Monday, October 25, 2010

What the Pattern Change Means for Us

Since we last got together the final totals for Saturday's rainfall have been tallied, and the result is that the Rockford Airport had a grand total of 1.71" of rain for a new record for October 23rd.  It is also the greatest amount of rainfall in a calendar day since July 24th when 2.81" was recorded.  The 2 day total for Rockford is 2.28" brought an end one of the driest starts to October in many years.  A line of heavy thunderstorms developed off to the southeast of Rockford earlier tonight moving across the Chicagoland area into northwest Indiana.  All that is left of precipitation over northern Illinois are some scattered light rain showers over Stephenson County and Whiteside County as of 12:20 am on Monday morning.  After those showers move into Wisconsin, rains should be over for the rest of the night, and Monday.  North central Illinois will be in a  warm sector on Monday under partly sunny skies, a southerly wind with afternoon temperatures reaching the low to middle 70's.  A power jet stream (160 - 180+  knots) is crossing the Rockies tonight, and entering the central plains.  It will spin up an rapidly intensifying surface low pressure near Kansas City Missouri on it's nose by 7 pm on Monday evening with a central pressure of 29.18".  By   1 am on Tuesday morning it will be located just southwest of Minneapolis with a pressure down to 29.00", and it will be dragging a cold front south across eastern Iowa.  Strong southwesterly winds (with a low level jet of 55 to 60 knots) will increase ahead of that front across the Stateline on Monday night pumping in mild moist air from the Gulf of Mexico.  Showers and thunderstorms will spread from Missouri and eastern Iowa northeast across northwestern and north central Illinois overnight with winds increasing to 15 to 25 mph with gusts above 40 mph by morning.  Because of the continuing intensification of this storm system  HIGH WIND WATCHES have been issued by the National Weather Service beginning late on Monday night for northwestern Illinois, and by noon on Tuesday for north central Illinois.  The storm will be centered near Duluth, Minnesota by 7 am on Tuesday, and the central pressure will be down to 28.73" as is slings a powerful cold front across northern Illinois into Lake Michigan.  By 7 pm Tuesday the storm will be centered just northwest of Lake Superior with an amazingly low central pressure of 28.38".  Because of the extremely low pressure associated with the storm and the exceptionally tight pressure gradient, winds in northern Illinois will be Illinois will be increasing from 20 to 40 mph with gusts to 55 mph, and possibly higher until late Wednesday.  If the strong does intensify to around 28.38", it may end up being the strongest Great Lakes Cyclone since the great Armistice Day Storm of 1940!  As of this writing, winds are expected to reach 64 mph on Wednesday out over the open waters of Lake Superior with waves to 21 feet.    Impressive... don't you think?  Hang on to your hats!
By Meteorologist
Eric Nefstead

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