000
AXPZ20 KNHC 180318
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 06N77W TO 03.5N82W TO 
03N93W. THE ITCZ AXIS EXTENDS FROM 03N93W TO 06.5N111W TO BEYOND 
04N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WAS 
NOTED WITHIN 210 NM N OF AXIS BETWEEN 110W AND 120W. 

...DISCUSSION...

HIGH PRES 1030 MB IS CENTERED N OF THE AREA NEAR 33N127W WITH 
RIDGE EXTENDING SE TO NEAR 17N106W. THE PRESSURE GRADIENT 
BETWEEN THIS FEATURE AND LOWER PRESSURE IN THE VICINITY OF THE 
ITCZ IS MAINTAINING FRESH TRADEWINDS FROM 07N TO 20N W OF 120W 
AND FROM 07N TO 11N BETWEEN 110W AND 120W. THIS AREA OF 
EXTENSIVE FRESH TRADEWINDS IS HELPING TO ABSORB MORE ENERGY FROM 
THE SEA SURFACE. IN TURN THE CONVERGENCE OF THIS MORE ENERGETIC 
AIR INTO THE ITCZ IS ENHANCING CONVECTION BETWEEN 110W AND 120W 
AS MENTIONED ABOVE. THE AREA OF HIGH PRESSURE WILL CONTINUE TO 
SHIFT SOUTHWARD AND CLOSER TO THE FORECAST AREA. THIS WILL 
MAINTAIN THE LARGE COVERAGE OF FRESH TO STRONG TRADEWINDS 
THROUGH AT LEAST THU NIGHT. 

THE PROXIMITY OF THE AREA OF HIGH PRESSURE AND A TROUGH OF LOW 
PRESSURE OVER MEXICO HAS TIGHTENED THE PRESSURE GRADIENT OVER 
THE GULF OF CALIFORNIA AND OFF THE COAST OF MEXICO NEAR CABO 
CORRIENTES. THIS HAS RESULTED IN FRESH NW TO N WINDS OVER THE 
GULF OF CALIFORNIA S OF 25N AND S TO NEAR 20N OFF THE COAST OF 
MEXICO. WINDS WILL EXPAND OVER THE NEXT 24 HOURS AS THE AREA OF 
HIGH PRESSURE SHIFTS CLOSER TO THE AREA TIGHTENING THE PRESSURE 
GRADIENT. BY WED NIGHT...FRESH 20 KT WINDS WILL PREVAIL OVER THE 
GULF OF CALIFORNIA S OF 30N. 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...WITH WINDS VEERING OVER THE GULF OF 
MEXICO...WINDS FUNNELING THROUGH THE CHIVELA PASS INTO THE GULF 
OF TEHUANTEPEC HAVE DIMINISHED. CURRENTLY FRESH WINDS TO 20 KT 
PREVAIL OVER THE GULF OF TEHUANTEPEC. NOCTURNAL DRAINAGE FLOW 
DURING THE OVERNIGHT HOURS WILL YIELDS NLY WINDS 20-25 KT LATE 
TONIGHT THROUGH WED MORNING. HIGH PRES BEHIND A WEAK COLD FRONT 
EXPECTED ACROSS THE NE GULF WED IS EXPECTED TO INCREASE THE 
GRADIENT WIND FLOW THROUGH THE GULF OF TEHUANTEPEC TO NEAR 30 KT 
BY WED EVENING. WINDS WILL DIMINISH TO 20 KT BY THU EVENING AS 
WINDS OVER THE GULF OF MEXICO VEER ONCE AGAIN. 

GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE N 
OF THE CARIBBEAN AND LOWER PRESSURE OVER SOUTH AMERICA IS 
PRODUCING FRESH TO STRONG TRADEWINDS OVER THE FAR WESTERN 
CARIBBEAN. THESE WINDS ARE FUNNELING THROUGH GAPS IN THE THE 
TOPOGRAPHY OF NICARAGUA AND COSTA RICA INTO THE GULF OF 
PAPAGAYO. THIS WILL CONTINUE THROUGH AT LEAST THU 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