SPC AC 120511
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1211 AM CDT WED MAY 12 2004
   
   VALID 121200Z - 131200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 70 WNW
   ANJ 15 ESE JVL 45 NE COU 15 NNW SGF 50 NW FYV 30 NE OKC 25 NE FSI 35
   NW LTS 35 E LBL 35 SW GCK 20 SSW LAA 40 E COS 30 SE CYS 20 WSW SNY
   35 S MCK 10 ENE CNK OMA 30 WNW RWF 20 NNW INL.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 SE DRT 35 N HDO 10
   SE BWD 30 N ABI 40 S CDS 65 ENE AMA 20 S LBL 50 SSE LHX 20 W TAD 10
   N DRO 15 SSW CNY 20 W ENV 40 S OWY 60 W OWY 20 SSE BNO 10 NNE PDT 35
   W PUW 40 SSW 3DU 20 SSW LVM 20 ENE CPR BFF 10 NE LBF 15 NE BUB 60
   ENE ANW 10 WSW HON JMS 70 N GFK ...CONT... 25 E MSS 30 SE SLK 25 NNE
   PSF ISP ...CONT... WAL 30 W RIC 20 SSE LYH 15 WNW GSO 40 SE CLT 15
   SSE CHS ...CONT... 40 SSE JAX 45 SE CTY.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE WRN GREAT LAKES SWWD
   INTO PORTIONS OF THE CNTRL AND SRN PLAINS...
   
   ...SYNOPSIS...
   DEEP...MID-LEVEL TROUGH WILL REMAIN IN PLACE ACROSS THE
   INTERMOUNTAIN W/HIGH PLAINS REGION THROUGH THE DAY 1 PERIOD WITH
   SEVERAL SMALLER-SCALE VORTICITY MAXIMA TRANSLATING THROUGH THE MEAN
   TROUGH POSITION. THE FIRST OF WHICH /CURRENTLY OVER S-CNTRL WY/WRN
   NEB/ WILL EJECT NEWD ACROSS ERN ND/NWRN MN LATER TODAY AND INTO
   MANITOBA/WRN ONTARIO OVERNIGHT. THE NEXT SIGNIFICANT UPSTREAM
   VORTICITY MAX IS CURRENTLY OVER CNTRL NV/WRN UT. THIS FEATURE WILL
   ROUND THE TROUGH BASE AND LIFT NEWD INTO THE CNTRL HIGH PLAINS LATE
   THIS AFTERNOON OR EARLY EVENING...PRIOR TO PROGRESSING NEWD INTO ERN
   NEB/IA BY THURSDAY MORNING.
   
   AT THE SURFACE...CYCLONE ATTENDANT TO LEAD VORTICITY MAX WILL
   DEVELOP NEWD FROM W-CNTRL INTO N-CNTRL MN TODAY WITH TRAILING COLD
   FRONT SURGING SEWD. BY EARLY EVENING...FRONTAL POSITION SHOULD
   ROUGHLY EXTEND FROM WRN WI SWWD THROUGH CNTRL PORTIONS OF IA AND KS
   TO DEEPENING SECONDARY LOW OVER FAR SWRN KS/OK PNHDL REGION. PORTION
   OF COLD FRONT IN CLOSER PROXIMITY TO THIS SECONDARY LOW PRESSURE
   SHOULD TEND TO REMAIN MORE QUASI-STATIONARY OWING TO PRESSURE
   FALLS/WAA ON COLD SIDE OF BOUNDARY. FINALLY...DRYLINE SHOULD SHARPEN
   THROUGH THE DAY AS IT MIXES EWD...LIKELY EXTENDING FROM SECONDARY
   LOW SWD THROUGH ERN TX PNHDL OR WRN OK INTO W-CNTRL TX.
   
   ...WRN GREAT LAKES...
   PRE-FRONTAL TSTM CLUSTERS/LINE SEGMENTS WILL LIKELY BE ONGOING
   INITIALLY FROM N-CNTRL MN/MN ARROWHEAD SWD INTO CNTRL MN AND NERN
   NEB. ALTHOUGH CONVECTIVELY-PROCESSED MID-LEVEL LAPSE RATES ARE
   EXPECTED TO BE ONLY MOIST ADIABATIC AT BEST...MOIST FEED OF LOWER TO
   MID 60S DEWPOINTS AHEAD OF SURFACE CYCLONE AND ATTENDANT COLD FRONT
   SHOULD AID IN DESTABILIZATION PROCESS. THIS MOISTURE COUPLED WITH
   DIABATIC HEATING WILL ALLOW POCKETS OF MODERATE INSTABILITY TO
   DEVELOP ACROSS WI SWD INTO WRN IL AND CNTRL/ERN IA WITH MLCAPES
   APPROACHING 500-1500 J/KG.
   
   REDEVELOPMENT AND/OR RE-INTENSIFICATION OF ONGOING TSTMS IS
   ANTICIPATED BY AFTERNOON WITHIN DESTABILIZING AIRMASS OVER ERN MN
   INTO WRN WI AND CNTRL/ERN IA. STORMS SHOULD TEND TO BECOME ALIGNED
   IN FRONTAL-PARALLEL BANDS OR CLUSTERS AND SPREAD EWD ACROSS WI INTO
   THE WRN UP OF MI TONIGHT. ALTHOUGH THE STRONGEST MID AND UPPER-LEVEL
   WIND FIELDS WILL REMAIN TO THE W IN THE POST-FRONTAL COLD
   AIR...MARGINALLY STRONG DEEP-LAYER SHEAR IS STILL FORECAST ALONG AND
   E OF SURFACE FRONT. THIS IN CONJUNCTION WITH STRONGER ISALLOBARIC
   FORCING INVOF SURFACE LOW MAY SUPPORT A FEW INTENSE STORMS WITH THE
   POTENTIAL FOR PRIMARILY DAMAGING WINDS.
   
   ...CNTRL/SRN PLAINS...
   MOIST LOW-LEVEL AIRMASS /CHARACTERIZED BY DEWPOINTS IN THE MID TO
   UPPER 60S/ IN COMBINATION WITH STEEP LOW TO MID-LEVEL LAPSE RATES
   WILL CONTRIBUTE TO A STRONGLY UNSTABLE AIRMASS THIS AFTERNOON S OF
   COLD FRONT AND E OF DRYLINE WITH MLCAPES INCREASING TO 2000-3000
   J/KG FROM CNTRL KS SWD INTO W-CNTRL TX. INITIATION OF DEEP MOIST
   CONVECTION WILL LIKELY OCCUR BY MID AFTERNOON ALONG SWD-MOVING COLD
   FRONT OVER PORTIONS OF NERN KS...WITH SUBSEQUENT DEVELOPMENT SWWD
   INTO PROGRESSIVELY STRONGER CAP OVER CNTRL INTO SWRN KS.
   
   WHILE STRONGEST MID AND UPPER-LEVEL WINDS WILL REMAIN OVER
   POST-FRONTAL AIRMASS...MODESTLY STRONG 500MB WINDS OF 35-45KTS WILL
   GRADUALLY SPREAD NEWD ACROSS NRN PORTION OF INSTABILITY AXIS. WHEN
   COMBINED WITH THE EXPECTED DEGREE OF INSTABILITY...A FEW SUPERCELLS
   CAPABLE OF VERY LARGE HAIL AND DAMAGING WINDS APPEAR LIKELY.
   ISOLATED TORNADO THREAT MAY TEND TO INCREASE EARLY THIS EVENING
   ACROSS S-CNTRL KS/N-CNTRL OK OWING TO STRENGTHENING LOW-LEVEL SHEAR
   ALONG AXIS OF DEVELOPING LLJ. UPSCALE EVOLUTION OF TSTMS INTO
   CLUSTERS/MCS IS ANTICIPATED TONIGHT AHEAD OF EJECTING NV/UT
   VORTICITY MAX. WITH DAMAGING WIND THREAT EXTENDING NEWD ACROSS ERN
   KS INTO W-CNTRL/NWRN MO.
   
   ADDITIONAL...MORE ISOLATED SEVERE STORMS WILL ALSO BE LIKELY IN
   POST-FRONTAL UPSLOPE REGIME OVER THE CO FRONT RANGE. WHILE
   INSTABILITY WILL REMAIN SOMEWHAT LIMITED WITH MLCAPES GENERALLY LESS
   THAN 1000 J/KG...STRONG VERTICAL WIND SHEAR WILL SUPPORT THE
   POTENTIAL FOR SUPERCELLS WITH LARGE HAIL.
   
   FINALLY...A COUPLE OF ISOLATED STORMS MAY DEVELOP SWD ALONG DRYLINE
   WHERE BOUNDARY-LAYER BECOMES SUFFICIENTLY MIXED TO OVERCOME CAP.
   THOUGH DEEP-LAYER SHEAR DECREASES WITH SWD EXTENT... POTENTIAL FOR
   SUPERCELL/ORGANIZED MULTICELL STRUCTURES WILL EXIST WITH LARGE HAIL
   AND DAMAGING WINDS BEING THE MAIN THREATS.
   
   ..MEAD/TAYLOR.. 05/12/2004
   
   ...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 1300Z