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Mesoscale Discussion 1917
NWS Storm Prediction Center Norman OK
1128 AM CDT Fri Nov 04 2022
Areas affected...southeastern Oklahoma across north-central and
northeastern Texas
Concerning...Severe potential...Tornado Watch likely
Valid 041628Z - 041730Z
Probability of Watch Issuance...95 percent
SUMMARY...Potential for severe/supercell storms is expected to
gradually increase into the afternoon. All-hazards severe risk is
expected, including likelihood for for significant tornadoes,
widespread damaging winds, and large hail. A tornado watch will
likely be required by early afternoon.
DISCUSSION...Latest radar loop shows convection increasing in
coverage/intensity along an advancing cold front now stretching from
southeastern Kansas across central and southwestern Oklahoma and
into western North Texas. Ahead of the front/frontal convection, a
moistening boundary layer is indicated, with mid 60s dewpoints into
southeastern Oklahoma and low 70s dewpoints now spreading toward the
Dallas/Fort Worth Metroplex.
The low-level moistening is occurring beneath a rather substantial
capping inversion, revealed by the recent 15Z FWD RAOB, and which
extends across the warm sector as suggested by the character of the
low cloudiness as revealed by recent visible satellite imagery.
This cloudiness will continue to retard heating, and thus low-level
destabilization, over the next several of hours, but cooling aloft
-- associated with the advancing upper system -- will allow gradual
airmass destabilization, particularly above 700mb.
Weak warm-advection-induced showery convection indicated across the
warm sector continues to gradually increase, with some small/higher
reflectivity cores beginning to become apparent. Expect a gradual
ramp-up in this convection to continue -- with eventual growth into
cellular/lightning-producing cells as cooling aloft continues within
the capping layer and above.
Once deep convection becomes established, rapid intensification to
severe levels is expected, as very favorable shear -- provided by
low-level southerly flow veering to south-southwesterly and
increasing to 50 kt at around 1km along with additional veering
above -- resides across the warm sector. Risk for
strong/significant tornadoes will then ensue, as storms acquire
strong rotation. Large hail and locally damaging winds are also
expected.
Risk for damaging winds will likely increase later this afternoon
and beyond, as convection strengthens linearly along the front with
time, likely merging gradually with pre-frontal cellular convection
to evolve into a well-developed squall line by early evening. This
anticipated evolution will likely require tornado watch issuance
within the next hour or two, extending eastward across southeastern
Oklahoma and North Texas toward the Arklatex region.
..Goss/Hart.. 11/04/2022