000
AXPZ20 KNHC 212150
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED NOV 21 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...

MONSOON TROUGH EXTENDS FROM 07N78W TO 09N85W TO 06N94W...WHERE 
THE TROUGH TRANSITIONS TO ITCZ...CONTINUING ON 09N135W TO BEYOND 
057N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION 
NOTED FROM 05N TO 10N E OF 87W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION NOTED WITHIN 60 NM EITHER SIDE OF THE ITCZ W 
OF 130W.

...DISCUSSION...

GULF OF TEHUANTEPEC...THE MAIN FORECAST ISSUE CONTINUES TO BE A 
LONG LIVED GALE FORCE EVENT IN THE GULF OF TEHUANTEPEC. THE 
SURFACE ANALYSIS FROM 18 UTC INDICATES A 1025 MB SURFACE HIGH 
PRES AREA CENTERED OVER NE MEXICO. A 1630 UTC ASCAT PASS 
INDICATED WINDS TO NEAR GALE FORCE ALONG THE COAST AND 
OBSERVATIONS FROM SALINA CRUZ AND IXTEPEC NEAR THE SOUTHERN 
TERMINUS OF THE TEHUANTEPEC ISTHMUS INDICATE SUSTAINED WINDS 15 
TO 20 KT...WITH GUSTS TO 30 KT AT SALINA CRUZ. CONTRIBUTIONS 
FROM OVERNIGHT DRAINAGE MAY ALLOW WINDS TO REACH GALE FORCE 
AGAIN DURING LATE TONIGHT INTO EARLY THU MORNING. THE HIGH PRES 
IN THE GULF OF MEXICO WILL SHIFT E THROUGH THU...ALLOWING FOR 
THE GRADIENT TO RELAX. WINDS WILL STILL REACH 30 KT THU NIGHT 
AND EARLY FRI MORNING...BUT REMAIN BELOW GALE FORCE. THE 
REPRIEVE WILL BE SHORT LIVED HOWEVER...SINCE THE NEXT SURGE OF 
COOLER AND DRIER AIR WILL PUSH ACROSS THE WESTERN GULF OF MEXICO 
INTO THE GULF OF TEHUANTEPEC BY LATE FRI NIGHT INTO EARLY 
MORNING...INDUCING ANOTHER GALE EVENT.

GULF OF PAPAGAYO...ANOTHER GAP WIND EVENT IN THE GULF OF 
PAPAGAYO IS PRODUCING STRONG BREEZE CONDITIONS.  THIS EVENT 
SHOULD CONTINUE FOR THE NEXT COUPLE OF DAYS WITH LITTLE 
CHANGE...BUT WITH THE TYPICAL DIURNAL VARIABILITY WITH WEAKER 
WINDS AND LOWER SEAS DURING THE AFTERNOON AND EARLY EVENING. 
FORCING FOR THIS EVENT SHOULD SUBSIDE BELOW OUR 25 KT CRITERION 
BY MONDAY.

A BROAD AREA OF CONVECTION IS NOTED ON SATELLITE IMAGERY AROUND 
PANAMA. SCATTEROMETER DATA FROM 17 UTC SHOWED MODERATE TO FRESH 
CROSS-EQUATORIAL SW FLOW INTO THIS AREA CONVERGING WITH MODERATE 
TO FRESH N TO NE FLOW OVER THE SW CARIBBEAN. GOES DERIVED WINDS 
AND WATER VAPOR IMAGERY SHOW WEAK UPPER LEVEL TROUGHING JUST 
WEST OF THE CONVECTIVE AREA...LIKELY PROVIDING ADDITIONAL UPPER 
DIVERGENCE AND LIFT. GLOBAL MODELS CONTINUE TO SHOW THE 
DEVELOPMENT OF A WEAK LOW PRES AREA ALONG THE MONSOON TROUGH 
NEAR 08N97W AROUND COCOS ISLAND THROUGH FRI...INTERACTING WITH 
THE PAPAGAYO PULSES TO THE NORTH TO ENHANCE EASTERLY FLOW. 
ASIDE FROM THE SLIGHTLY ELEVATED WINDS AND SEAS...THE MAIN 
IMPACT WILL BE AREAS FROM 05N TO 10N E OF 87W. 

FARTHER WEST...A 18 UTC ASCAT PASS CONFIRMED AN AREA OF 20 TO 25 
KT TRADE WINDS FROM 12N TO 19N BETWEEN 125W AND 135W...SOUTH OF 
A 1024 MB CENTERED NEAR 28N129W. THESE WINDS WILL DIMINISH AS 
THE HIGH PRES WEAKENS AND DRIFTS N. 

LONG-PERIOD...13-15 SECOND...NW SWELL WITH SIGNIFICANT WAVE 
HEIGHTS OF UP TO 12 FEET ARE OCCURRING IN OUR NW AREA OF 
RESPONSIBILITY DUE TO FORCING FROM A WINTER STORM SOUTH OF 
ALASKA.  THIS NW SWELL WILL BE PUSHING SOUTHEASTWARD AND 
GRADUALLY DIMINISHING OVER THE NEXT COUPLE OF DAYS. THE NEXT 
NOTEWORTHY LONG-PERIOD SWELL EVENT MAY OCCUR BEGINNING NEXT 
WEDNESDAY.

$$
CHRISTENSEN