Severe Storm Outlook Narrative (AC)
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829
ACUS11 KWNS 201453
SWOMCD
SPC MCD 201452
OKZ000-TXZ000-201645-

Mesoscale Discussion 0075
NWS Storm Prediction Center Norman OK
0852 AM CST Tue Feb 20 2018

Areas affected...North-Central/Central TX...Far South-Central OK

Concerning...Severe potential...Watch unlikely

Valid 201452Z - 201645Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated hail and damaging wind gusts are possible as a
convective line moves north-northeastward across north-central TX.

DISCUSSION...Regional radar imagery shows a pre-frontal convective
line extending from Montague county in far north-central TX
southwestward to San Saba county in central TX. Given the lack of
surface response as this line moves through as well as low-level
stability noted on regional 12Z soundings, this line predominantly
consists of elevated thunderstorms. Updraft strength within this
line has varied over the last hour but current radar imagery shows a
few fairly strong updrafts with at least 30 dBZ reaching above 9
km/30kft. Additionally, vertical veering VAD wind profiles from FWS
and GRK are supportive of rotating updrafts, which is verified by
modest mid-level rotation observed by FWS within a few cells.

These kinematic and thermodynamic conditions will likely persist as
the band moves north-northeastward, supporting the potential for
isolated hail. This hail is generally expected to be sub-severe
although some instances of hail around 1" are possible.
Additionally, despite the low-level inversion and resulting
low-level stability, strong low-level wind fields (i.e. 50 kt at 1km
from both GRK and FWS) may support downdrafts strong enough to
occasionally reach the surface. Consequently, isolated damaging wind
gusts are also possible. Even so, instances of severe weather are
expected to be isolated, precluding the need for a watch.

..Mosier/Weiss.. 02/20/2018

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

ATTN...WFO...FWD...OUN...EWX...SJT...

LAT...LON   33269806 34219757 34449708 34409669 34169646 33659634
            32939645 32289660 31689678 30949716 30529821 30719891
            31539886 32479845 33269806




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