Day 1 Severe Weather Outlook

Valid 271200Z – 281200Z


Scattered thunderstorms are expected over eastern New Mexico and
west Texas, mainly during the evening and overnight hours. A
marginally severe storm is possible.

An upper trough will become elongated from MT southward into the
Four Corners states as one upper low moves east across AZ and NM,
and another drops south across MT. Ahead of the upper trough,
meridional winds aloft will strengthen over the central and southern
High Plains, with cooling aloft spreading into these areas

At the surface, high pressure will move from the mid MO Valley
toward the OH Valley, beneath shortwave ridging aloft. To the west,
low pressure will develop from CO into west TX, with a cold front
from western NE/KS into west TX by early Saturday. Meanwhile, a warm
front will lift slowly northward from north TX into OK, with
dewpoints into the mid 50s F to I-40 in OK by 12Z Saturday.

…Southern and central High Plains…
Lift will increase during the day over northeast NM into eastern CO
and western KS as relatively warm/moist air overspreads a cool air
mass at the surface. The result will be scattered elevated
thunderstorms. While weak instability will mitigate overall hail
threat despite favorable effective shear, minimal melting potential
may support very small hail with a few of the elevated cores.

To the south, surface convergence will be maximized over eastern NM
into southwest TX during the late afternoon, where backed surface
winds in the moist sector meet veering winds with the cold front.
Heating and subsequent steepening of low-level lapse rates east of
the wind shift are in question, but at least a small area of heating
is likely over southeast NM into southwest TX, where 250-500 J/kg
MLCAPE may develop. Isolated storms are expected along the front by
around 00Z in eastern NM, then spreading into TX during the evening
with increasing coverage near the front. The late initiation, as
well as meridional nature of the trough suggest a low threat of
severe, but a conditional threat of a supercell exists due to
briefly favorable wind profiles. This scenario would support
marginal hail, or perhaps a weak/brief tornado before midlevel winds
back and low-level winds veer.

..Jewell/Bentley.. 12/27/2019


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