Jul 31, 2010 2000 UTC Day 1 Convective Outlook
Updated: Sat Jul 31 21:29:20 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20100731 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100731 2000 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100731 2000 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100731 2000 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 312127
   
   DAY 1 CONVECTIVE OUTLOOK AMEND 1
   NWS STORM PREDICTION CENTER NORMAN OK
   0427 PM CDT SAT JUL 31 2010
   
   VALID 312000Z - 011200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE NRN
   INTERMOUNTAIN WEST...NRN ROCKIES AND NRN PLAINS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER OH/TN VLYS TO
   THE SERN ATLANTIC SEABOARD...
   
   AMENDED FOR SEVERE THUNDERSTORM WATCH WRN SD/ERN WY
   
   ...NRN HIGH PLAINS...
   UPDATED TO ACCOUNT FOR SEVERE THUNDERSTORM WATCH IN WRN SD AND ERN
   WY.
   
   /JPR
   
   
   .PREV DISCUSSION... /ISSUED 244 PM CDT SAT JUL 31 2010/
   
   ...NRN INTERMOUNTAIN REGION INTO NRN PLAINS...
   ONLY CHANGE TO THIS GROUP WAS TO TRIM THE SEVERE RISKS OUT OF
   CABINET AND NRN ROCKY MOUNTAIN FRONT REGIONS OF MT.  A COLD SURGE
   HAS SPREAD SWD...ESPECIALLY E OF THE NRN ROCKY MOUNTAIN FRONT WITH
   SFC TEMPERATURES HAVING FALLEN INTO THE 60S.  THIS SHOULD SET THE
   WRN END OF THE SEVERE RISKS TODAY.  PRIMARY SEVERE THREAT SHOULD
   EVOLVE FARTHER E AND S ACROSS SW-CNTRL MT.  STRONG STORMS HAVE
   ALREADY DEVELOPED OVER THE SW MT MOUNTAINS AHEAD OF A MID-LEVEL
   WAVE.  DOWNSTREAM INVERTED-V SOUNDING STRUCTURES AND HOT BOUNDARY
   LAYER SHOULD AUGMENT WIND GUSTS WITH SEVERE/DAMAGING WINDS POSSIBLE
   INTO THIS EVENING.  REFER TO LATEST ACUS11 MESOSCALE DISCUSSIONS AND
   
   REMAINDER OF FORECAST DISCUSSION REMAINS VALID FOR LOCATIONS FARTHER
   E IN THE NRN PLAINS.
   
   ...CNTRL HIGH PLAINS...
   HAVE EXTENDED LOW PROBABILITIES FOR SEVERE HAIL/WIND INTO ERN CO
   WHERE A CLUSTER OF SLOW MOVING MULTICELL STORMS CONTINUE IN THE
   VICINITY OF A WEAK BOUNDARY.  ALTHOUGH THERMODYNAMIC/KINEMATIC
   SET-UPS WERE VERY MARGINAL FOR SUSTAINED SEVERE STORMS...AN ISOLATED
   DAMAGING WET MICROBURST CANNOT BE RULED OUT.
   
   ...SERN ATLANTIC COAST...
   REFER TO LATEST ACUS11 MESOSCALE DISCUSSIONS AND WWUS20 SEVERE
   THUNDERSTORM WATCH FOR DETAILS.  NO CHANGES TO THIS GROUP NEEDED. 
   FORECAST ON TRACK WITH SMALL CONVECTIVELY-INDUCED SHORTWAVE
   MIGRATING INTO THE CAROLINAS.  LARGELY MULTICELL STORMS CONTINUE TO
   THRIVE ALONG/SW OF A STALLED NW-SE ORIENTED FRONT FROM N GA INTO
   COASTAL SC/GA.  STORM MERGERS AND VERY HOT BOUNDARY LAYER/LARGE
   DCAPE VALUES WILL RESULT IN PRECIPITATION LOADING AND SUBSEQUENT WET
   MICROBURSTS WITH A FEW STORMS.  SEVERE THREATS WILL DIMINISH WITH
   SUNSET.
   
   ...LOWER OH/TN VALLEYS...
   REFER TO LATEST ACUS11 MESOSCALE DISCUSSIONS AND WWUS20 SEVERE
   THUNDERSTORM WATCH FOR DETAILS.  NO CHANGES TO THIS GROUP NEEDED. 
   LARGE-SCALE UPPER TROUGH ROTATING THROUGH THE MIDWEST WILL GRAZE THE
   WARM/UNSTABLE WARM SECTOR ACROSS THE REGION THROUGH THIS EVENING. 
   THUNDERSTORMS CONTINUE TO DEEPEN ACROSS THE KY BLUEGRASS AND MIDDLE
   TN AT MID-AFTERNOON.  A FEW STORMS MAY PRODUCE DAMAGING WINDS AND
   PERHAPS HAIL.  
   /JPR
   
   ..SELECT A FORECASTER.. 07/31/2010
   
   .PREV DISCUSSION... /ISSUED 1109 AM CDT SAT JUL 31 2010/
   
   ...SYNOPSIS...
   WHILE RIDGE DOMINATES SRN U.S. WITH UPR HIGH CENTER SRN PLAINS...THE
   TROUGH THAT HAS BEEN OFFSHORE PAC NW HAS MOVED TO THE COAST WHILE
   TROUGH PERSISTS NERN STATES.
   
   ..NRN INTERMOUNTAIN REGION INTO NRN PLAINS...
   
   AHEAD OF THE PRIMARY UPPER TROUGH AN IMPULSE/SPEED MAX MOVING NEWD
   ACROSS WA/OR WILL MOVE TO NRN INTERMOUNTAIN REGION BY THIS EVENING. 
   MEANWHILE...A WEAKER DOWNSTREAM IMPULSE /NOW OVER CNTRL PORTIONS OF
   MT INTO NRN WY/ WILL TRANSLATE EWD TODAY INTO ND AND NRN SD.  IN THE
   LOW LEVELS...WEAK LOW PRESSURE WILL CONSOLIDATE OVER ERN MT BY THIS
   AFTERNOON WITH A NNW-SSE ORIENTED TROUGH/BAROCLINIC ZONE PERSISTING
   FROM FAR ERN MT INTO THE CNTRL HIGH PLAINS.  FARTHER W...A WEAK
   PACIFIC FRONT WILL PROGRESS THROUGH THE PACIFIC NW INTO NRN
   INTERMOUNTAIN REGION TODAY.
   
   THE PRIMARY FOCUS FOR STRONG TO SEVERE TSTM DEVELOPMENT APPEARS TO
   BE ALONG THE FAVORED TERRAIN AND EWD-ADVANCING PACIFIC FRONT BY
   MID/LATE AFTERNOON FROM ERN WA/NERN ORE ACROSS THE ID PNHDL INTO WRN
   MT.  HERE...INCREASED HEIGHT FALLS/DYNAMIC FORCING FOR ASCENT
   ATTENDANT TO ABOVE-MENTIONED SYSTEM WILL INTERACT WITH A STEEP LAPSE
   RATE THERMODYNAMIC ENVIRONMENT WHERE MLCAPE WILL APPROACH 1000 J/KG.
   THE EWD PROGRESSION OF 80-90 KT UPPER-LEVEL JET STREAK AND 50+ KT
   MIDLEVEL WIND MAXIMUM WILL RESULT IN 45-60 KT OF DEEP SWLY
   SHEAR...SUFFICIENT FOR ORGANIZED STORM MODES...INCLUDING SUPERCELLS
   AND BOWING STRUCTURES.  LARGE HAIL AND DAMAGING WIND GUSTS WILL BE
   THE PRIMARY HAZARDS GIVEN THE COOLING THERMODYNAMIC PROFILES AND
   STEEP LAPSE RATE/HIGH LCL ENVIRONMENT.
   
   HAVE EXTENDED THE RISK EWD ACROSS SRN ID GIVEN THE GREATER
   AVAILABILITY OF THE MONSOON MOISTURE FROM THE S TO AID THE
   INSTABILITY ALONG WITH UP TO 40 KT OF SHEAR.
   
   STORM INITIATION AND EVOLUTION IS A BIT MORE UNCERTAIN FARTHER E
   ACROSS ERN MT INTO THE DAKOTAS TODAY OWING TO EWD PROGRESSION OF
   LEAD IMPULSE AWAY FROM N-S ORIENTED SURFACE BOUNDARY.
   NONETHELESS...IT APPEARS THAT AT LEAST ISOLATED...DIURNAL
   STORMS WILL BE POSSIBLE IN ADVANCE OF THE LEAD IMPULSE OVER ND...AS
   WELL AS ALONG THE PRIMARY BOUNDARY WHICH SHOULD BE SITUATED OVER FAR
   ERN PARTS OF MT/WY.  ALSO...SOME MODEL GUIDANCE SUGGESTS THE
   POSSIBILITY OF STORMS PROGRESSING SEWD FROM SERN SASKATCHEWAN/SRN
   MANITOBA INTO CNTRL/ERN ND.  IN ANY EVENT...THE COMBINATION OF 40-50
   KT OF DEEP-LAYER SHEAR AND AFTERNOON MLCAPE VALUES APPROACHING
   1000-1500 J/KG SUGGESTS THE POTENTIAL FOR SUSTAINED/ROTATING
   UPDRAFTS CAPABLE OF LARGE HAIL AND DAMAGING WIND GUSTS.
   
   TSTMS WILL LIKELY PERSIST OVERNIGHT MAINLY ACROSS ND IN ASSOCIATION
   WITH STRENGTHENING WAA REGIME ATTENDANT TO 40+ KT LLJ.  A FEW OF THE
   MORE INTENSE STORMS WILL REMAIN CAPABLE OF HAIL AND STRONG WIND
   GUSTS INTO SUNDAY MORNING.
   
   
   ..SERN ATLANTIC COAST...
   REF MCD 1510
   
   MIDLEVEL IMPULSE RESPONSIBLE FOR ONGOING TSTMS NOW MOVING ACROSS ERN
   TN WILL CONTINUE SEWD TODAY...SUPPORTING AN INCREASE IN TSTM
   COVERAGE AND INTENSITY WITHIN A VERY MOIST AND MODERATELY UNSTABLE
   AIR MASS WITH MLCAPE OF 1500-3000 J/KG. THE MODERATE
   INSTABILITY COUPLED WITH VEERING WIND PROFILES AND AROUND 30 KT OF
   DEEP NWLY SHEAR WILL FAVOR UPSCALE GROWTH OF STORMS INTO MULTICELL
   CLUSTERS WITH THE THREAT FOR DAMAGING WIND GUSTS.
   
   ...LOWER OH/TN VALLEYS...
   
   A FAIRLY STRONG MIDLEVEL IMPULSE AND ASSOCIATED 40-45 KT WIND
   MAXIMUM TRANSLATING SEWD THROUGH THE UPPER MIDWEST.  THIS IMPULSE
   WILL CONTINUE SEWD TODAY IN CONJUNCTION WITH A SURFACE LOW AND
   ATTENDANT FRONTAL SYSTEM.  STRONG DIABATIC HEATING UNDERWAY LWR OH
   AND WRN TN VLYS THIS AM AND WILL SUPPORT THE DEVELOPMENT OF A
   MODERATELY UNSTABLE AIR MASS BY AFTERNOON AHEAD OF SWD-MOVING FRONT
   WITH MLCAPE OF 1000-2500 J/KG.
   
   EXPECT TSTMS TO GRADUALLY INCREASE IN COVERAGE AND INTENSITY THROUGH
   THE AFTERNOON IN ADVANCE OF UPPER SYSTEM WITHIN A KINEMATIC
   ENVIRONMENT FEATURING VERTICALLY-VEERING WIND PROFILES AND 30-40 KT
   OF DEEP NWLY SHEAR.  AS SUCH...THE SETUP WILL FAVOR THE DEVELOPMENT
   OF ORGANIZED STORM CLUSTERS...PERHAPS EVOLVING INTO AN MCS WITH
   DAMAGING WINDS BEING THE PRIMARY HAZARD.
   
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