SPC AC 180517
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1217 AM CDT SUN JUL 18 2004
   
   VALID 181200Z - 191200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 NE
   MQT 45 NNW GRB 25 ENE LSE 35 SSE RWF 25 NW ABR 60 N ISN.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 45 WSW FHU 60 NE PHX
   45 NNE LAS 55 S BIH 45 NNE FAT 30 NE RBL 50 ESE CEC 35 SSE OTH 30 E
   BLI ...CONT... 50 W ANJ 30 ESE VOK 30 SE GRI 20 NNE EAR 25 NW REJ 30
   NNW 4BQ 20 SW SHR 40 SSE CPR 30 SSE GLD 10 NW DDC 25 WSW CSM 10 WNW
   BWD 10 ENE CLL 20 N POE 20 SSW JAN 45 SW 0A8 15 NNW BHM 45 SSE MKL
   25 SW PAH 20 NNW MTO 30 NNE BEH 40 SE OSC.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 80 SW P07 30 WSW CNM
   15 SSE TCS 30 WSW SVC 40 ESE DUG.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NRN
   PLAINS INTO THE WRN GREAT LAKES...
   
   ...SYNOPSIS...
   LITTLE CHANGE IS FORECAST IN THE LARGE-SCALE PATTERN THROUGH THE
   PERIOD WITH DOMINANT FEATURES BEING DEEP TROUGH IN THE E AND
   AMPLIFIED RIDGE ACROSS THE ROCKIES. MORE SPECIFICALLY...SHORTWAVE
   TROUGH AND ASSOCIATED UPPER-LEVEL JET STREAK WILL LIFT NEWD FROM
   MEAN TROUGH POSITION ACROSS MIDDLE ATLANTIC STATES/DELMARVA REGION
   TODAY. FARTHER NW...SHORTWAVE TROUGH / CURRENTLY AMPLIFYING OVER
   CNTRL SASKATCHEWAN/MANITOBA / WILL TRANSLATE SEWD ACROSS ONTARIO AND
   THE UPPER MS VALLEY/WRN GREAT LAKES...WHILE NEXT UPSTREAM SYSTEM
   PROGRESSES NEWD ONTO THE PACIFIC NW COAST.
   
   AT THE SURFACE...PRIMARY LOW ASSOCIATED WITH MIDDLE ATLANTIC
   SHORTWAVE TROUGH WILL DEVELOP NEWD FROM SC INTO THE CHESAPEAKE BAY
   REGION BY EARLY EVENING WITH TRAILING BAROCLINIC ZONE BEING
   REINFORCED ACROSS THE CAROLINA PIEDMONT SWWD INTO THE CNTRL GULF
   COAST. MEANWHILE...COLD FRONT OVER CNTRL CANADA WILL PROGRESS
   SEWD...LIKELY EXTENDING FROM A SURFACE LOW OVER NWRN ONTARIO SWWD
   ACROSS N-CNTRL MN/CNTRL ND AND INTO THE NRN ROCKIES BY EARLY
   EVENING.
   
   ...NRN PLAINS INTO THE WRN GREAT LAKES...
   LARGE MCS HAS EVOLVED TONIGHT AHEAD OF SHORTWAVE TROUGH OVER CNTRL
   PARTS OF SASKATCHEWAN/MANITOBA. THIS CONVECTION WILL LIKELY CONTINUE
   TO MOVE/DEVELOP SEWD OVERNIGHT...POSSIBLY REACHING THE ND OR MN
   BORDER EARLY IN THE FORECAST PERIOD. RATHER STEEP LOW TO MID-LEVEL
   LAPSE RATES COUPLED WITH DEWPOINTS GENERALLY IN THE 60S SHOULD ALLOW
   DOWNSTREAM AIRMASS ACROSS THE DAKOTAS INTO MN TO BECOME MODERATELY
   UNSTABLE WITH MLCAPES APPROACHING 1500-2000 J/KG.
   
   GREATEST POTENTIAL FOR SEVERE WEATHER APPEARS TO BE ASSOCIATED WITH
   ANY MCS THAT MOVES SEWD OUT OF S-CNTRL CANADA DURING THE DAY AND/OR
   WITH ANY TSTMS THAT DEVELOP ALONG APPROACHING COLD FRONT. FORECAST
   SOUNDINGS WITHIN PRE-FRONTAL AIRMASS INDICATE STRONGLY VEERING WIND
   PROFILES WITH 35-45KTS OF DEEP-LAYER SHEAR AND 150-250 M2/S2 0-3KM
   SRH...SUGGESTING THE LIKLIHOOD OF SUPERCELLS IN ADDITION TO BOWING
   STRUCTURES. LARGE HAIL AND DAMAGING WINDS APPEAR TO BE THE PRIMARY
   SEVERE WEATHER THREATS. POTENTIAL FOR ISOLATED TORNADOES WILL ALSO
   EXIST...ESPECIALLY LATE THIS AFTERNOON INTO EVENING ACROSS NRN INTO
   CNTRL MN WHERE BEST COMBINATION OF LOW-LEVEL HUMIDITY AND SHEAR IS
   EXPECTED TO CO-EXIST.
   
   DAMAGING WIND THREAT COULD SPREAD AS FAR E AS WRN UP OF MI INTO
   NRN/CNTRL WI OVERNIGHT IN ASSOCIATION WITH FORWARD-PROPAGATING MCS
   WHICH SHOULD BE MAINTAINED AHEAD OF AMPLIFYING SHORTWAVE TROUGH.
   
   ...SRN NEW ENGLAND SWD ACROSS THE DELMARVA REGION INTO CNTRL/ERN
   CAROLINAS...
   STRONG...DYNAMIC FORCING FOR ASCENT AHEAD OF SHORTWAVE TROUGH AND
   WITHIN EXIT REGION OF UPPER JET STREAK WILL SPREAD NWD FROM THE
   DELMARVA TOWARD SRN NEW ENGLAND TODAY WITH SCATTERED TO NUMEROUS
   TSTMS LIKELY FOCUSED ALONG AND N OF RETREATING WARM FRONT. LATEST
   MODEL GUIDANCE SUGGESTS THAT PRIMARY FACTOR LIMITING SEVERE TSTM
   DEVELOPMENT WILL BE WEAK INSTABILITY OWING TO THE ANTICIPATED
   WIDESPREAD CLOUDS/PRECIPITATION.
   
   FARTHER S...IT APPEARS THAT TSTMS MAY DEVELOP LATER TODAY ALONG COLD
   FRONT WITHIN DRY SLOT REGION OF SHORTWAVE TROUGH LIFTING NEWD
   THROUGH THE AREA. DIABATIC HEATING COUPLED WITH STEEPER MID-LEVEL
   LAPSE RATES ON CYCLONIC SIDE OF UPPER-LEVEL JET SHOULD CONTRIBUTE TO
   MLCAPES OF 500-1000 J/KG. COMBINATION OF HIGH-LEVEL FLOW OF 80-90KTS
   WITH 30-40KTS IN THE MID-LEVELS SHOULD BE SUPPORTIVE OF ORGANIZED
   TSTMS CAPABLE OF ISOLATED DAMAGING WINDS AND LARGE HAIL.
   
   IF IT BECOMES APPARENT THAT MORE INSTABILITY WILL DEVELOP THAN IS
   CURRENTLY ANTICIPATED...PORTIONS OF DISCUSSION AREA MAY NEED TO BE
   UPGRADED TO SLIGHT RISK.
   
   ...NRN ROCKIES...
   RATHER STEEP LOW TO MID-LEVEL LAPSE RATES AND BOUNDARY-LAYER
   DEWPOINTS IN THE 50S SHOULD CONTRIBUTE TO AIRMASS DESTABILIZATION
   THROUGH THE DAY WITH MLCAPES INCREASING TO 500 J/KG. APPROACH OF
   PACIFIC NW MID-LEVEL TROUGH AND ASSOCIATED FRONTAL SYSTEM...IN
   CONJUNCTION WITH LOW-LEVEL UPSLOPE COMPONENT IN
   TOPOGRAPHICALLY-FAVORED AREAS SHOULD LEAD TO AN INCREASE IN STORM
   COVERAGE AND INTENSITY THROUGH THE AFTERNOON AND EVENING HOURS.
   THOUGH IT APPEARS THAT THE STRONGEST SHEAR WILL BE DISPLACED TO THE
   W OF THE BEST INSTABILITY...POTENTIAL WILL STILL EXIST FOR A FEW
   INTENSE STORMS CAPABLE OF ISOLATED STRONG WIND GUSTS AND MARGINALLY
   SEVERE HAIL.
   
   ..MEAD/CROSBIE.. 07/18/2004
   
   ...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