Wednesday, April 19, 2017

Wednesday Evening Storm Update

11:10pm Update: Thunderstorms out west have weakened running into a little more stable air mass over eastern Iowa and northwest Illinois.  While a new severe thunderstorm watch had been issued for eastern Iowa, the severe threat seems to be lowering.  Storms will continue to progress to the east crossing over into southwest Wisconsin and northwest Illinois towards midnight.  Stronger storms may produce gusty winds and small hail, but the overall severe threat appears to be weakening.

Original Post:

Strong to severe thunderstorms have been developing over far western Iowa, eastern Nebraska and northeast Kansas.  Locally, storms from earlier in the day clearing allowing a little more sun to develop during the mid to late afternoon.  This helped to warm temperatures into the mid and upper 60's.  East winds, however, have cooled temperatures from Janesville to Rochelle into the low 50's.

Skies have cleared from the rain over southern Wisconsin and northern Illinois, but not for long as what's developing back out west moves east with an advancing cold front and low pressure system.

A warm front sits over central Illinois with temperatures in the 70's and 80's to the south and 50's and 60's to the north.  The front remains in place through much of the evening, lifting north with the passage of low pressure over Iowa and into Wisconsin.  As this happens the storms out west will move east, weakening a little as they do.  Storms that do form and maintain their strengthen closer to the warm front over northeast Iowa, southwest Wisconsin and northwest Illinois could pose a hail and wind threat between 10pm and 2am.

The image on the left is a simulated radar image at 1am.  While the storms will weaken some with the loss of daytime heating, the strength of the low may be able to maintain a few stronger storms during the early overnight.  Heavy rain and hail would be the primary threats. 

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