May 11, 2011 0600 UTC Day 1 Convective Outlook
Updated: Wed May 11 05:52:05 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110511 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110511 1200 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
20110511 1200 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
20110511 1200 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 110548
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1248 AM CDT WED MAY 11 2011
   
   VALID 111200Z - 121200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF WCNTRL KS AND
   WRN OK...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...CNTRL PLAINS AND MID-MO VALLEY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF WRN SC AND ERN
   GA...
   
   ...SEVERE WEATHER EPISODE WILL BE LIKELY ACROSS THE SRN AND CNTRL
   PLAINS TODAY WITH AN ISOLATED THREAT FOR STRONG TORNADOES...
   
   ...SRN AND CNTRL PLAINS...
   AN UPPER-LEVEL LOW OVER THE FOUR CORNERS REGION WILL MOVE EWD ACROSS
   THE SRN ROCKIES AND DECELERATE AS THE SYSTEM MOVES INTO THE CNTRL
   PLAINS THIS AFTERNOON. AHEAD OF THE SYSTEM...A WELL-DEVELOPED
   LOW-LEVEL JET WILL BE IN PLACE ACROSS THE SRN AND CNTRL PLAINS WITH
   AN AXIS OF MODERATE TO STRONG INSTABILITY LOCATED FROM CNTRL AND NRN
   TX EXTENDING NWD ACROSS OK AND KS. MODEL FORECASTS DEVELOP A CLUSTER
   OF STRONG THUNDERSTORMS THIS MORNING ACROSS THE TX HILL COUNTRY
   ASSOCIATED WITH A SUBTLE SHORTWAVE TROUGH MOVING NEWD ACROSS THE
   REGION. THIS ACTIVITY MAY HAVE A HAIL THREAT AS THE CONVECTION MOVES
   INTO THE AXIS OF THE LOW-LEVEL JET ACROSS EAST AND NORTH TX THIS
   AFTERNOON. FURTHER TO THE NORTH...ACROSS WCNTRL OK AND WCNTRL
   KS...THE AIRMASS SHOULD REMAIN UNDISTURBED THROUGH EARLY AFTERNOON
   AS A DRYLINE SHARPENS ACROSS WRN KS AND WRN OK. AS LOW-LEVEL
   CONVERGENCE INCREASES ALONG THE DRYLINE AND THE CAP WEAKENS THIS
   AFTERNOON...SCATTERED THUNDERSTORM INITIATION SHOULD TAKE PLACE ON
   THE WRN EDGE OF THE MODERATE RISK AREA. INCREASING DEEP LAYER SHEAR
   ASSOCIATED WITH AN APPROACHING MID-LEVEL JET AND MODERATE
   INSTABILITY SHOULD BE FAVORABLE FOR SUPERCELL DEVELOPMENT. AS
   SUPERCELLS RAPIDLY DEVELOP...A HIGHER-END SEVERE WEATHER EVENT
   SHOULD UNFOLD LATE THIS AFTERNOON INTO THE EVENING ACROSS THE SRN
   AND CNTRL PLAINS.
   
   CONVECTIVE INITIATION SHOULD TAKE PLACE FIRST THIS AFTERNOON ACROSS
   NRN KS ALONG A WARM FRONT EXTENDING ENEWD FROM SFC LOW IN WRN KS.
   FORECAST SOUNDINGS FROM GOODLAND KS EWD TO SALINA KS AT 21Z SHOW
   MLCAPE VALUES OF 1500 TO 2500 J/KG AND 0-6 KM SHEAR VALUES AROUND 40
   KT. THIS COMBINED WITH COLD TEMPS ALOFT ASSOCIATED WITH THE
   UPPER-LEVEL LOW TO THE WEST...SHOULD PROVIDE CONDITIONS FAVORABLE
   FOR LARGE HAIL AS SUPERCELLS AND/OR BOWING LINE-SEGMENTS ORGANIZE
   DURING THE LATE AFTERNOON. FURTHER SOUTH ALONG THE
   DRYLINE...FORECAST SOUNDINGS AT 21Z TO 00Z SHOW MLCAPE VALUES OF
   2000 TO 3000 J/KG WITH 0-6 M SHEAR VALUES AROUND 40 KT. DEEP LAYER
   SHEAR SHOULD INCREASE BY 00Z AS A 60 TO 70 KT MID-LEVEL JET MOVES
   INTO THE SRN PLAINS. THIS COMBINED WITH 700 TO 500 MB LAPSE RATES OF
   8.0 TO 8.5 C/KM SHOULD BE VERY FAVORABLE FOR LARGE HAIL. A THREAT
   FOR 2 INCH OR GREATER HAIL SHOULD EXIST WITH THE MORE INTENSE
   SUPERCELLS. IN ADDITION...LOW-LEVEL SHEAR WILL ALSO INCREASE DURING
   THE EARLY EVENING AS A 35 TO 50 KT LOW-LEVEL JET BECOMES FOCUSED
   ACROSS CNTRL OK AND SRN KS. THE GREATEST THREAT FOR TORNADOES SHOULD
   EXIST TO THE WEST OF THE JET CENTER IN WRN OK AND WCNTRL KS AS
   SUPERCELLS MATURE DURING THE EARLY EVENING. AN ISOLATED THREAT FOR
   STRONG TORNADOES MAY EXIST WITH THE MORE DOMINANT SUPERCELLS.
   
   THE MAIN UNCERTAINTY WITH THE FORECAST IS STORM COVERAGE. MOST OF
   THE MODELS KEEP CONVECTIVE COVERAGE ACROSS WRN OK AND WRN KS
   RELATIVELY ISOLATED. THIS IS PROBABLY DUE TO THE UPPER-LEVEL LOW
   WHICH IS FORECAST TO SLOW DOWN CONSIDERABLY...KEEPING MOST OF THE
   LARGE-SCALE ASCENT WEST OF THE DRYLINE. AT THIS POINT...THE NAM
   SOLUTION AT 00Z APPEARS REASONABLE SUGGESTING THE STORMS MAY TEND TO
   REMAIN WIDELY GAPPED. IN SPITE OF THIS...THE SYNOPTIC PATTERN WITH A
   STRONG LOW-LEVEL JET RESPONSE...EJECTING MID-LEVEL JET AND
   WELL-DEVELOPED DRYLINE SHOULD RESULT IN A HIGHER-END SEVERE THREAT.
   FOR THIS REASON...WILL MAINTAIN A MODERATE RISK ACROSS WCNTRL KS AND
   WRN OK.
   
   ...SRN APPALACHIAN MTNS AND CAROLINAS...
   NNWLY FLOW WILL BE IN PLACE AGAIN TODAY FROM THE CNTRL APPALACHIAN
   MTNS SWD INTO THE CAROLINAS. SFC HEATING AND SFC DEWPOINTS AROUND 70
   F SHOULD RESULT IN MODERATE TO STRONG DESTABILIZATION BY THIS
   AFTERNOON. SCATTERED THUNDERSTORMS APPEAR LIKELY TO DEVELOP THIS
   AFTERNOON IN THE WRN CAROLINAS AS A SUBTLE SHORTWAVE TROUGH MOVES
   SSEWD ACROSS THE REGION. MLCAPE VALUES OF 2500 TO 3500 J/KG ALONG
   WITH 45 TO 50 KT OF DEEP LAYER SHEAR SHOULD BE SUFFICIENT FOR
   SUPERCELL DEVELOPMENT. ANY SUPERCELL THAT DEVELOPS SHOULD CONTAIN AN
   ISOLATED THREAT FOR LARGE HAIL AND WIND DAMAGE.
   
   ...MID TO UPPER MS VALLEY...
   AN AXIS OF MODERATE INSTABILITY SHOULD EXIST FROM THE LOWER OH
   VALLEY NWD INTO THE UPPER MS VALLEY WHERE MLCAPE VALUES SHOULD BE IN
   THE 3000 TO 4000 J/KG RANGE BY MID-AFTERNOON. ALTHOUGH LARGE-SCALE
   ASCENT SHOULD REMAIN RELATIVELY WEAK...A FEW STORMS MAY INITIATE
   FROM SRN MN AND ERN IA EWD ACROSS WI AND NRN IL. THE STRONG
   INSTABILITY AND STEEP LOW-LEVEL LAPSE RATES COULD RESULT IN A
   MARGINAL WIND DAMAGE THREAT WITH HAIL ALSO POSSIBLE WITH THE MORE
   INTENSE CELLS.
   
   ..BROYLES/STOPKOTTE.. 05/11/2011
   
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