Official Forecast through Wednesday Night.

As most of you have probably noticed, today was not as nice of day as I was originally forecasted.  I believe the cloud cover hung on a longer than it should have, mainly because of the fact that the low pressure system was a lot slower than anticipated and caused warm air advection in the mid levels of the atmosphere, allowing the low clouds to hang on for a much longer time.  For now, I can assure you, the clouds will be gone for the rest of the afternoon, except for a few areas east and south of Defiance, who will still see persistent cloud cover, probably through 5 or 6 p.m. at least.  As for most of us, especially west of Defiance, expect clearing skies, gusty winds, and chilly temperatures through the evening hours.  In areas west of central Indiana, temperatures have warmed considerably, so expect much nicer conditions farther west.  After the early evening hours, the winds should slacken quite a bit.  This combined with clear skies, and a cold air mass, I would expect temperatures in most areas to drop to about 30-33 area wide, except for areas close to Lake Michigan, as strong winds blowing off Lake Michigan will cause warming overnight.  For this reason, the National Weather Service has issued a frost advisory, for extreme western Ohio (Paulding, Defiance, Williams, and Van Wert), and for most of the counties in central and eastern Indiana.  The coldest temperatures will be found in extreme eastern Indiana and extreme western Ohio, where highs did not make as high as they were supposed to, and where the clouds have begun to clear up.   Some areas may even see temperatures below freezing, which could really kill some plants.  So remember to take any frost-sensitive plants indoors tonight.  Even with an exceptionally chilly morning, tomorrow, the day will warm nicely with highs in the low to mid 60's.  As the large high pressure system shifts eastward slowly, expect temperatures to warm throughout the week.  The upper level air flow will cause a rather large and intense ridge to reside over our area for several days, especially after Wednesday.  With clear skies, light winds, and warm air aloft, expect temperatures to climb into the upper 70's and lower 80's at the peak of the warmth. 
 
Saturday Night: Low 31-33. Areas farther west 32-36.  Mostly clear. Large area of high pressure to shift eastward slowly.  North winds at 5 mph. Frost likely.  Some areas, especially areas that are more isolated, expect temperatures 28-30.
Sunday: High 62.  Mostly sunny.  Light winds from the north.  A very comfortable and nice day.  Chance of rain 0%.
Sunday Night: Low 41. Mostly sunny. Winds light and from the North-Northeast.  Chance of rain 0%.
Monday: High 68.  Partly Cloudy. Winds light and variable. Surface high pressure system on top of our area. Chance of rain 0%.
Tuesday: High 73. Partly cloudy for the most of the day, thicker and higher clouds moving in from the upper level low over the east coast.  Winds from the west at 10 mph. Very comfortable, warm day to be outside.
Tuesday Night: Low 52.  Partly cloudy in the evening, with clouds clearing up as upper level low moves off the east coast.  Chance of rain 10%.
Wednesday: High 77. Mostly sunny, with a few clouds from time to time. Upper level ridge beginning to move over the area, allowing much warmer temperatures.  Chance of rain 0%.
Wednesday Night: Low 53. Mostly clear, with surface high pressure causing warm southerly winds.  Upper level ridge continues to move eastward, causing warmer temperatures to move in. Chance of rain 0%.

Forecast Analysis

Right now, mostly cloudy to overcast conditions prevail across Northwest Ohio.  In Northeast Indiana, skies are beginning to clear up, especially west of Fort Wayne.  The surface low pressure system has weakened from 992 millibars this morning, to about 1000 millibars by this afternoon.  Currently, the system is located over western New York and moving eastward slowly, as the upper level air flow becomes locked in place, as another upper level cut-off low comes into play.  This upper level low should not affect our area much except for the fact that it is pulling very cold air into the eastern United States.  As this surface low moves eastward, expect mostly cloudy conditions through 8 or 9 p.m. tonight, with partly cloudy to clear skies after 10 p.m.  With this earlier than anticipated clear up of clouds, expect even lower temperatures than was originally forecast for lows tonight.  I would say that lows will drop to around 36 or 35, especially in areas that are already clearing up right now.  Generally, because of lake-effect rain showers overnight, I would expect the best chance for a frost tonight is areas Fort Wayne and east.  Tomorrow, temperatures will rise pretty slowly throughout the day, with highs only expected to hit the lower to middle 50's, fairly close to today's high temperature.  Even with the chilly temperatures, expect a very nice day tomorrow with partly cloudy to mostly sunny skies.  Overnight, Saturday, due to strong radiational cooling, clear skies, a cold air mass and light winds, expect temperatures to fall to near freezing.  The current MOS computer models are forecast lows from 29 to 34.  Due to wet ground from recent heavy rains, I am going to expect lows right near 33 or 34, but in areas that did not experience as much rain, and in areas east of Defiance, I would expect lows to dip near 30 or 29.  Which ever forecast holds true, I would bring in any plants that could suffer from the cold, because this could be our first hard frost of the year, with even a freeze in a few places.  I do expect the National Weather Service to issue a frost advisory or warning for the area by tomorrow afternoon, as their is a high potential for frost.  Over the weekend, the upper level air flow pattern is expected to shift.  Sunday, their will be a major cut-off low over the East Coast, while around here, a ridge will try and advect eastward from the Central United States.  By Monday, this upper level low will finally begin to break down, allowing the slow eastward progression of the ridge over the plains.  By the middle of next week, the ridge will be right on top of us, causing above normal temperatures and very sunny conditions.  Temperatures could even top 80, especially by the end of next week.  This pattern will not last though, as a major trough begins to dig into the plains, which will cause some storm systems to form and traverse the area.

Official Forecast Through Tuesday, October 4, 2011

Friday Night: Low 35. Colder in regions with less evening cloud cover  Mostly cloudy in the early evening, becoming clear after 9 p.m. Windy at first, becoming calm later in the evening.  Frost possible, especially in the early morning hours.
Saturday: High 54.  Mostly sunny.  Much drier than in recent days.  Very nice day, but chilly at the same time.
Saturday Night: Low 33.  Mostly clear.  Light winds and clear skies, make for a great night for the formation of frost.  Some areas, especially east and north of here, could hit temperatures below 30.
Sunday: High 61.  Mostly sunny.  Light winds from the north.  A very comfortable and nice day.  Chance of rain 0%.
Sunday Night: Low 42. Mostly sunny. Winds light and from the North-Northeast.  Chance of rain 0%.
Monday: High 68.  Partly Cloudy. Winds light and variable.
Tuesday: High 73. Partly cloudy.  Winds light and variable. Very comfortable and one of the warmest days in several weeks.

Forecast Update and Analysis.

surface pressure map

Currently, a very large band of rain is barreling down on Northeast Indiana and Northwest Ohio.  This band of rain is producing generally light to moderate, with pockets of some heavier rain.  Generally, expect little or no severe weather in the area, mainly because the initial conditions that were supportive of severe thunderstorms have moved out of the area.  Any thunderstorms that do become severe, will probably become severe east of Defiance.  East of Defiance, many areas have a pretty good chance of getting of hit by severe thunderstorms, unless other factors come into play.  The instability that was originally forecast to be over the area, never came about.  This is probably because dew points are a lot lower than I was expecting this morning.  So expect widespread rain and embedded thunderstorms for the next several hours, before the rain clears up for the most part at least for a few hours.  The forecast is calling for conditions to be overcast for the first part of the night tonight and then gradually become mostly cloudy by the early morning hours before the next round of showers arrive.  Here is the synopsis: the low pressure system currently over the U.P. of Michigan will slide southeastward as it intensifies.  The intensification process will be aided by the rapidly falling 500 millibar height falls, a strengthening of the troughs and upper level lows in each mandatory pressure level, and a very cold Canadian air mass.  It currently has a surface pressure of 996 mb, and it is forecast to deepen to low pressure of 992 millibars before its gradual weakening trend kicks.  At its lowest surface air pressure reading, the center of the surface system will be located over central Michigan.  By Friday afternoon, this low pressure system will begin to move into New York state and towards the east coast, where by that time it will have weakened to a 998 millibar low, which is still pretty intense.  With the tight pressure gradient expected with this system, I believe that we could sustained winds of 25-30 mph early Friday morning and wind gusts of 35-40 mph possible.  In areas close to Lake Michigan, expect sustained winds of 30-40 mph, and wind gusts to 60 mph.  This, combined with high temperatures in the lower 50's, showery, cloudy conditions, will make for a very uncomfortable day on Friday.  Friday Night, expects to clear up especially after midnight, which allows the possibility of frost, as temperatures are expected to drop into the mid and upper 30's, especially in areas that are east of Fort Wayne.  Saturday, expect sunny conditions, along with light winds, but with temperatures in the lower 50's also.  By Saturday Night, we will have our greatest potential for frost, as temperatures are expected to fall into the lower to mid 30's, and along with light winds and clear skies, temperatures may even drop to near freezing.  On Sunday through Wednesday, expect a significant warming trend, as large upper level ridge moves over the area.  On Sunday and Monday expect temperatures in the lower to middle 60's, while Tuesday hits the low to mid 70's, while even further yet, Wednesday we could see highs in the upper 70's. (Yes!)

Update

Today, its looking like we may see some severe weather from the cold front moving through.  According to computer models, there may be enough instability and shear to cause a line of severe thunderstorms.  These thunderstorms will not only be capable of producing damaging winds but also some hail too.  There also may be enough shear to cause some thunderstorms to produce isolated tornadoes, especially in Northwest Ohio.  After this line of potentially damaging thunderstorms moves through in the late afternoon hours.
According to computer models, it could get very windy around here tonight and tomorrow, with wind gusts in the 35 to 45 mph range.  Sustained winds will likely be around 25 to 30 mph, especially in the overnight hours.  This 992 millibar low over central Michigan will begin to lift Friday into Canada, leaving nice, chilly conditions for Saturday, along with light winds and clear skies.  This could lead to us to frost both Friday and Saturday Night.

Thunderstorms: Life cycle, development, and structure.

Generally, when you think of thunderstorms, you think of spring and early summer. You're probably wondering why I'm talking about thunderstorms in the fall. I mainly want to communicate to you how you can tell whether thunderstorms will form or not without the aid of forecasters or forecasting experience. This I want to explain because next spring, long-range forecasters are predicting a violent severe weather season for the Ohio Valley and the Lower Great Lakes region. They are expecting an even greater threat for severe weather around here than last year, with the possibility of a very strong EF-3 or EF-4 arriving in the Northern Indiana forecast area by mid-April, which could create some major problems for this area. I want to people to prepare for next spring, as all the signs look just right for a damaging severe weather season in the United States.

First I want to talk about the life cycle of a typical thunderstorm (air-mass variety), as compared to a severe thunderstorm's life-cycle. Back in the 1940's, there was a study done to show the life-cycle of a typical thunderstorm, so that meteorologists could make better forecasts on thunderstorm development and to help save lives. The first part of the cycle that they found was the convective stage or cumulus stage. During this stage, superheated air from the surface rises and cools to saturation, forming a cumulus cloud. This updraft continues to build and causes the cumulus cloud to build, as long as the temperature of the updraft is warmer than surrounding air (instability). Soon the cumulus cloud becomes large enough that it is called a cumulus congestus, which in Latin means “large heap”. As you can tell, these cumulus clouds are very large and are nearly as large as a cumulonimbus cloud. At the cumulus congestus stage, light rain may fall, but it is very rare. Usually, a cumulus congestus cloud has a very dark base, giving it an ominous look. In the second stage of the cycle, the updraft strengthens causing the cloud to build to heights of 40,000 feet or greater. In this stage, the cloud can be properly called a cumulonimbus cloud. Soon the large cloud begins to produce heavy downpours, lightning, and if conditions are right, high winds, large hail, and tornadoes. The heavy rain falling out of the cloud causes a weak downdraft to form, strengthening as the rain becomes heavier. This downdraft descends out of the base of the cloud, and if it is strong enough, it will lift warm, humid air at the surface into the cloud, strengthening the storm for a short while. Soon, the downdraft gets so strong that rain begins to fall into the updraft. This leads us to the third stage, the dissipation of the storm. As rain falls into the updraft, it cools it, causing its temperature to be closer the surrounding air. This reduces atmospheric instability and the updraft weakens, and dies out. At this part, the downdraft has taken over the entire storm and at this time, the rain is at its heaviest as all the cloud droplets are forced downward. As water content in the storm drops, the downdraft is able to warm when it descends, causing a drop in relative humidity and the storm's cloud droplets begin to evaporate. This is why storms dissipate from the bottom to the top. These are the three stages of a typical air-mass thunderstorm.

Many times, the different types of thunderstorms will be associated with the different environmental conditions. The main environmental conditions that we will looking at in this article are wind shear and atmospheric instability (there are other environmental conditions in association with thunderstorms but these are less significant than the ones mentioned. In this section, we will ignore the fact that there could be an atmospheric cap, which would limit thunderstorm activity.). There are two types of wind shear, directional and speed. In directional shear, the winds change with height and in speed shear, wind speed increases with height. There are generally several different types of situations that are encountered that affect the type of thunderstorm. In the first situation, there is a low amount of speed shear and directional shear, with a low amount of instability. In this situation, thunderstorms will not form unless, a cyclone comes into play. In that kind of a situation, the thunderstorm will form above the friction layer and it will generally in the form of a line of thunderstorms just before a cold front passage. If you are in this kind of situation, do not expect much severe weather, but if the cold front is slow moving and there is a lot moisture available, expect heavy rainfall and flooding. In the second situation, speed shear is low and directional shear is low, while instability values are very high due to afternoon heating of the lower atmosphere. Generally, the type of thunderstorm that develops will be a typical air mass thunderstorm with possibly heavy rain, lightning, and even some hail if the storm lasts long enough. They will occur on most hot summer days, and are usually scattered to isolated in nature. If the atmosphere above your town has a significant amount of speed shear and directional shear, but not much instability (because it is the dead of winter), expect widespread thunderstorms and maybe a few severe thunderstorms. This type of situation occurs usually north of a warm front during the late winter, in association with a strong mid-latitude cyclone. When this situation occurs and especially if the mid-levels of the atmosphere are unstable, expect dynamic lifting of air above the friction layer, which will cause widespread heavy thunderstorms and embedded severe thunderstorms, with an isolated tornado possible. If the speed shear is very high while directional shear is low, and atmospheric instability is high, you can expect the formation of a major squall line by early evening (depending on other conditions as well). If this situation occurs with a mid-latitude cyclone, the squall line could be very large and damaging and could cause a widespread severe wind event over an area. Heavy rain and the isolated tornado could occur within the squall line also. If speed shear if virtually non-existent, and directional shear and instability are high, expect the formation of strong air mass thunderstorms. They will be similar to regular air mass thunderstorms, but they will have a twisting component to them. A tornado is possible during these situations, but the tornado has to form before the storm weakens quickly. In the final situation, all three factors are high, expect a major severe outbreak, including large, violent tornadoes, extremely large hail, and very strong gusty winds. The predominant storm type that will develop in this case, will be a large supercellular thunderstorm. This situation usually occurs in the Midwest and Southern United States at least 5-10 times a year, which is why during these situations is when most of the United States' tornadoes form. This usually occurs in tandem with a strong low pressure center, a dry line, and strong low-level jet stream, and a strong polar jet stream in the upper levels of the atmosphere. One of the most famous cases of this happening was on April 27, 2011, the day of those prolific tornadoes that killed nearly 340 people. If you are ever caught in this situation, prepare for a wild day of severe weather, because odds are that a major tornado outbreak will result.

If you would like to know more about what will happen on a day when thunderstorms are possible, read NWS forecast discussions, at: http://forecast.weather.gov/product.php?site=IWX&issuedby=IWX&product=AFD&format=CI&version=1&glossary=1.

The forecast discussions give the main reasons for the why the forecasts are the way they are. The meteorologists at the National Weather Service explain what factors went into this forecast. So if you are ever worried about what kind of thunderstorms will form on a certain day, read the forecast discussion and you will receive what you need to know about what will happen.

Synopis through Saturday.

Currently, mostly cloudy to overcast conditions prevail across Northwest Ohio, with embedded showers in this mass of swirling clouds.  The upper level low is currently over Northwest Indiana, which has been weakening very steadily over the last day.  This weakening will allow the upper level jet stream over Canada to pick up the remnants of the upper level low, while at the same time causing several strong shortwaves to build a rather large longwave trough.  With the showers today, the National Weather Service has predicted the possibility of funnel clouds in any shower that hits your area.  They said that these are not dangerous and are not the same kind of funnel clouds as the ones that form in strong thunderstorms.  Do not be alarmed.  If you see one, report it to the emergency manager and you can also send me pictures and I can relay them to the National Weather Service.  Today, conditions are expected to remain overcast through most of the day.  Due to the weakening of the upper level low, there may be some clearing of the cloud cover over the area today, as dry air tries to enter into the system.  Expect highs today in the lower 60's, while some areas that receive less cloud cover may see highs in the mid 60's.  Any daytime heating will cause convective instability, and combined with cold air aloft, this may cause the development of scattered thunderstorms that may produce heavy rain and some gusty winds, with the possibility of small hail also.  Tonight, expect scattered light showers to continue, with continued mostly cloudy to overcast conditions likely.  Expect lows in the upper 40's and maybe lower 50's, especially in areas with thicker cloud cover tonight.  From Thursday through Sunday, as the jet stream begins to pick up the remnants of the upper level low, a major trough will begin to form over the Eastern United States.  At the surface, a major storm system will form, as a 992 mb low forms in Southern Canada.  This major storm system will cause a tight pressure gradient, allowing for strong winds to traverse the area on Friday and Friday Night.  Expect sustained winds of 20-25 mph, gusting to 30 mph.  This along with cloudy, showery, cool conditions on Friday, will cause uncomfortable conditions for people who are outside.  This major trough, will continue to deepen, becoming another upper level low, but this time just off the East Coast.  This means that we won't get the same dreary conditions that we have been having this week.  By Saturday, the surface cold air mass and associated high pressure system, will allow for strong radiational cooling, and presenting the possibility of frost to the area.  According to the National Weather Service, there is a strong possibility of frost Saturday, because of the forecast of light winds, clear skies, and a cold Canadian air mass.  By Sunday, a lower level ridge is expected to move into the area, bringing a very dry, but warmer air mass into the region.  As next week progresses, an upper level ridge will also move into the area, influencing the weather over a large part of the United States.  With this ridge, I expect temperatures to be warm, while skies will be clear and free of rain.  As I said in yesterday's forecast, temperatures could even warm into the upper 70's and lower 80's by next Wednesday or Thursday.

Official Forecast Through Saturday Night

Wednesday: High 62. Overcast.  Numerous showers likely.  Some showers may have funnel clouds, brief heavy downpours, and thunder.  Chance of rain 90%.  Rainfall amounts ranging from 0.2 inches to 0.75 inches in areas that receive heavy rain bands.
Wednesday Night: Low 49.  Scattered to numerous showers over the area.  Overcast at first, becoming mostly cloudy.  Chance of rain 70% decreasing to 30%. Fog possible.
Thursday: High 71.  Mostly cloudy. Instability and shear will be enough to generate widespread showers and thunderstorms, with some severe by afternoon, especially in Northwest Ohio. Patchy fog possible in the morning. Chance of rain 90%.
Thursday Night: Low 51.  Overcast.  Widespread showers likely, especially after midnight.  Chance of rain 30% at first, becoming 70% after 3 a.m.
Friday: High 56. Overcast.  Windy.  Winds from northwest at 20-30 mph.  Scattered showers throughout the area.  Showers likely.
Friday Night: Low 37.  Mostly cloudy in the early evening, becoming clear after 9 p.m. Windy at first, becoming calm later in the evening.  Frost possible, especially in the early morning hours.
Saturday: High 56.  Mostly sunny.  Much drier than in recent days.  Very nice day, but chilly at the same time.
Saturday Night: Low 35.  Mostly clear.  Light winds and clear winds, make for a great night for the formation of frost.  Some areas, especially north of here, could hit below freezing, especially in more isolated areas.

Forecast through Friday

About two hours ago, a large and intense band of heavy rain moved through Antwerp, and was heading north-northeast.  With this system, expect heavy rain with amounts in excess of a half inch, with some gusty winds including.  If you happen to get hit by some of the heavier bands of rain, expect rainfall amounts closer to one inch.  Here in the Antwerp, the band of rain dumped just over four-tenths of an inch, in a little less than an hour.  Currently, the clouds over Antwerp are just beginning to break, forming a raggedy appearance in the sky, with some sunshine peaking through.  As the surface low over Northwest Indiana moves slowly to the east, expect clouds to increase and become overcast once again along with showers and possibly a thunderstorm increasing in coverage over the area, especially during the overnight hours.  Tonight, skies will remain overcast as the rain bands continue to affect the area.  Lows will fall to around 51 tonight, as overcast skies will keep temperatures steady.  Any rainfall tonight will not be that heavy with rainfall amounts amounting to 0.25-0.4 maximum.  By tomorrow, the surface low will be located just north of South Bend right along the state line, and it will weaken and dissipate by Wednesday afternoon, ahead of the next storm system. Tomorrow's highs will be around 62, with areas farther east, such as in Defiance, will see temperatures near 65 tomorrow.  Most areas will see mostly cloudy to overcast skies, along with the renewed threat for showers.  Showers will likely still be numerous tomorrow, with some of the showers becoming especially in areas that see some sunshine, which will add to the instability in the atmosphere.  Expect rainfall amounts to be on the lighter side with about 0.25 inches falling during the day in Antwerp.  By Wednesday night, expect light scattered showers to continue even after the surface low pressure system dissipates.  Lows will fall into the upper 40's, around 48.  Skies Wednesday night, will likely begin to clear up.  Instead of overcast skies all night, expect skies to become mostly cloudy, especially by early morning.  On Thursday, highs will probably be higher than in recent days, mainly due to less cloud cover, and the fact that the next cold front will approach from the north on Thursday.  Highs will rise into the upper 60's and lower 70's, even as the chance of scattered light showers prevails along with partly cloudy to mostly cloudy skies.  Overnight, skies will begin to cloud up again, as the next storm system approaches from the north.  Because of increasing clouds, expect lows in the upper 40's or lower 50's. During the overnight hours, the storm system approaching from the north will curve toward the southeast and east, while intensifying rapidly at the same time.  According to the GFS computer model, this low will intensify to minimum low pressure of 992 millibars by early Friday morning.  The intensification of this low pressure system and its movement will determine how much rain we get Friday, and how windy it will get.  According to computer models, this strong storm system will be located over the far eastern part of the U.P. of Michigan (near Sault St. Marie).  So I expect that showers will increase in coverage across the area early Friday morning and into the afternoon under cloudy skies.  I also expect winds to significantly increase early Friday morning, with sustained winds increasing to about 20-25 mph, with gusts up to 30 mph.  Not only will Friday be miserable with gusty winds, cloudy, wet conditions, but temperatures will also be on the cool side with highs in the 56-59 degree range.  This will make for a miserable day Friday.

For the long range, on Friday night, expect scattered showers to continue, along with gusty winds early on, but decreasing in intensity later on in the night, along with clearing skies.  Saturday, the intense low pressure system over southern Canada, will begin to weaken and move eastward, decreasing our threat for rain on Saturday.  Due to a major cold air mass moving into the region, temperatures on Saturday will be very similar to Friday's, with temperatures in the mid to upper 50's.  But instead of cloudy, wet conditions, expect partly sunny skies and light winds for Saturday.  By Sunday and Monday, and a warming trend will begin, with highs sliding back into the upper 60's and lower 70's.  Throughout next week, I am expecting a major ridge to move into the area, which could support highs in the lower to middle 80's by next Wednesday or Thursday.  This large ridge of high pressure, will become stagnant over the area for several days, before a major longwave trough digs into the central plains, causing the first in a series of storm systems that could affect us by the end of next week.

Ridge of high pressure aloft will cause above normal temperatures next week

Official Forecast through Thursday Night.

This forecast is based on MOS guidance, current conditions, and trends.
Tuesday:  High 62. Overcast. Numerous and widespread showers throughout the day.  Chance of rain 90%.  Rainfall amounts around 0.25 inches
Tuesday Night: Low 49.  Overcast.  Numerous showers in the area.  Chance of rain 70%.
Wednesday: High 63. Variable clouds ranging from mostly cloudy to overcast. Numerous, widespread showers more likely in the afternoon. Perhaps a rumble of thunder.  Chance of rain 60%.
Wednesday Night: Low 49. Mostly cloudy to overcast. Scattered light showers possible.  Chance of rain 40%. 
Thursday: High 70. Mostly cloudy to overcast. Showers possible.  Chance of rain 40%.
Thursday Night: Low 49. Mostly cloudy.  A few scattered showers possible.  Chance of rain 30%.
 
Long range forecast; Friday through Monday: On Thursday, conditions will generally clear up ahead of the next system.  Along with mostly cloudy conditions, expect a slight chance of showers on Thursday with highs in the lower 70's, making for a pretty comfortable day.  On Friday, the next storm system will bring a renewed chance of showers.  These showers will arrive with gusty winds and chilly conditions, as highs will probably only make it to the upper 50's.  By Saturday, mostly cloudy conditions will be the rule with temperatures even colder than the day before, with highs around 57.  Saturday Night brings the possibility of our first frost, as the month of October gets underway.  By Sunday, a 500 millibar ridge will begin building in the central plains, and move eastward by Monday, allowing warmer temperatures to reside over the region.

Rain is Upon a Large Portion of the Area

As of 7:50 p.m., rain is falling heavily here in Antwerp.  According to the radar, the large band of rain that stretches from the Michigan/Ohio border to Memphis, TN, is moving northward and intensifying, just as expected.  Over the next several hours, the rain will continue to increase in areal coverage and intensity, producing rainfall amounts up to a half inch in the next two hours or so.  After this even heavier rain will arrive, causing heavy rainfall amounts.  The arrival of the thunderstorms will only make matters worse, as their downpours will tremendously increase rainfall amounts.  This along with saturated ground from previous rains, could cause some localized urban and small stream flooding, especially in the overnight hours when the rain will be at its heaviest.  As a reminder, tomorrow is expected to have widespread rain and thunderstorms in the morning, followed by scattered light showers in the afternoon, under mostly cloudy skies.  As for temperatures tonight and tomorrow, temperatures currently in the upper 50's (highs only made it to the lower 60's at Fort Wayne, but in areas farther east, such as Defiance and Toledo, temperatures made it into the upper 60's and lower 70's.), will continue to rise due to warm-air advection occurring in the 850 millibar layer of the atmosphere.  As I said in the last blogpost, warm-air advection is part of the reason for the intensification of the rain band and the formation of the thunderstorms overnight.

Official Weather Forecast Through Tuesday Night.

This forecast is based on MOS guidance, current conditions, and trends.
Sunday Night: Low 58.  Overcast. Widespread, numerous showers and thunderstorms, in the form of bands of rain and storms swinging through the area.  Chance of rain 100%.  Heavy rainfall possible.  Rainfall amounts of 1 to 2 inches expected in most areas.
Monday: High 70.  Mostly cloudy to Overcast.  Widespread rain and thunderstorms in the morning, becoming scattered and light by afternoon, with some breaks in the clouds. Chance of rain 75%.
Monday Night: Low 53.  Mostly cloudy.  Scattered light showers and possibly a thunderstorm, especially after midnight.  Chance of rain 50%.  Rain will generally increase in coverage in the later evening hours. Rainfall amounts 0.25 inches or less.  
Tuesday:  High 65. Mostly cloudy to overcast. Numerous showers in the morning, giving way to widespread light rain in the afternoon.  Chance of rain 60%.  Rainfall amounts on the order of 0.25-0.5 inches.
Tuesday Night: Low 49.  Overcast.  Showers likely, becoming more intermittent by early morning.  Chance of rain 60%
Long range forecast; Wednesday through Saturday: Showers will continue on Wednesday as the upper level low continues to sit and move slowly eastward.  Further more, by Thursday, clouds will be clearing up and the sun will finally come out.  Temperatures on Thursday will warm into the lower 70's, which will feel like a nice change compared to what's been happening.  On Friday, a long wave trough builds into the region, allowing a much colder air mass to settle into the area.  Because of little moisture accompanied with this trough, I would only expect at the most a few showers on Friday.  Friday's highs will be in the lower 60's, while Saturday temperatures will be even colder with highs in the upper 50's.  By Sunday, temperatures will moderate as the flow aloft becomes very unstable and meridional, meaning that large troughs and ridges are causing large fluctuations in surface weather.  Temperatures will rise into the upper 60's, ahead of the next storm system on Sunday.

Main area of rain Moving into the Region.

After hours of light shower activity, the main area of rain is finally shifting into our area from the southwest.  The rain will become heavier and more widespread as the evening progresses, becoming heavy by late evening.  As the rain becomes heavier, we have an increased chance for thunderstorms overnight.  Tonight, there are several factors that will support the chance of heavy rain and possibly localized flooding.  One is higher Precipitable Water values over the area, especially areas northeast of Fort Wayne.  Higher amounts of Precipitable Water in the atmosphere indicates the potential for heavy rainfall (generally rainfall amounts will be near the precipitable water value over a location, without the addition of other factors).  Another factor is convergence induced by convective processes and dynamic processes.  The convective processes that are causing convergence are higher values of Theta-E (measure of instability and buoyancy in the atmosphere) and moisture/warm air advection, which is also causing the air to become more buoyant and unstable.  One of the major factors associated with the convergence caused by dynamic processes is the jet stream.  The jet stream over us (or a branch of the jet stream), is causing upper level divergence over our area, which indicates low level convergence is occurring at the same time.  Convergence will cause a concentration of moisture over a smaller area, the corridor from Fort Wayne into Northwest Ohio.  The uplift with the convergence will cause thunderstorms to form, which will enhance heavy rainfall and possibly flooding.  Rainfall amounts from this evening to overnight will be from 1-2 inches area wide, with some areas picking up 2.5 inches (but this is very unlikely).  So expect rain to begin shortly and become more widespread and intense over the area especially by the late evening hours.  Overnight, thunderstorms are possible, with some producing intense rainfall for long periods of time.  I really don't expect much in the way of severe weather, expect for the possibility of flash flooding.  At this time, widespread flooding is really not expected because of near normal soil moisture conditions, while areas west of here have drier than normal soil moisture conditons.  According to forecast models, heavy rain/thunderstorms will occur into the early to mid morning hours tomorrow.  After that, conditions will generally clear up and by mid to late afternoon partly cloudy conditions will appear over some parts of the area, especially in areas farther west, as the main rain bands move into central Michigan.

Official Weather Forecast Through Tuesday.

This forecast is based on MOS guidance, current conditions, and trends.
Sunday: High 68.  Mostly cloudy. Scattered light showers and possibly a thunderstorm, becoming more widespread and numerous by late afternoon and evening.  Chance of rain 60%.
Sunday Night: Low 58.  Overcast. Widespread, numerous showers and thunderstorms, in the form of bands of rain and storms swinging through the area.  Chance of rain 95%.  Heavy rainfall possible.  Rainfall amounts of 1 to 1.5 inches possible in some areas.
Monday: High 70.  Mostly cloudy to Overcast.  Widespread rain and thunderstorms in the morning, becoming scattered and light by afternoon, with some breaks in the clouds. Chance of rain 60%.
Monday Night: Low 53.  Mostly cloudy.  Scattered light showers and possibly a thunderstorm, especially after midnight.  Chance of rain 50%.  Rain will generally increase in coverage in the later evening hours. Rainfall amounts 0.25-0.4 inches.
Tuesday:  High 65. Mostly cloudy to overcast. Numerous showers in the morning, giving way to widespread light rain in the afternoon.  Chance of rain 60%.  Rainfall amounts on the order of 0.25-0.5 inches.
Long-range; Wednesday through Friday: On Wednesday, the upper level low over the area will have moved east of the area.  This will allow skies to clear up and to allow some sunshine into the area for Wednesday afternoon.  By Thursday, expect partly cloudy conditions and highs in the 70's.  By Friday, expect slightly cooler temperatures due to a colder air mass moving into the region.  Highs on Friday will be in the upper 60's.
Synoptic forecast: The upper level low will finally move out of the area by Wednesday afternoon and become part of the mean flow aloft, meaning it will finally dissipate.  Over the next week or so, several shortwaves will move over the area causing several storm systems to form, even though we will be in a warmer pattern.  Then, according to computer models, a major longwave trough will develop over the East Coast.  After this the shortwaves rounding the peak of the ridge in the west will cause the eastward progression of the strong ridge of high pressure from the West to the East, which will influence the much warmer temperatures expected to move into our area.