GREAT LAKES WEATHER: A Tricky Forecast

01 December 2011

A Tricky Forecast

(The ECMWF look at the weather for Monday night/Tuesday morning).

This post this morning will be mainly focused on the weather ahead towards the end of the weekend and the start of next week.

On Saturday night an elongated upper level trough at the 500-mb level will begin to enter the Plains. This upper trough is going to extend down into the southwestern Plains as it develops. With the location of this upper level trough, a weak surface low pressure will develop in the central Plains and begin to make a beeline towards the western half of the Great Lakes region. This surrface low will not be strong, but its influence from the upper level trough behind it will make it just as good as a normal low pressure.

The surface low pressure will develop a cold front which will drag behind it as it moves through the U.P. of Michigan (give or take a few counties at this point for location) and this front is going to push through the region. Ahead of the front, warm advection from the souternly winds will begin to place which will not only raise the temps into the upper 40’s on Sunday, but it will add to the moisture.

As this happens on Sunday afternoon, the upper level trough will begin to “bulge” (for lack of a better word) a little bit as it passes through Minnesota area. This will help move the low pressure centre out of the area on Monday. At the same time, a good sized high pressure is going to develop on the backside of this trough and provide a ridge of high pressure that will influence much of the Great Plains.

The models are in fair agreement this morning as to the passage of this trough of low pressure through Monday, however the question starts arise of what will happen on Tuesday and Wednesday. Half of the models are hinting that a cut off upper low will develop at the southern edge of this trough and move through the region, while a couple others this morning want to keep the cut off low in the southern Plains.

Right now, I am leaning more towards the models that bring a cut off low at the edge of the trough towards the region in a way. Following these ones, I can get the following picture of generally what will happen through Tuesday and Wednesday in the region:

As this upper trough begins to near the region, it will become rather tight and full of short waves. High vorticies. Love them. As this happens, it will spawn a few surface lows off in the eastern half of the region which might add to some rain shower chances. The influence of the surface high pressure in the Plains at this time will continue to make this trough very elongated as the upper low develops in the central Plains on Tuesday.

This cut off low will begin to become more developed on Wednesday, but the only problem with it for us is that it wont arrive in the region until its too late…the ridge of high pressure will have already slid into the region. This will put that cut off low near to us, however it wont really start doing its work until after we’re off to the west of it. This sounds simple enough, but it isn’t because there is something that we will want to keep an eye on. A developing surface low pressure along the eastern side of this cut off low/trough.

If nature has its way, a very nice surface low pressure will develop on Wednesday and miss the region by a schmidge. If the course of this upper low flucuates towards the west, then it puts us in the path of this surface low.

See where the uncertainty develops? The forecast through Tuesday is looking rather certain, but the forecast for Wednesday isn’t so much. Upper level patterns will needed to be monitored throughout the morning.

The surface low in the southern states on Wednesday could be close enough that we could be seenig some precipitation from it, however the question is where in relavence to the region will the surface high pressure be. If the surface high remains to the west of the region and stays over in Wisconsin, then we could be in for a little precip (whether it be rain or snow is not a concern of mine right now) but if the high slides into Michigan at this time then we’d be watching as places to our east get some interesting weather.

The only locations in the forecast region that might be able to pick up some interesting weather if the latter happens will be Erie and possibly Cleveland. But I wont be putting anything into the forecasts about that at this point.

So with that being typed, lets quickly go over what is going to happen towards the end of the weekend and into the start of the week:

Elongated trough of low pressure moves into the Plains towards the end of the weekend which will help to develop a surface low pressure in the central Plains towards the end of the weekend. Surface low will be weak, but the influence of the trough will be enough that it will seem as a normal low. Cold front gets brought into the region on Sunday night/Monday which will be enough to allow for some warm advection to take place. Cold front pushes through on Monday, then the upper trough will near the region on Tuesday and from there that is when the weather gets a little uncertain.

And due to the forecasting that I will be doing this morning, I wont have the usual 10.00 a.m. Update, but I will be having the full Noon Update along with the revised extended forecasts.

I’ll keep you updated as always, but for now, I am Timmy Albertson and that’s the weather!

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Wednesday forecast

Cleveland: Mostly cloudy throughout the day and overnight. Highs in the mid 40's with overnight lows in the mid 30's. Winds NW at 5-10 mph, shifting to the SE at 10-15 mph this evening.
Erie: Mostly cloudy throughout the day and overnight. Highs in the lower 40's with overnight lows in the low to mid 30's. Winds W-WNW at 5-10 mph, shifting to SE at 10-15 mph this evening.
Toledo: Mostly cloudy throughout the day and overnight. Highs in the lower 40's with overnight lows around 40°. Winds SW at 10-15 mph, gusting to 25 mph, then shifting to SW at 10-15 mph this evening.

http://www.rap.ucar.edu/weather/radar/displayRad.php?icao=KIWX&prod=n0r&bkgr=black&endDate=20110419&endTime=-1&duration=0 Link to regional radar.

Extended forecasts (made at 8.07 wednesday)

CLEVELAND
Tomorrow: Mostly cloudy with rain showers developing in the mid morning and then rain showers likely after noon. Highs in the lower 50’s. Winds S at 15-20 mph with gusts of 35 mph possible.
Tomorrow Night: Mostly cloudy with rain showers likely in the early evening, then becoming scattered before midnight and mixing with snow. Scattered snow showers possible after midnight. Lows in the lower 30’s. Winds becoming W at 20-25 mph with gusts of 40 mph likely.
Friday: Mostly cloudy with scattered snow showers possible in the morning, then scattered snow showers likely throughout the afternoon. Highs in the mid 30’s. Accumulations around an inch or two possible. Winds NW at 25-30 mph with gusts of 40 mph likely in the late afternoon.
Friday Night: Mostly cloudy with lake effect snow showers likely throughout the evening and then lessening up after midnight. New accumulations around an inch or two likely. Lows around 30°. Winds NW at 25-35 mph with gusts of 45 mph likely.

ERIE
Tomorrow: Mostly cloudy with rain showers developing in the late afternoon. Highs in the upper 40’s. Winds SE at 15-20 mph with gusts of 30 mph possible by the late afternoon.
Tomorrow Night: Mostly cloudy with rain showers likely throughout the evening, then becoming scattered and mixing with snow after midnight. Scattered snow showers possible towards sunrise. Lows in the lower 30’s. Winds W at 20-25 mph with gusts of 40 mph possible.
Friday: Mostly cloudy with scattered snow showers possible in the morning, then lake effect snow showers likely throughout the afternoon. Highs in the mid 30’s. New accumulations around an inch or two possible. Winds NW at 25-30 mph with gusts of 40 mph likely in the late afternoon.
Friday Night: Mostly cloudy with lake effect snow showers likely throughout the night. New accumulations around an inch or two likely. Lows around 30°. Winds of 25-35 mph with gusts of 45 mph likely.

FORT WAYNE
Tomorrow: Mostly cloudy with rain showers likely throughout the morning and early afternoon. Rain showers becoming scattered in the late afternoon. Highs around 50°. Winds S-SW at 15-20 mph with gusts of 35 mph likely.
Tomorrow Night: Mostly cloudy with scattered rain showers likely in the early evening, then mixing with snow in the evening and becoming all snow before midnight. Scattered snow showers possible overnight. Lows in the lower 30’s. Winds W-WNW at 20-25 mph with gusts of 40 mph possible after midnight.
Friday: Mostly cloudy with scattered snow showers and flurries possible throughout the day. Highs in the lower 30’s. Winds NW at 25-30 mph with gusts of 40 mph likely by the late afternoon.
Friday Night: Mostly cloudy with scattered snow showers and flurries possible in the evening, otherwise lingering flurries after midnight with a low in the mid to upper 20’s. Winds NW at 20-25 mph with gusts of 40 mph likely.

TOLEDO
Tomorrow: Mostly cloudy with scattered rain showers developing in the early morning, then rain showers by noon. Highs around 50°. Winds S-SW at 15-20 mph with gusts of 35 mph possible.
Tomorrow Night: Mostly cloudy with rain showers becoming scattered in the early evening, then mixing with snow in the evening. Scattered snow showers possible after midnight. Lows in the lower 30’s. Winds becoming W at 15-25 mph with gusts of 40 mph possible after midnight.
Friday: Mostly cloudy with scattered snow showers likely in the morning, then lingering scattered snow showers and flurries possible throughout the afternoon. Highs in the lower 30’s. Winds NW at 25-30 mph with gusts of 45 mph likely by the late afternoon.
Friday Night: Mostly cloudy with scattered flurries possible throughout the overnight. Lows in the mid 20’s. Winds NW at 25-35 mph with gusts of 45 mph likely.