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ACUS11 KWNS 261950
SPC MCD 261949

Mesoscale Discussion 0335
NWS Storm Prediction Center Norman OK
0249 PM CDT Sun Mar 26 2017

Areas affected...Central/Northeast OK...North-Central TX

Concerning...Severe potential...Tornado Watch likely

Valid 261949Z - 262115Z

Probability of Watch Issuance...95 percent

SUMMARY...Supercell thunderstorms capable of all severe hazards,
including tornadoes and very large hail, are expected across
portions of central OK and north-central TX this afternoon and
evening. A tornado watch will likely be needed by 21Z.

DISCUSSION...Recent surface analysis shows a low centered just
northwest of GAG with a dryline arcing southeastward to just west of
CSM and then southwestward through FDR (in southwest OK) and ABI (in
the low rolling plains of TX).  A warm front also extends from this
low eastward/southeastward from GAG to END to CUH and on into
southeast OK. Low-level moisture continues to advect northward in
the warm sector between the dryline and warm front, with 60 degree F
dewpoints as far north as Love, Carter, and Marshall counties in far
south-central OK. Mid-50 degree F dewpoints extend as far north as
Caddo, Grady, and McClain counties. Given the filtered sun across
the region, some modest mixing is possible but dewpoints are still
expected to range from the mid-50s to low 60s from central OK
southward into north-central TX. This low-level moisture coupled
with steep mid-level lapse rates will result in moderate instability
(i.e. MLCAPE from 1500 to 2000 J/kg) by 21Z ahead of the approaching

Visible satellite imagery continues to show agitated cumulus beneath
the mid/high-level cloud band with some towering cumulus also noted
near the western edge of the cloud band, close to current position
of the dryline. The western edge of the cloud band also likely
represents the leading edge of strong forcing for ascent associated
with the approaching shortwave trough. As such, the current thinking
is that convective initiation will occur as the dryline and stronger
forcing for ascent interacts with the destabilizing airmass across
central OK around 21Z. Favorable kinematic profiles characterized by
0-6 km bulk shear near 50 kt will support quick storm organization,
resulting in supercells capable of all severe hazards including
tornadoes. Additionally, low-level jet increase around 00Z will
lengthen hodographs in the presence of ongoing storms, resulting in
a locally higher threat for tornadoes from south-central OK into
northern portions of north-central TX.

Somewhat different scenario will lead to the chance of a few
tornadoes farther north within the marginally moist environment
across north-central OK and possibly into far south-central KS.
Here, some severe threat, including tornadoes, is possible as storms
interact with the warm front draped across the region.

..Mosier/Guyer.. 03/26/2017

...Please see for graphic product...


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