Dan Robinson
EF5
Sunday afternoon's event looks like a conditionally potent low-instability, high-shear tornado setup. An approaching strong upper wave will spin up a very deep powerhouse of a low, pulling moisture with dewpoints as high as the upper 50sF all the way up into northern Illinois. An equally-strong cold front (with arctic air upstream) will plow through this warm sector, initiating storms by midday. These quasi-linear storms are shown intensifying through the afternoon and evening as they race northeast into the nighttime hours.
The main tornado risk for this setup appears to be after dark, but two daytime targets appear evident: the typical northeast-quadrant arc of storms where the front curves back into the low from Davenport, IA to Peoria, IL, and an area of higher instability roughly from Memphis back through southern Arkansas where dewpoints will make it into the 60sF. The dynamics in the northern target make it the preferred one if there is any meaningful instability - and models do show sufficient 0-3km CAPE there. CAPE is better in the southern target, but with weaker low-level dynamics.
The biggest question is where will the storms be in relation to the front. As it's shown now, the cold front's push is strong enough that all of the convection could be easily undercut. In fact, it appears that in some areas, the storms may even be completely anafrontal and elevated. The cold advection behind the front is potent enough that some of the trailing stratiform precip behind the squall line is shown actually changing over to snow, and only a couple of hours after the line's passage!
Storms will be moving too fast to chase, so this also looks like a one-and-done intercept type event, with even the ability to cell-hop over to the next storm in question. A high-speed east-west road will be best.
The main tornado risk for this setup appears to be after dark, but two daytime targets appear evident: the typical northeast-quadrant arc of storms where the front curves back into the low from Davenport, IA to Peoria, IL, and an area of higher instability roughly from Memphis back through southern Arkansas where dewpoints will make it into the 60sF. The dynamics in the northern target make it the preferred one if there is any meaningful instability - and models do show sufficient 0-3km CAPE there. CAPE is better in the southern target, but with weaker low-level dynamics.
The biggest question is where will the storms be in relation to the front. As it's shown now, the cold front's push is strong enough that all of the convection could be easily undercut. In fact, it appears that in some areas, the storms may even be completely anafrontal and elevated. The cold advection behind the front is potent enough that some of the trailing stratiform precip behind the squall line is shown actually changing over to snow, and only a couple of hours after the line's passage!
Storms will be moving too fast to chase, so this also looks like a one-and-done intercept type event, with even the ability to cell-hop over to the next storm in question. A high-speed east-west road will be best.
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