Virginia Beach, VA...Omaha, NE...Norfolk, VA...Lincoln, NE...Greensboro, NC...
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
New York, NY...Philadelphia, PA...Jacksonville, FL...Baltimore, MD...Washington, DC...
SPC AC 200558
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Thu Jun 20 2019
Valid 201200Z - 211200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS AND SOUTHERN VIRGINIA...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID MISSOURI VALLEY AND CENTRAL HIGH PLAINS...
Thunderstorms associated with damaging wind gusts and hail are
likely today across parts of the Carolinas into the Middle Atlantic
and Southeast. Isolated severe storms may also develop across parts
of the Great Plains and Mid Missouri Valley.
An upper-level trough will move eastward from the Ohio and Tennessee
Valleys across the Southern and Central Appalachians into the
Carolinas today. Ahead of the trough, a moist airmass will be in
place from Georgia northeastward across the Carolinas into the
Mid-Atlantic with surface dewpoints in the upper 60s and lower 70s
F. In response, a large corridor of moderate instability is forecast
to develop from the southern Appalachian foothills eastward to the
Atlantic coast. Thunderstorms appear likely to initiate and organize
just ahead of the shortwave trough in the southern Appalachians
around midday with this activity moving eastward into the foothills
during the afternoon. Forecast soundings in the foothills in
northwestern South Carolina and west-central North Carolina at 21Z
show MLCAPE values reaching 2,000 J/kg with 0-6 km shear of 30-35
kt. This combined with veered southwesterly winds at the surface and
westerly flow in the low to mid-levels will be favorable for
quasi-linear development. As low-level lapse rates become steep in
the afternoon, conditions will become favorable for wind damage
along the leading edge of an MCS moving eastward away from the
southern Appalachians. For this reason, will upgrade to Enhanced
risk for wind damage across parts of northern South Carolina, North
Carolina and southern Virginia. Isolated large hail will also be
possible with the stronger parts of the linear MCS.
Further north into the Mid-Atlantic, instability is not forecast to
be quite as strong as across the Carolinas. For that reason, the
wind damage threat is expected to remain more isolated and will
depend upon which areas destabilize the most. Wind damage would be
the primary threat across the Mid-Atlantic this afternoon.
Westerly mid-level flow will be in place in the central U.S. today
as a shortwave ridge develops across the central and northern
Plains. Beneath the ridge, an axis of moderate to strong instability
is forecast to develop ahead of a cold front from Kansas northward
into the mid Missouri Valley. Convection appears likely to initiate
along the front with thunderstorms moving eastward across parts of
eastern Nebraska and western Iowa during the late afternoon.
Forecast soundings at 21Z for Omaha, Nebraska and Kansas City,
Missouri show MLCAPE reaching 2,500 J/kg and have strong deep-layer
shear profiles. 0-6 km shear is forecast to be around 55 kt at both
locations suggesting that supercells will be the likely storm mode.
Convective coverage should remain relatively isolated due to a weak
cap but any cells that can initiate and mature should have severe
potential. The strong instability combined with steep low to
mid-level lapse rates would be favorable for wind damage and large
hail. A brief tornado would also be possible with supercells mainly
during the early evening as low-level flow increases across the
...Central High Plains...
Mid-level flow is forecast to become west-southwesterly today across
the central High Plains in the wake of a developing upper-level
ridge in the mid Missouri Valley. At the surface, backed
east-southeasterly flow will be in place which will reinforce an
axis of moisture and instability from southern Kansas extending
northwestward into northeastern Colorado and western Nebraska. As
surface temperatures warm, convection will initiate in the higher
terrain of northeastern Colorado and spread eastward into the
central High Plains this afternoon. Steep low to mid-level lapse
rates and moderate to strong deep-layer shear, evident on forecast
soundings, will be favorable for severe storms. Dry air in the
low-levels may contribute to downburst potential but isolated large
hail will be possible especially if a supercell can develop.
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