ACUS01 KWNS 131247
SWODY1
SPC AC 131246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sun Oct 13 2024

Valid 131300Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL/SOUTHERN APPALACHIANS AND TENNESSEE VALLEY...

...SUMMARY...
Strong to locally severe thunderstorms are possible, mainly this
evening, across parts of the central/southern Appalachians and
Tennessee Valley. Isolated wind damage and marginally severe hail
should be the main threats.

...Central/Southern Appalachians into the Tennessee Valley...
Ongoing elevated thunderstorms across northeast OH and western PA
should continue eastward this morning in tandem with an enhanced
west-southwesterly low-level jet. This activity is expected to
outpace low-level moisture return and related destabilization today,
and eventually weaken. But in the short term, small hail remains
possible. Meanwhile, a vigorous shortwave trough over the Upper
Midwest will dig southeastward through the base of a large-scale
mid/upper trough, and yield amplification of this trough southward
across the Great Lakes through Monday morning. Ascent preceding this
shortwave trough will overspread parts of the central/southern
Appalachians into the TN Valley, mainly during the evening and
overnight.

A leading and weaker mid-level perturbation will encourage the
primary surface low to develop eastward across PA this afternoon
through early evening. A surface cold front will extend southwest of
this low into the TN Valley. Convective development along the front
appears likely to be delayed until early evening, as the
strengthening large-scale ascent aids in increasing low-level
convergence along the front amid generally veered flow within the
warm sector. Surface dew points should largely range from the mid
50s in WV to a narrow corridor of low 60s in TN, yielding a plume of
MLCAPE around 500-1500 J/kg amid initially steep mid-level lapse
rates.

Recent guidance still differs regarding storm coverage along/ahead
of the cold front this evening, from almost none to scattered. This
is perhaps in response to the ascent with the shortwave trough
strengthening after peak diurnal heating. The strongest 700 mb
westerlies (around 40-55 kt) should be confined to mainly northeast
of the TN Valley. Forecast hodographs above this level appear small,
owing to weakening winds with height as fast mid/upper flow lags to
the north-northwest. This suggests supercell structures may struggle
to develop/be sustained. But the strong 700 mb flow could support
localized damaging winds in any multicell clusters that can form.
Farther southwest, somewhat greater buoyancy could foster small to
marginally severe hail as well. The overall severe threat appears
likely to remain rather isolated, and no changes have been made to
the Marginal Risk with this update.

..Gleason/Jewell.. 10/13/2024

$$
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