May 23, 2010 2000 UTC Day 1 Convective Outlook
Updated: Sun May 23 20:09:25 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20100523 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100523 2000 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100523 2000 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100523 2000 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 232006
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0306 PM CDT SUN MAY 23 2010
   
   VALID 232000Z - 241200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY
   THROUGH THE CNTRL PLAINS INTO THE SRN HIGH PLAINS...
   
   ...UPPER MS VALLEY PORTION OF SLIGHT RISK...
   MODEL GUIDANCE SUGGESTS STORMS THAT DEVELOP ACROSS THE NRN EXTENT OF
   THE SLIGHT RISK AREA IN MN WILL HAVE A TENDENCY TO SPREAD/MOVE INTO
   NWRN WI.  THUS...THE SLIGHT RISK HAS BEEN EXPANDED INTO NWRN WI.  IN
   ADDITION...BACKED S/SELY SURFACE WINDS ALONG AND EAST OF THE SURFACE
   FRONT EXTENDING FROM SWRN-NERN MN SUGGESTS AT LEAST A LOW TORNADO
   PROBABILITY...RESULTING IN A NEWD EXTENSION OF THE 2 PERCENT TORNADO
   PROBABILITY.
   
   ...CENTRAL/SRN HIGH PLAINS THIS AFTERNOON AND TONIGHT...
   5 PERCENT TORNADO PROBABILITY HAS BEEN EXTENDED SWD INTO THE TX
   PANHANDLE WHERE INCREASING SSELY LOW LEVEL WINDS WILL ENHANCE LOW
   LEVEL SHEAR INTO THIS REGION.  OTHERWISE...THE FORECAST FOR THIS
   PART OF THE SLIGHT RISK AREA REMAINS ON TRACK.  SPC MESOSCALE
   DISCUSSION 674 WILL PROVIDE SHORT TERM MESOSCALE AND SEVERE WEATHER
   THREAT DETAILS ACROSS PARTS OF WRN KS TO THE TX PANHANDLE.
   
   ...SOUTH CENTRAL TO NERN KS...
   17Z LAMONT OKLAHOMA SOUNDING SUGGESTED THAT THE ISOLATED STORM
   TRACKING NEWD THROUGH SOUTH CENTRAL KS /15 ENE HUT AT 20Z/ IS LIKELY
   ELEVATED.  GIVEN THIS FACTOR AND THAT THIS STORM WILL REMAIN LOCATED
   EAST OF STRONGER SHEAR...SEVERE WEATHER THREAT SHOULD BE MINIMAL
   WITH THIS STORM.  THIS OUTLOOK HAS EXTENDED THE GENERAL TSTM LINE
   AND 5 PERCENT HAIL/WIND PROBABILITIES EWD FOR THIS STORM.
   
   ...CENTRAL AND SRN VA TO CAROLINAS...
   TSTMS WILL CONTINUE TO DEVELOP ACROSS VA/SRN CHESAPEAKE BAY REGION
   SWD INTO THE CAROLINAS AS FORCING FOR ASCENT ATTENDANT TO A COUPLE
   OF EMBEDDED IMPULSES OBSERVED PER WATER VAPOR IMAGERY CONTINUE TO
   ROTATE CYCLONICALLY WITHIN SWD DRIFTING MID-UPPER LEVEL PARENT LOW. 
   ALTHOUGH DEEP LAYER SHEAR IS WEAK ACROSS MUCH OF THIS REGION...NWD
   EXTENT OF MODERATE INSTABILITY INTO SRN/CENTRAL VA WARRANTS LOW
   SEVERE WIND/HAIL PROBABILITIES.  GREATEST POTENTIAL FOR STORM
   ORGANIZATION SHOULD REMAIN OVER ERN SC AS STORMS DEVELOP AND/OR
   INTERACT WITH THE SEA BREEZE BOUNDARY.  HERE...E/SELY SURFACE WINDS
   ALONG COASTAL AREAS AND NWLY WINDS ALOFT ARE ENHANCING EFFECTIVE
   BULK SHEAR TO AROUND 30 KT...AIDING IN MULTICELL STORM MODE. 
   ISOLATED HAIL AND STRONG WIND GUSTS SHOULD BE THE PRIMARY THREATS
   ACROSS ERN SC...ESPECIALLY WITH ANY STRONGER UPDRAFTS. 
   
   ...LOWER OH AND LOWER TN VALLEYS...
   GENERAL TSTM AREA ACROSS THIS REGION HAS BEEN EXPANDED SWD AND EWD
   BASED ON BOTH TSTM DEVELOPMENT OVER SWRN KY PER RADAR IMAGERY/
   LIGHTNING DATA AND ADDITIONAL SIGNS OF MORE PERSISTENT UPDRAFTS PER
   VISIBLE SATELLITE IMAGERY.  THIS CONVECTION HAS THUS FAR BEEN
   CONFINED TO A ZONE OF LOW LEVEL CONVERGENCE EXTENDING FROM WRN TN
   NWD TO THE SERN IL/SWRN IND BORDER REGION.  ALTHOUGH THIS AREA IS
   BOTH VERY WARM /ABOVE NORMAL TEMPERATURES/ AND MOIST WITH STEEP
   LAPSE RATES...THE LACK OF STRONGER FORCING AND WEAK DEEP LAYER SHEAR
   SHOULD PRECLUDE A SEVERE THREAT.
   
   ...ELSEWHERE...
   GENERAL TSTM LINES HAVE BEEN ADJUSTED /EXPANDED SPATIALLY/ OVER NRN
   HALF OF FL AND SRN CA PER TRENDS IN REGIONAL RADAR IMAGERY AND
   LIGHTNING DATA...WITH THE LATTER AREA ASSOCIATED WITH A STRONG MID
   AND UPPER LOW/TROUGH ADVANCING EWD INTO THE LOWER CO VALLEY.
   
   ..PETERS.. 05/23/2010
   
   .PREV DISCUSSION... /ISSUED 1130 AM CDT SUN MAY 23 2010/
   
   ...SYNOPSIS...
   
   THE PRIMARY FEATURE OF INTEREST THIS PERIOD IS A STRONG MID AND
   UPPER-LEVEL LOW CURRENTLY DIGGING SEWD OVER CA/NV.  THIS SYSTEM WILL
   BEGIN TO TURN EWD LATER TODAY PRIOR TO ACCELERATING NEWD INTO THE
   FOUR CORNERS REGION TONIGHT AS MID/HIGH-LEVEL JET STREAKS ROUND THE
   TROUGH BASE AND DEVELOP DOWNSTREAM OVER THE ROCKIES.  THIS EVOLUTION
   WILL RESULT IN A CORRIDOR OF SIGNIFICANT HEIGHT FALLS/DYNAMIC
   FORCING FOR ASCENT SPREADING EWD/NEWD FROM THE LOWER CO VALLEY INTO
   THE CNTRL/SRN ROCKIES.
   
   AT THE SURFACE...CURRENT MESOANALYSIS SHOWS PRIMARY SYNOPTIC FRONT
   EXTENDING FROM CNTRL MN SWWD THROUGH THE MID MO VALLEY INTO THE SRN
   HIGH PLAINS AND SRN ROCKIES.  THE NRN PORTION OF THIS BOUNDARY WILL
   SHIFT SLOWLY EWD TODAY GRADUALLY WEAKENING WITH TIME BENEATH
   BUILDING MIDLEVEL HEIGHTS.  MEANWHILE...THE SWRN EXTENSION OF THIS
   FRONT WILL RETREAT NWD THROUGH THE CNTRL PLAINS IN RESPONSE TO LEE
   CYCLOGENESIS OVER ERN CO LATER TODAY INTO TONIGHT.  AS THIS
   OCCURS...A LEE TROUGH/DRY LINE WILL BE ENHANCED OVER THE HIGH
   PLAINS...ALLOWING FOR THE WWD/NWWD ADVECTION OF A MOIST BOUNDARY
   LAYER INTO THE HIGH PLAINS REGION.
   
   ...UPPER MS VALLEY TODAY...
   
   12Z MODEL GUIDANCE CONTINUES TO SUGGEST THAT DIURNAL STORM
   DEVELOPMENT WILL BE POSSIBLE ALONG THE WEAKENING COLD FRONT TODAY
   WITHIN A MOIST AND MODERATELY UNSTABLE ENVIRONMENT BASED ON 12Z MPX
   SOUNDING.  FACTORS POTENTIALLY LIMITING A MORE ROBUST SEVERE WEATHER
   THREAT APPEAR TO BE RISING MIDLEVEL HEIGHTS ACROSS THE REGION AND
   THE PRESENCE OF WIDESPREAD LOW CLOUDS WHICH COULD LIMIT THE
   DEVELOPMENT OF STRONGER AIR MASS DESTABILIZATION.  NONETHELESS...THE
   PRESENCE OF 30-40 KT DEEP...SWLY SHEAR AND THE MOIST BOUNDARY LAYER
   MAY YIELD A FEW SEVERE STORMS/CLUSTERS CAPABLE OF MAINLY DAMAGING
   WINDS AND HAIL.
   
   ...CNTRL/SRN HIGH PLAINS THIS AFTERNOON AND TONIGHT...
   
   12Z OBSERVED SOUNDINGS INDICATE THE PRESENCE OF A STRONG CAP
   ASSOCIATED WITH AN ESTABLISHED EML OVER THE REGION.  STEEP MIDLEVEL
   LAPSE RATES ASSOCIATED WITH THE EML...BOUNDARY LAYER DEW POINTS IN
   THE 60S AND DIABATIC HEATING WILL CONTRIBUTE TO A MODERATE TO
   STRONGLY UNSTABLE WARM SECTOR AIR MASS TODAY WITH MLCAPE OF
   2000-3000 J/KG.
   
   GIVEN THE TENDENCY FOR SLIGHT MIDLEVEL HEIGHT RISES/RIDGING IN
   ADVANCE OF THE SWRN U.S. SYSTEM...IT APPEARS THAT THE CAP MAY
   SUPPRESS SURFACE-BASED STORM INITIATION THROUGH MUCH OF THE
   AFTERNOON.  BY 24/00Z THE COMBINATION OF NEUTRAL TO WEAK HEIGHT
   FALLS COUPLED WITH THE INITIAL DEVELOPMENT OF A 50+ KT LLJ SUGGEST
   AN INCREASED LIKELIHOOD OF STORM FORMATION ALONG THE RETREATING WARM
   FRONT ACROSS WRN KS/ERN CO...AND PERHAPS SWD ALONG THE LEE
   TROUGH/RETREATING DRY LINE.
   
   THE PRESENCE OF 45-55 KT SWLY FLOW ACROSS THE HIGH PLAINS WILL
   RESULT IN SUFFICIENT DEEP-LAYER SHEAR FOR SUPERCELLS CAPABLE OF
   LARGE HAIL THROUGH THE DIURNAL HEATING CYCLE INTO TONIGHT. 
   MOREOVER...INITIALLY VEERED LOW-LEVEL FLOW WILL BACK AND
   STRENGTHEN...PARTICULARLY THIS EVENING...SUGGESTING AN INCREASED
   THREAT FOR TORNADOES WITH ANY SURFACE-BASED SUPERCELLS THAT CAN
   BECOME ESTABLISHED.
   
   STRONG-SEVERE TSTMS ARE EXPECTED TO INCREASE IN COVERAGE TONIGHT
   ALONG THE RETREATING WARM FRONT FROM NERN CO/NWRN KS THROUGH NEB/ERN
   WY INTO SD.  LARGE HAIL WILL BE THE PRIMARY HAZARD WITH THESE
   STORMS...THOUGH A TORNADO OR TWO WILL REMAIN POSSIBLE WITH ANY
   SUPERCELLS THAT CAN REMAIN MORE ISOLATED.
   
   ...CAROLINAS TODAY...
   
   12Z UPPER-AIR ANALYSIS SHOWED A POCKET OF RELATIVELY COOL MIDLEVEL
   TEMPERATURES /I.E. -11 TO -14 C AT 500 MB/ ASSOCIATED WITH A
   WELL-DEFINED VORTICITY MAXIMUM SLOWLY TRANSLATING SWD INTO THE
   REGION FROM WV/VA.  CLOUD SHIELD ASSOCIATED WITH ONGOING TSTM
   COMPLEX OVER ERN NC MAY LOCALLY INHIBIT DAYTIME HEATING AND AIR MASS
   DESTABILIZATION.  ELSEWHERE...STRONG DIABATIC HEATING...DEW POINTS
   IN THE 60S AND MIDLEVEL COOLING WILL CONTRIBUTE TO A MODERATELY
   UNSTABLE AIR MASS LATER TODAY WITH MLCAPE OF 1000-2000 J/KG. 
   VERTICAL SHEAR WILL REMAIN RELATIVELY WEAK...THOUGH THE DEGREE OF
   INSTABILITY AND INCREASED FORCING FOR ASCENT ASSOCIATED WITH THE
   UPPER SYSTEM MAY FOSTER ISOLATED SEVERE STORMS CAPABLE OF STRONG
   WIND GUSTS AND PERHAPS SOME HAIL.
   
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