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 |
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Probabilistic Tornado 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 |
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 |
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 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z