SPC AC 071938
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0238 PM CDT Sat Sep 07 2024
Valid 072000Z - 081200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Organized severe thunderstorms are not forecast today, though a few
strong gusts could accompany the more robust storms.
...20Z Update...
The forecast remains on track, and only minor changes were made to
the outlook with this update. In particular, the General Thunder
line was trimmed behind the frontal rain band and associated wind
shift in the Northeast, where cool post-frontal conditions have
generally depleted instability. Updrafts within this band have
remained too shallow/weak for an appreciable lightning risk thus
far. However, an isolated strike still cannot be ruled out,
especially over portions of eastern NJ and far southeastern NY/Long
Island -- where filtered boundary-layer heating has occurred amid
middle 60s dewpoints. Isolated/embedded strong gusts also remain
possible (earlier 44 mph gust in eastern PA), though the
weak/shallow updrafts (and associated downdrafts) should continue to
limit the severe risk.
Elsewhere, severe potential still appears too localized and/or
marginal for severe probabilities. See the previous discussion below
for details.
..Weinman.. 09/07/2024
.PREV DISCUSSION... /ISSUED 1131 AM CDT Sat Sep 07 2024/
...Northeast...
A cold front will move steadily east across the northeast today,
accompanied by showers and thunderstorms. Extensive cloud cover in
advance of the front will tend to limit heating/destabilization,
however modest MLCAPE (on the order of 250-500 J/kg) may develop
from the northern Delmarva Peninsula north into southeast NY this
afternoon. Ascent with an upper-level trough will continue to move
east in tandem with the front, and scattered thunderstorms may
develop this afternoon with some potential for locally gusty winds.
Weak instability and poor low-level lapse rates should limit severe
potential.
...Central High Plains...
Low-level moisture will be generally modest east of a surface trough
that will extend north-south across eastern portions of WY/CO this
afternoon. Still, lower 50s surface dew points and steep mid-level
lapse rates should contribute to MLCAPE of 750-locally near 1000
J/kg. Isolated thunderstorms may form and move southeast within a
northwest mid-level flow environment late this afternoon/evening,
and a deep/well-mixed boundary layer suggests some potential for
localized strong wind gusts. Thunderstorm potential may extend
eastward into western portions of NE/KS this evening as a low-level
jet strengthens. The overall coverage of any severe potential
remains too low to introduce severe probabilities.
...Interior Northwest...
The potential for isolated thunderstorms, already ongoing this
morning over south-central OR, will continue today as modest
large-scale ascent associated with a mid-level trough overspreads
inland areas of the Pacific Northwest. These storms may produce
limited rainfall, exacerbating fire weather concerns.
...Lower Colorado River Valley and Vicinity...
Strong heating will contribute to scattered thunderstorm development
this afternoon, and 12z hi-res guidance suggests that a couple of
stronger storms or small clusters may have the potential for gusty
outflow winds within a hot/well-mixed boundary layer.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
|