Wednesday Afternoon Storm Update

 5:32pm Update: A line of showers and thunderstorms is approaching the region from the southwest now. It has entered Jo Daviess, Carroll, and Whiteside Counties. So far, nothing severe for the Stateline, but moderate to heavy rain and lightning have been reported. The severe threat does not look as concerning as it awhile ago, but there is still a threat for some severe weather as this moves through this evening.


5:10pm Update: Thunderstorms continue to arc northeast through the Quad Cities, with a tornado warning earlier for the Quad Cities.  As low pressure moves through northeast Iowa, the amount of spin in the atmosphere will help sustain these thunderstorms.  

4:41PM UPDATE:
Here is the current radar as of 4:41PM this afternoon. Scattered showers and storms off to the southwest will continue moving quickly towards the region. Some of them have been strong to severe at times. Also on the radar is a rough estimate of when the line will affect portions of the Stateline this evening.

3:20PM UPDATE:
The Tornado Watch out until 8PM includes only Whiteside County at this time. This watch could be expanded to include more counties across the viewing area this afternoon.

3:00PM UPDATE:
As the newest model data come in, the time period with the highest probability of thunderstorms, including severe weather is from roughly 4:30pm until 8pm as storms that are currently developing in Northeast Missouri strengthen and rapidly move towards the Stateline from the southwest. Below is the current radar and the timeline for the rain and storms.

1:00PM Quick afternoon update: A severe watch is possible just south of the Stateline area. After rain and storms from earlier this morning, there is some clearing taking place across portions of Missouri as dry air wraps in around the low. Along with this a strong shortwave tough, or band of energy and upward motion, is being noted ahead of a cold front. With this there is plenty of atmospheric shear or winds changing direction with height in the lower levels of the atmosphere. We will watch for individual storm cell development to the southwest this afternoon, because those types of storms have a better ability to rotate. In this area heavy rain, damaging winds, hail, and an isolated tornado is possible.

With today being one of the busiest travel days of the year, you'll want to stay 'weather aware' today, as there is a threat for strong to severe storms for the Stateline this afternoon.

The rain that moved in this morning is beginning to lessen a bit as dry air filters in. Currently watching to the south west in Missouri where dry air is wrapping in around the low pressure. As the dry air moves it, it erodes the cloud cover in place. If the cloud cover is gone, the sun is able to heat the ground and the instability grows. Instability is a key ingredient for storm develop, and plays into our severe weather threat for the afternoon. We didn't see much instability earlier and thats why the rain and storms stayed below severe limits.

So getting into the forecast for tonight and our risk for severe weather. All of northern Illinois and southern Wisconsin is under a slight risk for severe storms (yellow shading). This means that isolated severe storms are possible as we head into the late afternoon. A bigger threat for severe weather is towards the southern tip of the state, southern Indiana and Ohio, as well as into portions of Tennessee and Kentucky with an Enhanced (orange) and Moderate (pink) risk in place. Their hazards include all severe possibilities, heavy rain, strong damaging winds, hail, and even tornadoes. So if you are doing any traveling today make sure you have a way to receive watches and warnings if any are issued.

For the Stateline area, our bigger concerns will be heavy rain, fast moving storms, strong damaging winds. There is a smaller risk for a tornado, it is not a zero threat we can't rule one out, but it isn't a large threat. The higher probability area to possibility see a tornado would be near the Mississippi River in northwestern Illinois, because this is where the low looks to track. Near the low pressure, winds will be turning with height, giving a bit of wind shear, which is also needed for strong storms.


The timing of these storms looks to be between 4pm and 8pm tonight. This comes as we get the low pressure to track northward into Missouri and Iowa today, and a warm front also lifts northward. We also combine this with a very warm and moist air mass. Temperatures today will break the old record high for today (which is 57° set in 1941) as our temperature already sits at 58°. Our dew points are also very high for this time of year, as they are climbing into the 50's as well. This is increasing the instability which is needed for storms.

These storms will be fast movers as well, as they get a lot of help from strong winds in the upper levels of the atmosphere, so you won't have much time to react as the move.

Make sure to keep checking back as we will continue to update the blog, facebook, and twitter!