormier, with frequent storm systems bringing the chance for snowstorms across the Upper Midwest, and severe weather outbreaks in the Central Plains to the Ohio Valley.

GFS ensembles indicate a strong Pacific jet stream in the long range, including a strong West Coast trough.

In all, expect this: The pattern will transition from a blocked, slow upper level wave pattern, to a transient (including a strong Pacific jet stream), highly variable weather pattern, including periods of warm and cold weather. Ultimately, this is a bit different from last year. Last year, blocking was in place, it just set up in the wrong places.. I believe that this fall and winter will most likely resemble the fall and winter of 2010. Do not be discouraged with warm patterns, because it is likely that a cold pattern will follow. Follow Northwest Ohio Storm Prediction Center for more information on the upcoming weather pattern.

Intense and Powerful Storm System Coming Onshore

As you may have heard on the news, a "historic" and "record-breaking" low pressure system will move onshore later tonight near the Delaware River in Southern New Jersey. There are many things that will make this system a literal "Storm of the Century". It's central pressure at landfall (it will have completed the transition to an extratropical cyclone) will be around 935 millibars, which would break ALL pressure records in the contiguous United States and quite possibly the ENTIRE United States. Also, it will be incredibly large. In fact, it surpassed Hurricane Igor as being the LARGEST hurricane on record, with a tropical storm force wind field 1000 miles in diameter! The hurricane force wind field is about 175 miles in radius, which is nearly double Hurricane Katrina's hurricane force wind field. The large wind field in combination with an extremely low pressure will create a massive storm surge along the East Coast, mainly near Delaware to New York City, where a surge of nearly 15 feet is possible. Also, since this storm will be transitioning into an extratropical low, it's wind field will only increase in size, to the point where our area will receive wind gusts up to 55 mph today, and possibly 60-65 mph tonight into tomorrow morning!

As for precipitation in our area, I'm expecting nearly an inch of precipitation from this storm, with precipitation occurring throughout the days Tuesday and Wednesday. One interesting thing though is that forecast soundings do support a steady snow from the overnight hours Monday night and Tuesday through mid-morning hours. This mainly goes for Northwest Ohio, which will be closer to the source of lift, and in cooler conditions. During this period of snow, sleet and rain could mix in. By noon, most of the precipitation will have changed to rain, and will continue as rain through Wednesday night.

I will have another update either late tonight on the facebook page or tomorrow morning on the blog. Stay safe!

Implications of Today's Model Runs.

After a rather depressing few runs the last few days (in terms of a big storm for parts of the East), ALL of the major global models, and even regional models are beginning to agree on the track, and even the intensity of this hurricane/hybrid storm. I am NO longer considering a solution that sends the storm out to sea, as this is very unreasonable given the current weather pattern.

In fact, the models have trended nearly 2000 miles west of the original storm tracks since yesterday. This is a MAJOR improvement over the last past several model runs. With this in mind, I expect a continuing westward trend until about Friday, when the models should begin to agree on the general storm track. Right now, the ensembles are even more reasonable with this storm, putting it much farther west than even the operational runs.

With all of this talk of the models, here is the reasoning and set up for this likely major and potentially devastating storm system.

Currently, and as we speak, Hurricane Sandy is rapidly intensifying in the Caribbean Sea, just south of Cuba. Just yesterday, it was named Sandy, so as you can see, this is a HUGE jump in intensity. Satellite imagery shows a well-developed eye forming in the center of the storm, along with a "stadium" like eye, usually indicative of rapid strengthening. I would not be surprised in the least bit if Sandy becomes a major hurricane before hitting Cuba tomorrow. Given the current slow storm movement, this seems extremely likely.

Another factor that will likely be in play is a giant West Coast long wave trough. A strong ridge will begin to push this trough out of the West, sending a cold front through our area Thursday night and Friday, along with widespread post-frontal rain, making for a rather gloomy day Friday. It is VERY important to track the strength of the trough, and its movement, as this will determine the strength and track of the hybrid storm once all of these come together.

A third and final factor in this "superstorm" of sorts is a mega North Atlantic blocking pattern. This ridge will get completely in the way of this storm's progress north. My theory is that it will have only one way to go once it gets "locked" into the upper level trough (previously mentioned), and that is straight west and a direct hit on the East Coast. The strength and position of the strongest blocking will determine the path of the storm as well.

Here's what I believe will happen: The hurricane will move due north through the Bahamas, maintaining hurricane status throughout (or just slightly below hurricane status). Once it re-emerges into the Gulf stream region east of Florida, it will likely strengthen, not only due to warmer waters, but because it will begin to "phase" with the upper level trough, providing energy and sustaining the storm. Depending on the degree of phasing (which at this time I believe will be strong), the now hybrid Sandy will continue moving north, and once it reaches around the Chesapeake Bay, it will make a likely sharp turn west, making landfall on the New Jersey coast. The storm system will continue to rapidly strengthen as it transitions to a baroclinic storm, and the upper level system will guide it west. Here's the problem for our area. A few models and ensembles are indicating that the storm will move far enough west to hit our area with very strong winds, and quite possibly SNOW. This is not set in stone in the least bit, but this is one of the more likely solutions. If the storm does move far enough west, we could have some adverse impacts from the storm, ranging from precipitation and wind.

At this point, I'm going to continue to watch. The most consistent and probably most accurate models are so far the NOGAPS and ECMWF. The GFS has not been consistent and is now considering a storm that moves out to sea and doesn't even affect the East Coast. The bottomline is this: The East Coast, if impacted by this storm, could be devastated, with widespread flooding and wind damage likely.

I'll continue to update the blog regarding forecasts on this storm.

Storm lingers on Horizon. Model Mayhem ensues.

After monitoring weather models for several days now, we have begun the model mayhem with this storm. Originally, the entire storm was expected to move inland by most models. Now, some are taking it out to sea, and others are taking it along the coast, and some are taking it inland. Everything has been rather crazy lately with this storm. I am really concerned about the potential impacts due to the sheer size and intensity that is forecast of the storm. For now, all I can say is that models are now trending back westward to an inland solution, which puts the area back under the gun for the possibility of inclement weather early next week. At this point, it is all I can say. Tomorrow, I will post an update about the physics behind the storm, and how it will likely develop.

Ice Crystal and Snowfall Formation (Continued...)

In the past article, I mainly explained how ice crystals and precipitation forms in warm core and cold core clouds. In this article, I will be explaining what conditions are necessary for snow growth. I will explain the temperatures and humidity levels that are needed for snowfall.

Let me start where I left off in the last article. Most precipitation in the mid-latitude regions results from the growth of ice crystals in the glaciated, and "mixed" (region of the cloud that contains both cloud droplets and ice crystals) regions of the cloud layer. The mixed region of the cloud always occurs from about the freezing level to -40 degrees Celsius. The glaciated part of the cloud will always occur above -40 degrees Celsius. But this is for spring and summer clouds, where temperature are very warm in the low levels. During the winter, clouds are made up of predominately ice crystals and water droplets, which tends to make them higher above the earth's surface. The cloud droplets that do make up at the cloud at it's lower levels are very tiny. Due to the lattice structure of an ice crystal, it loses very little water to evaporation. What this means is that vapor pressure is less around an ice crystal than it is around a cloud droplet (which means that when the air is saturated over an ice crystal, it is supersaturated over a water droplet, above 100% relative humidity). The vapor pressure "gradient" causes water vapor molecules to move from the water droplet to the ice crystal, and depositing on the crystal causing it grow. In this way, since the ice crystals are in relatively less abundance than are water droplets, they grow at the expense of the massive amounts of water, and continue on the process as they shatter. Eventually, if the thermodynamic profiles favor it, the shattered ice crystals will attach themselves to another ice crystal, and fall to the earth as a snowflake. The snowflake will only reach the earth's surface if the entire temperature profile is below or right near freezing temperatures. In the next section, I will talk about the required conditions for snow crystal growth.

In order for snow crystals to grow most rapidly at the expense of the water droplets around them, certain temperatures are required. In the field of cloud physics, much research has been achieved on the required temperatures for the most rapid snow growth. In most research experiments, it was found that dendrites (the most efficient type of ice crystal) that grow from accretion and deposition grow in the areas of the cloud that are in between -10 and -18 degrees Celsius (14 degrees Fahrenheit to 0 degrees Fahrenheit). These dendrites have the shape of a prism with a hexagonal shape. This is not the only condition that needs to be met for the most efficient snow growth. Another condition includes a relative humidity that is near or over 100%, which will allow the ice crystals to maximize growth. It also helps the situation when strong upper level lift is located in the same thermal layer.

Dendrites are not the only way snow can form. Other types include rimed ice, platelets, and the traditional snowflake. Rimed ice crystals usually form when the precipitation layer has temperatures near or around -4 to -6 degrees Celsius. In this case, the ice crystals tend to be very wet, and allow for a better surface for water to "stick" to. These are the very wet, and large snowflakes that we occasionally see during the late winter and late fall months. Platelets are another type of snow crystal, which are usually very, very small. They tend to form during the coldest winter patterns (namely cold lake effect snow events), where cloud temperatures are below -25 degrees Celsius. They create the sight in the air that makes it look foggy. They are usually the snow crystals that blow very easily, and are the main reasons for visibility problems during winter storms. On the otherhand, the traditional snow flake usually forms in relatively warm cloud conditions; Colder than with rimed ice crystals, but warmer than dendritic snowflake conditions. They can easily become bigger, but water vapor does not stick to them as well. Normally, snow events dominated by these type of crystals do not usually bring much accumulation (but it is possible).

Next week, I will be writing an article about the myths in the Arctic, mainly about Arctic sea ice extent, actual observed temperatures, and winter/summer time weather.

Yet Another Impressive Storm System on the Horizon.

By now, most of you are probably tired of the extreme weather we have been experiencing so far this fall. From extremely high winds and heavy rain, to chilly, freezing nights. We've had days where it was nearly 80 and the next day, it was in the 40's.

Well.. I'm here to announce that yet again, another extreme weather pattern is coming. This one looks to be quite violent too. This time it will be quite different from what we've usually seen this fall. The new pattern involves a tropical cyclone, a large West Coast trough, and unusually warm conditions over the North Atlantic.

Now to explain what's going on. Over the weekend, the trough that brought the chilly weather Thursday and Friday has moved off to the East over Maritime Canada. In the wake of this trough, a major warm up will ensue. Upper level ridging will build into the area, resulting in temperatures approaching 80 by midweek, under mostly sunny skies. Thursday night and Friday, the western trough splits, sending a shortwave eastward, which will deepen rapidly, cause the development of a large surface storm, and send a cold front eastward, approaching the area. This cold front will slide through the area, with some post-frontal rain.. Mainly a few showers and possibly a thunderstorm. Friday looks fairly dry, but cooler, under mostly cloudy skies with highs in the upper 50's. This is where everything gets interesting.. Depending on the timing of a deepening upper level trough, an incredibly strong storm system will affect the East Coast. This storm will not be ordinary in anyway.. In fact, it will likely be a hybrid storm of sorts. The surface cyclone that will develop in response to the upper level trough will phase with a tropical cyclone that will be strengthening along the west coast of Florida. The strengthening trough will likely draw the storm northward. Here's the problem, at this time, nothing is set in stone of when this storm will likely hit the region. In fact, some of the models are having the storm stall out along the East Coast and move northwest towards Michigan! And some of them are bringing the storm out to sea after Sunday. Looking at the 12z GFS, it is expecting the entire storm to impact the region with some gusty winds, and possibly a rain/snow mix (but the latest runs are suggesting that it is moving towards a warmer solution).  The 12z CMC and ECMWF are both expecting a rapidly deepening storm (this is what the NWS expects), with very cold air wrapping around the southwest side of the storm (where we are going to be at), and they are both expecting the storm to make landfall on the East Coast and travel up the Great Lakes. Most likely, the storm should hit around the Sunday-Monday-Tuesday timeframe (I don't agree with the NWS's forecast of the storm impacting us Saturday night, that is way too early for this tropical system to develop).  If the ECMWF and CMC are correct, expect rather cold temperatures for Saturday-through at least Tuesday. Highs will likely only make it as high as the middle 40's. Another interesting thing that both models are forecasting is high winds. The ECMWF is forecasting wind speeds of over 60 mph! Again, you have to remember that this is a hybrid tropical/extratropical cyclone, so not only will it bring cold air, but also high winds.

The one interesting thing that I saw on the ECMWF model, and NWS forecast discussions, is the possibility of ACCUMULATING SNOWFALL from this system. In fact, some models are forecasting several inches of it. This is something that I will have to monitor, because it seems as if a wind-blown, heavy wet snow could be likely by next Sunday or Monday. Even though the air behind the system will be rather cold, it won't be cold enough to support snow during the day. The snow will likely occur during the night hours.

In any case, this could be a dangerous storm, not only for this area, but for most of the East Coast (due to the size of the storm, and its hurricane force wind speeds.) I will continue monitoring it throughout the week.

This model forecast clearly depicts a very strong storm system in the East.

Impressive Storm System Coming Together For Mid-Week

Currently, I am monitoring the development of a storm system on the computer models. This system looks rather impressive at this time, and I am expecting it to have a significant impact on the Northwest Ohio/Northeast Indiana/Southern Michigan weather... In fact, before its all said and done, we may see everything from heavy rain and high winds, to even some wet snow!

  

The Details

Right now, a strong jet streak is taking shape over the Eastern Pacific. By Tuesday and Wednesday, this jet streak will "roar" into the Western United States, causing a storm system to move on shore. At the same time, a weak trough will move southeastward out of Canada. The jet streak will deepen the trough rapidly. As the trough deepens, the storm system will begin to take shape at the surface, and deepening rapidly. What this means for us is strengthening winds again for Wednesday. While a pronounced warm up will affect the area, it will also bring high winds to the area. This system will be the factor that allows for extremes this week. For example, the storm system will cause temperatures to jump from the lower 50's today, to the low and middle 70's by Wednesday! And then, the strong cold front will cause temperatures to jump back to the lower 50's with a chilly rain for Thursday and Friday!

Rain will be likely Wednesday night as the cold front pushes through the area. Thursday, the jet streak will allow for the development of additional periods of rain across the area, causing a rather cool and wet day. By Friday, the core of the cold will move over the area, allowing temperatures to only hit near 50. Keep checking tomorrow for additional updates regarding his impressive storm system.

(For additional information regarding the storm system, I suggest visiting the NWS's website at National Weather Service and/or WLFI Weather Blogs. Also, try The Weather Channel's site for any other information)

After that, general model agreement suggests another pronounced warm up as the PNA (Pacific North American index, a way of measuring the jet stream patterns over the North and East Pacific) goes negative. This will lead to another crazy weather pattern, and if the ECMWF is correct, it could lead to another major storm system coming through. If the ECMWF is correct, it is suggesting that this will be on the leading edge of a major arctic wave, possibly bringing the first snowflakes of the season by the end of October and early November.

The NAM clearly depicts the incredible jet streak, which will be the main "perpetrator" in the development of this exciting storm system.

The jet streak then is forecasted to dive into the Midwest, causing the deepening of the storm system.

Ice crystal formation

Sooner than we would like it to be, winter is approaching quite quickly. We have already seen the first frosts and freezes. We have seen wild storm systems move through with heavy rain, high winds, severe weather, and basically any type of weather you can think of (except of course snow). Soon, it will begin to become much colder, and we will soon be thinking of the holidays, and of course snow. If you recall my winter forecast, I specifically stated that I expect this winter season to be much more exciting than last year... What this means is that I expect more storms, more snow, and more cold weather. This article and the next one will primarily be about cloud formation, the crystals that make up the ice crystals, and what causes them to form.
   Before a cloud can form, two primary conditions must be in place that influence the development of the cloud. The first condition is primarily "lift". When I say "lift", what I mean is the literal lifting of air vertically in the atmosphere. Due to the laws of thermodynamics, this body of air must cool. This leads to the second condition, which is moisture. Without moisture clouds cannot form. A body of air will always have a specific amount of moisture. As it moves up, this value changes little (except when it changes due to changes in pressure). When an air parcel cools as it is lifted, its temperature approaches its dew point temperature, the temperature at which condensation occurs. As the relative humidity approaches about 80%, water vapor begins to condense onto hygroscopic cloud nuclei. As the body of air is lifted further, and the relative humidity approaches 100%, and water vapor begins to condense onto even non-hygroscopic particles (for later reference, hygroscopic literally means "water attracting".) As the air is lifted further, the cloud builds upward, towards cooler and cooler air temperatures. Even though water freezes at 0 degrees Celsius, cloud droplets do not because there is no flat surface for to freeze to, therefore there are relatively little amounts of ice crystals around and just above the freezing level. As it progressively gets colder with height, more and more ice crystals are found. This can only be explained by the fact that not only do ice nuclei exist at these levels, but it is cold enough for some of the large droplets to attach to them. At this point, there is still an abundance of cloud droplets. At the -40 degrees Celsius level, that is the point at which water can directly freeze, in a process called deposition. No ice nuclei is needed, which allows water vapor to freeze directly with each other into crystalline shapes. Since this article deals directly with snow crystal formation, I will not talk about this much. This is because most winter storms do not have cloud temperatures below -40 degrees. So then, how do snow crystals form? Exactly as I stated in the first process; This is the one I will elaborate on.
   Ice nuclei are quite rare in our atmosphere compared with condensation nuclei. This can be explained by the fact that ice crystals need an exact crystalline structure to cause snowfall formation. There are very few particles that cause the freezing of water droplets in a crystal shape. Therefore, ice crystals have very little competition for available water. Once water begins to attach itself and freeze to the ice nuclei, vapor pressure around the ice nuclei decreases. Once the crystal forms a flattened, ice crystal structure, the differences in vapor pressure between the ice nuclei and cloud droplets (this means that if the air is saturated with respect to water, it is supersaturated with respect to ice) cause water vapor to "gather" near the ice nuclei (due to the freezing cold temperatures, water tends to congregate in certain areas), and attach themselves to it, also known as the process of deposition. Once several ice crystals have formed on ice nuclei, this sets up the conditions for the formation of new ice crystals. Ice crystals are quite a bit heavier than cloud droplets, and so they fall. Different fall speeds between ice crystals and cloud droplets (and other ice crystals) cause collisions, which shatter the original ice crystal. This sets up an opportunity for new ice crystals to grow, because water droplets will now attach themselves to the shattered fragments. These shattered fragments begin to grow at the expense of the water around them. This process describes how precipitation forms in cold core clouds (temperatures below freezing in the cloud), not just snow. Snowfall requires very precise conditions for formation. At this.. I will leave snowfall formation for the next article. One thing I can tell you though, is that there is a persistent myth about snow in society today. This myth is that snow can only fall when it is below freezing outside.. That is NOT true. And I will explain this in the next article. The next article will focus on winter storm precipitation processes, and how precise conditions have to be for snowfall.

Large Scale Pattern Change Possible.

This won't be as long as most long-range posts, so I'll make it quick and simple. Over the past few days, NCEP ensembles have continuously forecasted that a large scale pattern change is underway. Ongoing research suggests that Ensembles (a group of several model permutations that are either averaged for a mean value or to show the differences between the possible solutions, in which the permutation in the model forecast could be a change in the physical schemes, dynamical schemes, grid spacing, etc...) are notoriously better at forecasting long-range patterns than the actual operational models themselves. The ensembles that the National Centers for Environmental Prediction is using is forecasting a drastic and extreme change in the teleconnections. Usually, during a medium to long-range period, models forecast one or two of the "important" teleconnections (which include the AO, NAO, and PNA; Arctic Oscillation, North Atlantic Oscillation, and the Pacific North American index, respectively) to go negative or positive. This time, each variable will be correlating with each other, which has very serious implications for the latter half of October and beginning of November. They are forecasting the AO to go strongly negative, the NAO to go strongly negative, and the PNA to go strongly positive in the long-range period, which is a very good indicator that it is going to be very cold for the end of October and beginning of November. It also indicates that a very strong storm system may be in the making for medium range period, especially after the 20th of October. I will continue to monitor the situation, but as I have already stated, the ensembles have been very, very consistent on this issue.

For those who don't want a technical outlook, here's the main thing. By the end of October and early November, expect a very cold air mass to move into the region, quite possibly bringing the chance for our first snowflakes, and likely on the tail end of a monstrous storm system.

Light blue represents below normal temperatures and dark blue represents much below normal temperatures. This will likely take place anywhere in the timeframe from October 23-November 3.

Different Weather Pattern

Over the past several days, models have continued to indicate the arrival of a very cool air mass into the United States. For this to occur, several things must happen first. For one thing, the large upper level low over the lower Mississippi Valley and Deep South will be "kicked" out of the United States by a large upper level wave moving southward out of Canada and into the Northern Rockies. This upper level wave will deepen and cause the formation of a surface low pressure system along a developing strong baroclinic zone (temperature changing over a given distance or a temperature gradient). This low pressure system will move in a hook shape, first moving southeast into South Dakota, and then making a sharp turn to the northeast and moving into Minnesota and Canada. At the current time, models are forecasting that the air will be cool enough to cause a significant snowfall over Northern Minnesota and North Dakota. But that is another story. As for here, I expect that the storm system will drag a cold front through the area by Thursday night.. Ahead of the strong cold front, temperatures will warm into the upper 70's for Thursday afternoon. At the same time, it could get fairly breezy. Thursday night, the cold front will be strong enough to generate a few showers and possibly a thunderstorm with the available moisture. As the cold front passes, temperatures will drop rapidly and then remain steady in the lower 50's.. On Friday, lingering cloud cover and lake effect rain showers will keep temperatures below 60. For the weekend, a secondary cold front will move through the region, reinforcing the initial shot of cold air, and causing temperatures to drop again. This will cause another lake response, causing widespread cloud cover for Saturday and possibly Sunday. This will limit highs to the lower and middle 50's! In fact, conditions may be just cloudy and breezy enough to limit highs below 50, making for quite a chilly weekend. Both Saturday and Sunday night look to bring a high potential frost. In fact, if the wind is light enough and cloud cover is limited during the night, we could be seeing the first FREEZES of the season. This will be quite early for this area, and if realized could be one of the earliest in many years. In any case, I expect a widespread frost both Saturday and Sunday nights, and possibly Monday night.

After the weekend, model solutions diverge, with some models holding the cold air mass across the region, and some moving it away rather quickly. This will all depend on the transition of the longwave pattern. At this time, I would lean more towards the models that hold the cold air mass in the region, due to the strength of the blocking ridge of high pressure in the Gulf of Alaska. Time will tell, but the next several weeks look to be rather cool across the area.

Map of forecasted temperature anomalies.. As you can see, there is a large area of below normal temperatures across the Midwest and Great Lakes regions.

Some Interesting Implications...

After doing some more research.. There hasn't been much correlation between this year's ENSO phase and other years. I've been looking for years that correlated well with an ENSO neutral event after a "double dip" La Nina. So far, 1977-1978, and 2009-2010 come up.. There haven't been any other "double dippers" (I have not included the years from 1998-2001 because that wasn't really a double dip La Nina, more of a continuous one that got us going in the so far downward trend in the PDO) than these.. And I want to opt out and not include 2009-2010 because of the strength of the El Nino (at this point it isn't likely we see a strong El Nino). In fact, most of the atmospheric signals indicate that this El Nino won't even survive for the beginning of the winter.  An ENSO neutral winter occurring after a double dip La Nina has not occurred in the history of record keeping of the ENSO phase. At this point, if weather patterns were to be followed, then I would predict a moderate or strong El Nino by winter. If I were to follow other signals, then an neutral ENSO winter would be more likely. I have made a map that shows the average temperature anomaly of all the ENSO neutral winters that are on record.

This clearly indicates that most ENSO neutral winters featured below normal temperatures, especially across the Northern Plains.

At this point, I really don't want to say what this winter will bring. With its unique weather patterns and variables, I cannot accurately use analogues to predict the winter temperature, snowfall, or precipitation. At this point, I'm going to lean on the side of caution. Quite a bit of data would suggest that a colder than normal winter is coming for the U.S. Some data would suggest that we will receive a warmer winter. In the history records, there have been two years that came out of a true double dip La Nina into an ENSO neutral or weak El Nino year, and one year that came out of an elongated La Nina. The two years that became a weak El Nino after the "double dip" La Nina were extremely cold years. The year that became a weak La Nina winter after the elongated La Nina, featured warmer temperatures across the East and cooler conditions in the West. At this point, the weather patterns are most similar to that of the first set of years, which occurred after a "double dip" La Nina. This would indicate that this upcoming winter could feature the same. More data will have to come up to prove this, but it is a very possible scenario. The only reason that I won't confidently project the idea of a very cold winter is because of what happened last year. For a few weeks I will wait and see what will happen.

For some entertainment, here is a map providing the average temperature anomaly across the United States from the winters of 1977-1978 and 1976-1977..

Temperatures during those two winters averaged nearly 10 degrees below normal.. According to archives and other records, the two winters featured extreme arctic cold, and several notable blizzards and snowstorms.

Longer Range Forecast...

Some interesting developments have occurred in the longer range forecasts of the ECMWF and GFS. One of the main things that I look for in the models longer range forecast hours is the general upper level flow patterns. In the 240 hour timeframe, the ECMWF is forecasting the development of a large upper level trough as the ridge in the Gulf of Alaska restrengthens (suggesting to me that the Polar vortex will remain weaker through the long-range). This upper level trough will show up as a slightly negative PNA teleconnection in the forecasts. With this kind of a jet stream configuration, strong southwesterly flow in the upper atmosphere is likely over our area. This is a pattern favorable for storm systems to transverse the Midwest and Central Plains. In the longer-range, I would anticipate near normal precipitation, due to the fact that most of these storm systems will be diverted to the north and west of the area. So far, this is an atmospheric set up very similar to the fall of 2010. The rather warm fall of 2010 eventually gave way to the very stormy and cold winter of 2010-2011. One forecast doesn't mean anything, but if this is consistent, I would bet on seeing a winter across the United States that will be very similar to the winters of 2009-2010 and 2010-2011. In the meantime, what it means for us is that we will likely continue with a warmer than normal, with a possible slight re-strengthening of the current moderate drought conditions.

El Nino and Tomorrow's Forecast

To begin today's forecast and outlook, I will begin with another update regarding the long range forecast. The El Nino has severely weakened over the past few days and weeks. Now, while I do refer to this event as an El Nino, it is not officially an El Nino. To be considered a true ENSO event, the Sea surface temperatures relative to normal (on either side of the spectrum) across the Equatorial Pacific need to be at least 0.5 for an El Nino and -0.5 for La Nina. This condition needs to be true for at least three months. In this year's case, neither has happened. SST anomalies have not been consistently above 0.5 degrees Celsius, and they have not persisted for three months. In fact, in the latest analysis of the El Nino, most of the remaining warmer waters have faded and shifted westward, causing an extreme weakening of the El Nino. This could be really good news for anybody who loves a good winter in our area. Using climateology, "neutral" winters  usually give us the best chance for heavy snowfall events across the area. Hopefully, this is true, as last year was too warm to support any "real" snowstorms.
    
For tomorrow's forecast, I expect clouds to build into the region ahead of a shortwave. I expect a few showers and even a thunderstorm in the afternoon hours. Yet another small "storm system" will move south out of Canada, sideswipe the area with some rain on Wednesday. A short period of cooler temperatures will come to the area after the passage of the cold front, with highs dropping into the middle 60's on Thursday. For most of the week, I expect temperatures to remain right near 70. By the beginning of next week, signs are pointing to cooler weather across the United States, and a stormier pattern looks to resume across the Northern Plains.

First Preliminary Winter Outlook

This is my first winter outlook for the area, and other regions close to us. Most of the year's featured, a near neutral ENSO (discounting 2008, which had a weak La Nina), a negative PDO (discounting 1993-1994), and had teleconnection patterns that matched with this years.. I could not find a single year that even came close to matching with this year's teleconnections. In the past fifty years, there hasn't been a single instance where the NAO and AO fluctuated as much as it has. This is telling me that something is up with the observed wind patterns over the North Atlantic. For the teleconnections, the closest fits were 2008-2009, 1993-1994, and 1977-1978. As for precipitation patterns, the best fits were 2006-2007, 2008-2009, and 1977-1978.. I don't want to sound like I'm "wishcasting" (that's what happened last year), so I'll give you my first thoughts. These years were also checked for correlations in the AO and NAO, and there were only two years that corresponded, and those were 1993-1994 and 1977-1978. Some of you who are older, probably remember the winters of 93'-94' and 77'-78'. During the winter of '77-'78, the area saw temperatures about 10 degrees Fahrenheit below the normal average temperature. In the winter of 1993-1994, we saw temperatures about 4-6 degrees below average, mainly in the month of January. This may have biased my winter forecast, so don't expect it to be as cold as those years.

I'll start with storminess and precipitation. In actuality, this could go either way this year. In my personal opinion though, I believe that El Nino will be non-existent by the time December comes around. If this occurs, then I expect precipitation to be above normal in the Ohio Valley, all the way into the Eastern United States. Any place south of Indiana or west of Indiana will likely see below normal precipitation. The jet stream will likely be directed across the southern and central United States this year. The biggest storms will occur when the NAO dips to negative values, and the PNA also goes negative, forcing a large trough into the Midwest. For right now, I'm going to go out on a limb, and state that snowfall may be slightly above normal for the winter season.

I don't believe we will see another split flow jet stream, which will allow for a stronger jet stream, more dynamic storm systems, and colder weather for areas north of the jet stream. From Southern California into the Southeast, I expect above normal precipitation for the first part of the winter season, but near normal precipitation for the rest of the winter. In the east, coastal storms will be frequent so precipitation should be well above average. As for temperatures, the analogue years are nearly "black and white", meaning that some of the analogue years clearly show above normal temperatures across the Ohio Valley, Northeast, Upper Midwest, and other parts of the Northern United States, while the other half of the analogues show below normal temperatures across the Northern United States. When they were averaged, most of the United States should end up cooler than normal east of the Rockies. West of the Rockies, due to the strength of the western ridge, I expect above normal temperatures. In other words, there is a very good chance that we end up with below normal temperatures for the winter, but I will keep the original forecast at equal chances for above or below normal temperatures.