SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sun Aug 18 2024
Valid 182000Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ALONG AN AXIS FROM SOUTHEAST KANSAS INTO
ARKANSAS/MISSISSIPPI...THEN EXTENDING ACROSS THE SOUTHEAST STATES
INTO THE CAROLINAS AND MID ATLANTIC REGION...
...SUMMARY...
Clusters of severe thunderstorms with strong/damaging winds are
possible today along an axis from eastern Kansas into
Arkansas/Mississippi, then extending across the southeast states
into the Carolinas and Mid Atlantic region.
...20Z Update...
The forecast generally remains on track, and very minor changes were
made with this update. In particular, the Slight Risk was trimmed
across much of northeast/eastern KS -- behind a remnant MCS now
tracking southeastward across southeast KS. Large uncertainty
remains regarding the evolution of these storms through the
afternoon, though strong diurnal heating/increasing instability and
favorable deep-layer shear could still favor an eventual increase in
intensity.
From the Southeast into the Mid-Atlantic, clusters of storms
continue to intensify and track southeastward and east-northeastward
respectively, posing a risk of damaging winds and isolated severe
hail. For details, reference MCDs 1945, 1946, 1947, and Severe
Thunderstorm Watches 634, 635, and 636.
Farther west, thunderstorms will continue spreading northward across
parts of the Great Basin, posing a risk of damaging winds. Reference
MCD 1944 for more details.
..Weinman.. 08/18/2024
.PREV DISCUSSION... /ISSUED 1121 AM CDT Sun Aug 18 2024/
...Eastern States...
A broad upper trough persists over the eastern US today, with the
main baroclinic zone extending from eastern NY/PA southward into the
Mid Atlantic region and western Carolinas. Pockets of strong
heating and a very moist surface air mass will result in widespread
moderate CAPE values ahead of the front this afternoon, where
scattered thunderstorms are forecast to develop. Cyclonic flow
aloft around the upper trough will be sufficient to help organize
storms into multicell clusters capable of damaging wind gusts and
some hail. This activity will slowly move eastward through the
early evening with a continued severe threat.
...Southern States...
Clear skies are present today across the southern tier of states,
with dewpoints in the mid 70s yielding afternoon CAPE of 2500+ J/kg.
Widely scattered thunderstorms will develop by mid-late afternoon
along the western extent of the aforementioned baroclinic zone that
will stretch from central GA/AL/MS then northwestward across AR.
Moderately strong mid-level winds, and considerable dry air aloft
will help to promote downburst winds in the strongest cores
throughout this corridor.
...Eastern KS...
A nocturnal MCS persists this morning over southeast NE. Most 12z
CAM guidance suggests this cluster of storms diminishes, however
given the mesoscale organization of the MCS, it could persist
through the morning diurnal min. If that scenario occurs,
conditions favor a potentially damaging wind event across parts of
eastern KS through the afternoon and evening.
...UT/ID/MT...
Several weak mid-level shortwave troughs are evident this morning
across the northern Great Basin. These features and associated
pockets of mid-level moisture will aid in the development of
scattered thunderstorm development from southern UT northward into
the mountains of western MT. Favorably strong southerly winds aloft
will support a risk of gusty/damaging wind in the strongest cells.
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