SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Fri Mar 15 2024
Valid 151630Z - 161200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
EDWARDS PLATEAU AND INTO PARTS OF SOUTH TEXAS...
...SUMMARY...
Scattered severe thunderstorms with very large hail and isolated
damaging winds are expected through this afternoon and overnight
from the Edwards Plateau into south-central Texas. Additionally,
damaging winds and hail will be possible extending eastward from
south-central Texas across the central Gulf Coast region.
...Edwards Plateau region into South Texas...
As a short-wave trough continues shifting eastward away from the
region/across East Texas/Arkansas/Louisiana, weak subsidence should
suppress convective development into early afternoon. However,
strong heating of the moist boundary layer near and south of the
front, combined with steep lapse rates aloft, will provide a very
favorable thermodynamic environment (mixed-layer cape in excess of
2500 to 3000 J/kg).
Despite the weak forcing aloft, low-level ascent near and just north
of the surface front, and near upslope-favored areas just west of
the Rio Grande, should result in at least isolated storm development
this afternoon, with any storms rapidly becoming supercells. While
low-level veering is sufficient to support low-probability risk for
a tornado, very large hail -- in excess of baseball size -- will be
the primary severe risk. Locally damaging winds will also be
possible -- particularly if storms can cluster together and spread
southeastward toward south Texas later this afternoon and evening.
...Southeastern Texas eastward to the Southeast...
Thunderstorms are ongoing this morning from Louisiana eastward
across Georgia and South Carolina, in the vicinity of the sagging
surface cold front. Near and south of the boundary, broken cloud
cover is allowing for some heating, which -- combined with the moist
boundary layer and sufficiently steep mid-level lapse rates -- has
pushed mixed-layer CAPE values into the 1500 to 2500 J/kg range from
the Texas Coastal Plain eastward to southwestern Alabama.
Flow just off the surface is veered/southwesterly across this
region, resulting in a unidirectional deep-layer wind field across
this area. While this should largely limit overall tornado
potential, the increasing flow with height is providing favorable
directional shear for organized storms, and attendant risks for
damaging winds and hail. Expect storms to increase in coverage
through late morning/early afternoon, with an attendant/expanding
severe threat to follow. Risk will sag southeastward with time,
possibly lingering into early evening before diurnally
decreasing/shifting offshore.
Farther west, across southeastern Texas and the Coastal Plain,
broken clouds are allowing ample heating/destabilization to occur.
CAMs continue to forecast a separate cluster of storms developing
across this region near the sagging front, which seems reasonable in
tandem with the short-wave trough presently moving eastward across
this area. With deep-layer shear plenty sufficient for
organized/rotating storms, locally damaging winds and large hail are
expected. This convection should spread eastward across
southeastern Texas this afternoon and evening, and possibly into
southwestern Louisiana before weakening overnight.
..Goss/Weinman.. 03/15/2024
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