SPC MD 21



MD 0021 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR NORTHERN LA…MUCH OF CENTRAL AND EASTERN AR…FAR NORTHWEST MS

MD 0021 Image


Mesoscale Discussion 0021
NWS Storm Prediction Center Norman OK
0550 PM CST Fri Jan 18 2019

Areas affected...Northern LA...Much of Central and Eastern AR...Far
Northwest MS

Concerning...Severe potential...Watch unlikely 

Valid 182350Z - 190215Z

Probability of Watch Issuance...20 percent

SUMMARY...Some isolated hail is possible from the Arklatex
northeastward into northeast AR and northwest MS tonight.

DISCUSSION...A combination of increased large-scale forcing for
ascent attendant to the approaching upper trough and strengthening
warm-air advection within the warm conveyor will result in an
increase in showers and thunderstorms from the Arklatex
northeastward into northeast AR and northwest MS. Gradually warming
and moistening low-levels beneath relatively cool mid-levels will
result in steep lapse rates (i.e. 7 to 7.5 deg C per km) across the
region. Consequently, MUCAPE values could exceed 1000 J/kg, which
could support some more robust, longer-lived updrafts. 

Additionally, strong unidirectional flow is already in place. Recent
SHV VAD profiles sampled 0-6 km shear over 45 kt and objective
mesoanalysis estimates closer to 60 kt farther north across northern
AR. These values support the potential for a few rotating/more
organized updrafts, which could contribute to an increase potential
for hail. Much of this hail would likely be sub-severe but a few
instances of one inch hail are possible. Anticipated marginal and
isolated nature of the threat are expected to preclude the need for
a watch.

..Mosier/Hart.. 01/18/2019

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

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

LAT...LON   34959282 35799174 35539024 34379042 33569079 32459203
            32719404 34959282 

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