BLOG: Today's Severe Weather Threat

After a benign start to the work week, the threat for some heavy, gusty storms returns to the Mahoning and Shenango Valleys today. The risk of storms will ramp up by mid to late afternoon. Things are quiet enough this morning. The current surface map (at 9am) shows low pressure to our west and a soupy air mass around the region. Check out the dewpoints:  It's also fairly cloudy. And this is a GOOD thing. The more clouds, the less unstable the atmosphere will become. 9am visible satellite:  Where the atmosphere was unstable enough, things got very bumpy yesterday with a lot of reports of wind damage from southern Ohio down into the Southeast: Notice there may have been a weak tornado or two in southwest Indiana.Today, the threat shifts north and east as this system tracks in that direction. Not only will the atmosphere be moist enough to support big storms, but we will be in a favorable region for air parcels to lift. This is the 500 millibar chart, a look at the atmosphere at about 18,000 feet. Vorticity, or spin in the atmosphere is shown, along with the position of troughs and ridges. The Valley will be on the east side of a trough of low pressure; this is a zone that favors lift.  Here is the Storm Prediction Center outlook for today/tonight....the yellow area is the "enhanced" risk area: Let's talk about what "type" of severe weather is most likely. Remember, the definition of a severe thunderstorm is: a storm that produces either hail 1" in diameter or higher or winds of 58 mph or greater.  Here are the odds of a tornado within 25 miles of any location: Odds are quite low in our area and higher to the southeast. Why? For one thing, the "wind shear", or the change in wind direction and/or speed with height in the atmosphere is higher there. Check out this afternoon's values: Pretty impressive along the Mason-Dixon line. What about hail? Here's the SPC hail odds: What is the most likely type of severe weather in the Youngstown area? Strong, damaging winds. Those odds are about 15% (within 25 miles of any location): This jives with this graphic that I put online last night and showed on 21 News at 11: How much, if any, severe weather there will be will, again, greatly depend on how much sunshine there is before mid-afternoon. The latest HRRR short range model does not have the CAPE (instability) going through the roof here this afternoon, so it may be picking up on the clouds being tough to break: Notice the higher values to our southeast and west.Here is an animation of the "simulated" radar, based on the HRRR model, from 3pm-9pm. Notice activity will generally be moving from SW to NE:  So, bottom line, we have the CHANCE for severe weather from late afternoon into early evening. Not enough instability will mean thunderstorms will be more "garden variety" and less severe. We will see how the midday and early afternoon plays out.Reminder of our severe weather policy: Severe Thunderstorm Warnings will prompt us to "cut in" in commercial breaks on TV to bring you up to date. In the (unexpected) event of a Tornado Warning ANYWHERE in our viewing area, we will break in over programming. If it turns out to be a long-duration severe weather event, we will have streaming coverage on WFMJ.com, your smartphone and tablet.Also a reminder....Facebook STINKS in severe weather situations, since it "filters" many posts from "like" pages such as mine. Twitter is much better...no filtering!!Thanks for reading!Eric