000 AXPZ20 KNHC 110332 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN OCT 11 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...SPECIAL FEATURE... AN AREA OF LOW PRES LOCATED OVER THE FAR ERN PORTION...ABOUT 370 NM SW OF MANZANILLO MEXICO...HAS SHOWN SOME ORGANIZATION IN ITS OVERALL APPEARANCE DURING THE PAST 24 HOURS WITH THE ACTUAL LOW PRES CENTER OF 1006 MB NEAR 15N108W. LAST AVAILABLE VISIBLE SATELLITE IMAGERY SHOWED THAT CLOUD PATTERN HAS BECOME MORE SYMMETRICAL WITH A BANDING FEATURE BECOMING MORE SOLIDIFIED W OF THE CENTER. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 150 NM NW OF THE CENTER...AND IN BAND WITHIN 60 NM OF 21N106W TO 19N110W AND WITHIN 30 NM OF 12N103W TO 15N105W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ELSEWHERE WITHIN 180 NM OF THE CENTER IN THE SW QUADRANT. 20-25 KT WINDS ARE WITHIN 180 NM OF THE LOW...EXCEPT FROM 150 NM TO 300 NM IN THE NE QUADRANT WITH SEAS TO 9 FT. ADDITIONAL BANDING FEATURES MAY FORM TO THE E AND SE OF THE LOW PRES CENTER OVERNIGHT INTO SUN MORNING. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE OVER THE NEXT 48 HOURS AS IT TRACKS NW TO N. ...TROPICAL WAVE... A TROPICAL WAVE WAS ALONG 92W N OF 6N MOVING W 15 KT. THE WAVE IS MOVING W IN TANDEM WITH AN UPPER LEVEL LOW LOCATED TO ITS W NEAR 14N94W. THIS SET-UP CONTINUES TO AID IN THE DEVELOPMENT OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ALONG THE WAVE WITHIN 30 NM OF 12N. CONVECTION EARLIER WAS MORE SCATTERED ALONG THE WAVE...BUT HAS RECENTLY DIMINISHED IN COVERAGE. EXPECT CONVECTION TO DEVELOP AGAIN OVERNIGHT. ...ITCZ... THE ITCZ AXIS WAS CENTERED ALONG 9N78W TO 11N86W TO 10N97W TO 12N105W TO 10N114W TO 13N127W TO 10N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS WITHIN 120 NM N OF THE AXIS BETWEEN 100W-104W ...AND WITHIN 60 NM S OF THE AXIS BETWEEN 107W-110W. SCATTERED MODERATE CONVECTION WAS WITHIN 120 NM N OF THE AXIS BETWEEN 112W-115W. ...DISCUSSION... A MID/UPPER LEVEL TROUGH STRETCHES INTO THE AREA FROM SRN CALIFORNIA THROUGH 32N120W AND S TO 26N120W AND SW TO 20N122W. TO THE SW OF THE TROUGH IS A MID/UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 17N129W...WITH A RIDGE EXTENDING E FROM THE ANTICYCLONE TO 17N116W...AND NE TO ACROSS THE LOW PRES AREA CENTERED DESCRIBED ABOVE AND NE TO A SMALL MID/UPPER LEVEL ANTICYCLONE OVER MEXICO NEAR 22N101W. A JET STREAM BRANCH RIDING ACROSS THE TOP OF THE RIDGE AS SEEN IN WATER VAPOR IMAGERY WILL CONTINUE TO ADVECT UPPER LEVEL MOISTURE IN THE FORM OF SCATTERED THIN CIRRUS ACROSS EWD ACROSS CENTRAL AND SRN BAJA CALIFORNIA AND TOWARDS FAR NW MEXICO. A SHARP AND VIGOROUS NEGATIVELY TILTED UPPER LEVEL TROUGH JUST NW OF THE AREA ALONG 143W TO 32N WAS SWEEPING EAST AT ABOUT 20 TO 25 KT. MODERATE SUBSIDENCE LEADING TO RATHER STABLE ENVIRONMENTAL CONDITIONS WAS PRESENT OVER THE AREA ALONG AND W OF THE FIRST TROUGH TO 128W. OVER THE FAR ERN PORTION OF THE AREA...A MID/UPPER LEVEL CYCLONIC CIRCULATION MOVING W 15 KT WAS NEAR 14N94W. THIS LOW WAS RESULTING IN SCATTERED STRONG CONVECTION OVER THE GULF OF TEHUANTEPEC IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG 92W. WEAKENING SURFACE HIGH PRES COVERS THE AREA N OF 22N W OF 125W. THE PRES GRADIENT E OF THE RIDGE IS TIGHT ENOUGH TO ALLOW FOR NW WINDS OF 20 KT FOR N OF 26N E OF 117W TO THE COAST OF BAJA CALIFORNIA. THESE WINDS ARE FORECAST TO DIMINISH IN JUST A LITTLE OVER THE NEXT 24 HOURS. OVER THE SRN PORTION...A TROUGH EXTENDS FROM 11N134W TO 17N131W MOVING W 10 KT. TO THE N OF THE TROUGH...NE TO E TRADES OF 20 TO 25 KT WITH SEAS TO 9 FT WERE NOTED FROM 12N TO 19N W OF 123W. THESE CONDITIONS ARE FORECAST TO DIMINISH BY 24 HOURS. A COLD FRONT IS FORECAST TO MOVE INTO THE FAR NW CORNER OF THE AREA IN ABOUT 12 HOURS. THE FRONT WILL THEN MOVE TO ALONG A LINE FROM 30N136W TO 27N140W IN 24 HOURS...AND TO 30N129W TO 23N140W IN 48 HOURS. SW WINDS TO 20 KT ARE EXPECTED AHEAD OF THE FRONT WITH SEAS TO 8 FT. NW TO N WINDS OF 20 KT ARE EXPECTED BEHIND THE FRONT WITH SEAS BUILDING 8 TO 10 FT IN LONG PERIOD NW SWELL. A STRONGER RE-ENFORCING COLD FRONT WILL MOVE IN BEHIND THIS FRONT REACHING FROM 30N135W TO 27N140W IN 48 HOURS. THIS FRONT WILL BE ASSOCIATED WITH A RATHER INTENSE LOW PRES SYSTEM N OF THE AREA...AND MODELS ARE SUGGESTING THAT IT COULD BE FOLLOWED BY STRONGER WINDS...IN THE RANGE OF 20-25 KT OR POSSIBLY UP TO 30 KT FROM W AND NW. WILL EVALUATE FUTURE MODEL GUIDANCE TO UPDATE ...IF NECESSARY...FORECAST WIND AND SEA CONDITIONS WITH COLD FRONT. $$ AGUIRRE