Jul 8, 2011 1300 UTC Day 1 Convective Outlook
Updated: Fri Jul 8 13:04:06 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110708 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110708 1300 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20110708 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20110708 1300 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
   SPC AC 081300
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0800 AM CDT FRI JUL 08 2011
   
   VALID 081300Z - 091200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN PLNS AND
   NRN HI PLNS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE TN VLY/SRN
   APPALACHIANS TO THE MID ATLANTIC/SRN NEW ENGLAND CST...
   
   ...SYNOPSIS...
   UPR RIDGE WILL REMAIN STNRY ACROSS THE SRN RCKYS AND SRN HALF OF THE
   PLNS THIS PERIOD AS A FAIRLY STRONG UPR LOW MOVES FROM SRN BC TO THE
   AB/SK BORDER...AND A LOOSELY ORGANIZED TROUGH PROGRESSES FROM UPR
   GRT LKS/OH VLY TO THE NEW ENGLAND AND MID ATLANTIC STATES BY 12Z
   SAT.
   
   AT THE SFC...A WELL-DEFINED FRONTAL SYSTEM WILL PRECEDE THE BC UPR
   LOW.  THE COLD FRONT SHOULD REACH ERN AND SRN PORTIONS OF MT BY THIS
   EVE...AND NE ND...NW SD...AND CNTRL WY BY THE END OF THE PERIOD. 
   AHEAD OF THE COLD FRONT...LEE TROUGH WILL PROGRESS E INTO THE WRN
   DAKOTAS LATER TODAY...WHILE WARM FRONT NOW FORMING OVER SRN SD
   ADVANCES NWD INTO CNTRL/ERN ND.
   
   ...NRN PLNS TODAY/TNGT...
   MAIN AREA OF FORCING FOR ASCENT WITH BC LOW WILL REMAIN N OF THE
   CANADIAN BORDER THROUGH THE PERIOD.  BUT ASSOCIATED LWR AMPLITUDE
   DISTURBANCES MOVING ENE FROM THE NRN INTERMOUNTAIN REGION WILL
   SPREAD WAVES OF ASCENT ACROSS THE NRN HI PLNS AND THE DAKOTAS
   TODAY/TNGT AS DEVELOPING WARM FRONT ADVANCES NEWD INTO ND WITH
   SUBSTANTIAL MOISTURE /PW 1.25-1.75 INCHES/.
   
   BY EARLY AFTN...COMBINATION OF RETURNING MOISTURE AND SFC HEATING
   SHOULD YIELD AN AXIS OF SBCAPE AOA 2000 J/KG FROM FAR ERN MT AND WRN
   ND SEWD INTO MUCH OF SD...ALONG/AHEAD OF LEE TROUGH AND ALONG/SW OF
   WARM FRONT.  THIS DESTABILIZATION ALONG WITH MODEST ASCENT WITH THE
   LOW AMPLITUDE WAVES SHOULD FOSTER INTENSIFICATION OF EXISTING STORMS
   OVER THE WRN DAKOTAS BY EARLY AFTN.  OTHER STORMS LIKELY WILL FORM A
   BIT LATER INVOF LEE TROUGH SWD INTO NEB...AND THE WARM AND COLD
   FRONTS.
   
   40 KT WSWLY MID LVL FLOW AND INCREASING HIGH LVL WINDS SHOULD
   SUPPORT SUPERCELLS...EVEN WITHIN STRENGTHENING ACTIVITY LEFT OVER
   FROM OVERNIGHT CONVECTION.  THESE STORMS COULD YIELD VERY LARGE
   HAIL...LOCALLY DMGG WIND...AND POSSIBLY A COUPLE TORNADOES.  THE
   LATTER THREAT SHOULD BE GREATEST NEAR THE WARM FRONT IN CNTRL ND/SD
   LATE THIS AFTN THROUGH EARLY TNGT.  A MORE ORGANIZED SVR WIND THREAT
   MAY EVOLVE THIS EVE/TNGT IN THE CNTRL/ERN DAKOTAS AS THE STORMS
   EVOLVE INTO FORWARD-PROPAGATING SEGMENTS.  ONE OR MORE NOCTURNAL
   MCSS WITH AT LEAST A SPORADIC SVR WIND/HAIL THREAT LIKELY WILL
   PERSIST THROUGH EARLY SAT.  THESE SHOULD MOVE MAINLY ESE TO SE INTO
   NRN MN...NE NEB...AND POSSIBLY NW KS...SUPPORTED BY 40+ KT SW TO
   SSWLY LLJ.
   
   WEST OF THE HIGHER THETA-E ENVIRONMENT DESCRIBED ABOVE...A SEPARATE
   AREA OF HIGH-BASED SUPERCELLS AND/OR BRIEF BOWING LINE SEGMENTS MAY
   FORM INVOF COLD FRONT OVER THE HIGHER TERRAIN OF NRN WY/SRN MT LATER
   TODAY/TNGT AS REGION IS GLANCED BY BASE OF MAIN UPR TROUGH. 
   ALTHOUGH SPARSE MOISTURE WILL LIMIT INSTABILITY...50 KT MID LVL WLY
   FLOW AND STEEPENING MID LVL LAPSE RATES MAY YIELD SVR HAIL AND WIND.
    THESE STORMS SHOULD WEAKEN OVER ERN MT OR PERHAPS THE FAR WRN
   DAKOTAS LATE TNGT/EARLY SAT.
   
   ...TN VLY/SRN APPALACHIANS TO MID ATLANTIC CST TODAY...
   SHORTWAVE TROUGH NOW OVER SRN IL SHOULD MOVE STEADILY E TODAY...MORE
   OR LESS IN TANDEM WITH IMPULSE AMPLIFYING ESE ACROSS ONT.  AHEAD OF
   THE IL TROUGH...RADAR/SATELLITE LOOPS SUGGEST POSSIBLE PRESENCE OF
   WEAK CIRCULATIONS LEFT OVER FROM OVERNIGHT CONVECTION IN THE LWR TN
   VLY.  A BELT OF SEASONABLY STRONG 35-40 KT WSWLY MID LVL FLOW WILL
   PRECEDE/ACCOMPANY THESE DISTURBANCES AS THEY CONTINUE E ACROSS PARTS
   OF THE APPALACHIANS AND THE MID ATLANTIC STATES.
   
   AT LWR LVLS...WEAK STNRY FRONT ORIENTED PARALLEL TO THE UPR
   JET...SIMILARLY ORIENTED OUTFLOW BOUNDARIES FROM OVERNIGHT
   STORMS...AND LEE TROUGH E OF THE MOUNTAINS EACH WILL SERVE TO FOCUS
   DIURNALLY ENHANCED STORMS OVER THE REGION TODAY.  WITH VERY RICH
   MOISTURE IN PLACE /PW AOA 2.00 INCHES/...AND EXPECTED CORRIDORS OF
   STRONG SFC HEATING...SETUP COULD YIELD NUMEROUS BANDS/CLUSTERS OF
   STRONG STORMS WITH DMGG WIND AND MARGINALLY SVR HAIL...DESPITE
   MODEST MID LVL LAPSE RATES.  WHILE A BRIEF SUPERCELL OR TWO MAY
   OCCUR...MAINLY OVER THE MID-ATLANTIC...MULTICELL CLUSTERS WITH
   BOWING SEGMENTS/WET MICROBURSTS SHOULD BE THE MAIN SVR THREAT.  ONE
   OR TWO LARGER ENE-MOVING MCSS MAY EVOLVE...ESPECIALLY OVER NRN
   NC...VA AND ERN MD/DE/NJ.
   
   FARTHER N...AN ISOLD SVR RISK MAY EVOLVE AHEAD OF THE ONT
   DISTURBANCE AND ASSOCIATED COLD FRONT OVER WRN/CNTRL NY. 
   INSTABILITY WILL BE WEAKER RELATIVELY TO POINTS FARTHER S...BUT
   MODEST WLY FLOW ALOFT MAY AUGMENT STORM ORGANIZATION...WITH
   HAIL/GUSTY WINDS POSSIBLE THROUGH EARLY EVE.
   
   ..CORFIDI/SMITH.. 07/08/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z