Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS02 KWNS 270535
SPC AC 270535
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 AM CDT Mon Mar 27 2017
Valid 281200Z - 291200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS TUESDAY
AFTERNOON AND EVENING OVER PARTS OF WEST-CENTRAL TEXAS AND SOUTHWEST
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
WESTERN-CENTRAL AND NORTH-CENTRAL TX INTO MUCH OF OKLAHOMA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
TEXAS AND OKLAHOMA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
THE MID-ATLANTIC REGION...
Severe storms are forecast on Tuesday over parts of west-central and
north-central Texas, and much of Oklahoma. A few strong to severe
storms are also possible over parts of the Mid-Atlantic region.
A strong shortwave trough currently off the coast of northern CA
will move into the southwestern states and deepen by Tuesday
afternoon. Strengthening southerly low-level wind fields over TX
will rapidly transport Gulf moisture northward, with dewpoints in
the 60s ahead of a dryline positioned over west-central TX. A warm
front will extend from southwest to northeast across OK by early
evening. The area near the triple-point of these boundaries is
likely to be the focus for supercell thunderstorm development.
Forecast soundings in the warm sector indicate ample low level
moisture beneath steep mid level lapse rates, yielding afternoon
MLCAPE values around 2000 J/kg. Substantial low-level and
deep-layer vertical shear are expected, supportive of supercells
capable of very large hail, damaging winds, and tornadoes.
There are still uncertainties regarding the details of this setup.
Most models suggest that considerable thunderstorm activity will
occur Tuesday morning over the TX Panhandle and northwest OK. This
will likely modulate the position of the warm front, and perhaps the
northern extent of greatest threat. Therefore will maintain the
ongoing ENH risk, with consideration for upgrade to MDT risk in
Storms will progress east-northeastward into south-central OK and
north-central TX during the evening, with a continued enhanced-risk
of severe weather.
...Mid Atlantic Region...
The shortwave trough currently affecting the Southern Plains will
track across the MS/OH valleys on Monday and affect the Mid-Atlantic
states on Tuesday. A consensus of model guidance suggests that warm
and relatively moist low-level conditions will be present, with
dewpoints around 60F and afternoon MLCAPE values around 1000 J/kg.
Scattered thunderstorms are forecast to develop ahead of the trough
over parts of PA/MD/VA/NC and track eastward toward the coast by
evening. The strongest cells in this area could produce hail and
locally damaging wind gusts.