|Mesoscale Discussion 43|
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Mesoscale Discussion 0043
NWS Storm Prediction Center Norman OK
0930 AM CST Sat Jan 14 2017
Areas affected...Portions of the TX/OK Panhandles...western
Valid 141530Z - 141930Z
SUMMARY...The risk for freezing rain accompanying showers and
thunderstorms will spread northward/northeastward through the day.
DISCUSSION...While water vapor loops indicate the primary upper
cyclone lagging well to the west of the region -- i.e. centered off
the Baja Peninsula coast -- peripheral midlevel height falls are
ongoing across the region. The larger-scale mass response to the
approach of the cyclone is encouraging a recent uptick in warm
advection, which has become manifested in clusters of showers and
thunderstorms developing across West TX. This activity is most
concentrated within a band from the central TX Panhandle into
west-central OK, and in clusters southward across the TX South
Plains. Continued elevated moisture transport and warm advection
will encourage development of this activity during the next several
hours, which will subsequently spread northward/northeastward
through the afternoon.
Maximum elevated warm-layer temperatures around 8C per Amarillo TX
and Dodge City KS 12Z soundings imply complete melting of descending
hydrometeors, while sub-freezing wet-bulb surface temperatures will
support freezing rain. Freezing-rain rates of 0.02-0.10 in/hour will
be possible -- highest in convective cores with lightning.
Occasionally, ice pellets could accompany the strongest convective
cores, as well.
Sensible heat fluxes extending downward from the elevated warm
layer -- facilitated within precipitation cores -- may eventually
contribute to sufficient surface warming across parts of the TX
Panhandle/South Plains for a transition to mainly rain by the
afternoon. Meanwhile, antecedent lower theta-e within the surface
layer across areas farther north and east -- into parts of
west-central/northwest OK, the OK Panhandle, and southwest KS --
will more likely support sustained ice accumulations in these areas.
LAT...LON 37599878 36899860 35449929 34410029 34380140 35110195
36420185 37570123 37849944 37599878
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