Yesterday, I spent the entire day in chemical process safety training. It was quite humid, and by the evening, quite rainy. The skies clouded up around dinnertime, and it rained until I went to bed.
This morning has been warm, humid, still and completely overcast.
National Weather Service (NWS) in Lincoln, IL, forecasts (for Decatur, IL) a cloudy day, with a 50% chance of showers and thunderstorms, and a high temperature of 82 F. The winds will be from the north at 5-7 mph. This evening will be mostly cloudy, with a 40% chance of showers and thunderstorms, with a low temperature of 66 F. Winds will be from the north at 7 mph.
The NWS in Chicago, IL, forecasts (for Chicago, IL) a mostly sunny day, with a 40% chance of showers and thunderstorms, and a high temperature of 77 F. The winds will be from the north-northeast at 5-15 mph. This evening will be mostly cloudy, with a 20% chance of showers and thunderstorms, and a low temperature of 68 F. Winds will be from the north at 15 mph, gusting to 20 mph.
The Storm Prediction Center (SPC) has issued a Marginal Risk for severe weather for most of the state today. This threat is based on the potential for severe wind gusts for storms that form ahead of the cold front, as steep lapse rates in low to moderate deep-layer shear helps to ventilate updrafts.
The visible satellite imagery is unavailable at this time.
The infrared satellite imagery shows that there is an ongoing Mesoscale Convective System (MCS) in the southern part of the state. You can see some of the anvil material blown out the back side of this MCS on the infrared imagery.
The water vapor imagery shows the large pocket of moisture associated with the MCS.
The 12Z sounding is unavailable at this time.
The surface observations (from the SPC Mesoscale Analysis Map) show mild temperatures and high humidity (based on the surface dewpoint depressions). The skies are overcast, and the winds are light. There are ongoing showers and thunderstorms running along the I-70 corridor.
The surface pressure chart shows no strong pressure systems or gradients over the state, so far this morning. The RAP shows that a low pressure system is expected to develop over central Illinois (1006 mb) over the next six hours.
Synoptically speaking, the 300 mb NAM chart (from Unisys) shows moderate zonal flow over much of the state, as a weak jetstreak moves over the northern part of the state this afternoon.
The 500 mb NAM chart shows no strong vorticity advection over the state today. This image has been excluded from today’s post.
The 700 mb NAM chart shows no large pockets of rapidly-rising air. This chart has been excluded from today’s post.
The 850 mb NAM chart shows no major thermal advection over the state today. This chart has been excluded from today’s post.
The Precipitation chart shows that rain is likely over the entire state through at least 00 Z. Notice that some of the rainfall amounts are quite large, and it would not surprise me to see a few Flash Flood Watches and Warnings issued.
I am hoping that the weather will clear up a little bit tonight, as I am planning on attending a White Sox vs. Cubs game tonight. I don’t know if we will pull it off, given the weather, but we’ll give it a try either way.
Thank you for reading my post.
The upper air soundings and mesoscale analysis plots are from the Storm Prediction Center website.
The forecasted upper air soundings are from TwisterData.com.
The surface observation and upper level charts are from Unisys Weather.
The satellite data is from College of DuPage – SATRAD