SPC Mar 12, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0754 AM CDT Wed Mar 12 2025

Valid 121300Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF NORTH
AND NORTHEAST TEXAS AND SOUTHEAST OKLAHOMA INTO SOUTHWEST ARKANSAS
AND NORTHWEST LOUISIANA...

...SUMMARY...
Scattered severe thunderstorms are possible from north Texas and
southeast Oklahoma into the Ark-La-Tex late this afternoon and
evening.  Large to very large hail and severe gusts are the primary
hazards.

...Synopsis...
Water-vapor imagery this morning shows a potent mid-level shortwave
trough over NM/Chihuahua quickly moving eastward into Far West and
Southwest TX.  This disturbance will reach the lower MS Valley and
central Gulf Coast by early Thursday morning.  A belt of strong
west-southwesterly 500-mb flow will move through the base of the
trough over TX into the lower MS Valley during the period.  In
response, a surface low will develop across western Texas and
Oklahoma with increasing southerly flow and moisture return across
Texas into Oklahoma and into the lower Mississippi Valley ahead of
the dryline/front.

...Parts of TX/OK eastward into the Lower MS Valley...
Surface analysis shows a plume of northward-moving moisture from a
modifying Gulf airmass across TX near and to the east of I-35 this
morning.  An initially strong cap (reference 12 UTC Fort Worth, TX
raob) will inhibit storm development through the mid afternoon as
southerly low-level moisture continues to stream northward into
northeast TX and eastern OK/western AR.  Moderate instability is
forecast by mid-late afternoon due in part to cold-air advection in
the mid-levels associated with the approaching trough.  Upwards of
1000-1500 J/kg MLCAPE is forecast east of the dryline.  Strong
heating will likely lead to surface dewpoints mixing into the
mid-upper 50s over north and northeast TX.  Model guidance indicates
scattered storms will likely develop once the cap erodes in parts of
eastern OK southward into TX with this activity spreading east into
adjacent portions of AR/LA this evening and eventually into the
Ark-La-Miss late.  Lower coverage of storms is forecast farther
south across east-central into parts of east TX.  However, stronger
deep-layer shear with southward extent will favor supercell modes
compared to a mix of strong/severe multicells and supercell
structures farther north.  Large to very large hail (potentially 2-3
inches in diameter) is possible with the stronger storms.  An
attendant wind risk will also accompany the stronger storms given
the steep lapse rates.  Upscale growth into one or two clusters is
possible during the evening as this activity moves east into the
lower MS Valley.  

...Elsewhere...
Short-term model guidance indicates a very low-topped forced band
will move southeast across parts of the southern CA coast in advance
of an approaching eastern Pacific mid-level trough.  A strong gust
cannot be ruled out with this activity, but the risk appears too
marginal for low-severe probabilities.

..Smith/Dean.. 03/12/2025

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