SPC MD 90



MD 0090 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR PARTS OF THE MID SOUTH TO THE LOWER OH VALLEY

MD 0090 Image

Mesoscale Discussion 0090
NWS Storm Prediction Center Norman OK
0926 AM CST Thu Feb 07 2019

Areas affected...Parts of the Mid South to the lower OH Valley

Concerning...Severe potential...Watch possible 

Valid 071526Z - 071700Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated damaging gusts will be possible through about
18z, though the severe threat may have peaked already and the need
for a watch is unclear.

DISCUSSION...A squall line with some embedded minor bowing
structures will continue to move east-northeastward through early
afternoon immediately in advance of a strong surface cold front. 
The warm sector has spread as far north as the OH River in KY, where
boundary-layer dewpoints have increased to the lower 60s with
surface temperatures in the mid-upper 60s.  Widespread clouds will
slow surface heating ahead of the squall line, and no appreciable
increase in low-level moisture is expected today (based on upstream
observations/12z soundings).  Thus, a marginally unstable
thermodynamic environment will persist into early afternoon, as the
stronger/deeper forcing for ascent spreads northeastward toward the
Great Lakes.  The net result will be a tendency for convection to
become shallower/weaker with time from south-to-north along the
frontal squall line, and the relatively greater threat for a few
damaging gusts is expected across the lower OH Valley.  Given the
marginal buoyancy and less favorable phasing of ascent/vertical
shear with the warm sector with time, the severe threat has probably
peaked and a watch may not be necessary.  Still, the lower OH Valley
area will be monitored closely for any short-term upswing in the
damaging wind threat.

..Thompson/Hart.. 02/07/2019

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

ATTN...WFO...LMK...IND...PAH...ILX...MEG...

LAT...LON   36328865 35828935 35918997 36259003 36568992 36958960
            37928894 38308851 38668779 38618726 38478676 38088666
            36328865 

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