000
AXPZ20 KNHC 191536
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU NOV 19 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 
04N77W TO 07N87W TO 05N99W TO 07N109W TO 04N123W TO 08N140W. NO 
SIGNIFICANT CONVECTION NOTED. 

...DISCUSSION...

SHIP OBSERVATIONS AND SCATTEROMETER DATA CAPTURE A 1026 MB HIGH 
PRES AREA CENTERED NEAR 34N129W N OF THE DISCUSSION AREA. 
SCATTEROMETER ALSO SHOWED A BROAD AREA OF 20 TO 25 KT TRADE 
WINDS S OF THE HIGH PRES...MAINLY FROM 10N TO 25N W OF 120W. 
GENERALLY ZONAL FLOW ALOFT N OF 25N WILL BECOME MORE AMPLIFIED  
AS A MID TO UPPER LEVEL TROUGH PUSHES EASTWARD INTO THE 
CALIFORNIA COAST THROUGH FRIDAY...ALLOWING AN ASSOCIATED COLD 
FRONT OVER THE NE PACIFIC TO PUSH SOUTHEAST. THE SURFACE HIGH 
PRES WILL WEAKEN AND SHIFT SOUTH TODAY AHEAD OF THE ADVANCING 
COLD FRONT. THE TRADE WIND FLOW WILL RELAX A LITTLE AS THE HIGH 
WEAKENS. THE COLD FRONT WILL REACH A POSITION FROM 30N125W TO 
25N140W BY LATE FRI...BUT WILL BE PRACTICALLY WASHED BY THAT 
TIME WITH ONLY A MODEST INCREASE IN NE WINDS BEHIND THE FRONT. 
MORE SUBSTANTIALLY...THE FRONT WILL HERALD THE ARRIVAL OF 
ANOTHER ROUND OF 11 TO 13S NW SWELL WITH HEIGHTS TO 10 FT 
PUSHING INTO THE AREA W OF 120W THIS WEEKEND. THIS IS IN 
ADDITION TO THE 8 TO 12 FT NW SWELL ALREADY IN PLACE N OF 10N W 
OF 120W AS DEPICTED TO AN EXTENT BY AN OVERNIGHT JASON ALTIMETER 
PASS.

FURTHER SOUTH...DESPITE PERSISTENT TRADE WIND CONVERGENCE INTO 
THE ITCZ...THE LACK OF SUBSTANTIAL UPPER SUPPORT GIVEN THE 
NEARLY ZONAL PATTERN ALOFT IS LIMITING CONVECTIVE DEVELOPMENT 
ALONG THE ITCZ W OF 120W. SUBSIDENT NORTHERLY FLOW ALOFT ON THE 
EAST SIDE OF AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 11N117W 
IS SUPPRESSING ALONG THE ITCZ FROM 110W TO 120W. HOWEVER...WEAK 
UPPER TROUGHING EAST OF THE UPPER ANTICYCLONE IS AIDING MODEST 
CONVECTION BETWEEN 105W AND 110W. A VERY DRY AIRMASS E OF 110W 
IS PROHIBITING ANY CONVECTIVE GROWTH.

STRONG GAP WIND FLOW CONTINUES THROUGH THE GULF OF TEHUANTEPEC 
THIS MORNING...WITH WINDS LIKELY STILL IN THE 25 TO 30 KT RANGE 
NEAR THE COAST. THIS WILL DIMINISH THROUGH TODAY TO LESS THAN 20 
KT BY EARLY FRI. MORNING DRAINAGE FLOW ALONG THE CENTRAL 
AMERICAN COAST IS RESULTING IN A BROAD PLUME OF 20 TO 25 KT FLOW 
THROUGH THE GULF OF PAPAGAYO...AND A SMALLER AREA OF 20 KT FLOW 
IN THE GULF OF FONSECA.

$$
CHRISTENSEN