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ACUS11 KWNS 140405
SPC MCD 140405

Mesoscale Discussion 0040
NWS Storm Prediction Center Norman OK
1005 PM CST Fri Jan 13 2017

Areas affected...Western North TX into western and central OK

Concerning...Freezing rain

Valid 140405Z - 140900Z

SUMMARY...Showers producing freezing rain with rates around 0.05
inch per 3 hours will continue to develop and spread north across
portions of western North TX into southwest, west, and central OK
into the overnight.  Locally greater freezing rain rates around
0.05-0.10 inches per hour will be possible, with stronger showers
and/or isolated thunderstorms.

DISCUSSION...Trends in evening surface observations showed
temperatures across much of western North TX through western and
central OK were in the upper 20s to around 30 F.  At 03Z, the
freezing line extended northeast from portions of western North TX
through extreme south-central to northeast OK.  Since 0130Z, mosaic
radar imagery indicated areas of showers increasing some in
coverage, intensity, and longevity in an area from KABI to KSEP to
southern OK from KFSI to KPVJ.  These showers appear to be
developing in a region of increasing low-level convergence within
the nose of a 30-kt south-southeasterly 850-mb jet across west and
central TX.  Meanwhile, an area of cooler cloud tops moving to the
north-northeast across this same region likely indicate greater
upward motion ahead of a shortwave trough located over Far West TX.

Composite map analysis of 00Z upper air data and recent surface
observations showed a shallow northward-sloping frontal zone with
the surface front extending from the Arklatex to DRT, while the
850-mb front was much farther north from central MO to central and
southwest KS and the northern TX Panhandle.  Lift will continue to
increase across the discussion area as the Far West TX trough moves
toward the north-northeast and the low-level jet strengthens.  These
factors may aid in the development of isolated thunderstorms, given
steeper midlevel lapse rates per 00Z soundings at MAF/AMA.  However,
the aforementioned frontal slope suggests showers should tend to be
mostly shallow, producing mainly light precipitation rates.

..Peters.. 01/14/2017

...Please see for graphic product...


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