000
AXPZ20 KNHC 202156
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI JAN 20 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 02N80W TO 04N88W TO 03N92W. 
THE ITCZ AXIS EXTENDS FROM 03N92W TO 06N118W TO BEYOND 04N140W. 
SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 180 NM N OF AXIS 
W OF 120W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 60 NM 
S OF AXIS BETWEEN 120W AND 125W.

...DISCUSSION...

SURFACE HIGH PRESSURE 1024 MB IS CENTERED NEAR 27N128W WITH 
RIDGE EXTENDING SE TO NEAR 20N110W. THE PRESSURE GRADIENT 
BETWEEN THIS AREA OF HIGH PRESSURE AND LOW PRESSURE OVER MEXICO 
IS PRODUCING FRESH NW WINDS JUST WEST OF NORTHERN BAJA 
CALIFORNIA. THE PRESSURE GRADIENT BETWEEN THE AREA OF HIGH 
PRESSURE AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ IS 
PRODUCING FRESH TO STRONG TRADEWINDS FROM 05N TO 18N W OF 125W 
AND FROM 05N TO 13N BETWEEN 115W AND 125W. WITH HIGH PRESSURE 
PREVAILING OVER THE N PART OF THE AREA THE NEXT TWO DAYS...BOTH 
THE NW WINDS OFF OF BAJA CALIFORNIA AND THE TRADEWINDS WILL 
CHANGE LITTLE.

A SHARP UPPER LEVEL TROUGH IS STRONGLY TILTED AND STARTING TO 
UNDERGO DEFORMATION AS IS TYPICAL WHEN ANTICYCLONIC FLOW STARTS 
TO PREVAIL. THE TROUGH AXIS EXTENDS ALONG 30N116W TO 17N128W AND 
IS ADVECTING ABUNDANT MID TO HIGH LEVEL CLOUDINESS FROM THE ITCZ 
TOWARD WESTERN MEXICO. THE STRENGTH AND DEPTH OF THE TROUGH NEAR 
20N125W THE PAST COUPLE OF DAYS WAS ENOUGH TO INDUCE LOW LEVEL 
LIFT AND MODERATE TO STRONG CONVECTION NEAR THIS AREA THE PAST 
COUPLE OF DAYS. THIS PERSISTENT CONVECTION AND ASSOCIATED LATENT 
HEAT RELEASE WAS ENOUGH TO INDUCE A WEAK SURFACE TROUGH FROM 
NEAR 20N124W TO 17N126W. THIS WEAK SURFACE TROUGH IS EXPECTED TO 
DIMINISH RAPIDLY AS CONVECTION CONTINUES TO WEAKEN. 

NW SWELL WITH A PERIOD AROUND 15 SECONDS ARE EXPECTED TO MOVE 
INTO THE NW CORNER OF OUR AREA OF RESPONSIBILITY STARTING SAT 
MORNING. THE SWELL WILL PEAK NEAR 14 FEET SAT EVENING INTO SUN 
MORNING AND SPREAD SE WHILE SLOWLY SUBSIDING.

...GAP WINDS...

GULF OF PAPAGAYO...FRESH TO STRONG WINDS OVER THE SW CARIBBEAN 
CONTINUE TO FUNNEL THROUGH THE GAPS IN THE TOPOGRAPHY OF 
NICARAGUA AND COSTA RICA ACROSS THE GULF OF PAPAGAYO. THESE NE 
TO E WINDS ARE FORECAST TO PERSIST THROUGH AT LEAST SUN 
AFTERNOON. THE STRONGEST WINDS WILL OCCUR DURING THE LATE NIGHT 
AND EARLY MORNING HOURS WITH THE ADDED COMPONENT OF NOCTURNALLY 
DRIVEN KATABATIC WINDS.

GULF OF PANAMA...FRESH WINDS FROM THE SW CARIBBEAN ARE ALSO 
FUNNELING ACROSS THE ISTHMUS OF PANAMA DOWNWIND ACROSS THE GULF 
OF PANAMA. THESE WINDS WILL DIMINISH TO LESS THAN 20 KT BY SAT 
NIGHT AS WINDS IN THE SW CARIBBEAN BEGIN TO DIMINISH.

$$
AL