Forecast through early next Week.

After all that rain we had yesterday, amounting to over an inch in most areas, clearing skies, light winds, and a nearly saturated lower level of the atmosphere, will allow for the development of fog, mainly in areas west of Fort Wayne, where skies have cleared longer and the wind is lighter.  I don't expect much fog around here this morning, except for a few patchy areas, and where it does form, it will be lighter, and not dense.  So far skies have cleared pretty nicely, as that wet rainstorm has marched off to the east, and intensified.  In fact, a rather large area of heavy snow has developed over most of Vermont, New York, New Hampshire, and Maine.  Some parts of these areas will pick up close to 10-15 inches of snow, while areas farther south will see 2 to 4 inches of rain, with embedded thunderstorms.  During the day today, expect temperatures to be warmer than yesterday, with highs in most areas reaching the lower 50's, under sunny skies.  After the storm system moves offshore, a ridge is forecasted to build into the area tonight, allowing for the continuation of clear skies and warm temperatures reflecting September and not November.  Tonight, more humid air will build into the region, along with the ridge bringing westerly winds aloft and clear skies, will allow for the formation of possibly dense fog tomorrow morning.  So beware, for those of you who travel on Thanksgiving Day, as tomorrow's fog will probably be widespread.  On Thanksgiving Day itself, temperatures will rise from the upper 30's in the morning hours to the mid fifties, making a very unseasonably warm day.  Light winds will continue on Thanksgiving, as the ridge moves quickly to the east, bringing southerly winds aloft.  This will allow for even warmer air to move into the region, and by Black Friday, temperatures could even hit the lower 60's.  At this point, I'm not actually sure if this will happen, because the sun is not strong enough to cause temperatures to rise into the lower 60's this time of year.  Second of all, if their is fog again Friday morning, I would not expect much warming until afternoon, allowing for temperatures to only hit the mid fifties.  By late afternoon and evening, increasing clouds will prevail, which will mean temperatures will not drop as much as they are forecasted to the night before.  By Saturday, I believe temperatures will hit the mid fifties, because the cloud cover will likely reduce any daytime heating.  Saturday afternoon, we could see some showers, but they will mainly be confined to areas west of Indiana.  By Saturday Night, showers and thunderstorms will be likely once again, possibly renewing the threat for heavy rainfall.  On Sunday, temperatures will fall into the mid 40's, as the low pressure system will move eastward, causing temperatures to fall and a decrease in rain chances.  By Monday, a secondary low pressure system forms and moves northward over the area, renewing rain chances but also drawing in cold air, as a large cut off low forms.  This will bring the chance for snow into the forecast.  In fact, a major winter storm is possible by next week around here, but because computer models can't seem to agree, I will refrain from making any forecasts on it until the models have come to a consensus.  After that, well, the computer models went haywire with the teleconnections that were supposed to go negative, so I really have no clue whether the cold weather will hit in December.  The GFS ensembles are still forecasting the NAO and the AO to take a nosedive into negative territory, finally allowing for cold air to dive into the United States.  Even if this doesn't happen, I still expect winter to be a mild one, mainly because all of that cold air is building up in Canada, and because of how much the polar ice caps are melting, they are allowing for warmer air to be trapped up north,  reinforcing the Greenland block, which is why I expect it to show up this winter for periods of time.  If the block doesn't show up until January, then expect even colder temperatures than originally forecast.  By February, I still expect this month to be our worst month in terms of cold and snow.  Stay tuned for further updates.

Forecast Update

Monday Night: Low 37. Skies mostly cloudy to overcast, as storm system begins to move northward.  Rain chances increase through the overnight hours.  Steady rain develops north of the warm front.  Winds increase from the east and northeast as pressure gradient tightens.
Tuesday: High 47. Skies overcast, as storm system moves northeastward.  Steady rain ahead of the warm front moves across the area, with some pockets of heavier rain by afternoon.  Thunderstorms are possible especially by early evening.  Rainfall amounts between a half inch and one and a half inches, with some areas especially in areas south of a line from Fort Wayne to Defiance will see up to two inches in the heavier thunderstorms.  Winds increasing from the east.
Tuesday Night: Low 38. Skies overcast throughout the night. Rain and thunderstorms continuing through midnight, becoming more scattered and lighter by the early morning hours.  Rainfall amounts about a half inch.  Winds diminishing in the overnight hours.
Wednesday: High 51. Partly cloudy to mostly sunny. Ridge rapidly building in to the area, bringing warm air aloft, and sunny skies.  Temperatures rise slowly after chilly morning.
Wednesday Night: Low 33.  Partly cloudy during the overnight hours, clearing by early morning. Chilly night, as ridge builds into the area bringing clear skies, light winds, and dry air to allow for rapid cooling during the night.
Thanksgiving Day: High 55. Mostly sunny and warm.  Ridge quickly moving eastward, causing a westerly flow to bring even warmer temperatures to the area.  Storm system begins to develop in the west, in the southern Rockies.
Thursday Night: Low 39.  A more humid air mass moves into the region, as ridge is still moving eastward, changing the westerly flow aloft to a southerly flow.  Clouds begin to move back in.  Partly cloudy.  Storm system still developing over Southern Rockies.
Black Friday: High 59. Partly cloudy early becoming mostly cloudy by late afternoon. Windy and blustery day.  Very warm with even more humid air mass moving in.  Major trough pushes storm system from the Southern Rockies through central Mississippi Valley, causing increasing pressure gradient and gusty winds.
Friday Night: Low 40. Mostly cloudy to overcast.  Rain moving in the early morning hours after 3 a.m. Wind increases ahead of the next storm system.
Saturday: High 55. Overcast with rain and thunderstorms by afternoon.  Wind begins to subside.  Heavy rainfall is possible.
Sunday: High 51. Overcast with rain and possibly a thunderstorm.  Rapidly dropping temperatures by late evening, by as much as 40-45 degrees.
Monday through Friday of next week: AO and NAO finally go negative, allowing that major trough to develop into a rather large upper level low, sparking storm systems periodically through the last week of November and the first few days of December.  During this time period, we could see some snowfall, on the amount of 1 or 2 inches, especially in early December.  This upper level low will pull some very cold air into the area, with some days not even making it above freezing.  Snow is a very good possibility during this time. 

Late November through December Long range forecast.

 Some of you may be wondering, "What in the world is going on?".  Well, I've got to tell you, I'm wondering the same thing.  Over the past 20 days, most days have seen above normal temperatures.  Truth be told, we have seen some pretty chilly days in between these warm periods.  Even this week, most computer models are forecasting a major ridge to form over a large portion of North America for the holidays.  This would cause a relatively warm and humid air mass to surge northward into a large chunk of the United States.  Along with this warm air mass, sunny conditions will prevail for Thursday and possibly Friday.  As the polar jet stream is very strong this year, the ridge will shoved out just as fast as it came in.  By Friday Night, clouds will be on the increase, ahead of the next strong storm system.  This storm system will develop quite rapidly, as a major trough develops in the Plains and surges eastward.  According to the GFS model, heavy rain and quite possibly thunderstorms will likely develop by Saturday and into Sunday.  During these days, temperatures will rise into the mid fifties, much above normal levels.  The storm system won't stop there.  After the surface system leaves, a rather large upper level low will develop and remain for several days, bringing colder air and possibly areas of snow, bringing the first accumulating snow of the season to many areas.  After this it is unclear what will happen, but the GFS is forecasting that the AO will plummet to negative values for the first time in several weeks.  This may cause a major trough to form for the first and second weeks of December, bringing widespread snow and cold to much of the Central Plains and East.  With all of that cold air in Canada, I'm sure it will spill southward into the US.  This would make the weather pattern eerily similar to last year.  In fact, according to the latest run of the GFS model, towards the beginning of December, that upper level low mentioned earlier, will likely cause multiple storm systems to form and swing around it, also drawing in very cold arctic air to start the season off.  With low upper level height anomalies, combined with surface cold air, and plenty of moisture to work with, I'm sure that we will see quite a bit snow for the first two weeks of December.  As for the rest of December, if the AO and NAO remain negative, and the PNA remaining positive, expect cold temperatures and frequent bouts of snow to continue even through Christmas.  Unfortunately, I don't believe any major storms will likely form this period, as most of the storms will traipse up the East Coast.  I will keep you updated as December gets underway.
   There is one thing I do want to touch up on is dealing with the current La Nina.  The values I want to speak about are the SOI values, Southern Oscillation Index.  The Southern Oscillation Index is determined by taking the difference of sea level pressure readings from Tahiti and Darwin, Australia.  If this difference (Tahiti-Darwin) is negative, usually this correlates to either an El Nino or weak La Nina.  If this difference is positive, usually this means that either a weakening El Nino exists or a rather established La Nina event is underway.  If values are either very high or extremely negative, this indicates a solid ENSO event is underway.  Today, the Climate Prediction Center released their weekly analysis of the ENSO.  They found that SOI values are only about 10.1, which is pretty modest for an expected strengthening La Nina.  Some meteorologists are pointing out that they may need to revise their winter forecast, due to the SOI values being much lower than last year's.  I really don't agree with this, mainly because first of all every ENSO event is different so SOI values will range differently.  Second of all, generally second year La Nina's are usually weaker than the previous La Nina, with generally weaker SOI values.  Also, during east and central La Nina events, SOI values will be weaker than normal because of the fact that the most dominant weather influence will be located farther east.  When I look at how strong a La Nina is, my first index will not be SOI values.  I will first look at sea surface temperature anomalies across the equatorial Pacific.  Currently, anomalies are between one and three degrees Celsius below normal, indicating a moderate La Nina is already underway.  The second factor I look at is 850 millbar and 200 millibar wind anomalies.  If the 850 millibar mean wind over the equatorial Pacific is stronger than normal from the east, this means the trade winds are stronger than normal, indicative of a persistent La Nina farther east.  Right now, 850 millibar winds are stronger than normal from the east over the Equator.  If 200 millibar winds are stronger than normal from the west, this is also indicative of a La Nina because higher pressure aloft is located over Indonesia during a La Nina, and lower pressure aloft is located over the equatorial Pacific, meaning the winds will blow strongly from Indonesia to Peru.  This is what I have been observing over the Pacific Ocean.  I believe with these factors in play, plus a favorable MJO (I will explain MJO in another blog post.) in December, has lead me to believe in the strengthening in the La Nina and SOI values during the month of December and peaking in February and March going along with the CFSv2 computer model's forecast.  Other things such as NAO, AO, and PNA, have made me shaky with this winter's pattern, as they have not been consistent with many forecasts in the month of November.  We will have to see if the GFS and ECMWF are right in their forecast for a change to a negative NAO/AO along with a positive PNA.  If these factors do not turn as they are forecasted, expect a winter that is not as cold as was originally expected, with most of the cold air bottled up over Alaska, Canada and the Northern United States.  The good thing is that if these factors do not come into play, if it is not as cold this winter, expect heavier precipitation, and a greater chance for a very stormy and snowy winter, just like the Farmer's almanac says.  According to extremely long range forecasts, this may be our last hurrah winter, as next winter there is expected to be an El Nino in the Pacific, making it very unfavorable for snow around here.  In fact, next winter, we may say a return in Nor'easters and East Coast snowstorms, while the Midwest and Northern Plains is snow starved.  With the forecast through December 2011, I will keep you updated if something changes.  Other than that, this is the official forecast.  Stay tuned.

Forecast Update

According to the latest 06z GFS run, a rather large area of Northwest Ohio and Northeast Indiana may see as much as 1.5-2 inches of rain from the storm on Tuesday.  Depending on where the heaviest band of rain sets up, this forecast may verify.  But the last several runs of the GFS model have shown the storm trending slightly southward, bringing the heaviest rain south of a line from Auburn to Toledo.  If the models continue trending south, I will drop this line to Fort Wayne to Toledo.  Another than that, it looks like skies will be clearing out Wednesday, with partly cloudy skies by afternoon.  Temperatures will be rather cool as the front moves through the area, with highs only expected to hit the low 40's and possibly upper 30's, if the cold front is strong enough.  By Thanksgiving Day, an upper level ridge is expected to build into the area, bringing above normal temperatures once again in the lower 50's to lower 60's.  Skies will also range from partly to mostly sunny.  By Friday, the ridge will have moved so that southerly flow develops aloft helping to warm surface temperatures.  If the warming is strong enough, I expect that temperatures will reach into the lower 60's, with increasing clouds throughout the day.  By Saturday, a major trough will develop in the plains, bringing stormy conditions back to the area.  According to the GFS, heavy rain and thunderstorms appears likely Saturday into Sunday.  THIS has remained consistent for the past several runs, which makes me think there might be a major storm system this weekend.  At the end of the storm, there looks to be snow developing, with colder surface and upper air temperatures.  This snow could turn heavy enough for our first accumulating snow of the year.  The greatest snowfall accumulations will occur north of a line from Fort Wayne to Toledo.  But remember this is a week from now, so this all may change by then.  After this I expect several major troughs to develop across the Midwest, bringing widespread cold and snowy conditions with each shortwave that moves around the base of these troughs.  Hopefully, by later this afternoon, I will release my long-range forecast update for December, as things look pretty interesting for next month.  Stay tuned for further updates.