BLOG: Midweek Severe Weather Threat

Good morning!I have been mentioning on TV, in my "Weather Geek" videos and on social media that midweek could bring the threat for severe weather to the Valley. This post is an update on the threat....and it's generally good news.First of all, we do have the chance to pick up a shower and thunderstorm during the midday and afternoon today. A cold front is slicing into a warm and humid air mass. Radar/satellite and 9am dewpoints: The odds of large hail in any storm are pretty low today, generally 5% or less (Storm Prediction Center forecast): The threat for damaging winds is in that same general range here today: Notice how much higher the chances for severe weather are to the west today and tonight. That's because a large complex of thunderstorms, known as a Mesoscale Convective System, is likely to form over the Plains this evening and then track east. Widespread wind damage, large hail and tornadoes will accompany that complex.What does that mean for northeast Ohio and western Pennsylvania? Remember that front I showed entering the region today? It will settle to our south tonight, stalling out near the Ohio River. The farther south that front settles, the lower our chances are for severe weather on Wednesday.  North of the front, a more stable, drier air mass will become entrenched. Check out the dewpoint map for Wednesday afternoon: Dewpoints will have dropped into the 50s here, but they will be in the 70s along the Ohio River. Thunderstorms NEED moisture and will try to track toward areas of higher moisture.This map shows the SPC's odds for severe weather (within 25 miles of any location) Wednesday. Percentages are on the left side: Odds certainly are higher closer to the higher dewpoint air. It's easy to see where the higher "fuel" for the storms will be tomorrow by looking at CAPE values: The instability is through the roof along the lower Ohio River Valley but NIL around Youngstown.Alright, so bottom line. I DO think it will rain across the Valley tomorrow, mainly in the afternoon. We will be in the northern fringes of that thunderstorm complex and it will be transporting quite a bit of rain east. This simulated radar, from 12am-2pm, seems reasonable. Notice the complex weakening as it runs into the more stable air:  Those are my thoughts this morning. STAY TUNED! As new information becomes available, these thoughts may change! The atmosphere is fickle.Thanks for reading,Eric