FLUS74 KFWD 130108 AWUFWD AREA WEATHER UPDATE NATIONAL WEATHER SERVICE FORT WORTH TX 1047 AM CDT TUE APR 2 2013 ...MESOSCALE FORECAST UPDATE FOR NORTH TEXAS... 14Z SUBJECTIVE SURFACE ANALYSIS INDICATED A LOW PRESSURE SYSTEM OVER WEST TEXAS...NEAR MIDLAND...WITH A COLD FRONT EXTENDING TO THE EAST-NORTHEAST TO THE DFW METROPLEX. THERE WAS A CYCLONIC CIRCULATION INDICATED IN THE WIND FIELD NEAR THE METROPLEX...WHICH LIKELY REPRESENTS THE REMNANTS OF INTENSE THUNDERSTORMS THAT DIMINISHED NEAR STEPHENVILLE EARLY THIS MORNING. HIGH RESOLUTION MODEL GUIDANCE INDICATED THAT A LINE OF CONVECTION WILL DEVELOP ALONG THE FRONT AND OVER THE DFW METROPLEX IN THE 16 TO 18Z TIME FRAME. BASED ON 15Z SATELLITE AND REGIONAL RADAR OBSERVATIONS...IT WAS NOT OBVIOUS THAT THUNDERSTORMS WERE GOING TO INITIATE ALONG THE FRONT THIS MORNING. A QUICK LOOK AT FORCING MECHANISMS AROUND THE REGION SHOWS THAT WARM AIR ADVECTION AND ISENTROPIC LIFT WERE PRESENT OVER THE FAR WESTERN CWA AND SHALLOW FRONTOGENETIC FORCING WAS LOCATED ALONG THE SURFACE COLD FRONT. THE SURFACE ANALYSIS OF THE COLD FRONT WAS WELL SOUTHEAST OF THE H850 SPC MESOSCALE ANALYSIS OF THE BAROCLINIC ZONE/FRONT ALOFT WHICH WAS LOCATED OVER THE SOUTHERN TX PANHANDLE. THERE WAS SOME WEAK LARGE SCALE FORCING FOR ASCENT OVER THE REGION...SLIGHTLY ENHANCED BY LATENT HEAT RELEASE ASSOCIATED WITH CONVECTION EARLY THIS MORNING. WHEN LOOKING AT THE DYNAMIC TROPOPAUSE...PERSISTENT LATENT HEAT RELEASE TENDS TO BUBBLE UP THE TROPOPAUSE WHERE STORMS HAVE BEEN ONGOING. WHEN COOLER AIR IS LOCATED UPSTREAM...IN THE FORM OF A SHORTWAVE TROUGH...THIS CAN ENHANCE THE OVERALL LARGE SCALE FORCING FOR ASCENT BY INCREASING THE MAGNITUDE OF POTENTIAL VORTICITY ADVECTION IMMEDIATELY UPSTREAM OF THE PERSISTENT CONVECTION. THIS PROCESS APPEARS TO HAVE HAD SOME IMPACT ON OUR MESOSCALE ENVIRONMENT THIS MORNING. WITH PERSISTENT OVERNIGHT AND EARLY MORNING CONVECTION RELEGATED TO THE WESTERN THIRD OF THE CWA...ENHANCED LARGE SCALE FORCING FOR ASCENT WOULD TEND TO BE LOCATED JUST SOUTHWEST OF OUR CWA DUE TO THE SOUTHWEST FLOW ALOFT/NEAR THE DYNAMIC TROPOPAUSE. LOW-LEVEL FRONTOGENETIC FORCING APPEARS TO BE WEAKER THAN EXPECTED WITH A SHALLOW COLD AIR MASS DEFINING THE COLD FRONT. SHALLOW BAROCLINICITY WILL LIMIT THE OVERALL DEPTH OF THE VERTICAL RESPONSE TO THE FRONTOGENETIC FORCING TO THE EAST/SOUTHEAST OF THE COLD FRONT UNTIL THE H850 FRONT /CATCHES UP/ HELPING TO DEEPEN THE FORCING FOR ASCENT. MODEL GUIDANCE SEEMS TO BE FAVORING THIS FRONT AS PLAYING A LARGE ROLE IN THUNDERSTORM CHANCES THIS AFTERNOON. IT MIGHT...BUT IT LOOKS LIKE WE WOULD NEED SOME GOOD DESTABILIZATION OUT AHEAD OF THE FRONT FOR THE SHALLOW LIFT TO RESULT IN CONVECTION INITIATION. HIGH RESOLUTION GUIDANCE THAT RAN AT 00 AND 06Z INDICATED THAT DESTABILIZATION WOULD PAN OUT...FORECASTING 500 TO 1000 J/KG OF SBCAPE OUT AHEAD OF THE BOUNDARY BY 18Z. OUR LOCAL OBJECTIVE ANALYSIS SCHEME WAS MUCH LESS OPTIMISTIC WITH SBCAPE VALUES OUT AHEAD OF THE FRONT AT 15Z WITH ONLY 50 TO 100 J/KG OF SBCAPE INDICATED. WHY THE DIFFERENCE? WELL IT APPEARS THAT HIGH RESOLUTION GUIDANCE WAS RUNNING 3-6 DEGREES TOO WARM ON SURFACE TEMPERATURES ALONG THE FRONT. THIS IS NOT A HUGE TEMPERATURE DIFFERENCE...BUT IN THIS ENVIRONMENT IT MEANS THE DIFFERENCE BETWEEN WEAK TO MODERATE DESTABILIZATION AND VIRTUALLY NO DESTABILIZATION OUT AHEAD OF THE COLD FRONT. WITH CLOUDY SKIES IN PLACE...THINK THAT THE PROSPECTS FOR DESTABILIZATION ALONG THE FRONT ARE SOMEWHAT LOW THROUGH EARLY THIS AFTERNOON...MEANING THAT CONVECTION INITIATION ALONG THE FRONT MAY NOT BE AS LIKELY AS PREVIOUSLY EXPECTED. AS A RESULT...THINK THE MAIN FOCUS FOR CONVECTION THROUGH EARLY THIS AFTERNOON WILL BE OVER THE SOUTHWESTERN CWA WHERE WAA AND SLIGHTLY ENHANCED LARGE SCALE SUPPORT WILL INTERSECT. IMPACTS...OVERALL THINK THAT THROUGH EARLY THIS AFTERNOON THUNDERSTORMS DEVELOPING RIGHT ON TOP OF THE DFW METROPLEX ARE LESS LIKELY THAN PREVIOUSLY EXPECTED. THE METROPLEX MAY HAVE TO WAIT FOR STORMS TO DEVELOP OUT WEST BEFORE MOVING EAST OVER THE AREA EARLY THIS AFTERNOON. WILL HAVE TO WATCH FOR HEAVY RAINFALL WITH STORMS DEVELOPING OVER THE SOUTHWESTERN CWA...AS THIS ACTIVITY WILL LIKELY CONTINUE TO REGENERATE FROM THE SOUTHWEST AND MOVE EAST-NORTHEAST THROUGH EARLY THIS AFTERNOON. CHANCES OF SEVERE STORMS ARE SOMEWHAT LIMITED BY A LACK OF BETTER DESTABILIZATION TODAY...BUT ARE BEST SOUTHWEST OF THE DFW AREA THROUGH EARLY THIS AFTERNOON. LATER THIS AFTERNOON...WILL HAVE TO WATCH THE RESPONSE OF TEMPERATURES ALONG AND SOUTHEAST OF THE FRONT TO BETTER EVALUATE STORM CHANCES ALONG THE COLD FRONT LATER THIS AFTERNOON. IF TEMPERATURES CLIMB INTO THE LOWER TO MID 70S AND DEW POINTS REMAIN IN THE LOWER 60S...THEN THUNDERSTORM INITIATION ALONG THE