SPC MD 2182

MD 2182 CONCERNING TORNADO WATCH 686… FOR FAR EASTERN OK/EXTREME SOUTHEAST KS/NORTHEAST TX TO WESTERN AR/SOUTHERN MO


MESOSCALE DISCUSSION 2182
NWS STORM PREDICTION CENTER NORMAN OK
1022 PM CST WED DEC 19 2012

AREAS AFFECTED...FAR EASTERN OK/EXTREME SOUTHEAST KS/NORTHEAST TX TO
WESTERN AR/SOUTHERN MO

CONCERNING...TORNADO WATCH 686...

VALID 200422Z - 200545Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 686 CONTINUES.

SUMMARY...DAMAGING WIND/ISOLATED TORNADO POTENTIAL CONTINUES WITHIN
TORNADO WATCH 686...ESPECIALLY A CORRIDOR FROM NORTHEAST
TX/SOUTHEAST OK INTO NORTHWEST AR/SOUTHWEST MO. ADDITIONAL PARTS OF
CENTRAL/NORTHERN AR AND SOUTH-CENTRAL MO WILL BE MONITORED THROUGH
LATE EVENING/OVERNIGHT FOR A NEED OF AREAL WATCH EXPANSION AND/OR AN
ADDITIONAL WATCH...ALTHOUGH SUCH A NEED IS NOT CERTAIN.

DISCUSSION...AS OF 04Z...A NEARLY CONTINUOUS BAND OF STRONG TO
SEVERE TSTMS CONTINUES TO CONSOLIDATE AND SPREAD EAST-NORTHEASTWARD
WITHIN A CORRIDOR FROM NORTHEAST TX/SOUTHEAST OK INTO NORTHWEST
AR/SOUTHWEST MO...WITH A SURFACE COLD POOL GRADUALLY BECOMING MORE
APPARENT ACROSS EXTREME EAST-CENTRAL/SOUTHEAST OK. A 55 KT WIND GUST
WAS RECENTLY /329Z/ MEASURED AT FORT SMITH AR. LINE-LEADING
SEMI-DISCRETE STORMS /SOME WITH PERIODIC ROTATION/ HAVE ALSO BEEN
COMMON IN WEST-CENTRAL/NORTHWEST AR AND SOUTHERN MO.

ACCENTUATED BY THE DEEPENING PHASE OF THE CYCLONE
TONIGHT...INCREASING DEEP LAYER FORCING FOR ASCENT AND A HIGHLY
SHEARED ENVIRONMENT WILL PROMOTE THE SUSTENANCE OF A FORCED
LINE/QLCS ACROSS SOUTHERN MO/MUCH OF AR TO THE ADJACENT
ARKLATEX...EVEN WITH MINIMAL BUOYANCY /AS LOW AS A FEW HUNDRED J PER
KG SBCAPE/. DAMAGING WINDS WILL REMAIN POSSIBLE INTO THE
OVERNIGHT...ALONG WITH THE POTENTIAL FOR A FEW TORNADOES WITH ANY
EMBEDDED MESO-VORTICES/SEMI-DISCRETE SUPERCELLS.

AN ISOLATED SEVERE THREAT MAY DEVELOP TO THE EAST-NORTHEAST OF
CURRENT TORNADO WATCH 686...ALTHOUGH SURFACE DEWPOINTS HAVE
GENERALLY BEEN DECREASING OVER THE PAST FEW HOURS ACROSS EASTERN
AR/SOUTHEAST MO OWING TO RESIDUAL LOW-LEVEL ANTICYCLONIC
TRAJECTORIES. WHILE THIS PUTS AVAILABLE INSTABILITY/STORM VIGOR A
BIT INTO QUESTION WITH EASTWARD EXTENT...FORCING/VERTICAL SHEAR WILL
BE CONSEQUENTIAL AND INCREASING STORM-SCALE ORGANIZATION MAY
NONETHELESS MAINTAIN A SEVERE THREAT ACROSS AR/SOUTHERN MO
OVERNIGHT. CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED INTO THE
OVERNIGHT FOR AN ADDITIONAL WATCH.

..GUYER.. 12/20/2012

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

ATTN...WFO...PAH...MEG...LSX...LZK...SGF...SHV...TSA...FWD...

LAT...LON   33649565 35039451 36069390 37309325 37869101 37199055
            35089203 33729290 33649565

via SPC Forecast Products http://www.spc.noaa.gov/products/md/md2182.html