Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 120938
SWOMCD
SPC MCD 120938
MSZ000-ARZ000-LAZ000-121545-

Mesoscale Discussion 0021
NWS Storm Prediction Center Norman OK
0338 AM CST Fri Jan 12 2018

Areas affected...Parts of southern AR...northern LA and west-central
MS

Concerning...Winter mixed precipitation

Valid 120938Z - 121545Z

SUMMARY...A mixture of freezing rain and sleet will continue to
spread eastward during the late overnight into the morning across
south-central and southeast Arkansas, north-central and northeast
Louisiana, and into west-central Mississippi.  Freezing rain rates
should generally be up to 0.05-0.10 inches per 3 hours, though
higher rates (0.10+ inch/hour) associated with a north-south band of
moderate precipitation will remain possible, as this band advances
east.  Locations in south-central Arkansas and north-central
Louisiana should have a decrease in wintry precipitation by 12-13Z.

DISCUSSION...GOES-16 IR imagery indicated a north-south band of
cooling cloud tops moving eastward through south-central AR and
north-central LA early this morning, with surface observations from
KCDH and KELD to KRSN indicating moderate to heavy precipitation
rates since 08-09Z in this band.  These higher rates and cooling
cloud tops are co-located with a compact area of forcing for ascent
attendant to the progressive shortwave trough.  Forecast soundings
suggest cooling of the surface to near-surface air (generally below
900 mb) will occur faster than the lower troposphere from 750-900
mb, such that freezing rain and eventually a mixture of sleet and
freezing rain will occur from west to east across the discussion
area.

..Peters.. 01/12/2018

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

ATTN...WFO...JAN...LZK...SHV...

LAT...LON   32699273 33059299 33619297 33809264 33829190 33739149
            33539090 33279064 33119066 32789074 32529110 32499197
            32529260 32699273




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