A quiet start to far to our Wednesday here in the Sauk Valley under mostly cloudy skies.
A complex of thunderstorms has developed very early this morning across parts of southern Iowa and will continue to move eastward over the next several hours. A few of these showers and storms may clip the area later this morning, however no severe weather is anticipated with this complex.
A Slight Risk of severe thunderstorms continues to be forecast by the Storm Prediction Center for the entire area. A higher, enhanced risk, has been added to our west.
A cold front is currently making slow progress through the region this morning. This front will then stall to our south and attempt to retreat northward as a warm front. At the same time, a lake breeze will be moving inland from Lake Michigan, impeding the progress of the warm front into the area this afternoon. The combination of this and the delayed arrival of the low pressure system expected to progress through Iowa will lead to better chances for severe weather remaining west of the area late this afternoon and evening where more forcing will exist along that portion of the warm front itself as well as a better environment featuring warmer temperatures and more moisture/instability.
Here's a look at today's forecast tornado probability. Our area will remain in the lower risk with a less favorable environment in place while areas in central and western Iowa will remain in a higher threat with better dynamics in place there.
Above is the damaging wind outlook with higher probabilities again remaining to the west of the area as questions arise as to whether these storms will hold together as they race into northwestern Illinois very late this evening.
Our primary severe weather threat here will arrive very late this evening as thunderstorms that develop in western and central Iowa this afternoon are expected to congeal and form a line segment. This feature will race eastward very late this evening and arrive here around midnight. These storms will run the risk of large hail, damaging winds and perhaps an isolated tornado. The higher probabilities of all three remain just to the west of the area.
Simulated reflectivity from the NAM 3km shows an approaching line of storms expected to arrive later this evening with the approaching cold front. Some models dissipate this line completely as it moves into the area however it is likely that some storms will progress into the area shortly before/after midnight tonight. The severe threat will be on the decrease but some gusty winds and hail remain possible.
-The highest threat for severe weather remains to the west of the area this afternoon and evening.
-Scattered storms may develop later this evening with the primary threat being hail and damaging winds.
-Line of storms will approach the area slightly before/after midnight with damaging winds the primary threat. Questions remain on whether this line will hold together as it enters the local area.
Stay tuned to later forecasts and outlooks today. Once storms form in Iowa later this afternoon a better idea of how long they may progress eastward will come to light.