Sep 6, 2012 1630 UTC Day 1 Convective Outlook
Updated: Thu Sep 6 16:33:29 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120906 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120906 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
20120906 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
20120906 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 061629
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1129 AM CDT THU SEP 06 2012
   
   VALID 061630Z - 071200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL AND SRN
    PLNS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE OZARKS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR GRT
   LKS/NORTHERN NEW ENGLAND...
   
   ...SYNOPSIS...
   SEASONABLY FAST...LOW AMPLITUDE CYCLONIC FLOW WILL PREVAIL ACROSS
   THE NRN THIRD OF THE NATION THIS PERIOD...S OF ELONGATED UPR LOW IN
   NRN ONT AND N OF PERSISTENT SW/S CNTRL U.S. RIDGE. THIS PATTERN WILL
   BEGIN TO AMPLIFY EARLY FRI AS STRONG SHORTWAVE IMPULSE NOW IN WRN MT
   SHEARS ESE INTO THE NRN PLNS...AND PARTIALLY PHASES WITH A
   DISTURBANCE DROPPING SWD ALONG THE W SIDE OF THE ONT LOW. IN THE
   MEAN TIME...A SERIES OF WEAKER DISTURBANCES WILL CONTINUE TO TRACK
   EWD WITHIN BELT OF ENHANCED FLOW IMMEDIATELY N OF THE UPR
   RIDGE...AND A WEAK IMPULSE WILL GLANCE THE LWR GRT LKS. FARTHER
   S...LONG-LIVED UPR VORT WILL PERSIST OFF THE E FL CST...WHILE
   NEIGHBORING VORT MAX SAGS SLOWLY S ACROSS N CNTRL GULF OF MEXICO.
   
   AT LWR LVLS...COLD FRONT ASSOCIATED WITH THE MT TROUGH SHOULD MOVE
   STEADILY E/SE THROUGH THE PERIOD. THE FRONT WILL OVERTAKE LEE LOW
   AND TROUGH...NOW IN SD...AS THOSE FEATURES TRACK E/SE TO NEAR SIOUX
   FALLS BY THIS EVE. THE FRONT/LOW SHOULD CONTINUE E/SE
   OVERNIGHT...AND EXTEND FROM NRN MI THROUGH SE IA TO SW KS BY 12Z
   FRI. STRENGTHENING SLY GRADIENT FLOW WILL ALLOW RICH LOW-LVL
   MOISTURE TO SPREAD NNE TOWARD COLD FRONT AND LEE TROUGH. COUPLED
   WITH SFC HEATING AND INCREASING LARGE SCALE ASCENT WITH AMPLIFYING
   UPR TROUGH...EXPECT THAT SEVERAL AREAS OF STRONG TO POSSIBLY SVR
   TSTMS WILL FORM ALONG THE LEE TROUGH LATER TODAY...AND ALONG THE
   FRONT TNGT AND EARLY FRI. SOME OF THE STORMS COULD PERSIST THROUGH
   12Z FRI OVER THE MID MS VLY.
   
   ...TX/OK PNHDLS TO CNTRL PLNS THIS AFTN/EVE...
   FORCING FOR ASCENT WILL REMAIN WEAK OVER WRN PARTS OF THE SRN/CNTRL
   PLNS TODAY...BENEATH A DEEP EML. THESE FACTORS SHOULD DELAY DIURNAL
   TSTM DEVELOPMENT ALONG/AHEAD OF LEE TROUGH/DRYLINE TIL LATE IN THE
   DAY. ONCE STORMS DO FORM...MOST LIKELY INITIALLY OVER WRN AND NRN
   KS...PRESENCE OF MODERATE TO STRONG INSTABILITY /SBCAPE TO 2000 J
   PER KG/ AND 35+ KT WNWLY DEEP SHEAR SUGGEST LIKELIHOOD FOR A FEW
   SUSTAINED STORMS/SUPERCELLS WITH LARGE HAIL/DMGG WIND. THE GREATEST
   THREAT SHOULD EVOLVE FROM CNTRL/NRN KS INTO SRN NEB DURING THE
   EVE...WITH MORE ISOLD ACTIVITY MAINLY POSING A WIND THREAT SWD INTO
   OK/TX. ONE OR TWO MCSS MAY FORM BY LATE EVE. THESE COULD POSE A
   DIMINISHING RISK FOR SVR HAIL/WIND INTO THE NIGHT OVER KS AND
   PERHAPS WRN OK AND/OR THE ERN TX PNHDL.
   
   ...MID MO/MID MS VLYS TNGT/EARLY FRI...
   TSTMS SHOULD INCREASE IN COVERAGE AND STRENGTH OVER PARTS OF ERN
   NE...SE SD...IA AND MN AFTER 00Z FRI AS SWLY LLJ/MOISTURE INFLOW
   INCREASE WITH THE CONTINUED APPROACH OF AMPLIFYING UPR TROUGH. 
   STORMS SHOULD FOCUS NEAR/E OF SFC LOW MOVING ESE FROM NEB/SD... AND
   MAY BE SLIGHTLY ELEVATED. NEVERTHELESS...WITH MUCAPE AROUND 1000
   J/KG AND STRONG CLOUD-LAYER SHEAR /500 MB WNW FLOW AOA 50
   KTS/...POTENTIAL WILL EXIST FOR SVR HAIL AND POSSIBLY LOCALLY DMGG
   WIND. THIS ACTIVITY COULD REACH NW IL BY THE END OF THE PERIOD.
   
   ...OZARKS THIS AFTN...
   SATELLITE SHOWS A SRN STREAM IMPULSE NOW IN SE KS THAT SHOULD
   CONTINUE E ACROSS THE OZARKS LATER TODAY. ASSUMING THAT THE 12Z SGF
   RAOB IS AND WILL REMAIN REPRESENTATIVE OF THE DOWNSTREAM ENVIRONMENT
   THROUGH LATER TODAY...AMPLE INSTABILITY SHOULD DEVELOP TO SUPPORT A
   CONDITIONAL RISK FOR SVR STORMS GIVEN DEEP EML AND RICH LOW-LVL
   MOISTURE. EXPECT THAT SFC HEATING WILL FOSTER ADDITIONAL STORM
   DEVELOPMENT ON DOWNWIND SIDE OF EXISTING SLIGHTLY ELEVATED STORM
   CLUSTER NOW IN SE KS. THIS ACTIVITY SHOULD FOCUS ALONG AND N OF WEAK
   W-E FRONT STALLED OVER THE REGION. THE STORMS MAY GROW INTO A SMALL
   MCS CAPABLE OF SVR HAIL AND WIND THAT MOVES ESE TOWARD THE MS RVR.
   
   ...LWR OH VLY TO LWR GRT LKS THIS AFTN...
   WDLY SCTD TO SCTD TSTMS SHOULD FORM OVER PARTS OF OH...NRN PA...AND
   UPSTATE NY...WHERE MODERATE DEEP WLY FLOW WILL PREVAIL ON SRN FRINGE
   OF ELONGATED UPR LOW OVER ONT. LARGE SCALE FORCING FOR ASCENT
   APPEARS NEUTRAL AT BEST...PER SATELLITE AND MODEL DATA.
   NEVERTHELESS...AREA SOUNDING SHOW AMPLE MOISTURE PRESENT FOR STORMS
   AND MINIMAL CIN. WITH DEEP FLOW LARGELY PARALLEL TO THE LONG AXES OF
   THE LAKES...EXPECT THAT LAKE BOUNDARIES MAY SERVE AS THE MAIN FOCI
   FOR LOW-LVL UPLIFT/STORM DEVELOPMENT. THIS ACTIVITY MAY ORGANIZE
   SEVERAL SHORT BANDS. WITH AFTN SBCAPE AVERAGING AROUND 1500 J/KG AND
   30 KT WLY DEEP SHEAR...SETUP COULD YIELD A FEW SMALL BOWS WITH
   LOCALLY DMGG WIND.
   
   DEEP SHEAR SHOULD DIMINISH WITH SW EXTENT THROUGH THE OH VLY...
   BUT BOTH INSTABILITY AND SHEAR MAY PROVE SUFFICIENT FOR
   ISOLD/BRIEFLY SVR STORMS.
   
   ...VA TIDEWATER/ERN NC THIS AFTN...
   A FEW STRONG TO ISOLD SVR STORMS MAY OCCUR OVER THE LWR CHESAPEAKE
   BAY AND ERN NC TODAY...WHERE A BELT OF 20-25 KT 700-500 MB WSW FLOW
   WILL LINGER PARALLEL TO AN AXIS OF VERY MOIST /PW AOA 2 INCHES/ AIR.
   STORMS SHOULD FOCUS ALONG WEAK W-E FRONT NOW EXTENDING ENE FROM S
   CNTRL VA...AND POSSIBLE ALONG SW-NE LEE TROUGH IN NC. UPLIFT ALSO
   MAY BE AIDED BY WEAK MID LVL SHEAR LOBE THAT APPEARS TO BE EDGING E
   TOWARD REGION IN WV IMAGERY. STORMS LIKELY WILL MERGE INTO SMALL
   CLUSTERS/SHORT LINES...AND MAY POSE A RISK FOR LOCALLY DMGG WIND.
   
   ..CORFIDI/HURLBUT.. 09/06/2012
   
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