405
FXUS64 KFWD 200837
AFDFWD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
337 AM CDT MON MAY 20 2013
DISCUSSION
A BROAD UPPER TROUGH REMAINS IN PLACE OVER THE WEST-CENTRAL CONUS
THIS MORNING. SHOWERS AND THUNDERSTORMS CONTINUE TO LIFT
NORTHEASTWARD FROM THE PLAINS TO THE UPPER MIDWEST...AS THE STRONG
SHORTWAVE ASSOCIATED WITH YESTERDAY EVENING/S SEVERE WEATHER ROTATES
NORTHWARD TOWARDS THE CANADIAN BORDER. AT THE SURFACE...A SLOW
MOVING COLD FRONT EXTENDS FROM THE PLAINS SOUTHWESTWARD INTO
NORTHWEST TEXAS...WITH A DRY LINE SOUTH OF THE FRONT FROM BETWEEN
CHILDRESS AND VERNON TO NEAR FORT STOCKTON. THE DRY LINE IS
EXPECTED TO BECOME THE FOCUS FOR THUNDERSTORM DEVELOPMENT OVER
WESTERN COUNTIES OF NORTH TEXAS THIS AFTERNOON. UNTIL
THEN...WARM AND BREEZY CONDITIONS CAN BE EXPECTED AS SOUTH WINDS
OF 15-20 MPH GUSTING TO 35 MPH CONTINUE.
STORMS WILL LIKELY DEVELOP IMMEDIATELY AHEAD OF THE DRYLINE LATE
THIS AFTERNOON DURING PEAK HEATING...AIDED BY A SUBTLE DISTURBANCE
PROJECTED TO CROSS FROM NORTHERN MEXICO EAST-NORTHEASTWARD INTO
TEXAS AND THE SOUTHERN PLAINS. THE BULK OF THE THUNDERSTORM COVERAGE
SHOULD BE NORTH OF THE RED RIVER WHERE INSTABILITY LEVELS ARE FORECAST
TO BE HIGHEST. IN FACT SOME OF THE HI-RES MODEL DATA INDICATES
DEVELOPMENT ACROSS OKLAHOMA BY EARLY AFTERNOON ALONG THE QUASI-
STATIONARY FRONT. SOUTH OF THE FRONT...THE DRYLINE SHOULD MIX EAST
TO NEAR THE WESTERN CWA BORDER...INITIATING STORMS BY 00Z/7 PM IF
NOT BEFORE. A NARROW AXIS OF MLCAPE IN EXCESS OF 3000 J/KG AHEAD
OF THE DRYLINE WILL RESULT IN SOME SEVERE STORMS...WITH LARGE
HAIL...DAMAGING WINDS...AND A FEW TORNADOES ALL POSSIBLE. THE
GREATEST THREAT WILL BE IN THE NORTHWESTERN-MOST REGIONS OF NORTH
TEXAS. THIS AREA IS CAPTURED WELL BY SPC DAY 1 CONVECTIVE OUTLOOK.
CELLS WILL MOVE NORTHEASTWARD THROUGH MUCH OF THE EVENING...PERHAPS
TAKING ON MORE OF AN EASTERLY MOTION AS MID LEVEL WINDS VEER LATE
IN THE EVENING. THERE IS THE POSSIBILITY THAT STORMS WILL REMAIN
ONGOING LATE THIS EVENING AND OVERNIGHT AS THE LOW LEVEL JET
BECOMES ESTABLISHED. WILL KEEP HIGHEST POPS OVERNIGHT OVER THE
NORTHERNMOST COUNTIES...WHERE MODELS ARE GENERALLY ROBUST ON QPF
OUTPUT. THE STRONG LLJ WOULD ALSO ALLOW FOR THE POSSIBILITY OF AN
EASTWARD OR SOUTHEASTWARD PROPAGATING MCS DURING THE OVERNIGHT
HOURS OVER THE NORTH AND NORTHEASTERN COUNTIES OF NORTH TEXAS.
THUNDERSTORMS WILL BE A GOOD POSSIBILITY ACROSS MUCH OF THE REGION
ON TUESDAY AS A PRONOUNCED SHORTWAVE SWINGS AROUND THE BASE OF THE
UPPER TROUGH. MESOSCALE SURFACE BOUNDARIES WILL LIKELY BE IN PLACE
FROM THE EXPECTED ACTIVITY MONDAY NIGHT...IN ADDITION TO THE
ACTUAL COLD FRONT WHICH SHOULD HAVE JUST ENOUGH PUSH TO PENETRATE
THE NORTHWESTERN COUNTIES. THESE BOUNDARIES WILL SERVE AS FOCUS
FOR CONTINUED DEVELOPMENT THOUGH THE DAY AS LIFT FROM THE
SHORTWAVE OVERSPREADS THE AREA. ACTIVITY WILL ADVANCE STEADILY
EAST-SOUTHEAST ACROSS NORTH TEXAS THROUGH TUESDAY NIGHT...EXITING
THE AREA TO THE SOUTHEAST BY EARLY WEDNESDAY. INSTABILITY WILL NOT
BE AS HIGH AS THIS EVENING AND TONIGHT...BUT WILL STILL BE
SUFFICIENT FOR A FEW SEVERE STORMS.
AN UPPER RIDGE WILL THEN BUILD OVERHEAD AS THE CENTRAL CONUS
TROUGH HEADS FOR THE THE EASTERN STATES. WILL MAINTAIN THE LOW
POPS OVER THE NORTHWESTERN THIRD OF THE REGION FOR BOTH LATE
THURSDAY AND LATE FRIDAY...WHERE MODELS ARE INDICATING THE
ISOLATED STORM DEVELOPMENT AROUND THE PERIPHERY OF THE
RIDGE...WHICH COULD HOLD TOGETHER LONG ENOUGH TO AFFECT THE
NORTHWEST ZONES. OTHERWISE TEMPERATURES SHOULD BE GENERALLY ABOVE-
NORMAL DURING THE EXTENDED PORTION OF THE FORECAST.
30
PRELIMINARY POINT TEMPS/POPS
DALLAS-FT. WORTH, TX 92 72 87 68 89 / 20 40 50 50 10
WACO, TX 91 72 89 68 88 / 10 20 40 60 10
PARIS, TX 89 70 82 65 85 / 10 60 50 50 10
DENTON, TX 92 71 86 64 89 / 30 40 40 40 10
MCKINNEY, TX 90 71 85 64 88 / 20 40 50 50 10
DALLAS, TX 91 72 87 69 89 / 20 40 50 50 10
TERRELL, TX 90 72 86 67 87 / 10 30 50 60 10
CORSICANA, TX 91 72 87 69 87 / 10 20 40 60 10
TEMPLE, TX 91 72 88 69 87 / 10 20 40 60 10
MINERAL WELLS, TX 94 69 87 65 89 / 30 30 40 40 10
FWD WATCHES/WARNINGS/ADVISORIES
NONE.
84/30
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