ACUS48 KWNS 220850
SPC AC 220848
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CDT Mon Apr 22 2019
Valid 251200Z - 301200Z
...Thursday/Day 4 to Friday/Day 5...
On Thursday, an upper-level trough is forecast to move from the
southern Plains into the Arklatex with a cold front moving eastward
across the western Gulf Coast States. Thunderstorms are forecast
ahead of the front in the lower Mississippi Valley. Moderate
instability and deep-layer shear should be sufficient for a severe
threat. The timing of the upper-level trough and magnitude of
instability suggest that there is some uncertainty for Thursday.
On Friday, the upper-level trough is forecast to move eastward to
the eastern Seaboard with the cold front advancing to the eastern
Gulf Coast States. Moderate instability and deep-layer shear are
forecast across the southern half of the Florida Peninsula where an
isolated severe threat will be possible. Timing issues with the
upper-level trough make uncertainty too great to add a severe threat
area at this time.
...Saturday/Day 6 to Monday/Day 8...
From Saturday into Sunday, the medium-range models move a shortwave
trough eastward into the Mississippi Valley and develop an
upper-level ridge across the southern and central Plains. Moisture
return is forecast to take place across the Great Plains where
thunderstorm development will be possible each day. The greatest
chance for a severe threat appears to be on Monday across Kansas and
southern Nebraska. Even so, model differences introduce a lot of
uncertainty so will maintain predictability too low.
On Monday, large model spreads suggest that predictability will be
very low late in the day 4 to 8 period.