SPC MD 2056

MD 2056 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF EASTERN OKLAHOMA...WESTERN AND CENTRAL ARKANSAS

Mesoscale Discussion 2056
NWS Storm Prediction Center Norman OK
0351 PM CDT Sun Oct 06 2019

Areas affected...Parts of eastern Oklahoma...western and central
Arkansas

Concerning...Severe potential...Watch unlikely 

Valid 062051Z - 062245Z

Probability of Watch Issuance...20 percent

SUMMARY...Strong thunderstorm development may continue and gradually
consolidate during the next few hours.  This may eventually pose
increasing risk for potentially damaging wind gusts through 6-7 PM
CDT.  It still appears that the overall risk is marginal enough that
a watch will not be needed, but trends will continue to be
monitored.

DISCUSSION...Deep-layer mean flow and shear to the south of the slow
moving frontal zone is generally modest to weak, but daytime heating
of a seasonably moist boundary layer has allowed for the development
of sizable mixed-layer CAPE of 2000-3000 J/k, roughly near and south
of the Interstate-40 corridor of eastern Oklahoma into central
Arkansas.  Increasing inflow of this moist air, coupled with
large-scale forcing for ascent mostly along and to the cool side of
the frontal zone, has allowed for initiation of vigorous
thunderstorm activity during the past few hours.

An area of 2-hourly surface pressure falls in excess of 2 mb has
become evident in 20Z surface analysis, along an axis from Fort
Smith through Russellville and Little Rock AR, and this may become
the focus for increasing and upscale growing convection through
23-00Z.  This may already be underway southwest through northwest of
Fort Smith area.

Given further upscale convective growth, 25-30+ kt westerly 500 mb
flow along this axis may be providing for sufficient shear to
contribute to an organizing convective system which could pose
increasing potential for strong surface gusts at least approaching
severe limits.  Otherwise, isolated stronger updraft pulses may
continue to pose a risk for marginally severe hail through the
remainder of the afternoon.

..Kerr/Thompson.. 10/06/2019

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

ATTN...WFO...LZK...SHV...TSA...

LAT...LON   35199549 35829392 35699303 35449224 34989192 34399259
            34039352 34449533 35199549 

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