SPC AC 131932
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0232 PM CDT Sun Oct 13 2024
Valid 132000Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN APPALACHIANS INTO PARTS OF THE TENNESSEE VALLEY...
...SUMMARY...
Strong to locally severe thunderstorms are possible, mainly this
evening, from Pennsylvania southward to the Tennessee Valley.
Isolated wind damage should be the main threat.
...20z Update...
The previous forecast largely remains on track with only minor
adjustments made. The 5% wind/Marginal risk area was expanded
slightly across portions of central to northeast PA where morning
cloud cover has cleared and allowed for stronger daytime
heating/destabilization (denoted by temperatures in the upper 70s to
low 80s). These observations appear to be well assimilated into
recent HRRR/RRFS runs, which have trended towards a slightly
stronger UH/convective signal compared to early-morning solutions.
The risk lines have been adjusted to account for these recent
trends.
..Moore.. 10/13/2024
.PREV DISCUSSION... /ISSUED 1116 AM CDT Sun Oct 13 2024/
...Central/Southern Appalachians into the Tennessee Valley...
Water vapor loop shows a fast-moving and deepening shortwave trough
over WI. This feature will dig southeastward across the Great Lakes
region through the day, with fast flow aloft extending eastward
across the central Appalachians. A surface low currently over
northern OH will track eastward across PA along a warm front, while
an associated cold front sweeps southeastward across OH/WV/KY/TN.
Low-level moisture is quite limited ahead of this system, which will
limit coverage and overall intensity of convection. However, over
half of morning CAM solutions suggest thunderstorm development along
the front this afternoon and evening, where winds aloft and steep
low-level lapse rates will promote a risk of locally gusty/damaging
winds.
The MRGL risk area has been extended northeastward into parts of
central/northeast PA, ahead of the surface low and along the warm
front. CAPE will be very weak in this area, but forecast soundings
and some CAM guidance suggest the potential for 1 or 2 rotating
storms capable of gusty wind or perhaps a brief spin-up around peak
heating.
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