[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 170546
SWODY1
SPC AC 170541

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1241 AM CDT FRI SEP 17 2004

VALID 171200Z - 181200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM TRI 20
SW PSK LYH 65 ENE DAN RDU 35 S CLT 30 S SPA 40 NNW AND 25 SE TYS 35
NE TYS TRI.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 E INL 50 S DLH 30
E RST 10 W IRK 35 WNW SGF 10 W MKO 40 ENE DAL 55 NNE CLL 20 SSE BPT
...CONT... 10 W ELP 40 WNW CVS 40 NNE CAO 45 NNW GLD 50 NE ANW 15 NW
BKX 45 WNW AXN 65 W RRT.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 ENE CTB 30 W BTM
25 N BOI 25 SSE CEC.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 WSW PNS 25 NNE CEW
20 ENE MGM 35 NNW BHM 50 WSW BNA 35 SW SDF 25 SSE CAK 35 WSW GFL 15
ESE PWM.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 S IPL 35 ENE TRM
15 SW EED 30 SSE IGM 55 WSW SOW 30 NE SAD 35 SSW DMN.

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE SRN
APPALACHIANS INTO THE SOUTHERN MID ATLANTIC COAST STATES....

IVAN HAS MERGED INTO BELT OF SUBTROPICAL WESTERLIES ACROSS THE
SOUTHERN TIER STATES...AND STEADY SLOW WEAKENING SHOULD CONTINUE 
TODAY. MID-LEVEL CIRCULATION...EMBEDDED WITHIN LARGER SCALE SHORT
WAVE TROUGH...IS PROGGED TO GRADUALLY SHIFT EAST OF THE SOUTHERN
APPALACHIANS INTO THE SOUTH ATLANTIC COAST STATES.  THIS WILL OCCUR
MORE OR LESS IN TANDEM WITH EASTWARD PROGRESSION OF EASTERN
CANADIAN/ST. LAWRENCE VALLEY SHORT WAVE TROUGH...TOWARD THE CANADIAN
 MARITIMES/NORTHERN ATLANTIC COASTAL AREAS.  NORTHERN SYSTEM IS
EMBEDDED IN THE STRONGER POLAR WESTERLIES...WITHIN WHICH MODELS
INDICATE SUBSTANTIAL AMPLIFICATION WILL OCCUR UPSTREAM THROUGH THIS
FORECAST PERIOD.  BY 18/12Z...A LARGE DIGGING UPPER TROUGH IS
PROGGED ALONG THE NORTHERN/CENTRAL PACIFIC COAST...WITH A SHARPENING
RIDGE ALONG AN AXIS FROM THE LOWER U.S. PLAINS INTO THE CENTRAL
CANADIAN PROVINCES.

...SOUTHEASTERN STATES INTO NORTHERN MID ATLANTIC COASTAL AREAS...
UNCERTAINTIES EXIST WITH REGARD RATE OF DECAY OF TROPICAL
SYSTEM...AS WELL AS EXTENT OF CLOUD COVER AND ASSOCIATED
DESTABILIZATION OF MOIST BOUNDARY LAYER SOUTH OF FRONTAL ZONE
ASSOCIATED WITH NORTHERN SHORT WAVE TROUGH.  BY LATE
AFTERNOON...FRONTAL ZONE IS EXPECTED TO EXTEND FROM SOUTHEASTERN NEW
ENGLAND AND NORTHERN MID ATLANTIC COASTAL AREAS...ALONG THE
PENNSYLVANIA/MARYLAND BORDER INTO THE CENTRAL APPALACHIANS. 
ALONG/SOUTH OF THIS BOUNDARY...LOWER/MID 70S DEW POINTS WILL BE
COMMON...AND SHOULD CONTRIBUTE TO AT LEAST WEAK CONDITIONAL
INSTABILITY.

IN ADDITION TO CLOUD COVER...WEAK MID-LEVEL LAPSE RATES WILL LIMIT
CAPE.  HOWEVER...INSTABILITY AND STRONGER FORCING ALONG FRONTAL ZONE
FROM THE CENTRAL APPALACHIANS INTO THE NORTHERN MID ATLANTIC COAST
IS EXPECTED TO BE SUFFICIENT TO SUPPORT CONVECTIVE BAND. 
HOWEVER...PRIMARY SEVERE THREAT IS EXPECTED TO REMAIN CONFINED TO
AREAS SOUTH/EAST OF FRONTAL ZONE.  ETA PROBABLY WEAKENS REMAINS OF
IVAN TOO QUICKLY... AND PRESENCE OF DEEP SURFACE LOW/SIGNIFICANT
AMBIENT VERTICAL VORTICITY NEAR LOW/MID-LEVEL CIRCULATION WILL
CONTINUE TO SUPPORT RISK OF TORNADOES IN TROPICAL-TYPE BOUNDARY
LAYER.

BEST CHANCE FOR TORNADOES APPEARS TO BE IN IMMEDIATE LEE OF
APPALACHIANS...FROM WESTERN NORTH CAROLINA INTO SOUTHWEST VIRGINIA. 
HOWEVER...BETTER HEATING/SURFACE-BASED DESTABILIZATION IS EXPECTED
ACROSS THE COASTAL PLAINS OF NORTH CAROLINA INTO EASTERN VIRGINIA
AND THE DELMARVA BY AFTERNOON...WHERE FLOW/SHEAR WILL BE WEAKER.

...PLAINS...
WEAKENING SHORT WAVE TROUGH...EMBEDDED WITHIN INCREASINGLY
ANTICYCLONIC BROADER SCALE FLOW...MAY CONTINUE TO SUPPORT SCATTERED
THUNDERSTORM ACTIVITY FROM THE EASTERN DAKOTAS INTO MINNESOTA EARLY
TODAY. HOWEVER...MID-LEVEL WARMING/WEAK SUBSIDENCE LIKELY WILL
EVENTUALLY SUPPRESS CONVECTIVE DEVELOPMENT THROUGH MUCH OF THE
CENTRAL U.S. DURING THE DAYTIME HOURS.

EXCEPTION MAY BE NEAR WEAK THERMAL LOW/SURFACE TROUGH ACROSS THE
CENTRAL HIGH PLAINS.  STRONG HEATING TO CONVECTIVE TEMPERATURES MAY
OCCUR ALONG WESTERN FRINGE OF BETTER LOW-LEVEL MOIST TONGUE
EXTENDING NORTHWESTWARD FROM THE WESTERN GULF OF MEXICO.  AIDED BY 
WEAK LOW-LEVEL FORCING ASSOCIATED WITH ENHANCED CONVERGENCE/WARM
ADVECTION...WIDELY SCATTERED THUNDERSTORM ACTIVITY APPEARS POSSIBLE.
 SHEAR PROFILES WILL GENERALLY BE WEAK...BUT FAVORABLE THERMODYNAMIC
ENVIRONMENT WITH STEEP MID-LEVEL LAPSE RATES AND DEEP MIXED BOUNDARY
LAYER WILL BE SUPPORTIVE OF MARGINALLY SEVERE HAIL AND ISOLATED
DOWNBURSTS.

MODEL FORECAST SOUNDINGS SUGGEST SUBSTANTIAL INHIBITION THROUGH MUCH
OF THE PLAINS OVERNIGHT...BUT FORCING ON NOSE OF NOCTURNALLY
ENHANCED SOUTHERLY LOW-LEVEL JET MAY SUPPORT SCATTERED CONVECTION
ACROSS PARTS OF THE MID MISSOURI VALLEY BY DAYBREAK SATURDAY.

...NORTHWEST STATES...
SCATTERED...MOSTLY WEAK...THUNDERSTORM ACTIVITY APPEARS POSSIBLE...
PRIMARILY IN ASSOCIATION WITH STRONGER MID-LEVEL COOLING ASSOCIATED
WITH DIGGING TROUGH.  THIS FORCING WILL SHIFT ACROSS PACIFIC COASTAL
AREAS AND THE CASCADES BY LATE TODAY...THEN INTO THE NORTHERN
INTERMOUNTAIN REGION TONIGHT.

...SOUTHERN PLATEAU...
MOISTURE RETURN ON SOUTHERLY FLOW AHEAD OF AMPLIFYING PACIFIC COAST
TROUGH MAY ALSO SUPPORT SCATTERED THUNDERSTORM ACTIVITY ACROSS PARTS
OF THE LOWER COLORADO VALLEY BY THIS EVENING... CONTINUING INTO THE
OVERNIGHT HOURS.

..KERR/BANACOS.. 09/17/2004

...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.