Bevo
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SPC Day 2 update for Thursday:
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Wed Apr 22 2020
Valid 231200Z - 241200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
THE SOUTHEAST...
...SUMMARY...
Significant severe storms are possible over parts of the Southeast
on Thursday, including the potential for a few strong tornadoes and
damaging winds.
...Synopsis...
A positive-tilt shortwave trough will move from the lower MS Valley
toward the Appalachians by evening, with gradual cooling aloft
across the region. A surface low is forecast to move northeast
across KY during the day and toward the coastal Mid Atlantic by 12Z
Friday. A warm front will lift north across AL, GA and SC during the
day, with mid 60s F dewpoints surging north. Farther south,
dewpoints near 70 F will be common along the Gulf Coast. The 850 mb
jet is forecast to be maximized over AL/GA/SC during the day at
around 50 kt, and will lift rapidly north across the Carolinas after
21Z. Meanwhile, a dryline will surge east across the lower MS valley
early, then into AL and northern GA during the afternoon. Given the
positive tilt to this system, the dryline will move slower over
southern AL, MS and LA, where heating may occur. The combination of
a moist and unstable airmass and favorable shear suggest a corridor
of tornado and severe wind potential, although there is significant
uncertainty with this forecast.
...Southeast...
Model consensus is for storms to be ongoing roughly across northern
AL and GA near the warm front. These will likely be elevated
initially, but localized wind damage or a tornado is possible along
the southern fringe. Given little if any capping extending
southwestward ahead of the dryline, other storms may form by 18Z
across AL, southern MS and LA. Some models develop a significant
amount of storms along the Gulf Coast, which may inhibit
destabilization to the north.
Low-level shear for tornadoes will be most favorable early in the
day across LA/MS/AL, and later in the day across GA and SC near the
warm front. Adding uncertainty to this forecast is potential outflow
boundaries from the early day storms, and questions regarding
airmass recovery in those areas (northern GA and SC). Tornado and
wind risk will largely depend on storm mode. If midday heating
occurs along the dryline, and the air mass has not been overturned,
supercells and tornadoes will be possible. A few strong tornadoes
might occur should sufficient SRH (200-300+ m2/s2) remain prior to
850 mb winds veering. Tornadoes will also be possible along the warm
front into GA/SC, assuming it is not reinforced with too much
outflow. Otherwise, a general upscale growth of storms is expected
for the remainder of the area including FL. Damaging winds are most
likely should the storm mode be linear. Given such large model
variability, large changes in area are possible in later updates.
..Jewell.. 04/22/2020
