000
AXPZ20 KNHC 182153
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC WED FEB 18 2015

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. 
  
...SPECIAL FEATURES...

GULF OF TEHUANTEPEC GALE WARNING...STRONG SURFACE HIGH PRESSURE 
IS BUILDING ACROSS THE WESTERN GULF INTO SOUTHERN MEXICO BEHIND 
A COLD FRONT THAT IS CURRENTLY MOVING ACROSS THE YUCATAN 
PENINSULA. THE TIGHT SURFACE PRESSURE GRADIENT ALONG WITH A PUSH 
OF DENSE DRY AND COLD AIR THROUGH THE CHIVELA PASS IN SOUTHERN 
MEXICO IS RESULTING IN GALE FORCE WINDS IN THE GULF OF 
TEHUANTEPEC. A RECENT SCATTEROMETER PASS CONFIRMED THE PRESENCE 
OF THESE WIND SPEEDS. MINATITLAN...ON THE NORTHERN END OF THE 
ISTHMUS OF TEHUANTEPEC...IS REPORTING GUSTY WINDS TO 35 KT. 
WINDS ARE FORECAST TO INCREASE TO 40 KT OVERNIGHT TONIGHT AND 
EARLY THU WITH THE AID OF THE NOCTURNAL DRAINAGE FLOW. THE SEA 
HEIGHTS WILL BUILD DOWNSTREAM OF THE GULF OF TEHUANTEPEC... 
REACHING AS HIGH AS 16 FEET BY LATE TONIGHT. THE GALE-FORCE 
WINDS WILL PERSIST THROUGH EARLY FRI MORNING...AND THEN DIMINISH 
AS THE HIGH PRESSURE TO THE N OF THE AREA WEAKENS AND SHIFTS 
EASTWARD.
                   
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 08N83W TO 04N92W. THE ITCZ 
CONTINUES FROM 04N92W TO 07N103W TO 05N120W TO 06N140W. 
SCATTERED MODERATE CONVECTION IS NOTED FROM 02N TO 04N BETWEEN 
91W AND 96W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION 
CAN BE FOUND FROM 03N TO 07N BETWEEN 127W AND 130W.

...DISCUSSION... 

A CUT-OFF MID TO UPPER LOW IS CENTERED NEAR 18N135W WITH A 
TROUGH EXTENDING SOUTH TO NEAR 05N135W. THE CUT-OFF LOW IS THE 
SOUTHERN REMNANT OF AN UPPER TROUGH THAT EXTENDS ACROSS THE NW 
CORNER OF THE AREA. A SURFACE TROUGH REFLECTION OF THIS UPPER-
LEVEL FEATURE IS ANALYZED FROM 11N132W TO 05N135W. SCATTERED 
SHOWERS WITH EMBEDDED TSTMS ARE NOTED 11N TO 16N BETWEEN 125W 
AND 131W IN ASSOCIATION WITH THESE SYSTEMS. SCATTEROMETER DATA 
INDICATE GENTLE TO MODERATE WINDS NEAR THE TROUGH. AN AREA OF 
SEAS TO 9 FT IS FROM 07N TO 15N W OF 130W. THIS IS DUE TO LONG 
PERIOD SWELL FROM THE NORTHWEST. THIS IS FORECAST TO DECAY TO 8 
FT AS IT PROPAGATES SE AND SHRINK IN AREAL EXTENT AFFECTING ONLY 
THE WATERS FROM 09N TO 12N BETWEEN 125W AND 128W BY 48 HOURS. 
THE UPPER FEATURES WILL GRADUALLY WEAKEN BUT REMAIN GENERALLY IN 
PLACE THROUGH THE NEXT 24 TO 48 HOURS. THIS WILL KEEP THE 
SURFACE TROUGH IN PLACE AS WELL. 

A 1026 MB HIGH PRES CENTERED NEAR 32N129W EXTENDS A RIDGE SE TO 
NEAR 16N110W. A SURFACE TROUGH...REMNANTS OF A COLD FRONT... 
STRETCHES FROM 30N137W TO 25N138W. THE HIGH PRES WILL STRENGTHEN 
BY THU MORNING...ALLOWING FOR A SLIGHTLY TIGHTER GRADIENT 
BETWEEN THE TROUGH AND THE RIDGE...ENHANCING TRADE WIND FLOW 
SOMEWHAT FROM 10N TO 20N BETWEEN 120W AN 130W. 

GAP WINDS...WINDS ARE FORECAST TO INCREASE TO 20-25 KT ACROSS 
THE GULF OF PAPAGAYO BY THU MORNING AS HIGH PRES BUILDS ACROSS 
THE NW CARIBBEAN AND NORTHERN CENTRAL AMERICA IN THE WAKE OF A 
COLD FRONT CURRENTLY REACHING THE NW CARIBBEAN. MARINE GUIDANCE 
SUGGESTS INCREASING WINDS TO 30 KT ACROSS THE GULF OF PAPAGAYO 
WITH BUILDING SEAS TO 9 FT BY FRI MORNING.

MODERATE TO FRESH NORTHERLY WINDS ARE ALSO EXPECTED ACROSS THE 
GULF OF PANAMA BY FRI MORNING AS WINDS FUNNELS INTO THE GULF 
FROM THE CARIBBEAN.

$$
GR