000
AXPZ20 KNHC 161549
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED DEC 16 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...
AXIS ANALYZED ALONG 06N78W TO 07N91W TO 07N108W TO 07N132W TO
06N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WAS 
WITHIN 120 NM OF THE AXIS E OF 80W AND WITHIN 90 NM OF THE AXIS 
BETWEEN 85W AND 105W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION WAS WITHIN 510 NM N OF THE AXIS W OF 120W AND WITHIN 
300 NM S OF THE AXIS W OF 130W.

...DISCUSSION...
A MID TO UPPER LEVEL TROUGH IS OVER THE NW PORTION OF THE 
DISCUSSION AREA EXTENDING FROM 34N127W TO 26N133W. AN ATTENDANT 
SURFACE COLD FRONT HAS DISSIPATED OVER OUR AREA AS IT 
ENCOUNTERED AN EXPANSIVE AREA OF HIGH PRES TO THE E-SE. 
SATELLITE IMAGERY INDICATED MAINLY MID TO HIGH LEVEL CLOUDS OUT 
AHEAD OF THIS TROUGH. A MID TO UPPER LEVEL RIDGE IS LOCATED JUST 
TO THE E... EXTENDING FROM 32N117W TO 21N122W. A DEEPER AND 
SHARPER MID TO UPPER LEVEL TROUGH IS LOCATED TO THE 
E...EXTENDING FROM NORTH CENTRAL TEXAS S ACROSS CENTRAL MEXICO 
AND TO 13N112W. A STRONG SURFACE COLD FRONT IS MOVING OUT AHEAD 
OF THIS DEEP TROUGH ACROSS THE WESTERN GULF OF MEXICO EXTENDING 
INTO SOUTHEAST MEXICO. PLENTIFUL MOISTURE IS BEING ADVECTED FROM 
THE ITCZ NORTHEASTWARD OUT AHEAD OF THIS TROUGH. 

MODERATE TO STRONG SUBSIDENCE IS N OF 17N ACROSS THE BASIN. 
THE SUBSIDENCE IS HELPING TO SUPPRESS ANY SIGNIFICANT CONVECTION 
ALONG THE ITCZ.

A 1024 MB AREA OF HIGH PRES IS CENTERED NEAR 29N125W. A BROAD 
AREA OF MODERATE TO STRONG TRADE WINDS EXISTS ON THE SOUTHERN 
PERIPHERY OF THE HIGH JUST N OF THE ITCZ...MAINLY FROM 08N TO
24N W OF 114W. A TIGHT PRES GRADIENT EXISTS OVER THE GULF OF 
CALIFORNIA DUE TO A HIGH PRES RIDGE W OF THE BAJA PENINSULA 
EXTENDING FROM THE AFOREMENTIONED 1024 MB HIGH...A TROUGH OF 
LOW PRES ALONG THE E COAST OF THE GULF OF CALIFORNIA...AND 
STRONG HIGH PRES OVER EASTERN MEXICO AND TEXAS. AS A RESULT NW 
TO N WINDS IN THE 20 TO 25 KT RANGE ARE OCCURRING IN THE GULF OF 
CALIFORNIA N OF 22N...AS CAPTURED BY AN EARLIER 0510 UTC ASCAT 
PASS AND SEVERAL SHIPS IN THE AREA. THESE WINDS WILL GRADUALLY 
WEAKEN OVER THE NEXT FEW DAYS AS THE PRES GRADIENT RELAXES.

TO THE SOUTH...TWO SURFACE TROUGHS ARE EMBEDDED WITHIN THE ITCZ. 
ONE EXTENDS FROM 12N109W TO A 1007 MB AREA OF LOW PRES NEAR 
07N110W AND TO 04N110W. CONVECTION ASSOCIATED WITH THESE 
FEATURES REMAINS SUPPRESSED DUE TO STRONG SOUTHWESTERLY WINDS 
ALOFT. THE OTHER TROUGH EXTENDS FROM 11N132W TO 03N133W. 
SCATTERED MODERATE AND ISOLATED CONVECTION IS OCCURRING WITHIN 
BOTH SIDES OF THE TROUGH AXIS W OF 120W DUE TO STRONG CONVERGENT 
FLOW AT THE SURFACE AND DIVERGENT FLOW ALOFT.

MEANWHILE LARGE NW SWELL IS PROPAGATING ACROSS THE NW PORTION OF 
THE DISCUSSION AREA BEHIND THE AFOREMENTIONED DIEING COLD FRONT 
WHICH MOVED INTO THE AREA S OF 30N YESTERDAY. SEAS WILL PEAK 
NEAR 17 FT ALONG 30N THIS AFTERNOON.

...GAP WINDS...
N TO NE WINDS OF 20 TO 25 KT ARE OCCURRING IN THE GULF OF 
TEHUANTEPEC AS CAPTURED BY AN EARLIER 0318 UTC ASCAT PASS...DUE 
TO A COLD FRONT THAT IS PUSHING SE ACROSS THE WESTERN GULF OF 
MEXICO AND BAY OF CAMPECHE. THESE WINDS WILL INTENSIFY AS COLDER 
AIR ARRIVES OVER THE BAY OF CAMPECHE WHICH WILL ENHANCE THE 
FUNNELING WINDS ACROSS THE ISTHMUS OF TEHUANTEPEC...AND MODEL 
GUIDANCE INCREASES WINDS TO MINIMAL GALE FORCE (NAM SURFACE 
WINDS AND 925 MB GFS WINDS). GALE WARNING IN EFFECT BEGINNING AT 
00 UTC THIS EVENING THROUGH 00 UTC FRI.

NE TO E WINDS OF 20 TO 25 KT CONTINUE ACROSS THE GULF OF 
PAPAGAYO AND DOWNSTREAM TO 90W...DUE TO A TIGHT PRES GRADIENT 
AND MODERATE TO STRONG TRADES OVER THE W CARIBBEAN. THESE WINDS 
ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT BY 48 HOURS AS 
THE PRES GRADIENT IN THE CARIBBEAN WEAKENS.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE
  
$$
LEWITSKY