000
AXPZ20 KNHC 042117
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED JAN 04 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 07N78W TO 07N86W. THE ITCZ 
AXIS EXTENDS FROM 07N86W TO 04N99W TO 08N120W TO BEYOND 03N140W. 
SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 120 NM N OF ITCZ 
AXIS BETWEEN 110W AND 121W.     

...DISCUSSION...

W OF 110W...A 1030 MB HIGH PRES CENTERED NEAR 34N127W WILL 
CONTINUE TO DISSIPATE THROUGH TONIGHT IN ADVANCE OF A COLD FRONT 
MOVING EASTWARD FROM THE N CENTRAL PACIFIC. THE FRONT WILL STALL 
AND BECOME DIFFUSE N OF 30N OVERNIGHT...AS STRONGER HIGH PRES 
BUILDS N OF THE AREA THROUGH THU. LATEST 1700 UTC ASCAT PASS 
SHOW 15 TO 20 KT TRADE WIND FLOW N OF THE ITCZ TO 20N. THE TRADE 
WINDS WILL INCREASE SLIGHTLY THROUGH THU AS THE SURFACE RIDGE 
BUILDS N OF THE AREA. SEAS OF 8 TO 11 FT...PRIMARILY IN NW SWELL 
COVERS MUCH OF THE AREA W OF 120W. AN AREA OF CONFUSED SEAS WILL 
PREVAIL S OF 15N BETWEEN 110W AND 120W THROUGH FRI AS THE NW 
SWELL MIXES WITH NE AND E SWELL MIGRATING INTO THE AREA. ANOTHER 
ROUND OF NW SWELL HAS PUSHED INTO THE FAR NW PART OF THE 
DISCUSSION AREA...AND WILL COVER MUCH OF THE AREA W OF 120W N OF 
10N BY LATE THU. 

GULF OF TEHUANTEPEC...THE STRONG HIGH PRES OVER THE WESTERN GULF 
OF MEXICO HAS WEAKENED AND SHIFTED EAST...ALLOWING THE SURGE OF 
COLD AIR INTO THE CHIVELA TO DIMINISH. WINDS TO GALE FORCE WILL 
STILL CONTINUE THROUGH THE OVERNIGHT HOURS DUE TO THE RELATIVE 
DIFFERENCE IN AIR DENSITY BETWEEN THE AIRMASS OVER THE GULF OF 
MEXICO AND THAT OVER THE EASTERN PACIFIC. OVERALL WIND SPEEDS 
ARE TRENDING DOWNWARD THROUGH THE GULF OF TEHUANTEPEC...ALTHOUGH 
MAY GET SOME MINOR SUPPORT OVERNIGHT DUE TO DRAINAGE EFFECTS. 
WINDS TO 30 KT ARE STILL LIKELY THU...THEN WILL DIMINISH FURTHER 
TO BELOW 20 KT BY LATE FRI AS THE AIRMASS N OF THE AREA MODIFIES 
FURTHER. 

GULFS OF FONSECA AND PAPAGAYO...STRONG EASTERLY GRADIENT FLOW IS 
FLOWING THROUGH THE GAP IN THE MOUNTAINS OVER NICARAGUA INTO THE 
GULF OF PAPAGAYO. LATEST 1552 UTC ASCAT PASS INDICATES WINDS OF 
30 KT OVER THE GULF OF PAPAGAYO. WITH THE 5 KT LOW BIAS OF ASCAT 
AT THIS WIND SPEED...GALE FORCE WINDS ARE LIKELY OVER THIS AREA. 
NORTHERLY GRADIENT FLOW ACROSS NORTHERN CENTRAL AMERICA ARE 
PRODUCING FRESH 20 KT WINDS OVER THE GULF OF FONSECA. THESE 
WINDS ARE MERGING WITH GAP FLOW FROM THE GULF OF PAPAGAYO. WINDS 
OVER THE GULF OF PAPAGAYO WILL DIMINISH BELOW GALE FORCE THIS 
EVENING WITH FRESH TO STRONG WINDS PREVAILING THU AND FRI. 

GULF OF PANAMA...STRONG NORTHERLY GRADIENT FLOW OVER THE SW 
CARIBBEAN WILL PUSH ACROSS THE PANAMA ISTHMUS INTO THE GULF OF 
PANAMA THROUGH THU.

ELSEWHERE E OF 110W...N TO NE SWELL ASSOCIATED WITH THE COMBINED 
STRONG GAP FLOW FROM PAPAGAYO AND TEHUANTEPEC WILL COVER MUCH OF 
THE AREA S OF 15N BETWEEN 85W AND 110W. NW SWELL WILL PUSH INTO 
THIS AREA THROUGH 48 HOURS.

GULF OF CALIFORNIA...1042 MB HIGH PRES OVER THE GREAT BASIN IS 
SUPPORTING FRESH NW FLOW DOWN THE LENGTH OF THE GULF AS DEPICTED 
BY THE LATEST 1730 ASCAT PASS. THIS AREA OF HIGH PRESSURE WILL 
WEAKEN THROUGH THU WHICH WILL DIMINISH WINDS BELOW 20 KT BY THU 
NIGHT. 

$$
AL