SPC AC 131255
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0755 AM CDT THU MAY 13 2004
   
   VALID 131300Z - 141200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 WSW
   BVE 30 E HEZ 60 N HOT 10 WNW UNO 25 S STL DEC 30 SE MLI 30 NW BRL 15
   WNW COU 25 SE PNC 25 ENE LTS 35 SSW CDS 40 ENE BGS 55 NNE P07 55 W
   JCT 15 NNW SAT 30 SSW PSX.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 S P07 25 WNW BGS
   45 SSW LBB 50 NNE HOB 20 W ROW 15 N 4CR 60 SW ALS 35 E CNY 30 S SLC
   65 NNE BOI 25 SSE GEG 45 NE 63S 40 ENE CTB 20 WNW GCC 35 NE DGW 45 E
   CYS 40 WSW IML 50 W EAR 40 ENE BUB 20 SSW FSD 40 SW STC 40 SW DLH 25
   NNW ELO ...CONT... 10 ESE SSI 15 SSW CTY.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM W CENTRAL IL SWD / SWWD
   INTO OK / TX AND THE LOWER MS VALLEY REGION...
   
   ...SYNOPSIS...
   WHILE UPPER HIGH PERSISTS ACROSS THE ERN THIRD OF THE CONUS...LARGE
   UPPER TROUGH OVER THE ROCKIES ATTM WILL CONTINUE MOVING EWD INTO THE
   PLAINS THROUGH THE END OF THE PERIOD.  SEVERAL SMALLER SCALE
   FEATURES ARE FORECAST TO EJECT EWD / NEWD IN MODERATE CYCLONIC FLOW
   AROUND SRN AND ERN PERIPHERY OF MAIN TROUGH.
   
   AT THE SURFACE...COLD FRONT NOW EXTENDS FROM UPPER MI / WI SWWD
   ACROSS THE UPPER MS / LOWER MO VALLEYS INTO WRN OK / NWRN TX.  THIS
   BOUNDARY IS FORECAST TO CONTINUE MOVING EWD / SEWD WITH TIME...AND
   BY THE END OF THE PERIOD SHOULD EXTEND FROM LOWER MI SWWD INTO THE
   HILL COUNTRY REGION OF CENTRAL / S TX. THIS FRONT AND A DRYLINE
   WHICH SHOULD SET UP ACROSS W CENTRAL TX SHOULD BE A FOCUS FOR
   CONVECTIVE DEVELOPMENT THROUGH THE PERIOD...WHILE CLUSTERS OF STORMS
    ARE ALSO FORECAST TO PERSIST / MOVE SLOWLY EWD IN WARM ADVECTION
   REGION ACROSS ERN TX INTO THE LOWER MS VALLEY.
   
   ...SWRN MO SWWD INTO W CENTRAL TX...
   COLD FRONT CONTINUES MOVING SWD ACROSS THE TX PANHANDLE / TX SOUTH
   PLAINS ATTM...WHILE OUTFLOW-ENHANCED PORTION OF BOUNDARY ACROSS NRN
   OK IS MOVING MORE SLOWLY SWD.  AS STORMS NOW OVER CENTRAL OK MOVE
   EWD...DAYTIME HEATING SHOULD COMMENCE ACROSS CENTRAL AND SWRN OK
   INTO ADJACENT NWRN TX INTO THE TRANSPECOS REGION.  WITH MORNING FTW
   / OUN RAOBS SHOWING A LOW-LEVEL CAPPING INVERSION...EXPECT
   CONVECTIVE INITIATION ALONG FRONT FROM CENTRAL OK SWWD TO BE
   INHIBITED THROUGH EARLY AFTERNOON...WHILE AIRMASS BECOMES MODERATELY
   TO STRONGLY UNSTABLE.  
   
   BY EARLY TO MID AFTERNOON...EXPECT A HEATING-INDUCED LOW TO DEVELOP
   OVER NWRN TX...WITH A DRYLINE EXTENDING SSWWD FROM THE LOW INTO THE
   TRANSPECOS REGION.  AS THIS OCCURS...STORMS ARE EXPECTED TO DEVELOP
   ACROSS SWRN OK AND NWRN TX IN INCREASING LOW-LEVEL CONVERGENCE INVOF
   LOW / COLD FRONT / DRYLINE.
   
   DESPITE ONLY 20 TO 30 KT MID-LEVEL FLOW FORECAST OVER THE WARM
   SECTOR THIS AFTERNOON...MODERATE / VEERING FLOW WITH HEIGHT COMBINED
   WITH DEGREE OF INSTABILITY SHOULD RESULT IN ORGANIZED / SUPERCELL
   STORMS.  VERY LARGE HAIL AND LOCALLY DAMAGING WINDS ARE
   EXPECTED...AND A COUPLE OF TORNADOES MAY ALSO OCCUR -- PARTICULARLY
   ACROSS A SMALL PORTION OF WRN N TX / SWRN OK INVOF SURFACE LOW AND
   ASSOCIATED DRYLINE / COLD FRONT INTERSECTION.  THE TORNADO THREAT
   WILL LIKELY BE RELATIVELY SHORT-LIVED HOWEVER...AS CONVECTION SHOULD
   INCREASE IN COVERAGE AND EVOLVE INTO ONE OR MORE MCSS WITH TIME
   ACROSS OK / NRN AND CENTRAL TX.  DESPITE A POTENTIALLY SHORT-LIVED
   TORNADO THREAT...THREAT FOR LARGE HAIL AND DAMAGING WINDS SHOULD
   CONTINUE WELL INTO THE EVENING / OVERNIGHT AREA AHEAD OF SLOW-MOVING
   FRONT.
   
   ...PORTIONS OF IL / MO...
   ALTHOUGH INSTABILITY IS FORECAST TO BE MUCH MORE LIMITED AHEAD OF
   COLD FRONT ACROSS THIS REGION...SUFFICIENT INSTABILITY SHOULD EXIST
   FOR A CONTINUATION OF SCATTERED STORMS THROUGH MUCH OF THE PERIOD. 
   ALTHOUGH DEEP-LAYER WIND FIELD IS EXPECTED TO REMAIN FAIRLY WEAK
   OVER THIS REGION...SUFFICIENT SHEAR / INSTABILITY SHOULD EXIST FOR
   AT LEAST A LOW-PROBABILITY SEVERE THREAT -- PARTICULARLY THIS
   AFTERNOON ACROSS W CENTRAL IL AND CENTRAL MO WHEN INSTABILITY SHOULD
   BE AT ITS MAXIMUM.
   
   ...ERN TX EWD INTO THE LOWER MS VALLEY...
   HAVE ADDED A LARGE AREA OF SLIGHT RISK FROM ERN / SERN TX EWD ACROSS
   LA...AHEAD OF SHORT-WAVE TROUGH MOVING ACROSS CENTRAL TX ATTM IN
   ADVANCE OF MAIN UPPER SYSTEM.
   
   STORMS HAVE DEVELOPED ACROSS ERN / SERN TX THIS MORNING...APPARENTLY
   WITHIN ZONE OF WARM ADVECTION ON THE COOL SIDE OF REMNANT OUTFLOW
   LEFT OVER FROM EARLIER LOWER MS VALLEY CONVECTIVE CLUSTER.  WITH
   DEWPOINTS IN THE LOWER TO MID 70S ACROSS THIS REGION...VERY MOIST
   LOW-LEVEL AIRMASS IS CONTRIBUTING TO MODERATE INSTABILITY.  WITH
   MODEL FORECASTS AND LATEST VAD / VWP DATA INDICATING MODERATE
   DEEP-LAYER WIND FIELD WHICH VEERS WITH HEIGHT... A THREAT FOR HAIL /
   LOCALLY DAMAGING WINDS WILL BE POSSIBLE WITH A FEW OF THE STRONGER
   STORMS.  ADDITIONALLY...AN ISOLATED TORNADO OR TO WILL ALSO BE
   POSSIBLE GIVEN MOIST BOUNDARY LAYER / LOW LCLS AND FAIRLY STRONG
   LOW-LEVEL SHEAR.  STORMS SHOULD DEVELOP / SPREAD SLOWLY EWD THIS
   AFTERNOON AS UPPER TROUGH CROSSES TX...WITH A LOW-PROBABILITY SEVERE
   THREAT EXTENDING AS FAR EWD AS SERN MS.
   
   ..GOSS/TAYLOR.. 05/13/2004
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1630Z