000
AXPZ20 KNHC 280327
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT NOV 28 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...

AXIS ANALYZED ALONG 06N77W TO 08N87W TO 06N95W TO 06N99W TO 
08N119W TO 08N122W TO 08N140W. SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION WAS NOTED WITHIN 90 NM EITHER SIDE OF THE AXIS 
BETWEEN 88W AND 95W...AND WITHIN 120 NM N OF THE AXIS AND 240 NM 
S OF THE AXIS BETWEEN 115W AND 134W. 

...DISCUSSION...

UPPER LEVEL TROUGH EXTENDS FROM THE U.S. ROCKY MOUNTAINS TO 
32N124W TO 31N142W WITH DEEP SW MOIST FLOW MOVING UP ALONG THE 
TROUGH AXIS FROM SE OF THE HAWAIIAN ISLANDS UP INTO SOUTHERN 
CALIFORNIA. N OF THIS TROUGH A LARGE UPPER LEVEL ANTICYCLONE IS 
CENTERED NEAR 39N128W WITH DRY AND STABLE AIR BUILDING IN BEHIND 
THE TROUGH. AT THE SURFACE A 1035 MB HIGH PRES IS CENTERED NEAR 
38N136W WITH A RIDGE AXIS EXTENDING FROM THE HIGH TO NEAR 
22N112W. A TIGHT PRES GRADIENT IS IN PLACE BETWEEN THE HIGH AND 
ITCZ W OF 120W AND A 1900 UTC ASCAT PASS INDICATED 20 TO 25 KT 
TRADE WINDS ACROSS THAT AREA. MEANWHILE LARGE LONG PERIOD NW 
SWELL UP TO 16 FT CONTINUES TO PROPAGATE THROUGH THE DISCUSSION 
AREA W OF 114W. THESE CONDITIONS WILL CONTINUE FOR THE NEXT FEW 
DAYS. A SECOND LONG WAVE AND DEEP LAYER TROUGH EXTENDS FROM THE 
W GULF OF MEXICO COAST TO NEAR 15N115W WITH DRY AND STABLE 
AIR ALOFT NW OF THE TROUGH SUPPRESSING ANY CONVECTION. 

ELSEWHERE...A 1007 MB LOW IS CENTERED NEAR 06N98W WITH A TROUGH 
FLANKING THE LOW FROM 02N98W TO 11N97W. THIS FEATURE IS 
PRODUCING SCATTERED MODERATE AND ISOLATED STRONG CONVECTION AND 
WINDS OF 20 KT...AND WILL CONTINUE TO MOVE TO THE W AROUND 10 KT 
DURING THE NEXT 48 HOURS. ANOTHER TROUGH IS LOCATED FROM 13N120W 
TO 21N115W WITH WINDS TO 20 KT REALIZED WITHIN 90 NM EITHER SIDE 
OF THE TROUGH AXIS. THIS FEATURE WILL DRIFT TO THE N-NE DURING 
THE NEXT 48 HOURS. LATEST GFS GUIDANCE EVOLVES THE TROUGH INTO A 
CLOSED AREA OF LOW PRES BY 48 HOURS HOWEVER THE ECMWF KEEPS IT 
AS A MUCH WEAKER SYSTEM AND REMAINING AS A TROUGH.  

...GAP WINDS...
HIGH PRES IN THE GULF OF MEXICO HAS WEAKENED TO 1023 MB AND THE 
COLD AIRMASS THAT HAD PUSHED INTO THE S GULF OF MEXICO IS 
BECOMING MODIFIED. STORM FORCE WINDS THAT WERE OCCURRING IN THE 
GULF OF TEHAUNTEPEC HAVE DIMINISHED TO GALE FORCE...AND WILL 
CONTINUE TO EASE TO LESS THAN GALE FORCE WITHIN THE NEXT 12 
HOURS. BY 30 HOURS WINDS ARE FORECAST TO BE LESS THAN 20 KT.

EASTERLY TRADES IN THE W CARIBBEAN WILL CONTINUE TO FUNNEL WINDS 
THROUGH GULF OF PAPAGAYO AND DOWNSTREAM WATERS TO NEAR 91W 
THROUGH SUN TO MAINTAIN A FRESH TO STRONG BREEZE. 

$$
LEWITSKY