[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 210541
SWODY1
SPC AC 210539

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1139 PM CST SAT NOV 20 2004

VALID 211200Z - 221200Z

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 WNW LAX 30 E EDW
30 SSE DRA 25 E P38 55 W 4HV 10 NNE U28 45 N GJT 15 E EGE 10 SSE ALS
45 SE SAF 60 E 4CR CVS 25 NNW PVW 15 NNE CDS 35 ENE SPS 25 ENE DUA
40 N TXK 35 WSW PBF 20 S UOX 20 NNE GAD 30 NW AHN 40 NNW AGS 45 SSW
AGS 50 SSE MCN 25 W MGR AQQ.

...NO SVR TSTM AREAS FORECAST...

CLOSED LOW WHICH HAS EVOLVED OVER THE GREAT BASIN IS BECOMING
INCREASINGLY DETACHED FROM STRONG BELT OF WESTERLIES NEAR THE
CANADIAN/U.S. BORDER.  MODELS SUGGEST AS VIGOROUS MID/UPPER JET
STREAK CONTINUES TO DIG TO THE WEST/SOUTHWEST OF THIS
FEATURE...CIRCULATION CENTER AND CORE OF COLDER AIR ALOFT WILL
DEVELOP SOUTHWARD INTO BASE OF BROAD SOUTHERN BRANCH TROUGH...ACROSS
SOUTHERN CALIFORNIA...EARLY TODAY. LATER TODAY...JET STREAK IS
PROGGED TO DEVELOP AROUND SOUTHERN/ SOUTHEASTERN PERIPHERY OF
LOW...PERHAPS IN PHASE WITH SPEED MAXIMUM EMBEDDED WITHIN
SUBTROPICAL JET...ACROSS THE NORTHERN MEXICAN PLATEAU. 

DOWNSTREAM...BROADLY ANTICYCLONIC MID/UPPER FLOW REGIME IS
DEVELOPING ACROSS THE SOUTHEASTERN STATES...AND WILL PERSIST THROUGH
THIS FORECAST PERIOD.

...SOUTHERN CALIFORNIA...
STRONG MID TROPOSPHERIC COOLING APPEARS LIKELY TO BE ONGOING EARLY
IN THE PERIOD...AND BY MID DAY...COLD CORE /500 MB TEMPS AOB -25C/
IS PROGGED ACROSS MUCH OF SOUTHERN CALIFORNIA. WEAK BUT MOIST
ONSHORE FLOW WILL CONTRIBUTE TO DESTABILIZATION...WHICH IS EXPECTED
TO BE SUFFICIENT FOR DEEP CONVECTIVE DEVELOPMENT... INCLUDING
SCATTERED THUNDERSTORMS.  ETA MODEL FORECAST SOUNDINGS INDICATE
FAVORABLE THERMODYNAMIC ENVIRONMENT FOR HAIL/GUSTY WINDS WHICH COULD
BRIEFLY APPROACH OR EXCEED SEVERE LIMITS AROUND THE SAN DIEGO AREA
THIS AFTERNOON.  STRONG AMBIENT VERTICAL VORTICITY WILL ALSO PROVIDE
SOME POTENTIAL FOR WATER SPOUTS NEAR COASTAL AREAS...AND AT LEAST
MINIMAL RISK OF AN ISOLATED TORNADO.

...SOUTHERN PLATEAU...
EXIT REGION OF CYCLONIC MID/UPPER JET IS PROGGED TO OVERSPREAD
NORTHERN AND CENTRAL ARIZONA DURING THE MID TO LATE AFTERNOON
HOURS...AND WILL CONTRIBUTE TO DESTABILIZATION/FORCING FOR
CONVECTIVE DEVELOPMENT.  ETA FORECAST SOUNDINGS SUGGEST INSTABILITY
IN FAVORABLY COOL AND SHEARED ENVIRONMENT MAY BECOME SUFFICIENT FOR
HAIL/GUSTY WINDS IN STRONGER STORMS...ONE OR TWO OF WHICH MAY
BRIEFLY EXCEED SEVERE LIMITS.

...TEXAS...
IN RESPONSE TO UPSTREAM CLOSED LOW...SOUTHEASTERLY LOW-LEVEL FLOW
WILL DEVELOP UP THE LOWER RIO GRANDE VALLEY...MOISTENING BOUNDARY
LAYER ACROSS THIS REGION.  AS MID-LEVEL WIND FIELDS BACK TO A MORE
SOUTHERLY DIRECTION...STEEPER LAPSE RATES WILL GENERALLY BECOME
CONFINED TO AREAS NEAR/WEST OF THE RIVER.  THIS SHOULD LIMIT OVERALL
SEVERE THREAT...BUT LOW/MID-LEVEL WARM ADVECTION ON EDGE OF CAPPED
ENVIRONMENT MAY SUPPORT SCATTERED STRONG STORMS DURING THE DAYTIME
HOURS.

AS UPPER FLOW REGIME BECOMES INCREASINGLY DIFLUENT AND DIVERGENT
LATE THIS AFTERNOON AND EVENING...CONVECTIVE DEVELOPMENT SHOULD
INCREASE NORTHWEST OF THE HILL COUNTRY AND THE DEL RIO AREA...INTO
THE TEXAS SOUTH PLAINS.  BY THE EVENING HOURS...TENDENCY WILL BE FOR
ACTIVITY TO BE UNDERCUT BY SOUTHWARD SURGING COLD FRONT.  THIS IS
EXPECTED TO FURTHER LIMIT SEVERE THREAT...BUT SOME HAIL MAY
ACCOMPANY MORE INTENSE CELLS...WITH STRONGER FORCING EVENTUALLY
SHIFTING EASTWARD INTO PARTS OF CENTRAL TEXAS OVERNIGHT.

..KERR/TAYLOR.. 11/21/2004

...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.