[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 202157
SWODY1
SPC AC 202154

DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
0454 PM CDT THU MAY 20 2004

VALID 202150Z - 211200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 10 NE
MSS SYR BFD 20 WNW HLG 40 SSE MIE 10 NNE UIN 10 NNE P35 40 NNW FNB
25 N OMA 45 SSW ALO 35 E VOK 15 SW GRB 25 ESE APN.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 40 NW
GLD EHA 40 WNW P07 50 S GDP 65 NE 4CR 25 WNW TAD 40 SSW PUB 10 S LAR
40 NE LAR 35 WNW BFF 20 NW SNY 40 NW GLD.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 NE JAX 15 SSW GNV
15 NE SRQ 15 SSW FMY ...CONT... 35 NE CRP 60 N VCT 40 N POE 50 NNW
MEI 20 W MSL 30 ENE MKL 20 SW PAH 10 SSW MDH 15 W BLV 30 S UIN 30
ESE STJ 25 WNW SLN LBL 15 SSE P07 ...CONT... 70 SSW GDP 60 S LVS 20
WSW RTN 30 W TAD 45 WSW COS 20 ENE ASE 45 W ASE 25 W U28 55 SE ELY
30 SE BIH 50 ENE MER 30 NE UKI 25 SE EKA 20 W PDX 15 ENE CLM
...CONT... 55 NNE MOT ABR 30 W MSP 40 E MQT ...CONT... 30 SE BOS 25
NE POU 35 WSW ABE 35 SSE MRB 35 NNW RIC 25 SE ORF.

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CORN BELT EWD ACROSS
THE GREAT LAKES...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL/SRN HIGH
PLAINS...

AMENDED FOR ADDED SLIGHT RISK IN SRN HIGH PLAINS

...SRN HIGH PLAINS...
ISOLD TSTMS HAVE DEVELOPED ALONG THE HIGHER TERRAIN ACROSS ERN NM
SWRN TX.  A FEW TSTMS WILL POSSIBLY MOVE OUT ONTO THE ADJACENT
PLAINS THROUGH THE EVENING.  VERTICAL SHEAR IS SUFFICIENT FOR
SUPERCELLS AND LARGE HAIL OR DAMAGING WINDS WILL BE POSSIBLE. 
REFERENCE SEVERE THUNDERSTORM WATCH #223.

REST OF DISCUSSION THE UNCHANGED FROM 20Z.

...LOWER GREAT LAKES REGION...
VSBL IMAGERY SHOWS CONVECTION ALONG LEADING EDGE OF MCS DEBRIS
ACROSS SWRN ONTARIO/NIAGARA AREA.  NARROW AXIS OF RAPIDLY
DESTABILIZING AIR MASS AHEAD OF THE CONVECTION MAY SUPPORT TSTMS
BETWEEN 21-03Z AS THEY MOVE TOWARD WRN NY.  THIS WILL BRING A RISK
OF HAIL AND DAMAGING WINDS LATER THIS AFTERNOON...BUT STORMS SHOULD
WEAKEN AS THEY HEAD EWD INTO CNTRL NY OWING TO MORE STABLE AIR MASS
IN PLACE.

...CNTRL GREAT LAKES/UPPER OH VLY/MIDWEST...
ELEVATED MIXED LAYER HAS EDGED NEWD AS EVIDENCED BY H85-H7 WARMING
ON THE DAVENPORT AND CENTRAL ILLINOIS SOUNDINGS.  THE H7 TEMPERATURE
AT CENTRAL ILLINOIS WAS AROUND 2 DEGREES C WARMER THAN THE ETA
SOLUTION.

LARGE SCALE ASCENT WAS INCREASING DOWNSTREAM FROM MIDLEVEL IMPULSE
MOVING TOWARD THE MID MS VLY AND ACCAS/ELEVATED CONVECTION HAS BEEN
PERSISTENT ACROSS IA INTO NWRN IL.  18Z RUC40 IS INSISTENT ON
CONVECTIVE INITIATION ACROSS SRN IA AND NRN IL BETWEEN 21-00 UTC. 
COMPLICATING FACTORS ARE THE WIDESPREAD CLOUDS ACROSS THE REGION AND
18Z SOUNDINGS SUGGEST CONVECTIVE TEMPERATURES IN THE UPPER 80S TO
MID 90S.  HOT PROD WAS NOSING NEWD TOWARD SCNTRL IA AND IT IS
CONCEIVABLE THAT SURFACE BASED TSTMS COULD INITIATE THERE IN A FEW
HOURS. OTHER MORE ELEVATED TSTMS SHOULD INCREASE DOWNSTREAM ACROSS
NRN IL.

VERTICAL SHEAR IS MORE THAN SUFFICIENT FOR SUPERCELLS...WHETHER
SURFACE BASED OR ELEVATED AND LARGE HAIL WILL BE LIKELY GIVEN VERY
UNSTABLE AIR MASS/STEEP MIDLEVEL LAPSE RATES IN PLACE. 
UNIDIRECTIONAL WLY FLOW REGIME WILL ENCOURAGE FORWARD PROPAGATING
ELEMENTS THAT COULD REACH AS FAR E AS THE UPPER OH VLY OVERNIGHT
WITH A RISK OF DAMAGING WINDS. HOWEVER...BACKBUILDING/TRAINING MCS
EVOLUTION IS ALSO POSSIBLE SINCE THE STRONGEST INSTABILITY RESERVOIR
WILL BE LOCATED UPSTREAM ACROSS THE MS VLY.

MEANWHILE...WILL MAINTAIN CONDITIONAL SLGT RISK/PROBABILITIES ACROSS
SRN WI INTO LOWER MI.  MUCH OF THE REGION IS EXPERIENCING SUBSIDENCE
BEHIND EARLY MORNING MCS...BUT A FEW TSTMS HAVE DEVELOPED ALONG COLD
FRONT MOVING SWD INTO NERN WI/NRN LOWER MI.  A FEW TSTMS CANNOT BE
RULED OUT THIS EVENING AS THE FRONT CONTINUES SWD WITH RISKS OF
HAIL/HIGH WINDS.  ALSO...NRN PERIPHERY OF PROBABLE MCS DEVELOPING
UPSTREAM OVER THE MID MS VLY MAY GRAZE SRN PORTIONS OF THE REGION
OVERNIGHT.

...CNTRL PLAINS...
SURFACE FLOW HAS TURNED UPSLOPE ACROSS THE FRONT RANGE/ERN CO WITH
DEW POINTS RISING INTO THE LOWER 50S.  USING A 74/50 PARCEL YIELDS
1300 J/KG SBCAPE AND WEAK CINH...AND UPSCALE DEVELOPMENT OF MOUNTAIN
CONVECTION SHOULD OCCUR THIS EVENING. ACTIVITY SHOULD THEN MIGRATE
ONTO THE HIGH PLAINS THIS EVENING.  VERTICAL SHEAR SUGGESTS STORMS
COULD ROTATE WITH LARGE HAIL...DAMAGING WINDS AND A TORNADO OR TWO.

AS LLJ INCREASES OVERNIGHT...ONE OR MORE MCS/S COULD EVOLVE AND
MOVE/DEVELOP NEWD INTO NEB/SD/IA/SRN MN OVERNIGHT.  SEVERE THREATS
SHOULD TRANSITION TO MAINLY ISOLD LARGE HAIL OUT ON THE PLAINS...SO
HAVE MAINTAINED A LOW PROBABILISTIC SEVERE THREATS.

.... 05/20/2004

...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.