000
AXPZ20 KNHC 182101
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED JAN 18 2012

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 04N77W TO 07N85W TO 02N94W. 
THE ITCZ AXIS EXTENDS FROM 02N94W TO 07.5N115W TO BEYOND 
05N140W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 150 NM N 
OF AXIS BETWEEN 112W AND 116W.

...DISCUSSION...
HIGH PRES 1030 MB IS CENTERED N OF THE AREA NEAR 33N125W WITH 
RIDGE EXTENDING SE TO NEAR 17N109W. THE PRESSURE GRADIENT 
BETWEEN THIS FEATURE AND LOWER PRESSURE IN THE VICINITY OF THE 
ITCZ IS MAINTAINING FRESH TRADEWINDS FROM 05N TO 20N W OF 114W. 
THE AREA OF HIGH PRESSURE WILL CONTINUE TO SHIFT SOUTHWARD AND 
CLOSER TO THE FORECAST AREA. THIS WILL MAINTAIN A LARGE COVERAGE 
OF FRESH TO STRONG TRADEWINDS THROUGH AT LEAST FRI AFTERNOON. 

THE PROXIMITY OF THE AREA OF HIGH PRESSURE AND A TROUGH OF LOW 
PRESSURE OVER MEXICO IS MAINTAINING A PRESSURE GRADIENT TO 
SUPPORT FRESH NW TO N FLOW OVER THE GULF OF CALIFORNIA S TO NEAR 
20N. THE AREA OF HIGH PRESSURE WILL WEAKEN THROUGH THU NIGHT. 
THIS WILL LOOSEN THE PRESSURE GRADIENT ENOUGH TO DIMINISH WINDS 
BELOW 20 KT OVER THE GULF OF CALIFORNIA. 

GAP WINDS...
GULF OF TEHUANTEPEC...HIGH PRESSURE BEHIND A COLD FRONT OVER THE 
GULF OF MEXICO HAS INCREASED THE PRESSURE GRADIENT OVER THE SW 
GULF. THIS HAS RESULTED IN FRESH TO STRONG WINDS OVER THE GULF 
OF TEHUANTEPEC...WITH WINDS EXPECTED TO INCREASE TO 30 KT THIS 
EVENING THROUGH THU MORNING. WINDS WILL DIMINISH TO 20 KT BY THU 
EVENING AS THE HIGH PRESSURE CENTER SHIFTS FURTHER EASTWARD 
WEAKENING THE PRESSURE GRADIENT...AND VEERING WINDS OVER THE 
GULF OF MEXICO. WINDS OVER THE GULF OF TEHUANTEPEC ARE EXPECTED 
TO DECREASE BELOW 20 KT BY FRI EVENING.

GULF OF PAPAGAYO...FRESH TO STRONG TRADEWINDS OVER THE FAR 
WESTERN CARIBBEAN ARE FUNNELING THROUGH GAPS IN THE THE 
TOPOGRAPHY OF NICARAGUA AND COSTA RICA INTO THE GULF OF 
PAPAGAYO. THIS WILL CONTINUE THROUGH AT LEAST FRI EVENING WITH 
WINDS PEAKING DURING THE EARLY MORNING HOURS WITH THE ADDED 
COMPONENT OF NOCTURNALLY DRIVEN KATABATIC WINDS. MEANWHILE THE 
WINDS OVER THE SW CARIBBEAN ARE ALSO FUNNELING INTO THE GULF OF 
PANAMA PRODUCING FRESH NLY WINDS. THESE WINDS OVER THE GULF OF 
PANAMA ARE ALSO EXPECTED TO CONTINUE THROUGH THE NEXT 48 HOURS.

$$
AL