Jul 27, 2012 1630 UTC Day 1 Convective Outlook
Updated: Fri Jul 27 16:34:27 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120727 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120727 1630 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
20120727 1630 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
20120727 1630 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 271631
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1131 AM CDT FRI JUL 27 2012
   
   VALID 271630Z - 281200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE OH VLY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE MID ATLANTIC
   STATES...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN HIGH
   PLNS...
   
   ...SYNOPSIS...
   DOMINANT CNTRL RCKYS/HIGH PLNS RIDGE EXPECTED TO SHIFT E AND
   SLIGHTLY AMPLIFY THIS PERIOD AS BROAD TROUGH NOW OVER THE GRT
   LKS/MID MS VLY SOMEWHAT AMPLIFIES UPON CONTINUING ESE INTO THE OH
   VLY.
   
   THE AMPLIFICATION OF THE GRT LKS TROUGH WILL BE ACCOMPLISHED IN
   LARGE PART BY JET STREAK/DISTURBANCE NOW OVER THE ERN DAKOTAS. THIS
   FEATURE SHOULD MOVE SE INTO IL EARLY SAT AS LEAD IMPULSE NOW OVER LK
   MI/NRN IL CONTINUES ESE INTO NRN OH.
   
   FARTHER DOWNSTREAM...ON SRN EDGE OF LARGER SCALE TROUGH...MODERATE
   WSW FLOW EXPECTED TO PERSIST FROM OH/WV TO THE MID ATLANTIC/SRN NEW
   ENGLAND CST. NO OBVIOUS SHORTWAVE DISTURBANCES ARE APPARENT IN
   SATELLITE OR OBJECTIVE ANALYSES...BUT AT LEAST WEAK LARGE SCALE
   ASCENT WILL BE PRESENT OVER PARTS OF THE REGION GIVEN GRADUAL
   AMPLIFICATION OF BROAD-SCALE TROUGH.
   
   IN THE WEST...MODERATE WSW TO WLY FLOW WILL PREVAIL FROM THE NRN GRT
   BASIN TO THE NRN PLNS.  THREE DISTURBANCES IN THIS FLOW...ONE NOW
   OVER SW MT/WRN WY...ANOTHER NOW ENTERING WRN NV...AND A THIRD
   NEARING SEATTLE...LIKELY WILL AFFECT DIURNALLY-ENHANCED STORMS OVER
   INTERIOR PARTS OF THE NORTHWEST AND THE NRN PLNS LATER TODAY/TNGT.
   
   AT LWR LVLS...WEAK SFC LOW NOW NEAR CHICAGO SHOULD TRACK ESE INTO
   WRN OH BY EVE AS TRAILING COLD FRONT ADVANCES SE INTO SRN MO/FAR SRN
   IL. THE LOW AND COLD FRONT SHOULD SERVE TO FOCUS STRONG TO POSSIBLY
   SVR TSTM DEVELOPMENT LATER TODAY INTO TNGT. OTHERWISE...WEAK
   OUTFLOW/DIFFERENTIAL HEATING BOUNDARIES...AND LEE TROUGH ALONG THE
   MID ATLANTIC CST...EXPECTED TO SERVE AS FOCI FOR AFTN STORMS FROM
   THE LWR MS AND TN VLYS NEWD INTO SRN NEW ENGLAND.
   
   ...OH VLY /MIDWEST THIS AFTN INTO TNGT...
   POTENTIAL WILL EXIST FOR STRONG TO SVR TSTMS...MAINLY THOSE WITH
   DMGG WIND...THIS AFTN INTO TNGT OVER A PARTS OF THE MID/LWR OH VLY
   AND PERHAPS ADJACENT LWR MI/LK ERIE. THIS ACTIVITY WILL BE FOSTERED
   BY /1/ ASCENT WITH LEAD UPR IMPULSE NOW NEAR CHICAGO...AND /2/ LATER
   TODAY INTO TNGT...BY UPSTREAM DISTURBANCE NOW IN ERN SD.
   
   RECENT CONFIGURATION OF UPR AIR PATTERN HAS NOT FAVORED ADVECTION OF
   A MARKED EML INTO THE OH VLY REGION. BUT MID LVL LAPSE RATES IN SLGT
   RISK AREA SHOULD BE SUFFICIENT TO SUPPORT SUSTAINED STORMS GIVEN
   LIKELIHOOD FOR STRONG SFC HEATING/STEEP LOW LVL LAPSE
   RATES...PRESENCE OF AFOREMENTIONED COLD FRONT/LOW...LARGE SCALE
   ASCENT...AND SUFFICIENT MOISTURE /PW AROUND 1.25-1.50 INCHES/.
   COUPLED WITH MODERATE DEEP WLY FLOW /30-40KT W TO WNWLY DEEP
   SHEAR/...SETUP SHOULD YIELD A COUPLE BANDS OR SMALL CLUSTERS OF
   STORMS CAPABLE OF DMGG WIND AND PERHAPS HAIL.
   
   THE STORMS MAY EVOLVE INTO BOWING LINE OR TWO...WITH MOVEMENT SE
   TOWARD/ACROSS THE OH RVR BY EVE.  SOME POTENTIAL ALSO WILL EXIST FOR
   CONTINUED STORM DEVELOPMENT ON THE SW EDGE OF STRONGER FORCING FOR
   ASCENT...I.E. OVER FAR SRN IL/SE MO/WRN KY...INTO TNGT. CLOSER TO
   TRACK OF SFC WAVE...A CONDITIONAL/LOW PROBABILISTIC THREAT FOR A
   BRIEF TORNADO MAY DEVELOP.
   
   ...MID ATLANTIC/SRN NEW ENGLAND THIS AFTN/EVE...
   SEASONABLY STRONG...UNIDIRECTIONAL WLY FLOW NOW ACROSS REGION WILL
   SOMEWHAT SUBSIDE TODAY...BUT REMAIN AMPLE FOR SUSTAINED/ORGANIZED
   STORMS. AREA SOUNDINGS AND CURRENT VIS SATELLITE DATA SUGGEST
   RELATIVELY MODEST MID LVL LAPSE RATES ACROSS REGION...IN ADDITION TO
   A LOW LVL INVERSION.
   
   NEVERTHELESS...SUBSTANTIAL LOW LVL HEATING/DESTABILIZATION WILL
   OCCUR OVER PARTS OF THE REGION TODAY...ESPECIALLY ALONG LEE TROUGH
   FROM NJ SW INTO CNTRL NC. THIS ENVIRONMENT MAY FOSTER EVENTUAL
   DEVELOPMENT OF A LONG...BROKEN BAND OF STORMS ALONG THE TROUGH.
   LOCALIZED STRONGER STORMS WITH THE BAND COULD YIELD DMGG WIND GIVEN
   ENHANCED ENVIRONMENTAL FLOW AND HIGH PW /AROUND 2 INCHES/ PRESENT
   ACROSS REGION.
   
   ...NRN HIGH PLNS/INTERIOR NORTHWEST...
   LOW LVL MOISTURE WILL INCREASE OVER THE NRN HIGH PLNS TODAY INTO
   TNGT AS LEE TROUGH BECOMES BETTER DEFINED WITH THE APPROACH OF MT/WY
   UPR IMPULSE AND WITH THE CONTINUED SE MOVEMENT OF ERN SD JET STREAK.
    MOISTURE WILL...HOWEVER...REMAIN RELATIVELY LIMITED THROUGH THE
   PERIOD...WITH PW EXPECTED TO REMAIN AOB 1.00 UNTIL LATE TNGT.
   
   DIFFERENTIAL SFC HEATING...MOISTURE RETURN...AND ASCENT WITH MT/WY
   TROUGH SHOULD SUPPORT SCTD STORM DEVELOPMENT OVER NRN/ERN WY/SRN MT
   AND WRN SD BY LATE AFTN. THESE STORMS SHOULD MOVE E TO NE INTO THE
   LWR PLNS THIS EVE/EARLY SAT. WITH SFC DEWPOINTS AROUND 50 F...STEEP
   MID LVL LAPSE RATES...AND AMPLE DEEP SHEAR FOR ORGANIZED
   UPDRAFTS...EXPECT MAINLY HIGH BASED STORMS WITH A THREAT FOR LOCALLY
   DMGG WIND.
   
   WAA/WARM FRONTOGENESIS WILL INCREASE OVER WRN/CNTRL SD TNGT...ON
   TAIL END OF COLD FRONT MOVING SE INTO OH VLY. ANY SUSTAINED STORMS
   THAT PERSIST AND OR REFORM OVER THAT AREA COULD BECOME A
   SUPERCELL...WITH A POTENTIAL FOR HAIL AND ISOLD DMGG WIND. A SMALL
   MCS ALSO MAY DEVELOP...BUT OVERALL SVR THREAT SHOULD REMAIN FAIRLY
   MARGINAL GIVEN MODEST MOISTURE/LIMITED CAPE.
   
   ...LWR MS VLY/SOUTH...
   POCKETS OF STRONG INSTABILITY/HIGH PW WILL EXIST FROM THE SRN
   APPALACHIANS WSW INTO THE LWR MS VLY/SRN PLNS....AREAS LARGELY
   REMOVED FROM STRONGER FLOW ALOFT. WHILE WDLY SCTD WET
   MICROBURSTS MAY OCCUR...POTENTIAL FOR ORGANIZED/CONCENTRATED
   ACTIVITY APPEARS LOW.
   
   ..CORFIDI/ROGERS.. 07/27/2012
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z