Sep 22, 2010 1630 UTC Day 1 Convective Outlook
Updated: Wed Sep 22 16:28:45 UTC 2010
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20100922 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20100922 1630 UTC Day 1 Tornado Probabilities Graphic
Torndao Legend Image
Probabilistic Damaging Wind Graphic
20100922 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Wind Legend Image
Probabilistic Large Hail Graphic
20100922 1630 UTC Day 1 Large Hail Probabilities Graphic
Hail Legend Image
   SPC AC 221625
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1125 AM CDT WED SEP 22 2010
   
   VALID 221630Z - 231200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE NRN AND
   CNTRL PLAINS INTO UPPER MIDWEST...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER CNTRL/SRN NEW ENGLAND INTO
   THE MID ATLANTIC STATES...
   
   ...NRN/CNTRL PLAINS INTO THE UPPER MIDWEST...
   
   ELEVATED...STRONG TO SEVERE TSTMS IN PROGRESS THIS MORNING OVER NERN
   NEB/SERN SD ARE EXPECTED TO MOVE/DEVELOP EWD/NEWD TODAY INTO
   CNTRL/SRN MN/NRN IA IN ADVANCE OF MIDLEVEL IMPULSE TRANSLATING ENEWD
   ACROSS SD/NEB.  FORCING ASSOCIATED WITH THIS FEATURE COUPLED WITH AN
   ENHANCED ZONE OF WARM THERMAL AND MOISTURE ADVECTIONS ALONG SSWLY
   LLJ STRENGTHENING TO 40-50 KT WILL SUSTAIN AN ENVIRONMENT
   CHARACTERIZED BY MUCAPE OF 1500-3000 J/KG --REF. 12Z OAX/LBF
   SOUNDINGS-- AND SUFFICIENT CLOUD-BEARING SHEAR TO SUPPORT SUPERCELLS
   CAPABLE OF MAINLY LARGE HAIL TO THE N OF RETREATING WARM FRONT.
   
   WITHIN SYSTEM WARM SECTOR...THE COMBINATION OF STRONG DAYTIME
   HEATING...BOUNDARY LAYER DEW POINTS IN THE 60S TO AROUND 70F AND
   STEEP LAPSE RATES WILL CONTRIBUTE TO A MODERATELY UNSTABLE...BUT
   CAPPED AIR MASS WITH MLCAPE INCREASING TO 1500-2500 J/KG.  GIVEN THE
   EARLY ENEWD PROGRESSION OF ABOVE-MENTIONED SHORT WAVE TROUGH ALONG
   NRN EXTENSION OF THE DEVELOPING WARM SECTOR OVER NEB/IA...THERE IS
   SOME UNCERTAINTY AS TO HOW SURFACE-BASED... DIURNALLY-ENHANCED TSTM
   ACTIVITY WILL EVOLVE.  CURRENT THINKING IS THAT PERHAPS THE SWD
   EXTENSION OF PERSISTENT...ELEVATED TSTM COMPLEX WILL BECOME
   PROGRESSIVELY MORE SURFACE-BASED AS SYNOPTIC WARM FRONT RETREATS NWD
   THROUGH NEB/IA TOWARD THE SD/MN BORDERS.  
   
   ANY STORMS THAT CAN BECOME ROOTED IN THE BOUNDARY LAYER WILL
   EXPERIENCE A MOIST AND STRONGLY SHEARED LOWER-TROPOSPHERIC
   ENVIRONMENT INVOF OF WARM FRONT WHERE A FEW TORNADOES WILL BE
   POSSIBLE IN ADDITION TO LARGE HAIL AND DAMAGING WIND GUSTS. 
   ADDITIONAL...DIURNALLY-ENHANCED STORMS WILL BE POSSIBLE IN ADVANCE
   OF DEEPENING LEE CYCLONE OVER WRN NEB WHERE ENVIRONMENT WILL ALSO BE
   SUPPORTIVE OF SUPERCELLS CAPABLE OF LARGE HAIL...DAMAGING WINDS AND
   PERHAPS A COUPLE TORNADOES.
   
   STRONG/SEVERE TSTMS ARE EXPECTED TO CONTINUE OVERNIGHT...PERHAPS
   EXPANDING IN AREAL COVERAGE...IN ASSOCIATION WITH NEXT SIGNIFICANT
   SHORT WAVE TROUGH WHICH WILL EMERGE FROM THE CNTRL HIGH PLAINS IN
   ADVANCE OF GREAT BASIN LARGE-SCALE TROUGH.  LARGE HAIL AND STRONG
   WIND GUSTS WILL BE THE PRIMARY HAZARDS WITH THE MOST INTENSE STORMS.
   
   
   ...CNTRL/SRN NEW ENGLAND INTO THE MID ATLANTIC STATES...
   
   12Z UPPER-AIR ANALYSIS AND MORNING WATER VAPOR IMAGERY INDICATE A
   SHORT WAVE TROUGH OVER THE LOWER GREAT LAKES AND UPPER OH VALLEY
   WILL PROGRESS EWD TODAY IN TANDEM WITH SURFACE COLD FRONT THROUGH
   THE REGION.  WHILE THE AMBIENT PRE-FRONTAL AIR MASS IS NOT OVERLY
   MOIST...VISIBLE SATELLITE IMAGERY SUGGESTS THAT STRONG DIABATIC
   HEATING SHOULD OCCUR...CONTRIBUTING TO STEEPENING LAPSE RATES AND
   MLCAPE VALUES INCREASING TO 1000-1500 J/KG.  FORCING FOR ASCENT
   ASSOCIATED WITH SHORT WAVE TROUGH AND FRONTAL UPLIFT SHOULD FOSTER
   SCATTERED TSTM DEVELOPMENT BY AFTERNOON ALONG/AHEAD OF COLD FRONT
   OVER CNTRL/ERN PARTS OF NY/PA WITH ADDITIONAL...MORE ISOLATED STORM
   FORMATION SWD ALONG LEE TROUGH SITUATED OVER THE PIEDMONT.
   
   FORECAST SOUNDINGS INDICATE STRENGTHENING WSWLY/WLY TROPOSPHERIC
   FLOW WITH THE APPROACH OF THE SHORT WAVE TROUGH WITH SETUP BECOMING
   INCREASINGLY FAVORABLE OF BOWING LINE SEGMENTS CAPABLE OF MAINLY
   DAMAGING WIND GUSTS THROUGH THIS EVENING.  VERTICAL SHEAR IS
   EXPECTED TO DIMINISH WITH SWD EXTENT ALONG THE LEE TROUGH...THOUGH
   THERMODYNAMIC ENVIRONMENT WILL STILL BE SUPPORTIVE OF LOCALLY STRONG
   WINDS.
   
   ...ERN GREAT BASIN...
   
   LARGE-SCALE FORCING FOR ASCENT IS FORECAST TO STEADILY STRENGTHEN
   OVER THE REGION TODAY IN ADVANCE OF LARGE-SCALE TROUGH PROGRESSING
   EWD THROUGH CA/NV AND THE LOWER CO VALLEY.  AT THE SAME
   TIME...INTENSIFYING SURFACE CYCLONE OVER WRN UT WILL BEGIN TO DRAW
   THE NRN EXTENSION OF GULF OF CA MOISTURE SURGE CURRENTLY OBSERVED
   OVER CNTRL/SRN AZ INTO THE AREA...SUPPORTING MODEST AIR MASS
   DESTABILIZATION THROUGH THE DIURNAL HEATING CYCLE.  GIVEN THE
   CONCURRENT INCREASE IN VERTICAL SHEAR AND DYNAMIC FORCING FOR
   ASCENT...SETUP WILL FAVOR THE DEVELOPMENT OF A FEW STRONG TO
   MARGINALLY SEVERE STORMS ALONG/AHEAD OF PACIFIC FRONT WITH A RISK
   FOR LOCALLY DAMAGING WIND GUSTS AND PERHAPS SOME HAIL.
   
   ..MEAD/GRAMS.. 09/22/2010
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z