[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 210554
SWODY1
SPC AC 210550

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT FRI MAY 21 2004

VALID 211200Z - 221200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 N
HSE 15 ENE RWI 15 ENE DAN 45 WSW EKN 35 WNW UNI 15 NE SDF 25 NNW EVV
25 SSW DEC 40 SW OTM 20 N FNB 20 SE RSL 30 S DDC 50 W GAG 50 SSE EHA
25 SSW EHA 55 NE LAA 40 ENE AKO 30 W SNY 35 SSE DGW 40 SW GCC 40 ENE
SHR 30 SE MLS 65 NNW REJ 30 SSE Y22 30 S ABR 45 E ATY 25 W MSP 25 NE
AUW 15 NNW HTL 60 N MTC ...CONT... 20 NE ERI 20 N PSB 30 E HGR 25 SE
DCA 20 SSW WAL.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 SSW HUM 50 SW CBM
20 N DYR 45 W STL 35 NNE COU 35 NNE SZL 30 NE EMP 15 SE ICT 35 S END
35 ENE ABI 30 SE DRT ...CONT... 55 SW MRF 20 ESE HOB 15 N DHT LAA
LIC DEN 25 NE EGE 25 NW GJT 10 WSW U28 50 NNE BCE 25 SSW P38 65 NNE
NID 40 ENE MER 35 N UKI 40 NE 4BK 40 NW RDM 20 SE OLM 15 NNE UIL
...CONT... 70 NW ISN 40 SSE DVL 15 SE CMX ...CONT... 15 W MSS 30 ESE
ISP ...CONT... 10 NE JAX 25 S CTY.

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL PLAINS ACROSS
THE MIDWEST/SRN GREAT LAKES...TO THE MID ATLANTIC...

...SYNOPSIS...
ANOTHER DAY OF ACTIVE WEATHER IS EXPECTED FROM THE CNTRL PLAINS TO
THE GREAT LAKES...AND POSSIBLY FROM THE OH VALLEY TO THE MID
ATLANTIC/SOUTHEAST COAST TODAY. WHILE MEAN UPPER TROUGH POSITION
WILL REMAIN ACROSS THE WRN U.S. WITH A REINFORCING SHORT WAVE TROUGH
DROPPING SEWD FROM SRN BC TO WA...SEVERAL SMALLER SCALE IMPULSES...
SOME CONVECTIVELY INDUCED...WILL ACT TO FLATTEN LARGE SCALE RIDGE
SITUATED OVER THE LOWER MS VALLEY AND GULF COAST. THESE IMPULSES
WILL TRAVEL WITHIN A BELT OF MODEST WSWLY MID LEVEL FLOW...AND ATOP
WAVY FRONTAL ZONE...FROM THE HIGH PLAINS...ACROSS THE MID/UPPER MS
VALLEY...TO THE GREAT LAKES. THE WRN EXTENSION OF THE FRONT LIFTS
NWD AS A WARM FRONT FROM IA TO SRN WI/LOWER MI TODAY THROUGH TONIGHT
AS MID LEVEL HEIGHT FALLS AND LEE-SIDE CYCLOGENESIS OCCUR OVER THE
PLAINS. THE WEAKER ERN SEGMENT OF THE FRONTAL BOUNDARY WILL BECOME
INCREASINGLY FRACTURED AND ILL-DEFINED BY CONVECTIVE OUTFLOWS BUT
WILL CONTINUE TO PROVIDE A FOCUS FOR GREATER BOUNDARY LAYER MOISTURE
AND HIGH INSTABILITY.

...OH VALLEY TO MID ATLANTIC...
MESOSCALE CONVECTIVE VORT CENTER IS LIKELY TO DEVELOP FROM INTENSE
MCS ONGOING ACROSS THE UPPER MIDWEST AT THIS TIME. THIS IMPULSE
COULD TRANSLATE ACROSS THE CNTRL APPALACHIANS/WV AREA LATER THIS
MORNING AND THEN AID DEEP LAYER ASCENT ACROSS LEE/THERMAL TROUGH
OVER ERN VA AND NRN NC. BACKGROUND ASCENT WITH THIS IMPULSE WILL
FAVORABLY COINCIDE WITH STRONG DIURNAL DESTABILIZATION AND SHOULD
PROMOTE TSTM DEVELOPMENT. SHEAR WILL REMAIN WEAK ACROSS THE REGION
BUT ANTICIPATED STORM COVERAGE AND TIME OF DAY WILL FAVOR  DAMAGING
WIND/DOWNBURST POTENTIAL.

FARTHER WEST...OUTFLOW BOUNDARY FROM ONGOING CONVECTION IS LIKELY TO
DRIFT SEWD TOWARD THE LOWER OH VALLEY AND INTO A VERY UNSTABLE
AIRMASS. ETA IS FCSTG CONVECTIVE INITIATION ON THIS BOUNDARY ACROSS
SRN IND BY 18Z. AGAIN...SHEAR WILL REMAIN MARGINAL BUT MAGNITUDE OF
INSTABILITY WOULD PROMOTE VIGOROUS MULTICELL UPDRAFTS WITH SOME
CHANCE FOR WIND AND HAIL.

...UPPER MS VALLEY/GREAT LAKES/MIDWEST...
STRONG MCS IS EXPECTED TO CONSOLIDATE BEFORE DAYBREAK ON THE LEADING
EDGE OF RETREATING WARM FRONT OVER ERN NEB/WRN IA. IN ADDITION TO
STRONG LLJ FEEDING THIS COMPLEX...MID LEVEL SHORT WAVE
IMPULSE...POSSIBLY CONVECTIVELY ENHANCED...WILL DRIVE A SURFACE WAVE
ALONG THE RETREATING FRONT FROM IA ENEWD ACROSS SRN MN/WI... AND
INTO LOWER MI BY EVENING. MODELS ARE IN VERY GOOD AGREEMENT THAT
CONVECTION WILL PERSIST WITH THIS SYSTEM AS IT TRACKS ENEWD THROUGH
THE DAY. THE LEADING PORTION OF THE CONVECTIVE SYSTEM IS LIKELY TO
ENCOUNTER ONLY WEAK SURFACE-BASED INSTABILITY IN THE WAKE OF
DEPARTING CP AIRMASS ACROSS THE UPPER MS VALLEY/WRN GREAT LAKES.
HOWEVER...ELEVATED CELLS COULD STILL PRODUCE HAIL. THE TRAILING
PORTIONS OF THE COMPLEX WILL OCCUR ALONG THE WARM FRONT AND WILL BE
FUELED BY ABUNDANT INSTABILITY ON THE NRN EDGE OF PLAINS CAPPING
INVERSION. SURFACE-BASED CONVECTION IN THE FORM OF SUPERCELLS OR
LINE SEGMENTS COULD PRODUCE DAMAGING WINDS...HAIL AND PERHAPS A
COUPLE TORNADOES DURING THE AFTERNOON AND INTO EVENING FROM ERN IA
ACROSS IL/WI AND INTO LOWER MI.

...PLAINS TO UPPER MS VALLEY (THIS AFTERNOON THROUGH TONIGHT)...
AS IA/MIDWEST STORM COMPLEX MOVES EAST LATER THIS MORNING... INTENSE
HEATING AND VERY HIGH BOUNDARY LAYER MOISTURE WILL  CONTRIBUTE TO
THE DEVELOPMENT OF STRONG TO LOCALLY EXTREME INSTABILITY AHEAD OF
THE DRYLINE FROM NEB TO THE OK PNHDL. SHORT WAVE IMPULSE CURRENTLY
ROUNDING BASE OF LARGE SCALE TROUGH OVER LOWER CO RIVER VALLEY IS
FCST TO EMERGE OVER ERN CO BY LATE AFTERNOON AND SHOULD SUPPORT
CYCLOGENESIS ACROSS THE CNTRL PLAINS...AND SHARPENING DRYLINE SWD.
DESPITE STRONG CONVECTIVE INHIBITION ACROSS KS/OK REGIONS OF SLGT
RISK...STRENGTH OF SURFACE HEATING...COMBINED WITH FAVORABLE LARGE
SCALE ASCENT COINCIDING WITH DRYLINE CIRCULATION...SHOULD PROMOTE
RAPID TSTM DEVELOPMENT. EXPLOSIVE DEVELOPMENT IS ALSO LIKELY FARTHER
NORTH...ACROSS NEB...WHERE CAP WILL BE WEAKER.
ADDITIONALLY...DIFFERENTIAL HEATING AND UPSLOPE FLOW INTO ERN WY AND
THE BLACK HILLS WILL ALSO AID STORM INITIATION IN THESE AREAS.

DEEP LAYER SHEAR OF 35-60KT WILL BE ORIENTED PERPENDICULAR TO THE
DRYLINE/LEE TROUGH AND INITIALLY FAVOR DISCRETE SUPERCELLS. HIGH LFC
WITH SWD EXTENT SUGGESTS HIGH-BASED...POTENTIALLY OUTFLOW
DOMINANT...SUPERCELLS WITH LARGE HAIL AND WIND POTENTIAL. TORNADO
HAZARD MAY BE GREATER NEAR THE WARM FRONT ON THE SD/NEB BORDER WHERE
LFC WILL BE LOWER AND SRH WILL MARGINALLY SUPPORT LOW LEVEL STORM
ROTATION. MOST FORECAST SOUNDINGS ACROSS THE REGION SUGGEST VERY
LARGE HAIL IS ALSO LIKELY.

ACTIVITY WILL EVENTUALLY CONGEAL INTO ONE OR TWO MCS/S AND MOVE
TOWARD THE MO RIVER VALLEY WITH SOME WIND AND HAIL THREAT CONTINUING
INTO EARLY SATURDAY MORNING.

..CARBIN/TAYLOR.. 05/21/2004

...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.