000
AXPZ20 KNHC 280954
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED DEC 28 2011

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH AXIS EXTENDS FROM 04N77W TO 08N85W TO 08N125W. 
ITCZ AXIS EXTENDS FROM 10N125W TO BEYOND 08N140W. NO SIGNIFICANT 
CONVECTION IS NOTED.

...DISCUSSION...

GULF OF TEHUANTEPEC...A 0404 UTC ASCAT PASS INDICATED WINDS TO 
30 KT THROUGH THE GULF OF TEHUANTEPEC. OVERNIGHT DRAINAGE IS 
ENHANCING STRONG GRADIENT FLOW IS PUSHING THROUGH THE 
TEHUANTEPEC ISTHMUS DUE TO HIGH PRES BUILDING OVER THE WESTERN 
GULF OF MEXICO BEHIND A COLD FRONT THAT MOVED THROUGH THE REGION 
YESTERDAY. THIS FLOW IS BEING ENHANCED BY OVERNIGHT DRAINAGE 
EFFECTS...AND WILL PERSIST THROUGH THE MORNING INTO THE EARLY 
AFTERNOON...THEN DIMINISH TO 20 KT AS THE AIRMASS TO THE NORTH 
MODIFIES AND SHIFTS E. GAP WINDS WILL DIMINISH FURTHER THU AND 
FRI AS THE WINDS OVER THE SW GULF OF MEXICO VEER MORE SE.  A 
LARGE AREA OF FRESH NE SWELL TO 9 FT GENERATED BY THE GAP WIND 
FLOW ARE REACHING AS FAR WEST AS 110W.

GULF OF CALIFORNIA...A 0408 UTC ASCAT PASS INDICATED FRESH 20 KT 
WINDS CONTINUE OVER THE GULF OF CALIFORNIA. THE PRESSURE 
GRADIENT BETWEEN PERSISTENT HIGH PRESSURE CENTER NW OF THE GULF 
OF CALIFORNIA...AND TROUGHING OVER MEXICO WILL MAINTAIN AREAS OF 
20 KT WINDS OVER THE GULF OF CALIFORNIA THROUGH THU MORNING. THE 
AREA OF HIGH PRESSURE WILL GRADUALLY WEAKEN THROUGH THU. THIS 
WILL WEAKEN THE PRESSURE GRADIENT ENOUGH TO DIMINISH WINDS BELOW 
20 KT OVER THE GULF OF CALIFORNIA BY THU AFTERNOON. 

GULF OF PAPAGAYO...FRESH TRADEWINDS OVER THE WESTERN CARIBBEAN 
WILL CONTINUE TO FUNNEL INTO THE GULF OF PAPAGAYO THROUGH AT 
LEAST THU NIGHT. WINDS WILL PEAK DURING THE EARLY MORNING HOURS 
WITH THE ADDITION OF NOCTURNALLY DRIVEN KATABATIC WINDS.

A 1030 MB HIGH PRES AREA CENTERED NEAR 32N130W WILL SLOWLY DRIFT 
SW THROUGH THU. ALOFT...A MID TO UPPER LEVEL TROUGH EXTENDS FROM 
30N132W TO A CYCLONIC CIRCULATION NEAR 20N142W. THE UPPER TROUGH 
IS SUPPORTING A SURFACE TROUGH TO ITS SE FROM 10N127W TO 
14N125W. THE TIGHT PRES GRADIENT BETWEEN THE SURFACE AND THE 
HIGH PRES TO THE NORTH IS MAINTAINING 20 TO 25 KT TRADEWINDS 
OVER MUCH OF THE AREA BETWEEN 12N TO 20N W OF 115W. THE AREA OF 
THE FRESH TO STRONG TRADES WILL RECEDE WESTWARD THROUGH 72 HOURS 
AS THE SURFACE TROUGH MIGRATES WEST. WHILE NO SIGNIFICANT 
CONVECTION IS NOTED CURRENTLY...SCATTERED MODERATE CONVECTION IS 
LIKELY N OF THE ITCZ AXIS ALONG AND WEST OF THE SURFACE TROUGH 
THROUGH 48 HOURS...DUE TO TRADEWIND CONVECTION AND DIVERGENT 
FLOW ALOFT SE OF THE UPPER TROUGH. MEANWHILE NW SWELL WILL 
CONTINUE TO PROPAGATE OVER MUCH OF THE AREA W OF 110W...MIXING 
WITH NE SWELL FROM THE PERSISTENT TRADE WIND FLOW N OF 10N AND 
WITH SE CROSS EQUATORIAL SWELL S OF 10N. 

$$
CHRISTENSEN