SWODY1
SPC AC 282047
DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CST THU JAN 28 2010
VALID 282041Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
OVER PARTS OF TX...
AMENDED FOR ADDITION OF CATEGORICAL SLIGHT RISK TO THE DALLAS/FORT
WORTH METROPLEX
...N-CNTRL TX...
SEVERAL REPORTS OF WIND DAMAGE HAVE BEEN RECEIVED WITH
ONGOING...BOWING MCS APPROACHING THE METROPLEX. WHILE BOUNDARY
LAYER REMAINS RELATIVELY COOL AND STABLE...IT APPEARS THAT A
SUFFICIENT NEGATIVE BUOYANCY IS BEING GENERATED BY
EMBEDDED...SMALLER-SCALE BOWS AND LEWPS SUCH THAT LOCALLY DAMAGING
WINDS WILL REMAIN POSSIBLE WITH MCS FOR THE NEXT COUPLE OF HOURS.
...CNTRL/SRN TX...
A BOWING MCS HAS EVOLVED TODAY OVER PARTS OF W-CNTRL TX WITH
BACKBUILDING/REGENERATIVE STORM DEVELOPMENT OCCURRING ALONG SWRN
EXTENSION OF SYSTEM N/NW OF DRT. RECENT TRENDS IN VISIBLE SATELLITE
IMAGERY SHOW A GRADUAL EROSION OF LOW CLOUDS OVER THE EDWARDS
PLATEAU AND LOWER RIO GRANDE VALLEY...WHICH IS ALLOWING FOR LOCALLY
STRONGER DIABATIC HEATING. AT THE SAME TIME...40-50 KT SELY LLJ IS
MAINTAINING THE INFLUX OF A MOIST BOUNDARY LAYER INTO REGION WITH
DEWPOINTS IN THE LOWER TO MID 60S. CONTINUED HEATING SHOULD SUPPORT
FURTHER DESTABILIZATION THIS AFTERNOON WITH MLCAPE APPROACHING
1000-1500 J/KG PER 18Z RUC GUIDANCE.
BOWING...NRN EXTENSION OF ONGOING TSTM BAND SHOULD TEND TO WEAKEN
WHILE MOVING EWD INTO A PROGRESSIVELY MORE STABLE AIR MASS IN PLACE
E OF I-35. FARTHER S/SW...STORMS DEVELOPING ALONG/AHEAD OF COLD
FRONT OVER THE EDWARDS PLATEAU REGION WILL LIKELY POSE A GREATER
AND/OR LONGER-LIVED SEVERE WEATHER THREAT. HERE...THE
MOIST/MODERATELY UNSTABLE AIR MASS WILL COEXIST WITH A KINEMATIC
ENVIRONMENT FEATURING PRONOUNCED VEERING OF WINDS THROUGH THE LOWEST
1-2 KM AGL AND 50-60 KT OF DEEP-LAYER SHEAR. AS SUCH...THE
POTENTIAL WILL EXIST FOR SUPERCELLS IN ADDITION TO BOWING LINE
SEGMENTS CAPABLE OF DAMAGING WINDS...HAIL /POSSIBLY SIGNIFICANT/ AND
A TORNADO OR TWO.
ACTIVITY SHOULD GROW UPSCALE INTO AN MCS TONIGHT WITH A PREFERRED
SEWD SYSTEM PROPAGATION/MOVEMENT INTO LOW-LEVEL INSTABILITY AXIS IN
PLACE OVER THE HILL COUNTRY AND LOWER RIO GRANDE VALLEY.
..MEAD.. 01/28/2010
.PREV DISCUSSION... /ISSUED 1025 AM CST THU JAN 28 2010/
A POWERFUL UPPER TROUGH CONTINUES TO PROGRESS EASTWARD ACROSS
NORTHERN MEXICO...WITH LARGE SCALE LIFT SPREADING EASTWARD ACROSS
TX/OK. MORNING VISIBLE SATELLITE IMAGERY SHOWS THINNING LOW CLOUDS
IN A NARROW CORRIDOR EXTENDING FROM THE LOWER RIO GRANDE VALLEY INTO
THE HILL COUNTRY. THIS AREA WILL SEE THE STRONGEST DESTABILIZATION
LATER TODAY WITH DEWPOINTS CLIMBING TO NEAR 60F AND MUCAPE VALUES OF
1000 J/KG. MULTIPLE BANDS OF THUNDERSTORMS WILL TRACK ACROSS THIS
REGION TODAY...WITH AN EVENTUAL INCREASE IN THE RISK OF
SURFACE-BASED CONVECTION. A COMBINATION OF RELATIVELY STEEP MID
LEVEL LAPSE RATES AND SUFFICIENT CAPE WILL PROMOTE A FEW INTENSE
STORMS THIS AFTERNOON AND EVENING. FORECAST SOUNDINGS SHOW
FAVORABLE DEEP LAYER AND LOW LEVEL VERTICAL SHEAR FOR
SUPERCELLS...CAPABLE OF LARGE HAIL AND DAMAGING WINDS. SOME CONCERN
WILL ALSO EXIST FOR ISOLATED TORNADOES EARLY THIS EVENING. STORMS
WILL PERSIST OVERNIGHT...BUT ARE EXPECTED TO BE LESS INTENSE AS THEY
TRACK EASTWARD ACROSS TX.
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