SPC AC 170730
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Sun Sep 17 2023
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHWEST TEXAS
INTO WESTERN AND CENTRAL OKLAHOMA...
Widely scattered severe thunderstorms are possible Tuesday and
Tuesday night across portions of the southern Great Plains. Large
to very large hail and severe gusts are the primary hazards.
...TX northward into southern KS...
A weak mid-level disturbance, initially over the CO/northern NM
vicinity, will move east-southeastward into OK by early evening and
be to the north of a flattened mid-level anticyclone over Mexico.
Isolated showers/thunderstorms may be ongoing Tuesday morning across
parts of OK/KS in association with a 40-kt south-southwesterly LLJ.
Models vary regarding the details and subsequent evolution of this
potential convective activity during the day. Regardless, southerly
low-level flow east of a lee trough/sharpening dryline will favor
increasing moisture across northwest TX into western OK (surface
dewpoints into the 56-62 deg F range). An appreciable westerly
component of the flow in the midlevels will aid in eastward
advection of steeper lapse rates. Strong heating in areas void of
cloud debris/early day storms will likely become moderately unstable
(1000-2500 J/kg MLCAPE). Elongated hodographs due to the proximity
of a 75-100 kt 250 mb jet over the TX Panhandle/northwest TX will
favor organized storms, including the possibility for supercells.
It seems the dryline will probably serve as a focus for isolated to
scattered thunderstorm development on Tuesday afternoon. Large to
very large hail and severe gusts are the primary hazards. A
strengthening LLJ during the evening centered over the Red River
Valley will probably lead to some upscale growth in the form of a
strong/severe cluster. This activity may continue into early
Wednesday with a lingering risk for severe.
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