SPC AC 220549
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1249 AM CDT MON AUG 22 2005
   
   VALID 231200Z - 241200Z
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM DRT AUS 10 E ACT MWL
   BGS FST 45 WSW MRF ...CONT... IPL 50 ESE DAG DRA LOL 4LW BNO LWS 4OM
   40 NNW 4OM ...CONT... 65 N DVL 25 NNW ATY FSD 20 SE OMA 10 N COU BWG
   10 SSE BLF 15 ENE WAL.
   
   ...NO SVR TSTM AREAS FORECAST...
   
   IN RESPONSE TO AMPLIFICATION IN SOUTHERN BRANCH OF POLAR JET...A
   LESS PROGRESSIVE UPPER FLOW PATTERN CONTINUES TO EVOLVE OVER THE
   U.S. AND MUCH OF CANADA.  ONE CLOSED LOW HAS ALREADY DEVELOPED
   WITHIN LARGE UPPER TROUGH ACROSS QUEBEC/ONTARIO AND THE LOWER GREAT
   LAKES. EASTWARD MIGRATION OF THIS SYSTEM WILL SLOW BY TUESDAY
   ACROSS THE NORTH ATLANTIC COAST...AS ANOTHER CLOSED LOW EVOLVES IN
   LARGE UPSTREAM TROUGH DIGGING ACROSS THE CANADIAN/NORTHERN U.S.
   ROCKIES.
   
   SUPPRESSION OF SUBTROPICAL RIDGE IS EXPECTED TO PERSIST THROUGH THIS
   PERIOD EAST OF THE APPALACHIANS...AS FAR SOUTH AS THE SOUTHERN MID
   ATLANTIC COASTAL STATES.  HOWEVER...AS LOW AMPLITUDE TROUGH IN
   SUBTROPICAL STREAM LIFTS OUT OF THE SOUTHERN PLATEAU THROUGH THE
   CENTRAL ROCKIES/HIGH PLAINS...UPPER RIDGE IS FORECAST TO SLOWLY
   BUILD NORTHWARD THROUGH THE SOUTHERN PLAINS AND LOWER MISSISSIPPI
   VALLEY.
   
   ...HIGH PLAINS...
   SURFACE LOW DEVELOPING TODAY ACROSS CENTRAL/EASTERN MONTANA IS
   PROGGED TO LIFT NORTHWARD AND WEAKEN ACROSS SASKATCHEWAN/MANITOBA
   TUESDAY.  AS THIS OCCURS...MODELS SUGGEST NEW LOW WILL FORM IN 
   PRE-FRONTAL SURFACE TROUGH ACROSS SOUTHEAST MONTANA BY LATE TUESDAY
   AFTERNOON...WITH TROUGH AXIS EXTENDING SOUTHWARD THROUGH THE CENTRAL
   HIGH PLAINS.  THIS IS NORTH OF SURFACE FRONT EXPECTED TO LINGER
   ACROSS THE SOUTHERN PLAINS...FROM THE TEXAS/OKLAHOMA PANHANDLE
   REGION THROUGH THE RED RIVER VALLEY...AND LACK OF MORE SIGNIFICANT
   NORTHWARD MOISTURE RETURN WILL BE ONE FACTOR LIMITING SEVERE THREAT
   THIS FORECAST PERIOD.  ADDITIONALLY...MID/UPPER FLOW ACROSS NORTHERN
   PLAINS...SOUTH/EAST OF DIGGING TROUGH IN POLAR WESTERLIES...IS
   EXPECTED TO REMAIN WEAK AND SOUTHERLY THROUGH AT LEAST TUESDAY
   EVENING.
   
   DESPITE LIMITING FACTORS...VERY STEEP LAPSE RATES WILL CONTRIBUTE TO
   FAVORABLE ENVIRONMENT FOR VIGOROUS CONVECTIVE DEVELOPMENT.  ISOLATED
   STRONGER STORMS MAY PRODUCE MARGINALLY SEVERE HAIL AND AN ISOLATED
   DOWNBURST OR TWO...BEFORE WEAKENING DURING THE EVENING WITH LOSS OF
   DAYTIME HEATING.
   
   FARTHER SOUTH...STRONGER FORCING ASSOCIATED WITH SUBTROPICAL IMPULSE
   MAY NOT OVERSPREAD PARTS OF EASTERN COLORADO/WESTERN NEBRASKA AND
   KANSAS UNTIL AFTER DARK.  HOWEVER...MODELS SUGGEST A BIT MORE
   PRONOUNCED VEERING WITH HEIGHT IN LOWER TO MID LEVELS DURING THE
   PEAK HEATING HOURS ACROSS THIS REGION...WHERE LOW-LEVEL MOISTURE
   RETURN MAY CONTRIBUTE TO MIXED LAYER CAPE OF 2000 TO 3000 J/KG.  AN
   ISOLATED SHORT-LIVED SUPERCELL OR TWO APPEARS POSSIBLE ...BUT SEVERE
   THREAT MAY DIMINISH FAIRLY QUICKLY DURING THE EVENING AS BOUNDARY
   LAYER COOLS/STABILIZES.
   
   ...SOUTHEAST STATES...
   AS FRONT ACROSS THE SOUTH ATLANTIC COAST STATES WEAKENS...MOIST
   UPSLOPE FLOW IS PROGGED TO DEVELOP TUESDAY.  IT IS STILL UNCERTAIN
   AS TO WHETHER A SHORT WAVE ROTATING INTO BASE OF LARGER-SCALE
   EASTERN TROUGH WILL CONTRIBUTE TO FORCING FOR CONVECTIVE DEVELOPMENT
   ACROSS THE SOUTHERN APPALACHIANS DURING THE DAYTIME HOURS. 
   HOWEVER...SCATTERED THUNDERSTORM ACTIVITY APPEARS LIKELY IN RESPONSE
   TO HEATING OF WEAKLY CAPPED BOUNDARY LAYER.  THOUGH LOW/MID-LEVEL
   WINDS WILL BE LIGHT...VEERING WITH HEIGHT BENEATH MODERATE WESTERLY
   HIGH-LEVEL FLOW MAY CONTRIBUTE TO SUFFICIENT SHEAR FOR AT LEAST
   BRIEF UPDRAFT ROTATION IN STRONGEST CELLS.  IF THIS
   OCCURS...POTENTIAL FOR HAIL/GUSTY WINDS WILL BE ENHANCED.
   
   ..KERR.. 08/22/2005
   
   ...NOTICE...
   THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE
   SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1...
   WUUS02 PTSDY2...WUUS03 PTSDY3.  THE INCLUSION OF POINTS
   IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005
   CONVECTIVE SEASON.  A PUBLIC NOTIFICATION STATEMENT (PNS)
   WILL PROVIDE DETAILS ON THE TRANSITION.
   
   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z