Damaging winds, hail, and even the possibility of an isolated tornado can be expected as we venture through our Thursday thanks to a frontal system very similar to last week. Here is how I think the storms will unfold as of Wednesday evening…….
A warm front will slowly lift North through the region tonight allowing for scattered showers and thunderstorms into the early morning hours Thursday. Severe storms in Illinois and Indiana will gradually move East along a warm front overnight and gradually weaken as they head towards West Central Ohio. Even though a gradual weakening trend is expected, a strong thunderstorm can’t be ruled out into tomorrow morning. The latest forecasts have decided not to push a warm front as far North as previously expected, because of this I have upped the chance for showers and thunderstorms into tomorrow morning along with dropped temperatures a few degrees for Thursday. Here is a look at the NWS’ short term model (HRRR) showing showers and t-storms in the region tomorrow morning.
By tomorrow afternoon, most models show a warm front that has moved to our North. What is interesting though is that the latest short-term model runs have been picking up on showers and thunderstorms in the region developing once again early tomorrow afternoon. Our own RPM model is showing a potential squall line moving through tomorrow early afternoon around 2 or 3 PM.
My previous forecasts have not accounted for thunderstorms moving through early tomorrow afternoon. But now that short-term models are picking up on this possibility a couple of things would likely change:
1) Damaging winds and hail would be possible earlier than anticipated. Originally I was holding off on the chance for severe weather until the late evening/overnight timeframe. If this trend in the models continues, that could change.
2) Temperatures will NOT warm quite as much. We’re probably not getting to 80 if we have showers and t-storms to deal with both in the morning and early afternoon. This would limit our overall instability, potentially lessening the severity of storms later in the evening and overnight.
Even though I’m now including a better chance for thunderstorms during the day Thursday, that doesn’t change the fact that I think our best chance for severe weather won’t come until the late evening/overnight time period. One thing all models have been VERY much agreeing on is a strong cold front plowing through the region into West Central Ohio in the midnight to 3 or 4 AM timeframe.
It looks as if the biggest threat as the front moves through will be damaging winds. But with very strong winds expected both at the surface and into the upper levels of the atmosphere, isolated tornadoes look to be a possibility. This will be a classic HIGH SHEAR low INSTABILITY environment. Winds at the surface as these storms move through will be out of the SOUTH at about 20 to 30 mph with stronger gusts. Only about 2000 feet above the surface, winds will be roaring at close to 70 mph.
When you have a change in wind SPEED or DIRECTION with height, that is called wind shear. We are expecting high winds through every layer of the atmosphere along with some directional shear too, this would lead to favorable tornadic conditions. HOWEVER, there is expected to be VERY little instability. This parameter is measured by CAPE (this is the atmospheres ability to produce rapidly developing thunderstorms) and with it being the middle of the night, little to no CAPE Is expected.
For an ideal severe weather situation you want to see both high CAPE and high WIND SHEAR. With high wind shear, it’s a safe bet to say that damaging winds will be the biggest concern tomorrow night. I’ll keep you updated!