000
AXPZ20 KNHC 281535
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC SUN DEC 28 2014

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH REACHES FROM THE PACIFIC COAST OF COLOMBIA 
NEAR 07N78W TO 06N95W...WHERE IT TRANSITIONS TO AN ITCZ. THE 
ITCZ REACHES FROM 06N95W TO 08N130W TO 07N140W. SCATTERED 
MODERATE CONVECTION IS NOTED WITHIN 60 NM S OF THE MONSOON 
TROUGH AXIS E OF 80W. SCATTERED MODERATE CONVECTION IS ALSO NOTED 
WITHIN 30 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 110W AND 115W. 

...DISCUSSION...                                                 

A SHARP NEGATIVELY TILTED UPPER TROUGH EXTENDS FROM THE N 
CENTRAL PACIFIC TO NE OF HAWAII TO ROUGHLY 20N145W. THE PRES 
GRADIENT IS TIGHTENING AT THE SURFACE BETWEEN AN ASSOCIATED 
1006 MB SURFACE LOW CENTERED NEAR 25N145W AND A BROAD SURFACE 
RIDGE EXTENDING ALONG THE CALIFORNIA COAST AND AS FAR SOUTH AS 
20N E OF 130W. EARLIER ASCAT SATELLITE DATA INDICATED STRONG SE 
TO S WINDS BETWEEN THESE FEATURE OVER THE WATERS N OF 22N AND W 
OF 130W. EARLIER SHIP OBSERVATIONS IN THIS AREA REPORTED SEAS OF 
10 TO 14 FT. WINDS MAY INCREASE SLIGHTLY TO NEAR GALE FORCE BY 
LATE TODAY AS THE SURFACE LOW DEEPENS FURTHER AND SHIFTS MORE TO 
THE NE INTO THE RIDGE. A FEW THUNDERSTORMS ARE POSSIBLE AS WELL 
GIVEN THE INSTABILITY AND LIFT ASSOCIATED WITH THE UPPER TROUGH. 

THE SURFACE LOW PRES ALONG WITH A WEAK COLD FRONT WILL MIGRATE 
NE IN THE NEXT 24 TO 48 HOURS REACHING 28N139W BY EARLY TUE. THE 
SUPPORTING UPPER TROUGH WILL CUT OFF AND WEAKEN AT THE SAME 
TIME...ALLOWING THE SURFACE LOW TO DISSIPATE TOWARD MID WEEK. 
WINDS AND SEAS WILL DIMINISH ACCORDINGLY.

THE INTRUSION OF THE LOW PRES INTO THE SUBTROPICAL RIDGE WILL 
LIMIT TRADE WINDS TO 15 TO 20 KT FARTHER SOUTH INTO THE DEEP 
TROPICS W OF 120W.  SEAS WILL REACH 8 FT IN THE TRADE WIND BELT 
IN PART DUE TO A CONTRIBUTION OF LONGER PERIOD NW SWELL THROUGH 
EARLY NEXT WEEK. 

DIVERGENCE ALOFT SURROUNDING A CUT OFF UPPER LOW CENTERED NEAR 
05N105W WAS SUPPORTING OVERNIGHT CLUSTERS OF SHOWERS AND 
THUNDERSTORMS OVER A LARGE AREA FROM 12N-17N BETWEEN 105W-
110W...BUT THIS HAS LARGELY DISSIPATED. FURTHER DEVELOPMENT IS 
POSSIBLE TONIGHT AS THE UPPER LOW COMES INTO PHASE WITH A 
MID/UPPER TROUGH DIGGING ACROSS NW MEXICO. 

GULF OF TEHUANTEPEC...BUILDING HIGH PRES OVER NE MEXICO BEHIND A 
WEAK COLD FRONT MOVING SOUTHWARD ACROSS THE WESTERN GULF OF 
MEXICO WILL DELIVER FRESH TO STRONG GAP WINDS TO THE GULF OF 
TEHUANTEPEC TONIGHT INTO EARLY MON...WITH SEAS BUILDING TO 8 FT. 
ALTHOUGH THE HIGH PRES WILL WEAKEN AND SHIFT EAST 
MON...OVERNIGHT DRAINAGE FLOW WILL ASSIST STRONG GAP WINDS MON 
NIGHT INTO TUE MORNING.

GULF OF PAPAGAYO...SURFACE HIGH PRESSURE IN THE NORTHWESTERN 
CARIBBEAN SEA WILL SUPPORT 20-25 KT WINDS IN THE GULF OF 
PAPAGAYO AND 8 FT SEAS MON THEN DECREASE TUE. 

$$
CHRISTENSEN