SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0220 AM CDT Fri May 20 2022
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST...
...SUMMARY...
Isolated severe storms with wind damage and hail will be possible
across parts of the Northeast on Sunday. A marginal severe threat
may also develop in parts of the lower Mississippi Valley and
central Gulf Coast states.
...Northeast/Mid-Atlantic...
An upper-level trough will move east-northeastward across
southeastern Canada on Sunday, as southwest mid-level flow remains
over the Northeast. At the surface, a low will move northeastward
across Quebec, as a front moves eastward into the central and
northern Appalachians. Ahead of the front, surface dewpoints in the
60s F will result in a moderately unstable airmass by afternoon.
Thunderstorms are forecast develop along the front around midday in
western New York, and move eastward into eastern New York and
western New England during the late afternoon. A few clusters or
line segments are forecast to persist into the early evening.
NAM forecast soundings late Sunday afternoon, along the instability
axis, have MLCAPE peaking in the 2000 to 3000 J/kg range. 0-3 km
lapse rates are forecast to approach 8.0 C/km. This thermodynamic
environment will likely support a wind-damage threat with the more
organized multicell line segments. Deep-layer shear is generally
forecast to be at 35 knots or less, suggesting that the supercell
threat will be minimal. Model forecasts indicate that most of the
convection will form along or near the boundary, as it moves from
west to east across the Northeast. A marginal wind-damage threat may
also develop near or after peak heating southward along the
instability axis from eastern Pennsylvania into northern Virginia.
...Lower Mississippi Valley/Central Gulf Coast States...
Southwest flow at mid levels will be in place across much of the
southern U.S. on Sunday. At the surface, a cold front is forecast to
move southeastward into the lower Mississippi Valley and northern
Gulf Coast states. Scattered thunderstorms should develop near and
ahead of the front during the afternoon as temperatures warm and
low-level convergence increases. The most likely area for
thunderstorm development will be from north-central Louisiana
northeastward into northwestern Alabama. Forecast soundings along
this corridor at 21Z have 0-6 km shear mostly below 30 knots. But
0-3 km lapse rates near 7.5 C/km and MLCAPE around 3000 J/kg should
be favorable for marginally severe wind gusts. Hail could occur with
the stronger updrafts.
..Broyles.. 05/20/2022
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