SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Tue Aug 30 2022
Valid 302000Z - 311200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST AND MID-ATLANTIC...
...SUMMARY...
Isolated wind damage may occur this afternoon and evening from parts
of Virginia northward into New York and northern New England.
...20Z Update...
Severe wind probabilities have been trimmed behind ongoing clusters
of convection across the Northeast and Mid-Atlantic. Occasional
damaging winds will continue to be the main severe threat with these
thunderstorms as they move eastward through the rest of the
afternoon and early evening.
..Gleason.. 08/30/2022
.PREV DISCUSSION... /ISSUED 1118 AM CDT Tue Aug 30 2022/
...VA to NY and northern New England this afternoon/evening...
A midlevel trough over IN/OH will move eastward to the Mid-Atlantic
and New England by tonight, along with an associated surface cold
front. A thick cloud band precedes the midlevel trough and
accompanies the frontal zone, and midlevel lapse rates are poor in
the warm sector. Differential heating and ascent along the east
edge of the thicker clouds will support thunderstorm development in
bands early this afternoon from northern VA northward across
central/eastern PA and NY. Surface temperatures warming into the
80s with boundary-layer dewpoints in the upper 60s to lower 70s will
support MLCAPE of 500-1500 J/kg, though poor midlevel lapse rates
and relatively moist profiles in the zone of storm initiation will
tend to mute downdraft potential. Thus, isolated strong outflow
gusts and some wind damage may occur with the stronger clusters/line
segments this afternoon in an environment with roughly 30 kt
midlevel flow, but the potential for severe outflow winds appears to
be low enough to maintain 5% wind/Marginal risk.
...Lower MS Valley area this afternoon...
Cloud breaks will allow surface temperatures to warm to near or just
above 90 F, while boundary-layer dewpoints will be maintained in the
low-mid 70s. Forcing for ascent and vertical shear will be weak,
but widely scattered thunderstorms will be possible this afternoon
as convective inhibition is removed via daytime heating/mixing.
Regional 12z soundings revealed the potential for afternoon MLCAPE
near 3000 J/kg, but relatively moist profiles will limit the
potential for intense downdrafts. Isolated/localized wind damage
could occur with precipitation-loaded downdrafts, but the potential
for severe outflow winds appears too low to warrant adding an
outlook area.
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