SPC AC 231255
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0755 AM CDT FRI APR 23 2004
   
   VALID 231300Z - 241200Z
   
   THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 NW
   FTW 25 WSW SEP 30 E SJT 25 WNW SJT 35 ESE BGS 65 WNW ABI 65 S CDS 35
   S LTS 25 NNE SPS 50 SW ADM 30 NW FTW.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 SSW
   P07 20 NE MAF 55 SSE LBB 35 SE AMA 60 W GAG 45 W P28 20 NE P28 35 N
   BVO 30 SSW JLN 15 W HRO 30 W DYR 25 SW MEM 35 NNE TXK 15 SSW PRX 40
   NE JCT 30 SE DRT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 90 SSE MRF 40 W P07
   25 SW MAF 20 ESE HOB 25 NW HOB 60 NE SAD 15 SW INW 10 WSW 4BL 45 NE
   ALS 25 SW MCK 10 S JEF 20 NNW PAH 30 SSE LUK 35 S HLG 25 SSW AVP 20
   N JFK ...CONT... 15 N HSE 10 SW CLT 35 SW TCL 45 ENE LFK 25 WSW GLS.
   
   ...THERE IS A MDT RISK OF SVR TSTMS PORTIONS W-CENTRAL/NW TX AND
   ADJACENT RED RIVER AREA...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SRN PLAINS TO AR...
   
   ...SYNOPSIS...
   SPLIT FLOW PATTERN IS FCST ACROSS CONUS THIS PERIOD.  NRN STREAM JET
   -- GENERALLY ALIGNED ALONG CANADIAN BORDER -- WILL BE BUCKLED BY TWO
   PRIMARY WAVES THIS PERIOD.  FIRST TROUGH -- NOW EVIDENT IN MOISTURE
   CHANNEL IMAGERY FROM ERN DAKOTAS NNEWD TO WRN HUDSON BAY -- IS FCST
   TO CROSS ALL OF ONT AND GREAT LAKES REGION BY 24/12Z.  AS THIS
   OCCURS SFC FRONTAL WAVES -- NOW EVIDENT OVER SWRN PA AND OVER PA/DE
   BORDER REGION...SHOULD CONSOLIDATE INTO DISCRETE LOW AND MOVE SEWD
   OFF DELMARVA.  ASSOCIATED COLD FRONT ALSO WILL MOVE SEWD OVER MID
   ATLANTIC/CENTRAL APPALACHIANS REGION.  FARTHER W SFC FRONT WILL
   EFFECTIVELY MOVE SWD THEN STALL...BECAUSE OF AGGREGATE OUTFLOWS
   ASSOCIATED WITH CURRENT CONVECTION ACROSS AR/TN.
   
   FARTHER W...PERSISTENT AND QUASISTATIONARY MID/UPPER LOW OVER
   4-CORNERS SHOULD BEGIN TO MOVE NEWD OVER CO TONIGHT...IN RESPONSE TO
    NRN STREAM HEIGHT FALLS AHEAD OF PACIFIC NW TROUGH.  AS THIS OCCURS
   COLD FRONT WILL MOVE SWD ACROSS W TX...MAKING FRONTAL WAVE OVER
   N-CENTRAL/NW TX MORE PRONOUNCED THROUGH THIS AFTERNOON AND TONIGHT. 
   DRYLINE NOW EVIDENT OVER PECOS VALLEY REGION IS FCST TO MIX EWD
   TOWARD CONCHO VALLEY/BIG COUNTRY AREA OF W-CENTRAL TX BY
   21Z...INTERSECTING COLD FRONT INVOF ABI.  FRONT WILL EXTEND NEWD
   ACROSS S-CENTAL/SERN OK AS QUASISTATIONARY BOUNDARY.
   
   ...SRN PLAINS...
   SCATTERED TSTMS SHOULD DEVELOP INVOF TRIPLE POINT BY MID-LATE
   AFTERNOON -- BOTH ON DRYLINE AND ON PORTIONS OF FRONT EXTENDING
   TOWARD RED RIVER.  ONCE FIRST FEW CELLS BREAK CAP EXPECT CONVECTIVE
   COVERAGE TO INCREASE DRAMATICALLY AMIDST FAVORABLE INSTABILITY AND
   FRONTAL FORCING...WITH MLCAPES 1500-2500 J/KG.
   MOIST ADVECTION SHOULD OFFSET VERTICAL MIXING ENOUGH TO KEEP SFC DEW
   POINTS MID 60S F ACROSS MOIST SECTOR.  SEGMENT OF FRONT NE OF TRIPLE
   POINT WILL BE NEARLY PARALLEL TO MEAN WIND AND DEEP LAYER SHEAR
   VECTORS...INDICATING STORMS MAY HAVE BRIEF SUPERCELL WINDOW BEFORE
   MERGING PRECIP PLUMES ENCOURAGE LINEAR TRANSITION.  LONGER LIVED
   DISCRETE STORMS ARE POSSIBLE ALONG DRYLINE...WHERE CAPPING WILL BE
   STRONGER.  WEAK LOW LEVEL SHEAR MAY PRECLUDE WIDESPREAD TORNADO
   EVENT...HOWEVER EXPECT DENSE ENOUGH CONCENTRATION OF SEVERE
   HAIL/WIND EVENTS TO WARRANT CATEGORICAL MDT RISK.
   
   MCS MAY DEVELOP FROM LATE AFTERNOON/EARLY EVENING CONVECTION AND
   MOVE NEWD ACROSS MDT RISK AREA TOWARD RED RIVER REGION AS
   WELL...CARRYING ADDITIONAL THREAT OF DAMAGING WIND AND HAIL.
   
   ...CENTRAL/SE TX...
   MODEL FCST SOUNDINGS VALID THIS AFTERNOON INDICATE DEEP/MOIST
   BOUNDARY LAYER WITH WEAK CAPPING.  THIS WILL BE JUXTAPOSED BENEATH
   7-8 DEG C/KM MIDLEVEL LAPSE RATES THAT RESULT FROM NEWD ADVECTION OF
   ELEVATED MIXED LAYER AIR OFF MEX PLATEAU.  EXPECTED DAYTIME HEATING
   COMBINED WITH SFC DEW POINTS UPPER 60S/LOW 70S F YIELD 1000-2000
   J/KG MLCAPE.  9Z RUC IS MUCH MORE AGGRESSIVE WITH BOTH CAPE AND
   SHEAR PROGS OVER THIS REGION...AND GENERATED PRECIP IN A PLUME
   EXTENDING NNEWD FROM LRD AREA. 20-30 KT SHEAR IN 0-1 KM LAYER AND
   LARGE LOW LEVEL HODOGRAPHS IN RUC SOUNDINGS INDICATES SOME SUPERCELL
   POTENTIAL.  HOWEVER...MODEL UNCERTAINTIES AND LACK OF APPARENT
   BOUNDARY LAYER FORCING MECHANISM PRECLUDE CATEGORICAL OUTLOOK ATTM.
   
   ...AR TO TN VALLEY...
   REF SPC MESOSCALE DISCUSSION 444 FOR NOWCAST DETAILS.  ONGOING MCS
   NRN AR MAY PRODUCE INTERMITTENT/MARGINAL SEVERE HAIL AND STRONG
   GUSTS AS IT MOVES ACROSS MS VALLEY INTO TN.  SOME REJUVENATION OF
   ASSOCIATED CONVECTION IS POSSIBLE THIS AFTERNOON OVER TN/ERN AR IN
   CONVERGENCE ZONE ASSOCIATED WITH REMNANT GUST FRONT...AND/OR JUST
   AHEAD OF ANY CONVECTIVELY INDUCED MESOSCALE VORTEX THIS COMPLEX MAY
   GENERATE.  OVERALL...HOWEVER...POTENTIAL FOR ORGANIZED SEVERE WILL
   BE LIMITED BY WEAKNESS OF BOTH LOW LEVEL SHEAR AND S-R INFLOW.
   
   ...TIDEWATER REGION VA/MD/DE...
   SCATTERED TSTMS IN ONE OR MORE NARROW BANDS MAY FORM INVOF FRONT
   THIS AFTERNOON AND EVENING...MOVING EWD ACROSS REGION LATE AFTERNOON
   INTO LATE EVENING.  MODIFIED FCST SOUNDINGS SUGGEST LESS THAN 500
   MLCAPE BECAUSE OF VERTICAL MIXING OF RELATIVELY LOW-RH BOUNDARY
   LAYER BY PEAK AFTERNOON HEATING TIME.  MORNING RAOBS SHOWING SHALLOW
   MOIST LAYER ABOVE SFC SUPPORT THIS SCENARIO.  NEARLY UNIDIRECTIONAL
   WIND FIELDS COMBINED WITH SMALL LOW LEVEL SHEAR VALUES AND WEAK
   INSTABILITY SUGGEST LITTLE POTENTIAL FOR ORGANIZED SEVERE...THOUGH A
   FEW STRONG TSTMS MAY OCCUR INVOF BOUNDARY INTERSECTIONS SUCH AS
   FRONT/BAY BREEZE OR OUTFLOW/FRONT.
   
   ...KS/OK BORDER REGION...
   ISOLATED/MARGINALLY SEVERE HAIL POSSIBLE FROM ONGOING CONVECTION
   OVER THIS AREA.  EXPECT PARCELS TO BE LIFTED ISENTROPICALLY TO LFC
   IN ZONE OF FAVORABLE LARGE SCALE MIDLEVEL ASCENT.  SATURATION
   OCCURRING NEAR 700 MB...AT BASE OF 7-8 DEG C/KM MIDLEVEL LAPSE
   RATES...YIELDS AMIDST 500-1000 J/KG ELEVATED MUCAPE.
   
   ..EDWARDS/CROSBIE.. 04/23/2004
   
   ...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