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Mesoscale Discussion 2229
NWS Storm Prediction Center Norman OK
0125 AM CST Mon Nov 18 2024

Areas affected...much of northwestern Texas into southwestern
Oklahoma

Concerning...Severe potential...Watch likely 

Valid 180725Z - 180930Z

Probability of Watch Issuance...80 percent

SUMMARY...Potential for damaging wind gusts and perhaps a few
tornadoes may begin to increase with an evolving squall line
accelerating northeast of the Texas South Plains through much of
northwestern Texas and southwestern Oklahoma by 3-5 AM CDT.

DISCUSSION...Downstream of a 90+ kt 500 mb jet streak beginning to
nose northeast of the Texas Big Bend into the Pecos Valley, strong
forcing for ascent continues to aid the evolution of a squall line
in advance of a deepening surface low now near/southwest of Lubbock.
Instability is still rather weak in the presence of thermodynamic
profiles characterized by modest mid-level lapse rates, but weak
low-level lapse rates and modest moisture.  However, low-level and
deep-layer shear is strong, and an ill-defined meso-beta scale
mid-level cyclonic circulation is now progressing  northeast of
Lubbock.  

A number of better defined meso-gamma scale cyclonic circulations
are evident along the line, which has been surging northeastward
around 30 kt, to the northeast of the mid-level circulation.  This
appears likely to propagate into the Altus OK vicinity through
09-11Z, with the southern flank of the line progressing across the
Abilene TX vicinity.
 
In response to the deepening surface troughing, a gradual
north-northwestward advection of mid 60s to near 70F surface dew
points toward the upstream squall line will gradually contribute to
somewhat more unstable updraft inflow.  This may also contribute to
a boundary-layer at least marginally more supportive of downward
momentum transfer to the surface and potential for tornadoes, as
low-level shear intensifies beneath an 850 mb jet forecast to
strengthen in excess of 50 kt.

..Kerr/Gleason.. 11/18/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FWD...OUN...SJT...LUB...AMA...MAF...

LAT...LON   33610035 34130064 35169968 35239810 34159800 32049873
            31479966 31470050 32160084 33610035