May 12, 2016 1300 UTC Day 1 Convective Outlook
Updated: Thu May 12 12:52:57 UTC 2016 (20160512 1300Z Day 1 shapefile | 20160512 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20160512 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 44,697 5,105,595 Memphis, TN...Nashville, TN...Clarksville, TN...Murfreesboro, TN...Jackson, TN...
MARGINAL 367,040 51,756,184 San Antonio, TX...Detroit, MI...Columbus, OH...Austin, TX...Charlotte, NC...
Probabilistic Tornado Graphic
20160512 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20160512 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 44,696 5,116,602 Memphis, TN...Nashville, TN...Clarksville, TN...Murfreesboro, TN...Jackson, TN...
5 % 366,799 51,759,032 San Antonio, TX...Detroit, MI...Columbus, OH...Austin, TX...Charlotte, NC...
Probabilistic Large Hail Graphic
20160512 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 411,495 56,875,634 San Antonio, TX...Detroit, MI...Columbus, OH...Austin, TX...Memphis, TN...
   SPC AC 121252

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0752 AM CDT THU MAY 12 2016

   VALID 121300Z - 131200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS MID SOUTH...

   ...THERE IS A MRGL RISK OF SVR TSTMS ELSEWHERE FROM PORTIONS S TX TO
   CAROLINAS AND LAKE ERIE VICINITY...

   ...SUMMARY...
   A FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE FROM SOUTHEAST LOWER
   MICHIGAN THROUGH THE OHIO AND TENNESSEE VALLEYS TO THE ARKLAMISS AND
   ARKLATEX REGIONS.  ADDITIONAL STRONG TO SEVERE STORMS WILL BE
   POSSIBLE ACROSS SOUTHERN VIRGINIA AND THE CAROLINAS.

   --- TECHNICAL DISCUSSION ---

   ...SYNOPSIS...
   PROGRESSIVE UPPER-AIR PATTERN WILL EXIST OVER CONUS...CHARACTERIZED
   BROADLY BY...
   1.  AMPLIFYING/EWD-MOVING RIDGE ACROSS PAC COAST REGION...AND
   DOWNSTREAM...
   2.  SERIES OF SHORTWAVES TRAVERSING CYCLONIC-FLOW BELT SW-SE OF
   500-MB CYCLONE NOW CENTERED OVER SERN AB.  THAT CYCLONE SHOULD MOVE
   ONLY VERY SLOWLY EWD TO ADJOINING PARTS OF NWRN ONT THROUGH PERIOD. 
   LEADING SHORTWAVE TROUGH -- NOW LOCATED FROM CENTRAL IA SWWD ACROSS
   ERN KS TO NERN NM -- WILL WEAKEN AS NRN PART ACCELERATES NEWD ACROSS
   UPPER MI AND LS.  SRN PART WILL MERGE WITH UPSTREAM TROUGH...NOW
   EVIDENT IN MOISTURE-CHANNEL IMAGERY FROM SERN ND SSWWD TO NWRN KS. 
   COMBINED PERTURBATION THEN SHOULD REACH MID/UPPER MS VALLEY BY
   00Z...PIVOTING EWD TO LOWER MI...WRN OH...WRN TN AND NRN AL BY END
   OF PERIOD.

   AT SFC...COLD FRONT WAS ANALYZED AT 11Z FROM DIFFUSE OCCLUSION AREA
   OVER NRN IL/SRN WI...SSWWD OVER SRN MO THEN ARCHING SWWD ACROSS NWRN
   AR...SERN OK...AND TX PERMIAN BASIN.  SEVERAL OUTFLOW BOUNDARIES
   WERE EVIDENT AHEAD OF COLD FRONT FROM TX TO MID SOUTH...INCLUDING
   ONE FROM PRIOR CONVECTION NOW LOCATED FROM NERN AR EWD ACROSS MID
   TN.  BY 00Z...COLD FRONT SHOULD MOVE TO WRN INDIANA...WRN TN...NWRN
   LA AND LOWER PECOS RIVER REGION OF SW TX.

   ...LOWER GREAT LAKES TO MID SOUTH...
   INTERMITTENTLY SVR MCS WITH WELL-DEVELOPED COLD POOL WAS APPARENT
   OVER E-CENTRAL AR...AND SHOULD MOVE INTO DESTABILIZING AIR MASS
   ACROSS MID SOUTH TODAY WITH PRIMARY THREAT BEING DAMAGING GUSTS. 
   MAIN CORRIDOR OF INTEREST FOR RELATIVELY CONCENTRATED/ORGANIZED SVR
   POTENTIAL NOW APPEARS TO BE FROM THAT COMPLEX EWD ACROSS TN AND
   PERHAPS PARTS OF ADJOINING STATES.  THIS CORRIDOR IS MARKED BY
   AFOREMENTIONED...NEARLY E-W OUTFLOW BOUNDARY ACTING IN SEVERAL
   SUPPORTIVE CAPACITIES...INCLUDING...
   1.  NRN BOUND FOR RELATIVELY RICH THETAE OF GULF AIR
   MASS...CHARACTERIZED BY SFC DEW POINTS MID-UPPER 60S F.  THIS WILL
   SUPPORT 1500-2000 J/KG MLCAPE.
   2.  LOW-LEVEL CONVERGENCE/LIFT ZONE AND RELATED FOCUS FOR FORWARD
   PROPAGATION AND CONTINUED LEADING-EDGE DEVELOPMENT THAT MAY HELP TO
   RE-INTENSIFY/MAINTAIN MCS...AS WELL AS SUPPORT ADDITIONAL
   DEVELOPMENT E OF THAT ACTIVITY.

   MCV RELATED TO THAT CONVECTION WAS APPARENT IN COMPOSITE-
   REFLECTIVITY ANIMATIONS OVER NRN AR...AND SHOULD PIVOT EWD TO ENEWD
   TODAY TO PROVIDE REGIONALLY ENHANCED FLOW ALOFT AND LARGE-SCALE LIFT
   IN SUPPORT OF CONVECTIVE POTENTIAL AS WELL.

   AIR MASS FARTHER N WILL BE CHARACTERIZED BY WEAKER LOW-LEVEL AND
   DEEP-LAYER LAPSE RATES...AS WELL AS SMALLER VALUES OF BOUNDARY-LAYER
   THETAE.  HOWEVER...MRGL DEEP SHEAR WILL DEVELOP FOR ISOLATED TO
   SCATTERED TSTMS...INCLUDING A FEW ORGANIZED MULTICELLS CAPABLE OF
   HAIL/GUSTS NEAR SVR LEVELS.

   ...CENTRAL/S TX...
   OUTLOOK HAS BEEN EXTENDED SWWD ACROSS THIS AREA NOT ONLY TO ACCOUNT
   FOR ISOLATED SVR HAIL/WIND POTENTIAL WITH ONGOING/COLD-POOL-DRIVEN
   ACTIVITY OVER CENTRAL TX...BUT ADDITIONAL DEVELOPMENT THROUGH AFTN
   ALONG RESULTANT BOUNDARY AND NEWD ALONG/AHEAD OF SFC COLD FRONT. 
   FOREGOING AIR MASS IS EXPECTED TO DESTABILIZE DIABATICALLY...IN
   CONCERT WITH SFC DEW POINTS MID 60S TO NEAR 70 F...TO YIELD
   AFTN/PRECONVECTIVE MLCAPE IN 2000-3000 J/KG RANGE.  STG HEATING MAY
   LOWER THOSE DEW POINTS LOCALLY INTO LOWER 60S F WHERE PARCELS CAN BE
   MIXED THROUGH BASAL EML INVERSION.  THOUGH LOW-MIDDLE LEVEL FLOW
   WILL BE WEAK...VEERING WITH HEIGHT STILL MAY STILL YIELD 30-40 KT
   EFFECTIVE-SHEAR MAGNITUDES.  THAT AND  50-KT ANVIL-LEVEL WINDS WILL
   HELP TO SUPPORT SOME STORM VENTILATION ALOFT AND MULTICELL
   ORGANIZATION.  ALTHOUGH COMBINED FRONTAL/OUTFLOW BOUNDARY SHOULD
   UNDERCUT ANY STORMS THAT DEVELOP ALONG IT OVER EDWARDS PLATEAU AND
   S-CENTRAL TX...BRIEF/ISOLATED RISK FOR SVR WIND AND HAIL SHOULD
   EXIST.

   ...CAROLINAS AND VICINITY...
   SCATTERED TSTMS ARE EXPECTED TO DEVELOP TODAY NEAR AND S OF FRONTAL
   ZONE THAT WAS ANALYZED AT 11Z OVER SRN NC...BUT IS
   1.  EXPECTED TO RETREAT SOMEWHAT NWD AND
   2.  IS BRACKETED ON BOTH SIDES BY FAVORABLE MOISTURE WITH SFC DEW
   POINTS MID 60S F.
   BETTER-ORGANIZED SVR POTENTIAL WILL BE PRECLUDED BY WEAK LAPSE RATES
   ALOFT...AND BY LACK OF SUBSTANTIAL LOW/MIDDLE-LEVEL FLOW.  MAIN
   CONCERNS WILL BE ISOLATED DAMAGING GUSTS APCHG SVR LIMITS...AS WELL
   AS MRGLLY SVR HAIL FROM MOST INTENSE/DEEP CORES.

   ..EDWARDS/PICCA.. 05/12/2016

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