SPC AC 190729
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CDT Tue Mar 19 2024
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THURSDAY INTO
THURSDAY EVENING ACORSS PARTS OF CENTRAL AND SOUTHEAST
TEXAS...ADJACENT SOUTHWESTERN LOUISIANA...
...SUMMARY...
Strong thunderstorms may impact parts of central and southeast Texas
into adjacent portions of southwestern Louisiana on Thursday. One
or two organizing clusters could evolve, accompanied by at least
some risk for severe hail and wind.
...Synopsis...
It appears that split westerlies will continue to trend more zonal
to the east of the Rockies during this period, in the wake of a
deepening and occluding cyclone migrating northeastward across the
Canadian Maritimes. Models suggest that the leading edge of a
significant cold intrusion trailing the cyclone will stall across
the southern Mid Atlantic, and perhaps substantively begin to modify
across the Tennessee Valley and Ozark Plateau into the lower Ohio
and Missouri Valleys.
Across the Great Plains, some of this cold air may continue to nose
southward toward the Texas South Plains, in the wake of mid-level
troughing progressing east of the southern Rockies/northern Mexican
Plateau toward the lower Mississippi Valley/northwestern Gulf of
Mexico. Although substantive spread is evident in the various model
output concerning a couple of smaller-scale embedded perturbations,
it appears that one mid-level cyclonic vorticity center will weaken
while progressing east-southeast of the Texas Panhandle vicinity
early the period. A trailing perturbation may become better-defined
while progressing east of the Permian Basin/Texas Bend through the
upper Texas coast vicinity by late Thursday night. Models suggest
that this could support a developing surface low across the upper
Texas coastal plain/northwestern Gulf coast vicinity, along the
western flank of a developing frontal zone extending
east-southeastward into the southeastern Gulf of Mexico. However,
it still appears that any cyclogenesis will be rather weak.
...Southeast Texas...
Moderate boundary-layer CAPE developing beneath warm and capping
elevated mixed-layer air may spread north-northwest of middle Texas
coastal areas, toward the Interstate 35 corridor of central Texas
during the day. This may be aided by a corridor of stronger daytime
heating, but much will depend on the extent of convective
development which may be spreading east-northeastward into middle
Texas coastal areas at the outset of the period, supported by
forcing for ascent associated with a perturbation emanating from the
subtropical eastern Pacific.
There is some signal in the model output that this activity could
grow upscale, supported by increasingly moist/unstable low-level
inflow, while progressing across the coastal plain into the western
Gulf of Mexico. If this occurs, potential for renewed vigorous
thunderstorm later in the day across parts of central into southeast
Texas becomes more unclear. Barring a substantive negative impact
on further inland destabilization, forcing for ascent with the
primary upstream short wave may contribute to the initiation of
scattered thunderstorm activity by late afternoon. In the presence
of strong deep-layer shear, supercells capable of producing large
hail and locally damaging wind gusts will be possible. Although
low-level hodographs may be modest to weak, a tornado or two will
probably also be possible.
Into Thursday evening, convection may tend to consolidate and grow
upscale into an organizing cluster near or just ahead of the
developing surface low across upper Texas into southwestern
Louisiana coastal areas.
It is possible that severe probabilities across at least parts of
upper Texas coastal areas will need to be increased in later
outlooks. However, this may take a few cycles with much depending
on sub-synoptic developments.
..Kerr.. 03/19/2024
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