We have been talking a lot about severe storms lately it seems.
Yet another cold front is heading toward our area. It is very difficult to get fronts through the Ohio Valley in late July---but when you do it with a record heat wave---watch out. The wind energy the thunderstorms can develop is intense. Thursday is shaping up to be one of those days.
First up...the setup.
Warm/Muggy overnight. Just blah! outside. Cold front sparking severe storms to our north and west this evening.
So far, nearly 40 reports of wind damage from these storms and they likely will last several more hours.
In fact, the HRRR model (can only see until 8am) does show some moving into southern IL just after sunrise. They should fade---but the clouds from these will play a role in instability for the midday/early afternoon hours. Something to watch. Right now---gut feeling is the cirrus from these weakening storms will thin out.
So let's dive into the details. I am about to get nerdy here---so bear with me.
I decided to start with the NAM ---since it is more details and has the future radar attached to it unlike the GFS.
The NAM brings the line of storms close to us by 5/6pm. It has a very intense line of storms in OH. And to show up in yellow this far in advance---that line will be nasty.
By 11pm, the NAM has the main line south of 64 pushing into our southern counties.
We should be able to reach 95-100 in the afternoon heating before the line sags into our region. The hotter we get---the more energy involved in this equation.
Speaking of energy---the main reason we are talking about severe weather to begin with is the winds aloft. It is hard to even get a breeze in the summers here in KY---let alone strong winds aloft. But that is what we are facing. So this will allow the storms to breath--and become long lasting. Not to mention---wind damage threat.
The winds aloft are strong over us...at about 30 kts. That is sufficent for severe weather. But it is over 40kts to our northeast in OH and the NE states. Both NAM/GFS below have a similar look to this idea.
NAM ( click to see larger) GFS
CAPES over us tomorrow vary a bit on each model---but certainly high enough for severe weather.
NAM 2500-3500 GFS 1500-2000
late afternoon (small threat in IN...very high threat in the NE. I would suspect a tornado watch in that area based on these values)
evening... the EHI's go up along the squall-line itself. That is pretty normal. Brief rotations/funnels possible---but not the main issue with this event.
Here is the latest from SPC:
SLIGHT RISK -for us.... MODERATE RISK to the N/E
% RISK for severe--- 30% over us... 45% hatched to our N/E. Hatched area means significant wind damage possible.
This looks to be a busy day with watches and warnings. We need to monitor the storms overnight to determine cloud cover for the area in the morning/midday. Otherwise--it will be a wait/see to when the storms fire. One thing to keep in mind---this line of storms will likely tilt..or become horizontal by mid to late evening. This means it will make SLOW progress to the south...and FAST progression on the northern side. So OH/PA region likely will see severe weather before it even pushes south to the Ohio River. The high wind threat/small tornado threat will be at its peak across IN/OH...and KY north of I 64. Once it crosses I 64 and becomes horizontal, I suspect we will transition from a severe storm threat to a heavy rain threat as "training" of storms could take place. The storms should push toward TN by Friday morning---but if the front lags on timing--- KY counties could see a storm threat on Friday as well--but to a much LESSER degree of intensity since the wind energy would have passed on to the east and off the coast. Will we see the MODERATE RISK pushed south into our area? The only way I see that is if the models/soundings come in later showing the winds could exceed 35kts over head and/or greater instablity. Right now---I think where SPC has the outlooks--lines up well with the data.
Morning/Midday- looks dry. Maybe some cirrus overhead. Humid. Hot.
Afternoon: storms pop across IL/IN/OH. Watches start coming out. Temps locally approach 100
Evening (likely after 7/8pm) : Active look to the radar with storms sagging south.
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As always, nothing is a sure thing in these setups---but the GFS/NAM are in decent agreement that the main show will be north/east of our viewing area---but we will be close enough to see a risk for damaging storms. We will watch it carefully.