000
AXPZ20 KNHC 171603
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE NOV 17 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG A LINE FROM 
08N78W TO 05N90W TO 07N100W TO 06N110W TO 10N130W TO 08N140W. 
SCATTERED MODERATE CONVECTION WITHIN 90 NM N OF AXIS BETWEEN 
100W AND 105W. SCATTERED MODERATE CONVECTION WITHIN 120 NM 
EITHER SIDE OF AXIS W OF 125W.

...DISCUSSION...

E OF 115W...GALE FORCE WINDS ARE SETTING UP IN THE GULF OF 
TEHUANTEPEC AS A COLD FRONT PUSHES THROUGH THE SW GULF OF MEXICO 
AND THROUGH THE TEHUANTEPEC ISTHMUS. THE GALE CONDITIONS ARE 
EXPECTED TO PERSIST THROUGH TONIGHT...THEN GRADUALLY DIMINISH 
INTO THU AS HIGH PRES SHIFTS E ACROSS THE GULF OF MEXICO. 
FURTHER SOUTH...GRADIENT FLOW ALONG WITH DRAINAGE EFFECTS WILL 
ALLOW WINDS TO REACH 20 TO 25 KT THROUGH THE GULF OF PAPAGAYO BY 
LATE TODAY. FURTHER NORTH...A 05Z ASCAT PASS SHOWED 20 TO 25 KT 
NW WINDS DOWN THE LENGTH OF THE GULF OF CALIFORNIA. THIS WILL 
DIMINISH THIS MORNING AS HIGH PRES OVER THE GREAT BASIN WEAKENS. 
THE MODEST AREA OF CONVECTION ALONG THE ITCZ BETWEEN 100W AND 
105W IS LIKELY DUE TO WEAK DIVERGENCE ALOFT ON THE NORTHERN END 
OF AN UPPER ANTICYCLONE REACHING OVER THE AREA FROM THE SOUTHERN 
HEMISPHERE. THIS CONVECTION WILL LIKELY PERSIST TO SOME DEGREE 
AS LOW LEVEL CONVERGENCE INCREASES DUE NE WINDS OUT OF THE 
TEHUANTEPEC AREA OVER THE NEXT DAY OR SO.

W OF 115W...1022 MB HIGH SURFACE HIGH PRES IS CENTERED NEAR 
29N132W. AN ASCAT PASS FROM AROUND 07Z THIS MORNING SHOWED FRESH 
TRADE WIND FLOW S OF THE HIGH PRES IN A BROAD AREA GENERALLY 
FROM 08N TO 22N W OF 125W. THE HIGH PRES WILL DISSIPATE TODAY 
AHEAD OF A COLD FRONT THAT IS PUSHING INTO THE AREA. THE FRONT 
WILL EXTEND FROM 30N125W TO 23N140W BY WED MORNING...THEN STALL 
AND DISSIPATE FROM 29N115W TO 20N120W BY THU MORNING. THE MAIN 
WILL BE LONG PERIOD NW SWELL WITH HEIGHTS TO 15 FT FOLLOWING THE 
FRONT. THIS WILL DECAY AS IT PUSHES SE OVER THE NEXT COUPLE OF 
DAYS. THE TRADES WILL PERSIST AS HIGH PRES BUILDS BEHIND THE 
ONCOMING FRONT. MODEST CONVECTION IS NOTED ALONG THE ITCZ W OF 
125W MAINLY DUE TO THE TRADE WIND CONVERGENCE AND DIVERGENT FLOW 
ALOFT ON THE SE SIDE OF AN UPPER TROUGH DIGGING NE OF HAWAII.

$$
CHRISTENSEN