000
AXPZ20 KNHC 011539
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE DEC 01 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 ITCZ AXIS IS ALONG 05N77W TO 07N100W TO 07N105W TO 08N113W 
TO 06N125W TO 11N140W. SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION WITHIN 60 NM EITHER SIDE OF AXIS BETWEEN 110W AND 
115W. SCATTERED MODERATE CONVECTION WITHIN 60 NM EITHER SIDE OF 
AXIS BETWEEN 132W AND 136W.

...DISCUSSION...
AN UPPER RIDGE EXTENDS ALONG 125W FROM CENTRAL CALIFORNIA TO AN 
UPPER ANTICYCLONE CENTERED NEAR 09N127W. AN ASCAT PASS FROM 07Z 
SHOWED A WEAK CIRCULATION ALONG THE ITCZ NEAR 09N135W...IN AN 
AREA OF CONVECTION. THIS FEATURE IS LOCATED UNDER A DIVERGENT 
AREA ALOFT W OF THE UPPER ANTICYCLONE...AND TO THE SE OF AN 
UPPER TROUGH THAT EXTENDS FROM 30N135W THROUGH HAWAII. DIVERGENT 
FLOW ALOFT TO THE EAST OF THE UPPER ANTICYCLONE IS ALSO 
ENHANCING A SMALL BUT VIGOROUS CLUSTER OF CONVECTION ALONG THE 
ITCZ BETWEEN 110W AND 115W.

THE NORTHERN EXTENT OF THE RIDGE AXIS WILL ERODE THROUGH TODAY 
AS A SHORT WAVE TROUGH NEAR 35N140W SHIFTS NE. A RELATED 1019 MB 
SURFACE HIGH PRES AREA NEAR 29N125W WILL WEAKEN SLIGHTLY AS A 
RESULT. ASCAT AND SHIP DATA SHOW A SWATH OF FRESH TRADES BETWEEN 
13N AND 20N W OF 115W. A 05Z ASCAT PASS ALSO SHOWED 20 KT WINDS 
OUT OF THE NORTH ALONG THE WEST COAST OF BAJA...TO THE EAST OF 
THE SURFACE HIGH PRES. JASON ALTIMETER PASSES ARE SHOWING SEAS 
OF 8 TO 11 FT IN TRADE WIND BELT...MAINLY DUE TO NW SWELL.

FURTHER EAST...AN UPPER LOW IS LIFTING THROUGH N CENTRAL MEXICO 
INTO W TEXAS. THIS DELIVERED A SHOT OF COOL AIR ACROSS BAJA AND 
NW MEXICO...LIKELY ENHANCING THE AFOREMENTIONED FRESH NLY FLOW 
OFF THE BAJA COAST AND POSSIBLY THE NORTHERN GULF OF CALIFORNIA. 
TO THE SOUTHEAST...EARLY MORNING SHIP OBSERVATIONS SHOWED 20 TO 
25 KT WINDS THROUGH THE GULF OF PAPAGAYO. THIS IS DUE TO A 
COMBINATION OF STRONG TRADES IN THE CARIBBEAN AND EARLY MORNING 
DRAINAGE FLOW EFFECTS. WINDS WILL DIMINISH LATER TODAY...BUT 
EXPECT 20 KT FLOW BRIEFLY AGAIN WED MORNING IN THE GULF OF 
PAPAGAYO.

LOOKING AHEAD...THE UPPER RIDGE AXIS REBUILDS ALONG 135W AHEAD 
OF A STRONG UPPER LONG WAVE TROUGH DIGGING EASTWARD TO THE N OF 
HAWAII. THE LONG WAVE UPPER TROUGH COMES IN PHASE WITH A REMNANT 
OF THE UPPER TROUGH NOW EAST OF HAWAII...WHICH LIFTS TO THE NE 
THROUGH THU. GLOBAL MODELS SHOW A SURFACE TROUGH FORMING OVER 
THE WATERS W OF 130W IN CONJUNCTION WITH THE UPPER TROUGH 
LIFTING NE...ALTHOUGH THERE REMAIN SOME DIFFERENCES ON TIMING 
AND THE EXTENT OF DEVELOPMENT. GFS CONTINUES TO SHOW A DEEPENING 
SURFACE LOW FORMING SE OF HAWAII AND MOVING TOWARD 
22N136W...ALTHOUGH IS LIKELY OVERDONE DUE TO CONVECTIVE 
FEEDBACK. ECMWF IS MORE CONSERVATIVE SHOWING A WEAKER LOW PRES 
AREA LIFTING NE THEN OPENING UP AND DAMPENING OUT BY FRI.

$$
CHRISTENSEN