SPC MD 1825

MD 1825 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF SOUTHERN OK...NORTH TX

MESOSCALE DISCUSSION 1825
NWS STORM PREDICTION CENTER NORMAN OK
1134 PM CST SUN NOV 27 2016

AREAS AFFECTED...PORTIONS OF SOUTHERN OK...NORTH TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 280534Z - 280800Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...THUNDERSTORMS ARE EXPECTED TO DEVELOP AND INCREASE IN
COVERAGE IN THE 06-09Z TIME FRAME AND MOVE RAPIDLY NORTHEAST. 
DAMAGING WINDS AND LARGE HAIL WILL BE PRIMARY THREATS...AND A TORNADO
IS ALSO POSSIBLE.  ENVIRONMENTAL AND RADAR TRENDS WILL BE MONITORED
AND A WATCH MAY BE NEEDED.

DISCUSSION...STRENGTHENING LOW-LEVEL FLOW WILL CONTINUE TO RESULT IN
AN INCREASE IN MOISTURE ACROSS NORTH TX AND SOUTHERN OK THROUGH THE
EARLY MORNING HOURS...WITH SURFACE DEW POINTS 55-60 DEGREES F.  THE
APPROACH OF AN UPPER-LEVEL DISTURBANCE CURRENTLY OVER SOUTHERN AZ
WILL RESULT IN MID-LEVEL COOLING AND AN ADDITIONAL MODEST INCREASE
IN CONVECTIVE INSTABILITY...WITH MUCAPE AVERAGING BETWEEN 500 AND
1000 J/KG DURING THE PRE-DAWN HOURS.  INCREASING LOW/MID-LEVEL WIND
FIELDS WILL RESULT IN EFFECTIVE SHEAR OF 40-50 KTS.  DATA FROM A
SUPPLEMENTAL SOUNDING FROM KFWD REVEALED NOTABLE MID-LEVEL COOLING
ALREADY UNDERWAY...AND STRONG LOW-LEVEL WINDS IN VERY CLOSE AGREEMENT
WITH EARLIER RAP FORECAST SOUNDINGS.

LARGE-SCALE ASCENT WITH THE APPROACHING UPPER-LEVEL DISTURBANCE AND
LOW-LEVEL WARM ADVECTION SHOULD LEAD TO THE CONTINUED DEVELOPMENT OF
THUNDERSTORMS AHEAD OF AN EASTWARD-MOVING COLD FRONT...MOST LIKELY IN
THE 06-09Z TIME FRAME ACROSS WESTERN PORTIONS OF THE MCD AREA.  A
LINEAR CONVECTIVE MODE SHOULD EVENTUALLY BECOME DOMINANT...WITH
DAMAGING WINDS POSSIBLE AS HIGH-MOMENTUM AIR IS TRANSPORTED DOWNWARD
IN CONVECTIVE DOWNDRAFTS.  MID-LEVEL COOLING/STEEPENING LAPSE RATES
WILL ALSO LEAD TO A MORE CONDUCIVE ENVIRONMENT FOR A FEW REPORTS OF
LARGE HAIL WITH THE STRONGEST UPDRAFTS.  RAP FORECAST SOUNDING
HODOGRAPHS DEPICT SUBSTANTIAL LOW-LEVEL CURVATURE...SUPPORTIVE OF AT
LEAST SOME TORNADO RISK WITH ANY SURFACE/NEAR SURFACE-BASED STORM...
AS GUSTY SURFACE WINDS CONTINUE TO SLOW BOUNDARY LAYER
COOLING/STABILIZATION. 

CONVECTIVE TRENDS WILL BE MONITORED AND A WATCH MAY BE NEEDED.

..BUNTING/HART.. 11/28/2016

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

ATTN...WFO...SHV...TSA...FWD...OUN...SJT...

LAT...LON   32749723 32619867 32859922 33329925 33419917 33539896
            34169768 34489685 34699629 34919540 34869493 34719473
            34539460 34269456 33799471 33389527 32989625 32749723 

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