000
AXPZ20 KNHC 060309
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE OCT 06 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 
0300 UTC.

...ITCZ...

THE ITCZ AXIS IS ALONG 06N77W TO 07N95W TO 11N109W 08N125W TO 
14N138W. SCATTERED MODERATE ISOLATED STRONG IS FROM 07N TO 09N 
BETWEEN 85W AND 95W. SIMILAR CONVECTION IS SEEN FROM 09N TO 11N 
BETWEEN 109 AND 114W.

...DISCUSSION...

AT THE SURFACE...A 1031 MB HIGH IS OVER THE NE PACIFIC NEAR 
46N142W...WITH RIDGE AXIS EXTENDING SE TO NEAR 18N11OW. THIS 
SYSTEM IS PRODUCING FRESH NW FLOW OFFSHORE THE BAJA CALIFORNIA 
PENINSULA. ANOTHER RIDGE IS EXPECTED TO BUILD OVER THE SW 
CONUS...LIKELY ALLOWING THE FRESH NORTHERLY FLOW CURRENTLY OVER 
THE NORTHERN GULF OF CALIFORNIA TO PERSIST THIS TUE BEFORE 
DIMINISHING. LATEST VISIBLE SATELLITE PICTURES SHOWED A COUPLE 
OF LOW PRES CENTERS EMBEDDED WITHIN THE ITCZ. THE EASTERN ONE IS 
NEAR 11N111W. AN EARLIER ASCAT PASS REVEALED THE CYCLONIC 
CIRCULATION ASSOCIATED WITH THIS LOW AND SE WINDS TO 20 KT 
WITHIN 120 NM SE QUADRANT. IN ADDITION...A PAIR OF CLUSTERS WITH 
SCATTERED TO ISOLATED STRONG CONVECTION ARE NOTED EITHER SIDE OF 
THE LOW CENTER. THE SECOND LOW PRES CONTINUES TO DRIFT WWD AND 
IS NOW NEAR 15N140W. AN EARLIER QUIKSCAT PASS INDICATED 
PERSISTENT 20 TO 25 KT TRADE WINDS BETWEEN THE LOW AND THE RIDGE 
TO THE NORTH...MAINLY FROM 14N TO 20N W OF 135W. A SWIRL OF 
MAINLY LOW CLOUDS WITH ISOLATED SHOWERS IS ASSOCIATED WITH THIS 
FEATURE THAT WILL CONTINUE TO MOVE WWD AND AWAY FROM THE 
DISCUSSION AREA.

ALOFT...A BROAD ANTICYCLONIC CIRCULATION CENTERED OVER WEST- 
CENTRAL MEXICO DOMINATES MUCH OF THE FORECAST AREA WITH THE 
RIDGE AXIS EXTENDING THROUGH 13N132W. THIS RIDGE IS EXPECTED TO 
SHIFT EAST AND WEAKEN AHEAD OF A MID TO UPPER LEVEL TROUGH 
EXTENDING FROM NORTHERN CALIFORNIA TO 30N130W TO 17N135W. 
SATELLITE IMAGERY SHOWS EVIDENCE OF A WEAK SURFACE TROUGH 
ASSOCIATED WITH THE MID TO UPPER LEVEL TROUGH...EXTENDING FROM 
29N129W TO 26N133W. AN ASCAT PASS ALSO SHOWED NE WINDS TO 20 KT 
MAINLY W OF THE TROUGH. A JET-STREAM BRANCH WITH CORE WINDS OF 
110-130 KT OVER THE SW U.S. IS NOTED BETWEEN THE ABOVE MENTIONED 
UPPER-LEVEL FEATURES. THE RIDGE IS HELPING TO INDUCE CONVECTION 
ALONG THE ITCZ. 

REGIONAL SEAS ARE IN THE 8 TO 10 FT RANGE W OF 115W IN MIXED N 
TO NE AND SE SWELL...WITH AN AREA OF FRESH TO STRONG SE WINDS S 
OF 10N AND W OF 130W. AN ASCAT PASS FROM AROUND 1900 UTC 
CONFIRMED THESE WIND SPEEDS. WAVEWATCH AND FNMOC WAVE MODELS 
BOTH SHOW THESE AREAS OF SWELL DECAYING BELOW 8 FT OVER THE NEXT 
COUPLE OF DAYS BEFORE THE TRADES INCREASE AGAIN IN THE WAKE OF A 
TROUGH PASSAGE.

$$
GR/EC