[SWODY2] SWODY2

[SWODY2 at goshenarc.org]

ACUS02 KWNS 211643
SWODY2
SPC AC 211641

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1141 AM CDT SAT AUG 21 2004

VALID 221200Z - 231200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 45 SW
ALO 15 S FOD 20 S FRM 15 NE MKT 40 NW EAU 30 WNW RHI 40 SW IMT 25 NW
OSH 25 W DBQ 45 SW ALO.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 45 SE OSC 10 S CGX 20
WNW UIN 45 SSE SZL 30 SSE UNO 45 W CSV 45 NE HKY 25 ESE ECG
...CONT... 65 NNW DVL 10 N JMS 65 NE ABR 35 E AXN 35 ENE ELO
...CONT... 40 SE ELP 35 WSW 4CR GNT U17 50 N BCE 10 W MLF 60 E TPH
30 SSW U31 40 NW U31 10 NE WMC 85 SSE BNO 45 S RDM 35 ENE SLE 10 N
BLI.

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE WRN GREAT
LAKES/UPPER MIDWEST...

...UPPER GREAT LAKES SWWD INTO IA/NEB...
SHORTWAVE TROUGH CURRENTLY OVER SRN ALBERTA/SASKATCHEWAN IS FORECAST
TO MOVE FROM SWRN ONTARIO/NRN MN EWD ACROSS THE NRN GREAT LAKES
SUNDAY AND INTO QUEBEC SUNDAY NIGHT. ASSOCIATED SURFACE LOW WILL
DEVELOP NEWD FROM VICINITY OF THE MN ARROWHEAD INTO ERN ONTARIO BY
EARLY EVENING WITH TRAILING COLD FRONT PUSHING SEWD ACROSS THE UPPER
MS VALLEY/WRN GREAT LAKES.

CLUSTERS OF STORMS WILL LIKELY BE ONGOING INITIALLY ALONG FRONT FROM
LS SWWD INTO SRN MN. LATEST MODEL GUIDANCE SUGGESTS THAT PERSISTENT
CLOUDINESS/PRECIPITATION WILL TEND TO LIMIT DESTABILIZATION AND
OVERALL SEVERE WEATHER THREAT ACROSS THE NRN GREAT LAKES/UP OF MI.
FARTHER SW...DEWPOINTS IN THE 60S BENEATH PLUME OF MODESTLY STEEP
/7-7.5 C/KM/ LAPSE RATES WILL CONTRIBUTE TO INCREASING INSTABILITY
WITH SWWD EXTENT. EXPECT AFTERNOON MLCAPES TO RANGE FROM AROUND 1000
J/KG OVER CNTRL WI...TO 1500-2000 J/KG FROM CNTRL IA INTO ERN NEB.

SUSTAINED CONVERGENCE AND A WARMING BOUNDARY-LAYER SHOULD SUPPORT
THE SWWD DEVELOPMENT OF TSTMS ALONG FRONT DURING THE AFTERNOON FROM
PARTS OF NERN/CNTRL WI INTO PORTIONS OF NEB/IA. THOUGH STRONGEST
WIND FIELDS ARE EXPECTED TO PERSIST TO N OF STRONGER
INSTABILITY...IT APPEARS THAT A MODEST SHEAR/INSTABILITY COMBINATION
WILL DEVELOP FROM CNTRL WI INTO SERN MN/NERN IA. HERE...A FEW SEVERE
STORMS WILL BE POSSIBLE WITH THE POTENTIAL FOR LARGE HAIL AND
DAMAGING WINDS.

...NRN HIGH PLAINS...
VIGOROUS SHORTWAVE TROUGH /EVIDENT IN WATER VAPOR IMAGERY OFF THE
B.C./WA COASTS/ WILL AMPLIFY AND BECOME PROGRESSIVELY
NEGATIVELY-TILTED ACROSS THE NRN ROCKIES DURING THE LATTER HALF OF
THE FORECAST PERIOD. IN RESPONSE...A SURFACE LOW WILL DEEPEN OVER
CNTRL MT WITH ATTENDANT COLD FRONT SHARPENING ACROSS THE NRN
ROCKIES. WRN EXTENSION OF FRONTAL ZONE ASSOCIATED WITH GREAT LAKES
SYSTEM WILL LIKELY STALL BEFORE RETREATING NWD AS A WARM FRONT OVER
THE NRN HIGH PLAINS SUNDAY AFTERNOON/NIGHT.

THOUGH LOW-LEVEL MOISTURE WILL REMAIN LIMITED...STEEP LOW TO
MID-LEVEL LAPSE RATES ARE EXPECTED TO CONTRIBUTE TO A WEAKLY
UNSTABLE AIRMASS ACROSS CNTRL/ERN MT WITH AFTERNOON MLCAPES
INCREASING TO AROUND 500-700 J/KG. STRONG UPWARD VERTICAL MOTION
AHEAD OF DEEPENING SURFACE/MID-LEVEL SYSTEMS IN CONJUNCTION WITH THE
STEEP LAPSE RATES WILL ALLOW FOR SCATTERED TSTM DEVELOPMENT ALONG
HIGHER TERRAIN BY AFTERNOON. ACTIVITY WILL THEN SPREAD EWD/NEWD
ACROSS CNTRL/ERN MT DURING THE AFTERNOON AND INTO THE WRN DAKOTAS
OVERNIGHT.

GIVEN THE STEEP LAPSE RATES AND MODERATELY STRONG ENVIRONMENTAL
SHEAR /I.E. 0-6KM BULK SHEAR OF 45-55KTS/...POTENTIAL WILL EXIST FOR
ISOLATED SEVERE STORMS CAPABLE OF LARGE HAIL/DAMAGING WINDS.  THE
FORECAST WEAK INSTABILITY PRECLUDES A CATEGORICAL RISK ATTM.
HOWEVER...IF IT BECOMES APPARENT THAT AIRMASS WILL BECOME MORE
UNSTABLE THAN IS CURRENTLY EXPECTED...A SLIGHT RISK MAY BE REQUIRED
ON UPCOMING DAY 1 OUTLOOKS.

...CNTRL/SRN PLAINS...
COMBINATION OF DEWPOINTS IN THE 60S AND RATHER STEEP MID-LEVEL LAPSE
RATES OF 7-8 C/KM ARE EXPECTED TO CONTRIBUTE TO MODERATE TO STRONG
INSTABILITY ON SUNDAY AFTERNOON WITH MLCAPES INCREASING TO 2000-3000
J/KG. LATEST SHORT RANGE MODELS ARE ALL FAIRLY CONSISTENT IN
DEVELOPING DEEP CONVECTION ALONG LEE TROUGH OVER PORTIONS OF
SWRN/S-CNTRL KS INTO ERN TX PNHDL/NWRN TX AND WRN OK. THOUGH
VERTICAL WIND SHEAR WILL REMAIN RATHER WEAK /AOB 20-25KTS/ THE
DEGREE OF INSTABILITY WILL SUPPORT A FEW STRONG STORMS CAPABLE OF
ISOLATED DAMAGING WINDS AND/OR LARGE HAIL.

..MEAD.. 08/21/2004

...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.