000
AXPZ20 KNHC 181605
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE DEC 18 2007

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...
INTERTROPICAL CONVERGENCE ZONE AXIS IS CENTERED ALONG 8N82W 
6N92W 9N120W 7N130W 7N140W. SCATTERED MODERATE TO STRONG 
CONVECTION WITHIN 60 NM S OF AXIS FROM 122W TO 124W. 

...DISCUSSION...
E OF 115W...AN UPPER RIDGE IS CENTERED OVER THE W COAST OF 
MEXICO. DIVERGENCE ALOFT ON THE FAR W SIDE OF THIS UPPER RIDGE 
IS ENHANCING CONVECTION ALONG THE ITCZ AS MENTIONED ABOVE. THE 
DENSITY GRADIENT BETWEEN THE GULF OF MEXICO AND THE GULF OF 
TEHUANTEPEC IS STILL JUST STRONG ENOUGH TO SUPPORT GALE FORCE 
WINDS THE MORNING...BUT THIS WILL BE DIMINISHING TO 20 TO 25 KT 
THROUGH THIS AFTERNOON AS SLY FLOW SETS UP OVER THE WESTERN GULF 
OF MEXICO. ENHANCED ELY FLOW OVER THE CARIBBEAN IS ALSO ALLOWING 
MODERATE GAP FLOW THROUGH THE GULF OF PAPAGAYO...BUT THIS WILL 
BE GENERALLY BELOW 20 KT. GFS INITIALIZED WITH 20 KT PLUS FLOW 
IN THE GULF OF PANAMA...BUT THIS IS INCONSISTENT WITH QUIKSCAT 
AND SURFACE DATA. WILL KEEP ONLY MODERATE SW FLOW IN THE 
FORECAST THROUGH 48 HOURS.

W OF 115W...AN UPPER TROUGH IS DIGGING EWD JUST OFF THE 
CALIFORNIA COAST COMING INTO PHASE WITH AN EXISTING UPPER TROUGH 
EXTENDING FROM 30N130W TO 21N140W. AN ASSOCIATED LOW PRES WELL N 
OF THE AREA IS MOVING INTO THE WESTERN U.S. COAST. STRONG AND 
PERSISTENT NLY FLOW BETWEEN THIS LOW AND HIGH PRES OVER THE E 
CENTRAL PACIFIC HAS GENERATED LARGE SWELL THAT IS NOW 
PROPAGATING INTO THE WATERS W OF NRN BAJA. SHIP AND JASON 
ALTIMETER OBSERVATIONS SHOW SWELL UP 10 FT IN THE AREA 
CURRENTLY...WITH SWELL TO 12 FT EXPECTED THROUGH THU. MEANWHILE 
1022 MB HIGH PRES IS PUSHED S OF THE TROUGH NEAR 26N121W. FRESH 
TO STRONG TRADES PERSIST S OF THE HIGH PRES FROM GENERALLY 10N 
TO 20N W OF 120W. THE HIGH  PRES WILL REMAIN IN PLACE 
MAINTAINING THE TRADE WIND FLOW FOR THE NEXT COUPLE OF DAYS. 

$$
CHRISTENSEN