000
AXPZ20 KNHC 080323
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE DEC 08 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 INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...05N77W TO 
06N105W TO 10N110W TO 10N125W TO 07N140W. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION IS WITHIN 45 NM OF THE POINT 
10N119.5W.

...DISCUSSION...

AN EXPANSIVE UPPER LEVEL RIDGE EXISTS ACROSS A LARGE PORTION OF 
THE DISCUSSION AREA EXTENDING FROM THE W CARIBBEAN INTO THE E 
PACIFIC BASIN TO NEAR 12N130W...ANCHORED BY AN UPPER ANTICYCLONE 
CENTERED NEAR 11N99W. DRY AND STABLE AIR EXISTS ON THE E SIDE OF 
THE ANTICYCLONE (E OF 99W) WITH STRONG SUBSIDENCE IN PLACE AS 
INDICATED BY WATER VAPOR SATELLITE IMAGERY. W OF THE RIDGE... 
MOISTURE IS BEING ADVECTED FROM THE ITCZ TO THE N AND NE AROUND 
THE ANTICYCLONE...WITH A BROAD AREA OF MID AND HIGH LAYERED 
CLOUDS IN PLACE...HOWEVER STRONG SOUTHWESTERLY WINDS ALOFT ARE 
LIMITING CONVECTIVE DEVELOPMENT AT THE SURFACE. 

N AND W OF THIS RIDGE...A LONGWAVE TROUGH IS POSITIONED FROM 
NORTHERN MEXICO TO 25N135W THEN SHARPLY CURVING DOWN TO 07N144W. 
A STRONG 90 TO 120 KT JET CORE IS IN PLACE ALONG E PORTIONS OF 
THE TROUGH AXIS FROM SOUTHERN TEXAS TO 23N115W TO 25N135W. NW OF 
THIS TROUGH AN UPPER LEVEL RIDGE EXTENDS FROM NEAR 30N137W TO 
41N140W. ONE UPPER LEVEL TROUGH IS RIDING DOWN THE FRONT SIDE OF 
THE RIDGE STRADDLING THE BORDER OF THE DISCUSSION AREA ALONG 
31/32N. A COLD FRONT ASSOCIATED WITH THIS UPPER LEVEL FEATURE IS 
BEING REFLECTED AT THE SURFACE EXTENDING FROM 30N119W TO 
25N125W. SW WINDS IN THE 20 TO 30 KT RANGE ARE OCCURRING AHEAD 
OF THE FRONT...WITH WINDS VEERING TO THE NW AT 20 TO 25 KT 
BEHIND IT. THIS FRONT IS ALSO PRODUCING 20 TO 30 KT SW 
WINDS IN THE N GULF OF CALIFORNIA N OF 29N. THE FRONT WILL 
CONTINUE TO MOVE TO THE E DURING THE NEXT 48 HOURS...REACHING 
FROM NEAR 31N115W TO 27N118W BY LATE TONIGHT...THEN MOVES WELL E 
OF THE AREA BY TUE AFTERNOON. A SURFACE RIDGE EXTENDING FROM 
23N117W TO 26N144W WILL PREVENT A MORE SOUTHEASTERLY TRACK OF 
THE FRONT. NW SWELL OF 8 TO 11 FT IS PROPAGATING INTO THE FAR N 
WATERS BEHIND THIS FRONT.

ANOTHER UPPER LEVEL TROUGH EXTENDS FROM 40N143W TO 36N140W TO 
24N154W...WITH A SURFACE COLD FRONT POSITIONED OUT AHEAD OF 
IT...JUST W OF THE DISCUSSION AREA. THE FRONT WILL CROSS INTO 
OUR AREA TO NEAR 30N139W TO 28N140W LATE TONIGHT WITH 20 TO 25 
KT SW WINDS OUT AHEAD OF IT. THE FRONT WILL CONTINUE TO THE E 
ONLY CLIPPING OUR FAR NORTHERN WATERS...WITH THE MAJORITY OF THE 
STRONGEST WINDS REMAINING N OF 32N. A LARGE AREA AND HIGH 
MAGNITUDE OF NW SWELL WILL ARRIVE BEHIND THE FRONT...WITH SEAS 
REACHING 20 FT IN THE FAR NW PORTION TUE THROUGH WED. THIS SWELL 
WILL THEN PROPAGATE THROUGH THE MAJORITY OF THE DISCUSSION AREA 
BY THE END OF THE WEEK...REACHING TO THE EQUATOR AND BEYOND.

S OF 20N...A 1010 MB LOW PRES SYSTEM IS EMBEDDED WITHIN THE 
ITCZ...POSITIONED NEAR 11N115W. WIDELY SCATTERED MODERATE 
CONVECTION IS OCCURRING WITHIN 120 NM OF THE LOW IN THE N 
QUADRANT...WITH ISOLATED MODERATE CONVECTION OCCURRING WITHIN 
150 NM OF THE REMAINDER OF THE LOW CENTER. THE CONVECTION HAS 
DECREASED DURING THE LAST SIX HOURS. THIS LOW IS MOVING INTO A 
REGION OF STRONG SOUTHWESTERLY UPPER WINDS WHICH WILL INHIBIT 
ANY FURTHER DEVELOPMENT OF THE LOW. TO THE W...A WEAK SURFACE 
TROUGH...THE REMNANTS OF A WEAK AREA OF LOW PRES...EXTENDS FROM 
11N129W TO 06N131W. ANY CONVECTION THAT WAS PREVIOUSLY OCCURRING 
IN ASSOCIATION WITH THIS FEATURE HAS DISSIPATED AS IT IS 
ENCOUNTERING STRONG SOUTHWESTERLY SHEAR ALOFT DUE TO THE 
APPROACHING UPPER TROUGH JUST W OF 140W.

IN ADDITION...MERGING SW AND NW SWELL IS RESULTING IN COMBINED 
SEAS OF UP TO 9 FT S OF 13N FROM 100W TO 120W. THESE SEAS WILL 
GRADUALLY DECAY TO BELOW 8 FT WITHIN THE NEXT 24 HOURS.

GAP WINDS...
GULF OF PAPAGAYO...EASTERLY TRADES IN THE W CARIBBEAN WILL 
CONTINUE TO CROSS OVER NICARAGUA AND COSTA RICA LEADING TO NE-E 
WINDS OF 20 KT IN THE GULF OF PAPAGAYO AND DOWNSTREAM TO 90W 
THROUGH LATE TONIGHT.

$$
LL