squall line later today


A squall line of thunderstorms is likely to form along a cold front this afternoon over our region. With this being the case the trick will be exactly where does this develop as regions to the south and east of where this line will be impacted.

Overall the models have been trending toward a more unstable set-up with each run. However two thoughts of caution the first Is this the NAM I’m showing which usually overdoes things a bit in severe set-ups, second a period of clouds and showers may move through east KY early which could limit instability. Though this new NAM run is quite unstable enough for severe later today.  Lapse rates in the afternoon approach 10*C/KM which is quite steep this aids in the instability and also promotes a gusty wind and hail threat with storms.  Once again I’ll show the instability region this time 1000J/KG is OK over 1500 is unstable. This is measure of the potential energy in the atmosphere.

Wed PM

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My thinking is this should be sufficient for the squall line along with a few other indicators that are showing a unstable atmosphere across the region.  However in terms of a tornado threat directional shear ( changing of wind direction with height)  will be very limited across the region which should inhibit anything more than an isolated tornado threat.

Onto the big challenge where does this line form and at what time?

– the NAM develops the squall line just south of the Ohio river and has it impact the entire region, my thinking is this model is to slow with the system. The faster movement will allow for storm to develop further southeast than this run shows. GFS overall supports this idea

NAM above. The front in the afternoon should be moving through the region behind the low pressure system by mid afternoon forcing ahead of the front is sufficient enough to develop thunderstorms which quickly become a line of strong to severe storms with gusty winds from 40-80 mph in spots and hail.

My thoughts

Zone A: best chance of impact from squall line or squall line/thunderstorm formation during the late afternoon with a signficant impact. regions southeast of this zone will see the squall line after initial formation.

Zone B; potential for squall line to develop near region best chance is further southeast (40%) chance impact from squall line of thunderstorms

Zone C: development will likely be further southeast low chance of squall lien formation in this region.

– Areas south and east of where the squall lien forms will have the potential for thunderstorms that contain wind gusts of 40-80 mph and hail, thus a severe thunderstorm watch may be issued later today for parts of the region based on where storms develop. This line will quickly move southeast through the late afternoon and evening.  

Hopefully I’ll have to time to update once i gain confidence later today in where the line will form and which regions will be most impacted.


One Response to “squall line later today”

  1. mitchg Says:

    GFS continues trend for a wintry weekend for the far north.

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