SPC MD 40



MD 0040 CONCERNING TORNADO WATCH 13…15… FOR PORTIONS OF CENTRAL INTO NORTHEASTERN AL

MD 0040 Image

Mesoscale Discussion 0040
NWS Storm Prediction Center Norman OK
0115 PM CST Sat Jan 11 2020

Areas affected...Portions of central into northeastern AL

Concerning...Tornado Watch 13...15...

Valid 111915Z - 112045Z

The severe weather threat for Tornado Watch 13, 15 continues.

SUMMARY...Damaging straight-line wind and isolated tornado potential
should be maximized across parts of central into northeastern AL
over the next couple of hours.

DISCUSSION...A mature squall line that has a history of producing
damaging straight-line winds and embedded tornadoes is moving
east-northeastward around 40-50 kt across central into northeastern
AL. Although diurnal heating has been stunted by widespread cloud
cover, surface temperatures have warmed into the low to mid 70s
across this area, with surface dewpoints generally in the low to mid
60s. An 18Z special sounding from KBMX just ahead of the line shows
the temperature inversion around 700 mb has almost completely
eroded, with about 340 J/kg of MLCAPE present. The observed wind
profile also shows very favorable low to mid-level shear that will
help maintain storm organization for at least the next couple of
hours. Effective SRH around 450-600 m2/s2 will likely foster
continued low-level circulations embedded within the line, with
isolated tornado potential. Otherwise, straight-line winds of 50-70
mph along the length of the squall line will continue to produce
damage through the afternoon. Portions of the line that are oriented
more orthogonal to the southwesterly mid-level flow will likely have
the greatest strong to severe wind potential (such as the bowing
segment moving from Jefferson, St. Clair, and Blount counties into
northeastern AL).

..Gleason.. 01/11/2020

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

ATTN...WFO...BMX...HUN...

LAT...LON   33928675 34478679 34758669 34908635 34918593 34768563
            34008545 33518574 32728661 32738701 33618670 33928675 

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