Sunday, May 27, 2012

Thunderstorms Monday Afternoon

Two records were broken in Rockford on Sunday. The first was the new record high established for May 27th of 99 degrees. The old record was 92 degrees set in 1978. The second record that was set today was that 99 degrees was the new record high for this early in the season. To get an idea about the scope of the heat today. It has only been warmer in May one time prior to today, and that was on May 31st back in 1934. So, one has to go back to the dust bowl days of the middle 30's to see a day that was comparable to today's heat. That was 76 years ago. Pretty impressive, eh?

Now down to brass tacks about what will happen next. It will be a mostly clear and unseasonably warm night in the Stateline with mostly clear skies, a brisk southerly breeze, with a low near daybreak around 70 degrees.

By 6 am on Memorial Day a cold front will stretch from Minneapolis, Minnesota southwest through Omaha, Nebraska, and continue on southwest through the Texas panhandle. Showers and thunderstorms will be moving toward the northeast along the frontal zone as the front progresses eastward during the day. This is not an ideal set up for heavy rain, or severe weather across the Stateline, but that said.... The severe storms prediction center has laid out a slight risk potential for severe thunderstorms on Monday afternoon across northern Illinois and southern Wisconsin. One of the ingredients missing is deep pure gulf moisture feeding in from the south. Dew points, however, will be moderate, reaching the low 60's. After a mostly sunny start to the day, clouds will increase in numbers and areal coverage. It will be very warm again by noon reaching the middle 80's by noon, and the upper 80's by mid afternoon. There will be a chance of thunderstorms by the noon hour, and areas of thunderstorms will be likely by mid afternoon. Some of those storms may produce large hail up to an inch and a half in size, and damaging winds to 60 mph. It does not appear to be a synoptic situation that will produce any tornadoes. The showers and thunderstorms will end in the evening. Skies will clear off from the west as drier air moves in form the plains again, and it will be cooler by daybreak with the overnight low dropping into the upper 50's.

By Tuesday morning the cold front will be well southeast of the Stateline approaching the Ohio River Valley. With high pressure over the plains, it will be mostly sunny, breezy, cooler, and less humid with a high around 74 degrees. Temperatures will drop back into the upper 40s on Tuesday night under mostly clear skies.

It will be partly cloudy on Wednesday with high pressure over North Dakota driving a breeze from the north. It will be cooler with a high in the middle 60's. A trough of low pressure edging southward across Wisconsin on the eastern edge of the high will help to re-enforce the cooling temperature trend. There may be some scattered light rain showers on Wednesday night as the trough pushes south across the Stateline the overnight temperature will drop to around 47 degrees.



Skies will be mostly cloudy on Thursday. A chilly northeasterly air flow will develop off of Lake Michigan as a system with an inverted trough of low pressure moves across Oklahoma. It appears as if there may be some rain development across northern Illinois with this system. Because of the clouds, the rain, and a chilly northeasterly breeze, temperatures on Thursday may have trouble reaching or getting much above 60 degrees. It does appear as if Thursday will be a chilly day!

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