Jul 12, 2011 2000 UTC Day 1 Convective Outlook
Updated: Tue Jul 12 20:03:10 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110712 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110712 2000 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
20110712 2000 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
20110712 2000 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 121959
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0259 PM CDT TUE JUL 12 2011
   
   VALID 122000Z - 131200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN
   ROCKIES...NRN HIGH PLAINS...CNTRL ROCKIES...CNTRL PLAINS...MID-MO
   VALLEY...MID-MS VALLEY...OH VALLEY...TN VALLEY AND SRN APPALACHIAN
   MTNS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF FAR NRN
   MAINE...
   
   SEVERAL CHANGES HAVE BEEN MADE TO THE OUTLOOK FOR THE 20Z ISSUANCE.
   THE FIRST IS TO REDUCE THE AREAL COVERAGE OF THE 30 PERCENT WIND
   DAMAGE PROBABILITY. THE ENHANCED WIND DAMAGE THREAT SHOULD BE
   CONFINED TO NE MO...SCNTRL IL AND WRN KY. THIS WILL BE THE FAVORED
   CORRIDOR ALONG A GRADIENT OF STRONG INSTABILITY FOR A LINE-SEGMENT
   IF A COLD POOL CAN BECOME ESTABLISHED WITH THE INTENSE STORMS IN NE
   MO. THE SECOND CHANGE IS TO REMOVE THE CAROLINAS FROM THE SLIGHT
   RISK AREA. VISIBLE SATELLITE IMAGERY SUGGESTS CUMULUS DEVELOPMENT IN
   THE CAROLINAS IS LIMITED AND MAY BE DUE TO SUBSIDENCE. ALTHOUGH A
   FEW MARGINALLY SEVERE STORMS MAY INITIATE LATE THIS AFTERNOON IN THE
   CAROLINAS AS SHORT-TERM MODELS SUGGEST...CONVECTIVE COVERAGE IS
   EXPECTED TO REMAIN ISOLATED DUE TO SATELLITE TRENDS. THE THIRD
   CHANGE TO THE OUTLOOK IS TO ADD A SLIGHT RISK AREA TO FAR NRN MAINE
   WHERE RADAR SUGGESTS SEVERE STORMS ARE ONGOING WITH A THREAT FOR
   HAIL AND WIND DAMAGE. OTHERWISE...THUNDER HAS BEEN REMOVED FAR PARTS
   OF SOUTH TX AND THUNDER HAS BEEN ADDED TO PARTS OF AZ NEAR THE
   MOGOLLON RIM.
   
   ..BROYLES.. 07/12/2011
   
   .PREV DISCUSSION... /ISSUED 1127 AM CDT TUE JUL 12 2011/
   
   ...LOWER MO VALLEY INTO KY...
   BAND OF ELEVATED STORMS IS MOVING EWD ACROSS CENTRAL IA THIS
   MORNING...WITH INDICATIONS OF NEW UPDRAFTS DEVELOPING ALONG THE
   LEADING EDGE OF CONVECTION.  THIS ACTIVITY IS CURRENTLY JUST NORTH
   OF THE PRIMARY SURFACE COLD FRONT THAT EXTENDS FROM THE SRN GREAT
   LAKES INTO NRN KS.  A VERY MOIST AIR MASS IS PRESENT SOUTH OF THE
   FRONT WHERE SURFACE DEW POINTS ARE IN THE LOW/MID 70S FROM NRN/ERN
   MO INTO THE OH AND TN VALLEYS...AND WITH CLEAR SKIES OVER THIS
   AREA...STRONG DIABATIC HEATING WILL OCCUR AND CONTRIBUTE TO FURTHER
   DESTABILIZATION /MLCAPE REACHING 3000-4000 J PER KG/.  
   
   THERE IS POTENTIAL FOR THE IA CONVECTION TO GRADUALLY INCREASE AND
   BUILD SWD INTO THE MORE UNSTABLE ENVIRONMENT ALONG THE SRN EDGE OF
   25-30 KT WLY FLOW ALOFT.  IF AN ORGANIZED COLD POOL CAN DEVELOP AND
   STORMS BEGIN TO PROPAGATE EWD/ESEWD...THERE WILL BE INCREASING
   POTENTIAL FOR DAMAGING WINDS TO OCCUR WITH THE MCS.  ADDITIONAL
   STORMS MAY ALSO DEVELOP ALONG A CONVERGENCE ZONE FROM CENTRAL MO EWD
   INTO THE LOWER OH VALLEY AS THE CAP GRADUALLY WEAKENS THIS
   AFTERNOON.  ALTHOUGH FLOW ALOFT AND VERTICAL SHEAR WILL BE WEAKER
   WITH SWD EXTENT...VERY LARGE INSTABILITY WILL SUPPORT OCCASIONAL
   SEVERE MICROBURSTS WITH STRONGER CELLS.
   
   ...SRN APPALACHIANS INTO SERN STATES...
   12Z SOUNDINGS AT FFC/BMX EXHIBITED A LAYER OF 15-20 KT NELY WINDS
   JUST ABOVE 700 MB...SUGGESTING THAT CURRENT STORMS FROM ERN TN INTO
   NWRN GA/NERN AL WILL SLOWLY SPREAD SWD/SWWD THIS AFTERNOON.  STRONG
   HEATING WILL FURTHER INCREASE LARGE DCAPE PRESENT IN THE 12Z
   SOUNDINGS AND SUGGEST POTENTIAL FOR WIDELY SCATTERED WET MICROBURSTS
   THIS AFTERNOON.  
   
   ...SRN VA/CAROLINAS...
   VERY MOIST AND UNSTABLE AIR WILL BE PRESENT THIS AFTERNOON FROM SE
   VA INTO THE CNTRL AND ERN CAROLINAS...WITH LOW TO MID 70S F
   DEWPOINTS AND PW CLOSE TO 2 INCHES.  EARLIER CLOUDS ARE THINNING AND
   WILL THIS WILL PERMIT AREAS OF STRONGER HEATING AND DESTABILIZATION.
    MODERATE NW FLOW WILL PERSIST ON THE NE FRINGE OF UPR RIDGE...AND
   THIS SETUP MAY SUPPORT SCTD STRONG TO SVR STORMS BY LATE AFTN OR
   EVE.  THESE MAY MERGE INTO A SMALL MCS...WITH A THREAT FOR MAINLY
   DMGG WIND AND POSSIBLY MARGINALLY SVR HAIL CONTINUING THROUGH EARLY
   TNGT.
   
   ...NRN/CENTRAL HIGH PLAINS...
   MOIST SELY UPSLOPE FLOW IS FORECAST TO STRENGTHEN THIS AFTERNOON AS
   PRESSURES FALL OVER THE NRN ROCKIES/INTERMOUNTAIN REGION.  THIS IS
   MAINTAINING CURRENT LOW CLOUD DECK OVER ERN WY/SWRN SD AND THE NEB
   PANHANDLE...BUT CLOUDS ARE EXPECTED TO DIMINISH THIS AFTERNOON AND
   ALLOW HEATING/DESTABILIZATION TO OCCUR.  STORMS ARE EXPECTED TO
   DEVELOP OVER THE HIGHER TERRAIN DURING THE MID/LATE AFTERNOON AND
   SLOWLY MOVE NEWD INTO THE HIGH PLAINS.  ALTHOUGH MID LEVEL SWLY FLOW
   WILL BE MODEST AT BEST /20-25 KT/...STRONG DIRECTIONAL SHEAR WILL
   AID IN STORM ORGANIZATION WITH MULTICELL AND ISOLATED SUPERCELL
   STRUCTURES POSSIBLE.  HAIL AND STRONG WIND GUSTS WILL BE THE PRIMARY
   THREATS.
   
   ...WRN/CENTRAL MT...
   SMALL CLUSTER OF MORNING STORMS OVER SERN ID/EXTREME NWRN WY APPEARS
   TO BE ASSOCIATED WITH A WEAK PERTURBATION IN THE UPPER FLOW THAT HAS
   LIFTED NWD ACROSS THE ERN GREAT BASIN.  THIS FEATURE IS LIKELY TO
   CONTINUE NEWD AND ENHANCE THUNDERSTORM POTENTIAL INTO PARTS OF
   CENTRAL AND POSSIBLY NERN MT.  PERSISTENT SELY LOW LVL FLOW WILL
   MAINTAIN/AUGMENT LOW LVL MOISTURE OVER NRN AND ERN MT TODAY...WHERE
   SFC DEWPOINTS IN THE 50S SHOULD YIELD SBCAPE OF 1000-1500 J/KG BY
   AFTN.  30-35 KT DEEP SW TO WSWLY SHEAR WILL EXIST OVER
   REGION...DESPITE FACT THAT LOW NOW OFF VANCOUVER ISLAND WILL REMAIN
   WELL TO THE WEST.  COMBINATION OF MODEST UPSLOPE FLOW AND HEATING
   SHOULD SUPPORT ADDITIONAL STORM DEVELOPMENT FROM NRN/CNTRL ID INTO
   WRN/SW MT BY AFTN.  THE STORMS SUBSEQUENTLY SHOULD SPREAD NNE ACROSS
   CNTRL AND NRN MT...POSING A THREAT FOR HAIL AND LOCALLY DMGG WIND.
   
   ...SRN KS/NRN OK AREA...
   UPR VORT NOW OVER EXTREME NWRN OK SHOULD MOVE SLOWLY ENE
   TODAY/TNGT...ON WRN FRINGE OF LWR MS VLY UPR RIDGE.  SFC HEATING AND
   WEAK ASCENT WITH SYSTEM MAY FOSTER ISOLD TO WDLY SCTD TSTMS OVER
   PARTS OF NW TX...WRN/NRN OK...AND SRN KS.  GIVEN VERY WARM/DRY SUB
   CLOUD LAYER ENVIRONMENT...SOME STORMS MAY YIELD MICROBURSTS THIS
   AFTERNOON AND EVENING.
   
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