MESO: Mesoscale Discussion 0015

ACUS11 KWNS 121926
SWOMCD
SPC MCD 121925
TNZ000-MOZ000-ARZ000-TXZ000-OKZ000-122200-

MESOSCALE DISCUSSION 0015
NWS STORM PREDICTION CENTER NORMAN OK
0125 PM CST SAT JAN 12 2013

AREAS AFFECTED...PARTS OF FAR NERN TX / SWRN-CNTRL-NERN AR / MO
BOOTHEEL

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 121925Z - 122200Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THE DEVELOPMENT AND/OR TRANSITION TO SURFACE-BASED STORMS
IS EXPECTED TO BEGIN OVER THE NEXT SEVERAL HOURS. ONCE THIS BECOMES
APPARENT...A TORNADO WATCH WILL LIKELY BE NEEDED TO ADDRESS AN
INCREASING THREAT FOR DMGG WINDS AND ISOLD TORNADOES BY THE LATE
AFTERNOON THROUGH THE EVENING HOURS.

DISCUSSION...19Z SURFACE MESOANALYSIS SHOWS A 1005 MB SURFACE LOW 30
MI E DAL AND A COLD FRONT DRAPED SW TO NE FROM NEAR THE DFW
METROPLEX THROUGH W-CNTRL AR AND INTO SERN MO. THE SRN PORTION OF
THE FRONT WILL ACCELERATE EWD INTO FAR NERN TX BY EARLY EVENING AS
THE LOW DEVELOPS NEWD...BUT THE PORTION OF THE FRONT OVER AR IS
EXPECTED TO MOVE LITTLE OR SLIGHTLY NWD OVER THE NEXT SEVERAL HOURS.
AS SUCH...LOW LEVEL MOISTURE /MID-UPPER 60S DEWPOINTS/ LEADING TO A
DESTABILIZING BOUNDARY LAYER WILL CONTINUE TO ADVANCE NWD INVOF THE
FRONT OVER CNTRL-NERN AR.

DESPITE A THICK MID-HIGH LEVEL CLOUD CANOPY RETARDING SURFACE
HEATING...TEMPS ARE GRADUALLY WARMING INTO THE LOW 70S OVER THE
ARKLATEX REGION. THIS HAS CONTRIBUTED TO UPWARDS OF 1500 J/KG
MLCAPE WHEN MODIFYING THE 12Z SHV RAOB --FEATURING A 14-15 G/KG MEAN
MIXING RATIO-- FOR THE 19Z TXK SURFACE OBSERVATION. MOIST LOW
LEVELS COMBINED WITH A STRENGTHENING LLJ TO 55 KTS BY 00Z...WILL
ENLARGE HODOGRAPHS /500 M2/S2 0-1 KM SRH/ AND FACILITATE AT LEAST
THE POTENTIAL FOR DMGG WINDS AND ISOLD TORNADOES WITH A MESSY
CONVECTIVE MODE FOCUSED NEAR THE FRONT.

..SMITH/HART.. 01/12/2013

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

ATTN...WFO...MEG...LZK...SHV...

LAT...LON 33259505 35209298 36489070 36118939 33529313 32669484
33259505

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