SPC AC 201711
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1211 PM CDT SAT SEP 20 2003
   
   VALID 211200Z - 221200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM OKC 40
   WSW END 40 ESE P28 40 ENE ICT MKC 40 WNW COU 15 ENE COU VIH 35 NE
   HRO 25 SSE MKO OKC.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM DRT TPL 25 ESE ACT 45
   WNW TYR 25 NE DAL 40 N MWL ABI SJT 50 S MAF 50 NNE HOB DHT HSI 25
   WNW SUX FSD ABR Y22 45 N MLS 80 ENE HVR ...CONT... ANJ HTL LAN 60 E
   LUK JKL 30 NW HSS 50 NW AHN LGC 30 ENE DHN VLD 15 E JAX.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF NRN
   OK...SERN KS...WRN MO AND EXTREME NWRN AR...
   
   ...SYNOPSIS...
   UPPER TROUGH...CURRENTLY MOVING THROUGH THE NRN/CENTRAL ROCKIES
   ...WILL AMPLIFY INTO THE CENTRAL PORTIONS OF THE COUNTRY ON SUNDAY
   AS A SERIES OF IMPULSES AND STRONGER FLOW ALOFT SPREAD SEWD FROM THE
   PACIFIC NW.  THIS TROUGH WILL ALSO AID IN EJECTING A WEAK AREA OF
   LOW PRESSURE ALOFT OVER MEXICO EWD INTO SRN TX DURING THE PERIOD. AT
   THE SURFACE...WEAK FRONTOGENESIS WILL DEVELOP AHEAD OF THE TROUGH
   ACROSS THE PLAINS STATES...WHILE A SURFACE LOW IS FORECAST TO
   DEVELOP IN THE NWRN GULF ALONG AN OLD FRONTAL SYSTEM.
   
   ...NRN OK/SERN KS NEWD INTO WRN/CENTRAL MO...
   THREAT FOR SEVERE WEATHER APPEARS TO BE SOMEWHAT MARGINAL ON SUNDAY
   AS THE STRONGEST SHEAR...LOCATED ACROSS THE MIDDLE MO RIVER
   VALLEY...IS EXPECTED TO REMAIN NORTH OF THE GREATER INSTABILITY 
   ACROSS THE OZARKS REGION. ELEVATED CONVECTION IS EXPECTED TO BE
   ONGOING AT THE START OF THE PERIOD ACROSS PORTIONS OF OK/KS...AS 35
   KT LOW LEVEL JET WILL RESULT IN THE STRONGEST ISENTROPIC LIFTING
   ACROSS THIS AREA. ALTHOUGH THE BOUNDARY LAYER WILL BE STABLE...MID
   LEVEL LAPSE RATES AROUND 7.5C/KM AND MOISTURE ADVECTION BETWEEN
   700-850 MB WOULD YIELD MUCAPE VALUES FROM 1000 TO 2000 J/KG. THIS
   SHOULD SUPPORT A FEW STORMS WITH SEVERE HAIL DURING THE MORNING
   HOURS ACROSS PORTIONS OF NRN OK AND SERN KS.
   
   EVEN THOUGH THE LOW LEVEL JET WEAKENS DURING THE DAY...SURFACE
   DEWPOINTS INCREASING INTO THE MID 60S AND AFTERNOON TEMPERATURES
   WARMING TO NEAR 80 DEGREES MAY BE SUFFICIENT FOR SURFACE BASED
   STORMS TO DEVELOP IN STRONGER DIFFLUENT FLOW ALOFT ACROSS THE OZARKS
   REGION. DEEP LAYER SHEAR FROM 25-30 KT AND MLCAPE VALUES AROUND 1500
   J/KG MAY SUPPORT A FEW STORMS WITH HAIL AND ISOLATED WIND DAMAGE.
   THE STORMS SHOULD WEAKEN SHORTLY AFTER DARK WITH THE LOSS OF DAYTIME
   HEATING.
   
   THUNDERSTORMS ARE ALSO EXPECTED TO SPREAD FROM KS/OK NEWD INTO SERN
   NEB/IA AND NRN MO DURING THE DAY. ALTHOUGH THE SHEAR WOULD BE
   SUFFICIENT FOR SEVERE STORMS...WIDESPREAD CLOUDS AND PRECIPITATION
   SHOULD RESULT IN MOIST ADIABATIC LAPSE RATES WITH VERY WEAK
   INSTABILITY. DESPITE THE COLD TEMPERATURES ALOFT...THE THREAT FOR
   SEVERE STORMS APPEARS LOW ATTM.
   
   ...LA/MS/WRN AL...
   CYCLOGENESIS IN THE NWRN GULF WILL RESULT IN INCREASED THUNDERSTORM
   COVERAGE/INTENSITIES INVOF OF DEVELOPING INVERTED TROUGH ACROSS SERN
   TX AND ALONG BAROCLINIC ZONE IN THE NWRN GULF. WINDS THROUGH THE
   TROPOSPHERE AND MOISTURE WILL INCREASE AHEAD OF THIS SYSTEM
   THROUGHOUT THE PERIOD. ETA/GFS ARE CONSISTENT IN DEVELOPING
   WIDESPREAD CONVECTION FROM SRN LA NEWD INTO CENTRAL
   MS/WRN AL LATE SUNDAY AFTERNOON AND NIGHT AS WARM FRONT LIFTS NWD.
   INSTABILITY IS FORECAST TO STRENGTHEN THROUGH DURING THE PERIOD
   ...THOUGH THE POOR LAPSE RATES SHOULD LIMIT THE SEVERE POTENTIAL.
   
   ..IMY.. 09/20/2003
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED FOR 0800Z