ZCZC SPCSWODY1 ALL
ACUS01 KWNS 241252
SPC AC 241252

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0752 AM CDT WED SEP 24 2003

VALID 241300Z - 251200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 N
ERI 50 SW CMH 40 SW SDF 15 W PAH 50 NE UNO 45 NE COU 15 ESE PIA 20
WSW CGX 20 WSW MKG 25 SSE TVC 30 ESE ANJ.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 N SAN 25 SSE DAG
25 W IGM 40 ESE PRC 50 N SAD 15 ENE DMN 35 SE ALM 15 WNW LBB 15 NNW
CSM 15 SW CNU 35 ENE MKC 15 SW CID 15 S CWA 20 NE IWD ...CONT... 40
WSW MSS 30 NW ELM 25 WNW MGW 20 WSW JKL 20 NNE BNA 20 NNW DYR 40 SSE
HRO 40 NE DAL 50 W TPL 50 SSE DRT.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 SE MOB 25 SSW SEM
10 W MCN 40 SSE SAV.

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MS VLY NEWD INTO
THE GREAT LAKES REGION...

...SYNOPSIS...
PROGRESSIVE UPPER FLOW REGIME WILL CONTINUE TODAY BEFORE
TRANSITIONING INTO A HIGHLY AMPLIFIED PATTERN BY WEEKS END.  A
POTENT UPPER SHORTWAVE TROUGH EMBEDDED IN THE POLAR WLYS WILL MOVE
FROM THE UPPER MS VLY THIS MORNING TO THE LOWER GT LKS AND OH VLY
REGIONS BY EARLY THURSDAY AS ANOTHER UPSTREAM IMPULSE DIGS INTO THE
SRN CANADIAN ROCKIES.  LEADING EDGE OF COLD AIR SPILLING SWD IN THE
WAKE OF THIS LEAD SYSTEM WILL SWEEP ACROSS THE UPPER MS VLY EARLY
TODAY...THEN ACROSS THE GRTLKS-UPPER MIDWEST-MID MS VLY THIS EVENING
AND BE ALONG A KBUF-KCVG-KDFW-KINK LINE BY 25/12 UTC.
MEANWHILE...TROPICAL DEPRESSION MARTY JUST SOUTH OF PUERTO PENASCO
MX WILL MEANDER IN THE NRN GULF OF CA REGION THROUGH THE PERIOD. 
WEAK SUBTROPICAL IMPULSES WILL CROSS NRN MX AND INTO SWRN TX.

...GRTLKS REGION INTO THE OH/MID MS VLYS...
LOW LEVEL THETA-E ADVECTION ALONG NOSE OF A 45-50 KT SWLY LLJ AXIS
AND LARGE SCALE SUPPORT FROM A LOW AMPLITUDE MIDLEVEL IMPULSE HAVE
BEEN SUPPORTING A SMALL MCS ACROSS THE UPPER MIDWEST THIS MORNING. 
THESE ELEVATED TSTMS COULD PERSIST FOR SEVERAL MORE HOURS AND SHIFT
ENEWD INTO NRN OH THIS MORNING.  PARCELS FEEDING THE CLUSTER RESIDE
UPSTREAM WITHIN A RESERVOIR OF MOIST AND UNSTABLE AIR /12 UTC KILX
SOUNDING SHOWING 4000 J/KG MUCAPE/.  GIVEN STEEP LAPES RATES
SPREADING OVER THE REGION FROM THE SW...ISOLD LARGE HAIL MAY
ACCOMPANY THESE STORMS BEFORE THEY WEAKEN LATER THIS MORNING.

ATTENTION WILL THEN TURN TO THE APPROACH OF A MUCH STRONGER
IMPULSE/CDFNT. TSTMS SHOULD DEVELOP RAPIDLY EARLY-MID AFTERNOON
FROM LWR MI INTO NRN IL AS STRONG LARGE SCALE ASCENT SPREADS ACROSS
THE GTLKS AND UPPER MIDWEST. 06 UTC AVN/ETA SLOW THE TIMING OF THE
CDFNT FROM PREVIOUS MODELS AND THIS SEEMS IN AGREEMENT WITH CURRENT
CONDITIONS.  THUS...PROBS/CATEGORICAL SLGT RISK HAVE BEEN ADJUSTED
SLIGHTLY WWD.

BOUNDARY LAYER MOISTURE WITH SURFACE DEW POINTS IN THE UPPER 50S ARE
ADVECTING QUICKLY NEWD TOWARD NRN IL/SWRN LWR MI BENEATH THE STEEP
MIDLEVEL LAPSE RATES ALREADY IN PLACE...BUT QUESTION REMAINS ON
MAGNITUDE OF INSOLATION.  DESPITE THE RATHER LOW INSTABILITY
EXPECTED... MAGNITUDE OF FORCING AND VERY STRONG KINEMATICS WILL
LIKELY COMPENSATE.  VERTICAL SHEAR WILL BE FAVORABLE FOR SUPERCELLS
AND THEY COULD OCCUR EARLY IN THE TSTM LIFE CYCLE...BUT AS THE
STRONGER FORCING APPROACHES...A QUICK EVOLUTION TO A SQUALL LINE
WITH EMBEDDED LEWPS/BOWS WILL LIKELY OCCUR AND MOVE ACROSS THE CNTRL
GTLKS AND UPPER MIDWEST.  IF TSTMS CAN DEVELOP INTO THE BOUNDARY
LAYER /IE NOT REMAIN ELEVATED/...DAMAGING WINDS WILL BE POSSIBLE
ALONG WITH LARGE HAIL.

FARTHER SW ACROSS THE MID MS VLY...POTENTIAL INSTABILITY WILL BE
GREATER THAN FARTHER N...BUT 12 UTC KSGF SOUNDING SHOWS A STOUT
ELEVATED MIXED LAYER.  STRONGEST UPPER SUPPORT/HEIGHT FALLS WILL
PASS NORTH OF THE REGION...BUT AS THE COLD FRONT MOVES INTO THE
INSTABILITY AXIS...A FEW TSTMS MAY MANAGE TO FORM WITH THE THREAT
FOR LARGE HAIL AND HIGH WINDS.

..RACY.. 09/24/2003

...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.

$$