SPC 0100Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0700 PM CST Wed Dec 30 2020

Valid 310100Z - 311200Z


A few locally strong wind gusts, some hail and a brief tornado
remain possible along a portion of the Texas Coastal Plain tonight.

...Texas Coastal Plain...

This evening a slow-moving cold front extends from northern LA into
the TX Coastal Plain. A moist boundary layer with mid to upper 60s F
dewpoints has advected inland through the pre-frontal warm sector
with 00Z RAOB data and objective analysis indicating MLCAPE from 800
to 1000 J/kg. A pronounced mid-level inversion (near 700 mb) was
indicated on the 00Z CRP RAOB data. So far most surface-based storms
have been developing along a pre-frontal convergence band extending
from the western Gulf into the central TX coastal area near
Palacios. Hodograph size in the 0-2 km layer remains modest with
150-200 m2/s2 storm relative helicity. Weak to modest winds are
evident between 850 and 700 mb. However, effective bulk shear from
35-45 kt is sufficient for some updrafts to develop weak rotation.

A somewhat greater chance for a couple of organized storms is
expected later tonight as deep forcing for ascent attending the
vigorous shortwave trough over northern Mexico intercepts the warm
sector across the southern and central TX coastal regions. Low-mid
level wind speeds and vertical shear will also undergo some increase
with the approach of the shortwave trough. Some erosion of the
mid-level inversion is also expected, and additional storms will
likely develop along and just ahead of the southward-advancing cold
front. A few organized storms including a couple of supercells are
possible as the environment becomes more favorable. However, the
warm sector will diminish in size as the cold front approaches the
coast. Tendency will be for more robust updrafts to be undercut by
this boundary which should provide a limiting factor for a more
widespread/robust severe threat.

..Dial.. 12/31/2020

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