Another Round of Severe Weather for the Area 5/21/14

The Storm Prediction Center has us in a high-end 30% slight risk for severe weather for tomorrow (5/21/14). Remember this means there is a 30% chance of severe weather within 25 miles of a point.

For severe weather we look for 4 main ingredients or SLIM. Shear, Lift, Instability, and Moisture. The setup for tomorrow will not be lacking moisture. The models are forecasting dew points (amount of moisture in the air) into the 70s. Honestly that is probably too high because dew points in the 70s are REALLY high even for summer (which we haven't hit yet) but dew points in the lower to mid 60s are likely and will provide ample energy for the storms.

The map above is a GFS run that shows instability (CAPE) for our area tomorrow. CAPE is often over estimated in the models. This run is showing values of 3000 J/kg for us, which is more than enough for some strong updrafts in the storms tomorrow.

Finally for shear. The forecasted skew-T seen above shows some good speed shear (changes in wind speed with height) but we don't see the directional shear (changes in wind direction with height) that we would need for supercell and tornado development. Also the freezing level (level where temperature = 0 degrees C) is around 600 mbs. Because of the high CAPE values and semi-low freezing layer we could see some hail tomorrow from these storms.

To sum it up. This will be a Wednesday evening, to late evening event. Strong winds and hail are the main threats with the tornado threat looking small.

Tornado Watch for the Area

The Storm Prediction Center has a SLIGHT RISK of severe weather for our area today. For this particular case there is a 15% chance of damaging winds and damaging hail occurring within 25 miles of any point within the slight risk area. Also there is a 5% chance of a tornado occurring within 25 miles in the risk area. Two different Tornado Watches have been issued for the Ohio Valley. The first watch, for central Kentucky, is until 8pm. The second watch, for Northern Ky extending into most of Ohio is until 9pm. A major severe weather outbreak IS NOT expected today but conditions are right for strong to severe storms to form with damaging winds, large hail, and ISOLATED tornados. Meteorologist tend to want to "cry wolf" or overstate the threat of severe weather which I try not to do. So to sum it up, slight risk of severe weather today with the main threat being damaging winds but an isolated tornado is possible. We have two different watches over our area until 8pm and 9pm and if you are put under a warning be smart and take appropriate action.

Watch 1

Watch 2 

Why is There a Temperature Difference Across the State?

        So far this week Maysville has been experiencing mild temperatures with highs in the low to mid 70s, while most of Kentucky has seen highs in the 80s. So why is that? The answer to that is actually quite simple, there is a stationary front located across Northern Kentucky and Southern Ohio/Indiana. A front is nothing more than a boundary between two different air masses. To the north of the stationary front we see cooler temperatures, while to the south of it we see warmer, and typically more humid conditions (but that isn't the case with this front). I got the picture below from the Kentucky Mesonet yesterday and nerded out because of how clear the front was from the surface observations.
         Two main ways to locate a front are by finding the temperature gradient and the change of wind speed and direction. The top part of the image shows the surface temperatures across the state, while the bottom shows the wind speed and direction. We can see temperatures in the high 70s above the line and temperatures in the low to mid 80s below it. The front is even more recognizable by the change in wind direction and speed. To the south of the front, where there is warm air advection, we see southerly flow while to the north we see northerly flow.

So what does this stationary front mean for our weather over the next few days? For Tuesday we will see the same sunny and mild conditions we saw on Monday. The front will lift north as a warm front Wednesday and temperatures will climb into the mid 80s for Wednesday and Thursday. These warmer temperatures wont last for long as a cold front sweeps through the area this weekend, which means the return of rain and temperatures back down into the 70s.