May 18, 2005 0600 UTC Day 1 Convective Outlook
Updated: Wed May 18 04:42:10 UTC 2005
Categorical Graphic
20050518 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20050518 1200 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20050518 1200 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20050518 1200 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 180438
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1138 PM CDT TUE MAY 17 2005
   
   VALID 181200Z - 191200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 W
   FNB 40 SW FOD 30 W ALO 30 E CID 15 SW BRL 25 SSW JEF 25 SSE UMN 10
   SE ADM 15 W SPS 30 WSW LTS 45 N CDS 55 SSW GAG 25 WNW P28 25 W FNB.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 55 SSW
   JMS 50 WNW JMS 20 ENE DVL 15 N TVF 10 NNE BJI BRD STC 25 W MKT 35
   NNW OTG 20 E ATY 55 SSW JMS.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 NNW
   LYH 25 E CHO 10 ESE RIC 60 NNE RWI 10 WSW RWI 20 SW RDU 20 S GSO 35
   NNW GSO 25 NNW LYH.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 SW HUM 30 NNW JAN
   45 NNE GLH 50 NE PBF 25 SW LIT 30 SE PRX 30 S SEP 30 NW JCT 70 ENE
   P07 25 S MAF 50 NW BGS 40 SE AMA 35 W GAG 35 ESE DDC 40 WNW CNK 20
   WNW OFK 25 ESE HON 35 NE MBG 25 S ISN 60 NNE OLF ...CONT... 10 N CMX
   25 SW ESC 35 NNW MKG 15 SE BEH 25 SSE LAF 45 N EVV 30 N PAH 30 SE
   PAH 15 SW LOZ 5I3 EKN 15 NNW DCA 10 NE NHK 35 SW WAL 20 NW ECG 20
   SSE FAY 30 S FLO 20 E CHS.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 N FCA 45 ESE FCA
   20 S 3DU 15 E 27U 30 NE BOI 45 SE BNO 40 WNW 4LW CEC.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 S PSM 10 SSE LEB
   10 WNW EFK.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF IA SWWD INTO
   OK...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF ERN ND/NERN SD
   AND WRN MN...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF VA AND NC...
   
   ...SYNOPSIS...
   SHORTWAVE TROUGH OVER ERN WY INTO WRN SD/NEB PNHDL WILL WEAKEN
   THROUGH THE DAY 1 PERIOD AS IT TRANSLATES EWD...AND EVENTUALLY
   SEWD...UNDERCUTTING AMPLIFIED DOWNSTREAM RIDGE IN PLACE FROM CNTRL
   CANADA INTO THE UPPER MIDWEST. IN THE LOW-LEVELS...OCCLUDED SURFACE
   LOW INITIALLY OVER CNTRL ND AT 18/12Z WILL SLOWLY FILL AS IT
   DEVELOPS EWD INTO THE UPPER MS VALLEY. SYSTEM COLD FRONT WILL PUSH
   EWD/SEWD AND WILL LIKELY EXTEND FROM THE SURFACE LOW OVER ERN ND SWD
   THROUGH THE MIDDLE MO VALLEY AND THEN SWWD INTO NWRN OK AND THE TX
   PNHDL BY LATE AFTERNOON.
   
   ...IA/MO SWWD INTO OK...
   BAND OF TSTMS WILL LIKELY BE ONGOING AT THE ONSET OF THE FORECAST
   FROM MN SWWD THROUGH WRN/CNTRL IA INTO NERN KS...LARGELY BEING
   DRIVEN BY LOW-LEVEL MOIST/THERMAL ADVECTION ALONG NOSE OF SWLY LLJ
   AXIS. THIS ACTIVITY IS EXPECTED TO CONTINUE EWD THROUGH THE DAY INTO
   PARTS OF WI AND IL...ALONG EWD-MIGRATING BRANCH OF LLJ. CONSIDERABLE
   CLOUDS AND PRECIPITATION WILL TEND TO LIMIT DESTABILIZATION OF
   DOWNSTREAM AIR MASS WITH STRONGEST STORMS POSING A MARGINAL DAMAGING
   WIND/LARGE HAIL THREAT.
   
   ADDITIONAL...MORE VIGOROUS STORM DEVELOPMENT IS ANTICIPATED LATER
   TODAY ALONG THE SRN/SWRN FLANK OF THIS ONGOING TSTM COMPLEX...AS
   WELL AS FARTHER TO THE W ALONG COLD FRONT FROM ERN KS/WRN MO SWWD
   INTO NRN OK. HERE...DAYTIME HEATING COUPLED WITH DEWPOINTS IN THE
   MID/UPPER 50S INTO LOWER 60S AND STEEP LAPSE RATES WILL CONTRIBUTE
   TO MODERATE INSTABILITY WITH MLCAPES OF 1500-2500 J/KG. MODEST WNWLY
   MID-LEVEL FLOW OF 20-30 KTS ABOVE SLY BOUNDARY-LAYER WINDS WILL
   RESULT IN EFFECTIVE BULK SHEAR OF 30-35 KTS...SUPPORTIVE OF
   ORGANIZED MULTICELL CLUSTERS AND POSSIBLY A COUPLE SUPERCELLS. LARGE
   HAIL APPEARS TO BE THE PRIMARY SEVERE WEATHER THREAT...THOUGH
   DAMAGING WINDS WOULD BECOME INCREASINGLY LIKELY WITH ANY STORM
   CLUSTERS THAT CAN FORWARD-PROPAGATE TO THE S OR SE.
   
   WWD EXTENT OF TSTM DEVELOPMENT ALONG FRONT THIS AFTERNOON AND
   EVENING IS UNCERTAIN ATTM...THOUGH IT APPEARS THAT BUILDING
   MID-LEVEL HEIGHTS AND DECREASING LOW-LEVEL CONVERGENCE WILL TEND TO
   DISCOURAGE DEEP CONVECTION OVER THE TX PNHDL INTO NWRN/WRN OK.
   
   ...ERN ND INTO MN...
   THOUGH AREAS OF CLOUDS AND PRECIPITATION WILL LIKELY LINGER THROUGH
   MUCH OF THE DAY INVOF MID-LEVEL COLD POOL AND SURFACE
   LOW...LOCALIZED BREAKS IN THE CLOUDS AND STEEP LAPSE RATES ARE
   EXPECTED TO CONTRIBUTE TO MLCAPES OF 500-1000 J/KG. VERTICAL SHEAR
   WILL NOT BE PARTICULARLY STRONG OWING TO CLOSE PROXIMITY TO
   VERTICALLY-STACKED SYNOPTIC SYSTEM...HOWEVER RATHER COLD
   THERMODYNAMIC PROFILES SUGGEST THE POTENTIAL FOR LARGE HAIL WITH THE
   STRONGEST STORMS.
   
   ...VA/NC...
   CURRENT SURFACE OBSERVATIONS INDICATE THAT AIR MASS IS RATHER DRY
   ACROSS SLIGHT RISK AREA WITH DEWPOINTS GENERALLY 45-55F.
   HOWEVER...INTENSIFYING NWLY MID-LEVEL FLOW ACROSS THE NRN AND CNTRL
   APPALACHIANS SHOULD ENHANCE LEE TROUGHING ACROSS THE
   PIEDMONT...ALLOWING BOUNDARY-LAYER MOISTURE TO INCREASE FROM THE S.
   WHEN COUPLED WITH DIABATIC HEATING...AIR MASS IS FORECAST TO BECOME
   MODERATELY UNSTABLE BY AFTERNOON WITH MLCAPES OF AROUND 1000 J/KG.
   
   HIGHER TERRAIN OF APPALACHIANS AND LEE TROUGH WILL BOTH SERVE AS A
   FOCUS FOR TSTM DEVELOPMENT THIS AFTERNOON. GIVEN RATHER STRONG
   MID-LEVEL FLOW ON SRN PERIPHERY OF UPPER LOW OVER NEW
   ENGLAND...FORECAST SOUNDINGS INDICATE THAT MORE THAN ENOUGH VERTICAL
   SHEAR WILL EXIST FOR ORGANIZED UPDRAFTS...INCLUDING A SUPERCELL OR
   TWO. DAMAGING WINDS AND LARGE HAIL APPEAR TO BE THE MAIN SEVERE
   WEATHER HAZARDS.
   
   ..MEAD/BANACOS.. 05/18/2005
   
   ...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 1300Z