Jul 13, 2012 1300 UTC Day 1 Convective Outlook
Updated: Fri Jul 13 13:01:32 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120713 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120713 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
20120713 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
20120713 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 131257
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0757 AM CDT FRI JUL 13 2012
   
   VALID 131300Z - 141200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE INTERIOR
   PACIFIC NW/NRN RCKYS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MO VLY NE INTO THE
   UPR MS VLY...
   
   ...SYNOPSIS...
   WHILE THE MAIN BELT OF THE WLYS WILL REMAIN IN CANADA...TWO TROUGHS
   OVER THE LWR 48 WILL SERVE TO FOCUS TSTM POTENTIAL OVER THE U.S.
   THIS PERIOD.  THE FIRST TROUGH...ALONG THE W CST...CONSISTS OF A
   CLOSED LOW THAT SHOULD REMAIN STNRY OVER WRN WA...WITH AN ELONGATED
   SRN MEMBER EXTENDING THROUGH THE GRT BASIN TO THE LWR CO VLY. 
   FARTHER E...BEYOND A RIDGE OVER THE RCKYS...A SIMILAR BUT WEAKER
   PAIR OF DISTURBANCES WILL EXIST OVER THE MS VLY.  THE NRN MEMBER OF
   THIS PAIR SHOULD MOVE SLOWLY E ACROSS MN...WHILE THE SRN ONE REMAINS
   QSTNRY OVER E TX/WRN LA.
   
   ...NRN RCKYS TODAY/TNGT...
   WRN WA UPR LOW IS EXPECTED TO REMAIN STNRY OR PROGRESS ONLY VERY
   SLOWLY E THIS PERIOD AS A SERIES OF WEAKER DISTURBANCES MOVE NNE
   ACROSS ERN ORE IN CORRIDOR OF 25+ KT SSWLY MID LVL FLOW ON ITS ERN
   FRINGE.  WITH LOW LVL MOISTURE CONTINUING TO PERSIST ACROSS NRN WA
   INTO NRN ID/NW MT /SFC DEWPOINTS IN THE UPR 50S F/...AND WITH
   RELATIVELY COOL /AOB MINUS 10 C AT 500 MB/ MID LVL TEMPS CONTINUING
   NEAR UPR LOW...POTENTIAL WILL EXIST FOR A FEW STRONG TO SVR STORMS
   GIVEN LIKELIHOOD FOR STRONG SFC HEATING/STEEPENING LOW LVL LAPSE
   RATES BENEATH ZONE OF UPR DIVERGENCE IN NE QUADRANT OF LOW. 
   SUFFICIENT SHEAR ALSO WILL BE PRESENT FOR SUPERCELLS WITH LARGE
   HAIL/LOCALLY DMGG WIND...ESPECIALLY OVER NRN WA AND PERHAPS NRN
   ID/NWRN MT.  A FEW ELEVATED STORMS POSING A THREAT FOR HAIL MAY
   SPREAD W TOWARD THE SEATTLE AREA GIVEN PERSISTENT ELY 700 MB
   FLOW/STEEP MID LVL LAPSE RATES N OF UPR LOW. 
   
   ...MID MO VLY TO UPR MS VLY THIS AFTN/EVE...
   SLOWLY-MOVING UPR TROUGH WILL CONTINUE E INTO NRN/CNTRL MN
   TODAY...WITH AN ASSOCIATED AREA OF LOW LVL WAA EXTENDING SE INTO
   TOWARD THE MID MS VLY. AS YESTERDAY...SCTD AREAS OF TSTMS SHOULD
   FORM/INCREASE WITH DAYTIME HEATING BOTH WITHIN THE TROUGH AND ALONG
   WEAK SFC REFLECTION/WIND SHIFT IN RELATIVELY WEAKLY-CAPPED
   ENVIRONMENT. BOTH LOW LVL CONVERGENCE AND DEEP SHEAR SHOULD REMAIN
   WEAK. BUT SUFFICIENT INSTABILITY /MAINLY DUE TO RELATIVELY COOL MID
   LVL TEMPS/ SHOULD EXIST TO SUPPORT A FEW  LONGER-LIVED MULTICELLS
   CAPABLE OF HAIL AND POSSIBLY LOCALLY DMGG WIND.
   
   ...SWRN U.S TODAY/TNGT...
   SRN CA UPR LOW/TROUGH EXPECTED TO FURTHER ELONGATE S-N ACROSS THE
   LWR CO VAL TODAY...ALLOWING MOISTURE TO CONTINUE SPREADING N ACROSS
   ERN NV AND UT. PW VALUES AOA 1.5 INCHES SHOULD PREVAIL FROM SW AZ
   NWD INTO SE CA/SRN NV...WITH VALUES ABOVE 1.0 INCH EXTENDING AS FAR
   N AS SALT LAKE CITY. MODEST...INCREASINGLY UNIDIRECTIONAL SLY FLOW
   AND THERMODYNAMIC PROFILES SUPPORTIVE OF SCTD TO NUMEROUS SHOWERS
   AND TSTMS...ESPECIALLY OVER THE CO RVR VLY...MAY YIELD ISOLD STRONG
   DOWNBURSTS GIVEN INCREASING WATER LOADING.
   
   ...NRN NEW ENGLAND THIS AFTN...
   A WEAK SHORT-WAVE TROUGH WILL GLANCE NRN ME LATER TODAY...ON SRN
   FRINGE OF MODEST WLY JET CROSSING SE QUE. COMBINATION OF STRONG SFC
   HEATING...MODEST MOISTURE /SFC DEWPOINTS IN THE UPR 50S F/...AND
   WEAK CONVERGENCE ALONG LOW LVL WIND SHIFT/FRONT MAY SUPPORT WDLY
   SCTD AFTN/EARLY EVE STORMS. 25-30 KT MID LVL WLY FLOW WILL LIMIT
   MAGNITUDE OF DEEP SHEAR. BUT GIVEN STEEPENING LOW LVL LAPSE
   RATES...SETUP COULD YIELD A FEW MULTICELLS WITH GUSTY WINDS AND
   MARGINALLY SVR HAIL.
   
   ..CORFIDI/ROGERS.. 07/13/2012
   
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