ZCZC SPCSWOMCD ALL
ACUS11 KWNS 290538 
SPC MCD 290538 
ALZ000-MSZ000-LAZ000-290815-

MESOSCALE DISCUSSION 1837
NWS STORM PREDICTION CENTER NORMAN OK
1138 PM CST MON NOV 28 2016

AREAS AFFECTED...PORTIONS OF CENTRAL/SOUTHERN AL...SOUTHEAST MS...
SOUTHEAST LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 290538Z - 290815Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE AREA WILL CONTINUE TO BE MONITORED FOR AN ISOLATED
SEVERE-THUNDERSTORM RISK THROUGH THE OVERNIGHT HOURS. PRESENT
INDICATIONS ARE THAT WATCH ISSUANCE IS UNLIKELY.

DISCUSSION...A REMNANT SQUALL LINE EXTENDS NORTHEAST/SOUTHWEST
THROUGH CENTRAL AL...WITH A RELATED OUTFLOW BOUNDARY/SURFACE TROUGH
TRAILING SOUTHWESTWARD INTO NORTHEAST LA. THE WESTERN PORTION OF
THIS BOUNDARY HAS BECOME DIFFUSE AS LIGHT SOUTHERLY SURFACE WINDS
HAVE RESUMED TO ITS NORTH. MEANWHILE...A PERSISTENT SOUTH-WIND
COMPONENT SOUTH OF THIS BOUNDARY IS FACILITATING MOISTURE TRANSPORT...
WITH THE RICHEST LOW-LEVEL MOISTURE CONFINED TO AREAS FROM SOUTHEAST
LA TO SOUTHWEST AL (WHERE SURFACE DEWPOINTS ARE IN THE UPPER 60S TO
THE LOWER 70S). WEAK WARM ADVECTION SHOULD CONTINUE TO SUPPORT
PERSISTENT CONVECTION THROUGH THE OVERNIGHT HOURS...WITHIN THE
ENTRANCE REGION OF A LOW-LEVEL JET.

HOWEVER...THE STRONGEST LARGE-SCALE UPWARD MOTION HAS BECOME
DISPLACED WELL TO THE NORTHEAST/NORTH OF ANY MORE APPRECIABLE
WARM-SECTOR BUOYANCY. FURTHERMORE...THIS BUOYANCY IS BEING TEMPERED
BY WEAK MID-LEVEL LAPSE RATES SAMPLED BY THE 00Z LIX RAOB.
ADDITIONALLY...SURFACE WINDS HAVE SHOWN SOME SIGNS OF VEERING ACROSS
PARTS OF SOUTHERN MS AND SOUTHEAST LA...ASSOCIATED WITH A REDUCTION
IN LOW-LEVEL SRH AND ASCENT. ACCORDINGLY...CONFIDENCE IN
SUSTAINED/ORGANIZED CONVECTION OFFERING ANY MORE THAN AN ISOLATED
SEVERE RISK IS LIMITED.

NEVERTHELESS...STRONG LOW/MID-LEVEL FLOW SHOULD CONTINUE TO OFFER
SUFFICIENT VERTICAL SHEAR FOR A CONDITIONAL SEVERE-THUNDERSTORM AND
PERHAPS TORNADO RISK...IF MORE SUSTAINED CONVECTIVE ELEMENTS WERE TO
ROOT IN THE MOISTENING BOUNDARY LAYER. THE INFLUX OF RICHER
LOW-LEVEL MOISTURE INTO THE REGION MAY CONDITIONALLY SUPPORT SUCH
POTENTIAL...THOUGH THE WEAKENING LARGE-SCALE ASCENT WILL REMAIN A
NOTABLE MITIGATING FACTOR. IF THERE WERE TO BE A PROMINENT CHANGE IN
THE CHARACTER OF CONVECTION...WATCH ISSUANCE PROBABILITIES COULD
INCREASE LATER TONIGHT.

..COHEN/HART.. 11/29/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BMX...MOB...JAN...LIX...

LAT...LON   30619095 31169026 32418719 32848595 32478556 31808630
            30608864 30159047 30619095 

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