Thunderstorms Moving In Produce Small Hail Monday Afternoon

10:45pm Update: The transition over to snow has begun north of the state line where Madison had already received close to an inch of snow.  Low pressure is now passing through northern Illinois, with a few showers lifting up north into southern Wisconsin.  But as the colder air becomes wrapped in behind the low, the transition over to a rain/snow mix, before eventually switching over to all snow will take place.  We can already begin to see that transition now over parts of NW Illinois.  So far there are no reports of snow reaching the ground locally, but I wouldn't be surprised to begin to see the snow develop between Midnight and 2am.

6:20pm Update: Moderate to heavy rain continues to fall over much of Winnebago County Monday evening.  The threat for hail has gone down, but the heavy rain threat remains.  The rain should begin to lighten up between 7pm and 9pm, with scattered showers through Midnight.  Localized flooding is possible with this additional rainfall as totals add up to, and surpass an inch of rain.




Storm Reports:


Local Storm Report by NWS LOT: SSW Ashton [Lee Co, IL] cocorahs reports HAIL of pea size (E0.25 INCH) at 04:39 PM CST --

(5:21:37 PM) nwsbot: Local Storm Report by NWS LOT: 1 NE Rockford [Winnebago Co, IL] trained spotter reports HAIL of pea size (M0.25 INCH) at 04:52 PM CST -- pea sized hail is covering the ground

(5:21:37 PM) nwsbot: Local Storm Report by NWS LOT: Malta [De Kalb Co, IL] trained spotter reports HAIL of penny size (M0.75 INCH) at 04:52 PM CST -- most hail stones were pea-sized, but a couple larger hail stones were penny-sized.

(5:21:37 PM) nwsbot: Local Storm Report by NWS LOT: 1 ENE Rockford [Winnebago Co, IL] cocorahs reports HAIL of pea size (M0.25 INCH) at 05:00 PM CST --

(5:21:38 PM) nwsbot: Local Storm Report by NWS LOT: Rockford [Winnebago Co, IL] trained spotter reports HAIL of half inch size (E0.50 INCH) at 05:03 PM CST --

(5:24:34 PM) nwsbot: Local Storm Report by NWS LOT: Sandwich [De Kalb Co, IL] trained spotter reports HAIL of pea size (E0.25 INCH) at 05:20 PM CST --

Skies cleared following the heavy rainfall Monday morning, allowing instability to build during the afternoon.  Thunderstorms were quick to develop over central Illinois, some of them turning severe, as low pressure moved through Iowa.


Scattered thunderstorms, some strong enough to produce pea to nickel sized hail, will continue to lift up through Highway 20 and eventually into southern Wisconsin by Monday evening.


These thunderstorms are moving into an environment with a little less instability than what they initially developed in, but the wind shear is strong enough to sustain the storms for the next couple of hours.  Hail and heavy rainfall will be the greatest threats with these storms.