SPC AC 191236
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0736 AM CDT TUE APR 19 2005
   
   VALID 191300Z - 201200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 10 NE
   HLC 20 NW LIC 15 SE DEN 20 SSW FCL 20 NW CYS 15 N AIA 15 WNW ANW 20
   NW SUX 35 WSW MCW 20 NE LSE 40 SSE CWA 25 S MTW 40 SSE MKE 35 NW MMO
   20 WNW BRL P35 10 NE HLC.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 SE
   P07 60 S CDS 40 SE CDS 30 S LTS SPS 35 NNW MWL 25 SSE DRT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 WSW BUF ELM AVP 25
   SSE NEL ...CONT... 15 S ILM SPA 65 WSW LOZ 30 SE SDF 30 NNW LUK 20
   ESE MIE 10 E CMI 35 SSW UIN 40 N JLN 35 ENE MLC 30 SE TYR 15 E LFK
   30 SSE POE 30 NE MSY 25 S GPT ...CONT... 35 SW P07 20 NNE BGS 35 W
   CDS 10 SSW LBL 45 E LAA 40 SSE LIC 50 WNW COS 20 WNW MTJ 50 SSW BCE
   35 ENE DRA 25 NE MER 50 SE RBL 15 N SVE 45 WSW MQM 20 NNE WEY 40 WNW
   GDV 35 SE ISN 45 ESE MOT DVL 70 W RRT.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL HI PLNS TO THE
   MID MS VLY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF WRN AND NW TX...
   
   ...SYNOPSIS...
   NRN NV CLOSED LOW EXPECTED TO EDGE ONLY SLOWLY E THIS PERIOD AS
   RIDGE BUILDING TO ITS N /WELL DEPICTED IN WV IMAGERY/ TEMPORARILY
   RESULTS IN DEVELOPMENT OF A REX BLOCK. A SPEED MAX NOW IN THE SWRN
   SECTOR OF THE LOW SHOULD REDEVELOP NE INTO ERN FLANK OF SYSTEM BY
   12Z WEDNESDAY AS ADDITIONAL MAXIMA DROP S/SE INTO THE SRN GRT BASIN.
   
   FARTHER S...SATELLITE DATA SUGGEST THAT SRN BRANCH JET HAS BECOME
   LESS WELL DEFINED AND ORIENTED MORE SW/NE RELATIVE TO PREVIOUS
   DAYS...POSSIBLY IN RESPONSE TO ENCROACHMENT OF GRT BASIN LOW. 
   NEVERTHELESS...SOME SEMBLANCE OF A SRN BRANCH DOES PERSIST...AND A
   POSSIBLE IMPULSE IN THIS FLOW IS APPARENT ATTM OVER SW TX.
   
   ELSEWHERE...VORT WHICH MOVED ACROSS THE SRN RCKYS AND CNTRL PLNS
   DURING THE PAST 48 HRS SHOULD SLOWLY WEAKEN AS IT TURNS MORE EWD IN
   CONFLUENT WLY FLOW OVER THE UPR MIDWEST.
   
   AT LWR LEVELS...ERN PORTION OF NRN PLNS COLD FRONT SHOULD CONTINUE
   SLOWLY SE ACROSS THE UPR GRT LKS/UPR MS VLY LATER TODAY/ TONIGHT...
   WHILE WRN PART NOSES S AT A FASTER RATE INTO ERN WY/WRN SD/NW NEB. 
   ATTM...SURFACE ANALYSES DEPICT A DOUBLE STRUCTURE TO THE FRONT IN
   NEB/WY...WITH A PREFRONTAL WIND SHIFT LINE EXTENDING FROM NEAR OFK
   TO NEAR OGA TO NEAR CYS.
   
   ...CNTRL HI PLNS TO LWR MO VLY...
   A CONCENTRATED AREA OF THUNDERSTORMS WILL LIKELY FORM THIS AFTERNOON
   AND PERSIST THROUGH TONIGHT ALONG AND BEHIND COLD FRONT CROSSING
   WY/SD AND NEB. THE FIRST SURFACE-BASED STORMS WILL PROBABLY DEVELOP
   DURING THE MID AFTERNOON INVOF PREFRONTAL TROUGH OVER WRN NEB/SE
   WY...WHERE COMBINATION OF DIURNAL HEATING... INCREASINGLY MOIST
   UPSLOPE FLOW AND UPR DIFFLUENCE WILL LEAD TO THE GREATEST
   DESTABILIZATION.  A BIT LATER IN THE DAY...ACTIVITY SHOULD ALSO
   DEVELOP EWD ALONG FRONT INTO ERN NEB AND IA...AND SWD INTO NE CO.
   
   THE MID/UPR FLOW WILL REMAIN MODEST OVER THE REGION...WITH THE 500
   MB FLOW RANGING FROM SSWLY AT 30 KTS IN NE CO/SE WY TO WSWLY AT 25
   KTS IN ERN NEB.  BUT THE RESULTING DEEP SHEAR SHOULD BE SUFFICIENT
   FOR SUSTAINED STORMS/SUPERCELLS...ESPECIALLY IN SRN/WRN NEB WHERE
   FAIRLY CLOUD-FREE SKIES AHEAD OF THE STORMS AND STEEP MID LEVEL
   LAPSE RATES COULD BOOST SBCAPE TO 2500 J/KG.  THIS WILL PROMOTE A
   THREAT FOR BOTH LARGE HAIL AND DAMAGING WIND THROUGH EARLY TONIGHT. 
   FARTHER E...SOMEWHAT GREATER MOISTURE AVAILABILITY AND SLIGHTLY
   STRONGER WIND FIELD IN WAKE OF IA UPPER VORT MAY COMPENSATE FOR MORE
   ABUNDANT CLOUDINESS TO SUPPORT A LOCALLY ENHANCED WIND/HAIL THREAT
   IN IA.
   
   THE RELATIVELY HIGH LCLS AND MODEST WIND FIELDS SHOULD MITIGATE
   OVERALL TORNADO THREAT.  BUT GIVEN THE DEGREE OF INSTABILITY AND THE
   LIKELIHOOD FOR BACKED FLOW INVOF PREFRONTAL TROUGH...A TORNADO OR
   TWO COULD OCCUR IN SRN NEB...AND PERHAPS IN IA.
   
   THE STORMS WILL LIKELY CONSOLIDATE INTO A SOLID BAND THAT DRIFTS
   SLOWLY S/SE ACROSS SRN NEB/IA AND PERHAPS INTO NE KS/NW MO TONIGHT. 
   BUT WITH SHORT WAVE RIDGING EXPECTED TO OVERSPREAD THE REGION THIS
   EVENING AS GRT BASIN LOW EDGES EWD...THE STORMS SHOULD WEAKEN BY
   MIDNIGHT.  ADDITIONAL /ELEVATED/ ACTIVITY MAY ALSO DEVELOP LATE
   TONIGHT ACROSS NRN NEB AND WRN SD.
   
   ...ERN IA/SRN WI INTO NW IL/WRN LWR MI...
   SURFACE-BASED INSTABILITY SHOULD REMAIN LIMITED /AOB 500 J PER KG/
   OVER THE UPR MS VLY/UPR GRT LKS REGION TODAY...DOWNSTREAM FROM IA
   VORT.  BUT IF SUFFICIENT SURFACE HEATING CAN OCCUR...FORCING BY THE
   DISTURBANCE...COUPLED WITH RELATIVELY DRY SUB-CLOUD LAYER AND
   MODERATE UNIDIRECTIONAL WLY FLOW...MAY SUPPORT THE DEVELOPMENT OF A
   LINE OF FORWARD-PROPAGATING STORMS OVER ERN IA/SRN WI. IF SUSTAINED
   ACTIVITY DOES INDEED DEVELOP...A CONDITIONAL THREAT WILL EXIST FOR
   DAMAGING WIND THIS AFTERNOON INTO EARLY TONIGHT.
   
   ...W CNTRL/NW TX...
   LEE TROUGH/DRYLINE WILL REMAIN IN PLACE ACROSS W CNTRL AND NW TX
   TODAY. AVERAGE SURFACE DEWPOINTS SHOULD BE IN THE LOW 60S EAST OF
   THE FEATURE...A BIT MORE MOIST THAN IN PAST DAYS.  THIS MOISTURE
   HAS...HOWEVER...TRANSLATED INTO SOMEWHAT GREATER COVERAGE OF
   BOUNDARY LAYER STRATOCU.  TEMPERATURES HAVE ALSO WARMED A DEGREE OR
   TWO AT MID LEVELS RELATIVE TO RECENT DAYS.  MODERATE SURFACE HEATING
   SHOULD...NEVERTHELESS...BOOST AFTERNOON MLCAPE TO AOA 1000 J/KG.
   
   AS PREVIOUSLY NOTED...WV LOOPS DO SHOW A WEAK SRN STREAM IMPULSE NOW
   OVER SW TX DRIFTING ENEWD.  BUT THIS DISTURBANCE WILL LIKELY HAVE
   MOVED BEYOND THE DRY LINE BY MAX HEATING TIME. GIVEN THE ABOVE
   RESERVATIONS...CONFIDENCE IS NOT HIGH FOR THE INITIATION OF DRY LINE
   STORMS THIS AFTERNOON. IF STORMS DO DEVELOP...HOWEVER... SETUP WILL
   BE FAVORABLE FOR SUPERCELLS WITH LARGE HAIL GIVEN STEEP MID LEVEL
   LAPSE RATES...RESPECTABLE BOUNDARY LAYER MOISTURE AND 30+ KT DEEP
   WNWLY SHEAR.  ANY STORMS THAT DO FORM SHOULD WEAKEN QUICKLY AFTER
   SUNSET.
   
   ..CORFIDI/TAYLOR.. 04/19/2005
   
   ...NOTICE...
   THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE
   SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1...
   WUUS02 PTSDY2...WUUS03 PTSDY3.  THE INCLUSION OF POINTS
   IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005
   CONVECTIVE SEASON.  A PUBLIC NOTIFICATION STATEMENT (PNS)
   WILL PROVIDE DETAILS ON THE TRANSITION.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z