SPC AC 231651
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1151 AM CDT Wed May 23 2018
Valid 231630Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
CORRECTED FOR THUNDER LINE
Isolated severe thunderstorms are possible this afternoon and
evening across the High Plains, eastern portions of Virginia/North
Carolina, and eastern Maine.
...Northern High Plains...
Morning water vapor imagery shows a large upper trough over the
western states, with an embedded shortwave trough lifting
northeastward through the four-corners region. Lift ahead of this
feature should overspread parts of WY and southeast MT this
afternoon and evening, leading to scattered thunderstorm
development. Strong daytime heating and surface dewpoints in the
50s, coupled with steep mid level lapse rates and relatively cool
temperatures aloft will yield afternoon MLCAPE values of 1000-1500
J/kg and only a weak cap. This, combined with favorable deep-layer
shear will promote rotating updrafts capable of large hail and
damaging winds. As storms spread eastward into parts of SD/NE,
outflow mergers will likely increase the risk of damaging wind gusts
through the evening.
...Southern High Plains...
Another round of afternoon/evening thunderstorms are expected to
affect eastern NM and west TX. Visible satellite imagery confirms
that considerable low-level moisture is in place over this area, and
as the low-clouds burn off this afternoon, a strongly unstable air
mass should develop. Despite the favorable thermodynamic setup,
vertical shear profiles are quite weak and steering flow is 5-10
knots. This will lead to rather disorganized thunderstorms capable
of locally damaging wind gusts and hail. Through the evening, CAM
solutions suggest that outflows may organize as they spread into
west TX, with an increased risk of gusty/damaging winds in the more
A warm/humid air mass is present today over parts of southern VA and
much of NC, leading to strong afternoon instability (MLCAPE values
of around 1500 J/kg). Models are in good agreement that scattered
thunderstorms will affect this region later this afternoon and
evening. Forecast soundings suggest low-level wind fields will be
quite weak with less than 10kt winds expected in the lowest 4-5km.
This suggests that isolated cells may briefly produce downbursts,
but the threat of a more organized severe event is rather low.
Scattered thunderstorms are expected to affect parts of ME as a
shortwave trough and associated cold front moves through the area.
Organized severe storms are not expected, but the strongest cells
could produce locally gusty/damaging wind gusts - especially in the
eastern parts of the state.
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