[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 201231
SWODY1
SPC AC 201228

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0728 AM CDT FRI AUG 20 2004

VALID 201300Z - 211200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 10 S
P07 10 NE FST 35 NW INK 40 NNW HOB 35 W LBB ABI AUS 45 SE HDO 40 SSE
DRT.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM GFL
LEB CON ORH 30 SSE POU ABE CXY MGW LEX BWG 50 NNW EVV 10 S LAF 40 N
CLE 15 NE JHW ITH GFL.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 80 ENE HVR 75 NNE BIL
25 WNW GCC 25 NNW CDR 35 E AIA IML 55 S GLD 30 S EHA 40 W CSM 15 SW
OKC 25 SW BVO 25 NNW JLN 45 S UIN 40 N LAF 15 SE DTW ...CONT... 55 W
3B1 10 ESE BHB ...CONT... 30 SW PSX 35 NW LRD ...CONT... 40 WSW MRF
30 N MRF 45 ESE GDP 15 N GDP 45 ENE ELP 10 ENE DMN 30 S SAD 50 SSE
IGM 45 NW NID 30 N FAT 40 WNW TVL 30 SSW LMT 35 NNE MFR 35 W RDM 55
WSW PDT 25 E EPH 45 NNW 4OM.

...THERE IS A SLGT RISK OF SVR TSTMS TODAY AND EARLY TONIGHT FROM
PARTS OF THE OHIO VALLEY INTO NEW ENGLAND....

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING
ACROSS PARTS OF WESTERN AND SOUTHERN TEXAS....

A BLOCK PERSISTS IN THE LARGE-SCALE UPPER PATTERN OVER THE NORTHEAST
PACIFIC/ALASKA.  SPLIT BELTS OF STRONGER FLOW AROUND THIS FEATURE
MERGE DOWNSTREAM ACROSS THE CANADIAN ROCKIES...THEN CONTINUE
EASTWARD IN BROADLY CYCLONIC FASHION ACROSS THE
NORTHERN/CENTRAL U.S...TO THE SOUTH OF DEEP CLOSED LOW NEAR HUDSON
BAY. MEANWHILE...BELT OF WEAK SUBTROPICAL WESTERLIES REMAINS
SUPPRESSED RELATIVELY FAR TO THE SOUTH...ACROSS THE SOUTHERN TIER
STATES...DOWNSTREAM OF BROAD TROUGH OFF THE SOUTHERN CALIFORNIA/BAJA
COAST.

...OHIO VALLEY/LOWER GREAT LAKES REGION...
STRONG SPEED MAXIMUM EMBEDDED WITHIN NORTHERN BRANCH IS EVIDENT IN
LATEST WATER VAPOR IMAGERY OVER SOUTHERN ONTARIO AND THE UPPER GREAT
LAKES REGION.  MODELS SUGGEST THIS FEATURE WILL CONTINUE DEVELOPING
AROUND SOUTHERN INTO EASTERN PERIPHERY OF CLOSED LOW TODAY.  THIS
WILL OCCUR AS WEAKER UPSTREAM SHORT WAVE TROUGH/JET STREAK DIG FROM
THE NORTH DAKOTA/CANADIAN BORDER INTO THE GREAT LAKES REGION.

JUST AHEAD OF SECONDARY IMPULSE...A SOUTHERN BRANCH SHORT WAVE
TROUGH IS PROGGED TO ACCELERATE NORTHEASTWARD OUT OF THE MIDDLE
MISSISSIPPI VALLEY...INTO THE ST. LAWRENCE VALLEY BY LATE TONIGHT. 
DIVERGENT UPPER FLOW AHEAD OF THIS SYSTEM...ENHANCED BY FORCING IN
ENTRANCE REGION OF DOWNSTREAM NORTHERN BRANCH JET STREAK...IS
CONTRIBUTING TO UPWARD VERTICAL MOTION FIELD NOW GRADUALLY SPREADING
INTO THE LOWER OHIO VALLEY.  THIS IS JUST DOWNSTREAM OF DEVELOPING
SURFACE LOW...WHICH BOTH ETA/GFS FORECAST TO DEEPEN SIGNIFICANTLY AS
IT MIGRATES ALONG WEAK SURFACE FRONT EXTENDING NORTH OF THE OHIO
RIVER INTO NEW ENGLAND.

SOME DISPARITY EXISTS AMONG THE MODEL RUNS WITH REGARD TO TIMING OF
MORE RAPID SURFACE DEVELOPMENT...BUT STRENGTHENING OF LOW-LEVEL WIND
FIELDS APPEARS LIKELY IN WARM SECTOR OF CYCLONE BY THE AFTERNOON
HOURS...AS IT TRACKS FROM SOUTHERN INDIANA THROUGH SOUTHERN/EASTERN
OHIO.  MODELS INDICATE SOUTH SOUTHWESTERLY LOW-LEVEL JET ON THE
ORDER OF 40 KT...BENEATH MODERATELY STRONG MID/UPPER FLOW...AND
VEERING WIND FIELDS WITH HEIGHT IN MOIST AND INCREASINGLY BUOYANT
BOUNDARY LAYER WITH UPPER 60S/NEAR 70F DEW POINTS.  DESPITE
CONSIDERABLE CLOUD COVER...SURFACE HEATING IS EXPECTED TO RESULT IN
SUFFICIENT INSTABILITY TO SUPPORT RISK FOR VIGOROUS CONVECTIVE
DEVELOPMENT...PARTICULARLY BY MID/LATE AFTERNOON.  IF THIS
OCCURS...ACTIVITY WILL LIKELY BE ACCOMPANIED BY A FEW DAMAGING WIND
GUSTS...WITH ISOLATED SUPERCELLS/TORNADOES ALSO POSSIBLE.

THREAT MAY CONTINUE INTO PARTS OF WESTERN PENNSYLVANIA BY EARLY
EVENING...BEFORE DIMINISHING AS LOW PROGRESSES INTO MORE STABLE/
STABILIZING ENVIRONMENT EAST OF THE LOWER GREAT LAKES REGION.

...NORTHERN MID ATLANTIC COAST STATES INTO NEW ENGLAND...
MODELS SUGGEST BETTER POTENTIAL FOR STRONGER SURFACE HEATING ALONG
STALLED FRONT ACROSS PENNSYLVANIA INTO SOUTHERN NEW ENGLAND.  BY MID
TO LATE AFTERNOON...MEAN MIXED LAYER CAPE OF 1000 TO 2000 J/KG WILL
BE SUPPORTIVE OF VIGOROUS UPDRAFTS.  SOME OF THESE MAY INTENSIFY
INTO SEVERE STORMS WITH POTENTIAL FOR DAMAGING WIND GUSTS/POSSIBLY
HAIL....AIDED BY FAVORABLE SHEAR PROFILES ON SOUTHERN FRINGE OF
STRONG SOUTHWESTERLY MID/UPPER JET.

...TEXAS...
TO THE SOUTH OF RAIN-COOLED BOUNDARY LAYER ASSOCIATED WITH ONGOING
CONVECTIVE ACTIVITY...SOUTHERLY/EASTERLY LOW-LEVEL FLOW ACROSS THE
LOWER RIO GRANDE VALLEY...AND PARTS OF THE HILL COUNTRY/PECOS
VALLEY...WILL MAINTAIN MOIST AND POTENTIALLY MODERATELY UNSTABLE 
ENVIRONMENT.  AIDED BY THE APPROACH OF A HIGH-LEVEL SHORT WAVE
TROUGH EMBEDDED WITHIN THE SUBTROPICAL WESTERLIES...SCATTERED STRONG
THUNDERSTORMS ARE EXPECTED BY THE PEAK AFTERNOON HEATING HOURS. 
DESPITE RATHER WEAK WIND FIELDS...PRONOUNCED VEERING WITH HEIGHT
BENEATH NORTHWESTERLY MID-LEVEL REGIME MAY CREATE SHEAR PROFILES
MARGINALLY SUFFICIENT FOR SUPERCELLS.  PRIMARY THREAT APPEARS TO BE
LARGE HAIL...BUT THERMODYNAMIC PROFILES WITH DEEP MIXED BOUNDARY
LAYER NEAR THE RIO GRANDE RIVER WILL BE FAVORABLE FOR DAMAGING
DOWNBURSTS.

...GREAT BASIN...
SIGNIFICANT CENTER OF CYCLONIC VORTICITY ASSOCIATED WITH A SOUTHERN
BRANCH SHORT WAVE TROUGH IS READILY EVIDENT IN LATEST WATER VAPOR
IMAGERY OVER SOUTHEAST OREGON. AS IT PROGRESSES EASTWARD
TODAY...THIS FEATURE MAY ENHANCE CONVECTIVE DEVELOPMENT ACROSS THE
NORTHERN GREAT BASIN...WHERE VERY WARM/DEEP MIXED BOUNDARY LAYER
LIKELY WILL PROVE FAVORABLE FOR A FEW DOWNBURSTS.

..KERR/GUYER.. 08/20/2004

...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.