Day 1 Severe Weather Outlook

Valid 281200Z – 291200Z


Scattered thunderstorms may impact portions of the southern Plains
into the northwest Gulf coast vicinity today into tonight, but the
risk for severe weather appears negligible.

The next in a series of significant short wave troughs emanating
from a strong jet over the mid-latitude Pacific is forecast to
accelerate northeastward toward the northern British Columbia coast
during this period. As it does, models indicate that sharp ridging
will build downstream, across the eastern Pacific through the
Pacific Northwest and Canadian Rockies by 12Z Wednesday.

To the east of the ridging, a vigorous short wave trough, initially
approaching the Pacific Northwest coast, is forecast to become
increasingly fragmented as it progresses inland, with most of the
emerging smaller-scale perturbations gradually turning sharply
south-southeastward through the Intermountain West. As this occurs,
downstream troughing, now east of the Rockies, appears likely to
remain progressive, and slowly shift across the Plains toward the
Mississippi Valley.

The elongated lead troughing is comprised of at least a couple of
smaller-scale perturbations, with perhaps the most prominent on the
southern end including an evolving mid-level cyclonic circulation to
the lee of the southern Rockies. Weak to modest cyclogenesis is
ongoing in association with this feature across the Texas Panhandle
into northwest Texas. However, models continue to indicate that
there will be little, if any, subsequent deepening today through
tonight. The low is forecast to redevelop southeastward across
eastern Texas into the vicinity of the Louisiana Gulf coast by 12Z
Wednesday, with a fairly sharp cold front surging southeast of the
Texas/Oklahoma Panhandle vicinity, through central Texas and Texas
Gulf coastal areas.

In the wake of a preceding cold front, associated with broad,
large-scale troughing continuing to slowly shift east of the
Atlantic Seaboard, boundary-layer dew points are relatively low
across much of the northwestern Gulf of Mexico. And models indicate
that modification sufficient to support a substantive inland return
flow of boundary-layer based moisture is unlikely during this

…Southern Plains into Texas/Louisiana Gulf coast…
Weak thunderstorm development is ongoing across the southern Plains,
aided by increasing large-scale ascent and destabilization
associated with elevated moisture return. This activity may linger
beyond 12Z this morning across the Red River Valley, while also
spreading east of the I-35 corridor of Texas, before diminishing as
initial forcing weakens and/or spreads through the moisture/weak
instability axis.

In the wake of this initial activity, despite marginal surface dew
points (lower/mid 50s F) for vigorous convective development,
various model forecast soundings do suggest that there is potential
for weak boundary-layer based destabilization to take place. Aided
by daytime heating beneath a mid-level dry slot, and subsequent
mid-level cooling, this probably will become focused along a
pre-frontal surface trough, which is expected extend from south of
College Station into areas near or just east of the Dallas-Fort
Worth Metroplex by late afternoon.

Although westerly deep-layer shear will be strong, low-level flow
and shear near this boundary may be weak, with the belt of stronger
southerly 850 mb flow shifting off to the east. And the extent to
which mid-level forcing for ascent is able to support sustained
convective development remains unclear. While an isolated strong
storm or two posing some risk for marginally severe hail and wind
may not be completely out of the question, severe weather
probabilities still seem less than 5 percent at this time.

..Kerr/Squitieri.. 01/28/2020


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