008  
AXPZ20 KNHC 062135  
TWDEP  
 
TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
2111 UTC TUE FEB 6 2018  
 
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
 
 
 
A SURFACE TROUGH EXTENDS FROM 00N80W TO 05N85W TO 04N99W. THE  
ITCZ CONTINUES FROM 04N99W TO 07N120W TO 09N140W. SCATTERED  
MODERATE CONVECTION IS FROM 05N TO 08N BETWEEN 110W AND 112W.  
SCATTERED MODERATE CONVECTION IS FROM 08N TO 10N BETWEEN 134W  
AND 140W.  
 
A SURFACE TROUGH EXTENDS FROM 23N118W TO 16N123W. THIS TROUGH IS  
THE SURFACE REFLECTION OF A MID TO UPPER-LEVEL LOW CENTERED NEAR  
21N122W. SCATTERED MODERATE CONVECTION IS FROM 17N TO 20N  
BETWEEN 120W AND 122W.  
   
..DISCUSSION
 
 
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  
 
A 1030 MB HIGH PRESSURE CENTER REMAINS LOCATED OVER THE NE  
PACIFIC NEAR 42N131W. A WEAK AND ELONGATED RIDGE EXTENDS SE FROM  
THE HIGH INTO THE OFFSHORE WATERS TO NE OF THE REVILLAGIGEDO  
ISLANDS. THE PRESSURE GRADIENT ALONG AND OFFSHORE OF THE BAJA  
CALIFORNIA PENINSULA IS PRODUCING GENTLE TO MODERATE NW WINDS,  
WITH SEAS GENERALLY RUNNING 4 TO 6 FT. THIS FAIRLY QUIET PATTERN  
SHOULD PERSIST THROUGH SAT.  
 
GULF OF CALIFORNIA: LIGHT TO GENTLE WINDS AND 1 TO 3 FT SEAS  
WILL GENERALLY PREVAIL THROUGH WEDNESDAY. A MODEST INCREASE IN NW  
WINDS DURING MID WEEK WILL CAUSE SEAS TO BUILD TO 3-4 FT,  
POSSIBLY AS HIGH AS 5 FT WED EVENING THROUGH THURSDAY. A LOW  
PRESSURE TROUGH WILL DEVELOP OVER THE BAJA PENINSULA ON FRI AND  
SAT. S TO SW WINDS OVER THE GULF OF CALIFORNIA E OF THE TROUGH  
COULD BECOME STRONG ON SAT IN ADVANCE OF AN APPROACHING COLD  
FRONT.  
 
GULF OF TEHUANTEPEC: THE PRESSURE GRADIENT OVER THE ISTHMUS OF  
TEHUANTEPEC WILL TIGHTEN BY EARLY THU AS HIGH PRES BUILDS  
SOUTHWARD ALONG THE SIERRA MADRE ORIENTAL MOUNTAINS OF MEXICO,  
WHILE A COLD FRONT ENTERS THE NW GULF OF MEXICO. ANOTHER GALE  
FORCE GAP WIND EVENT SHOULD COMMENCE OVER THE GULF OF TEHUANTEPEC  
THU EVENING THROUGH FRI NIGHT AS THIS PATTERN EVOLVES. THIS  
EVENT WILL PEAK ON FRI MORNING WITH SEAS AS HIGH AS 13 FT AND  
PRODUCE AN AREA OF 8 FT SEAS THAT WILL MERGE WITH THE AREA OF 8  
FT SEAS PROPAGATING DOWNWIND FROM THE GULF OF PAPAGAYO. THE  
MERGED AREA WILL SPREAD AS FAR S AS 06N AND AS FAR W AS 103W.  
WINDS OVER THE GULF WILL DECREASE ONCE AGAIN TO LIGHT AND  
VARIABLE BY SAT NIGHT.  
 
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND  
WITHIN 750 NM OF ECUADOR...  
 
FUEGO VOLCANO IN GUATEMALA: INTERMITTENT EXPULSIONS OF VOLCANIC  
ASH FROM THE VOLCANO HAVE BEEN OCCURRING DURING THE PAST SEVERAL  
DAYS. A PLUME OF ASH EXTENDING WNW ABOUT 75 NM OVER LAND FROM THE  
SUMMIT OF THE VOLCANO TO THE CHIAPAS BORDER OF MEXICO, BUT THE  
LATEST ADVISORY FROM THE WASHINGTON VAAC DOES NOT ANTICIPATE ANY  
FURTHER EMISSIONS FROM THE VOLCANO DURING THE NEXT 24 HOURS. NO  
LINGERING ASH IS CURRENTLY EVIDENT IN SATELLITE IMAGERY.  
 
NOCTURNAL WINDS WILL PULSE TO BETWEEN FRESH AND STRONG SPEEDS  
EACH NIGHT OVER THE GULF OF PAPAGAYO THROUGH THE WEEK. AREAL  
COVERAGE OF GAP WINDS NEAR THE GULF OF PAPAGAYO WILL INCREASE THU  
AND FRI. THIS WILL ALLOW THE WIND GENERATED SEAS OF 8 FT TO  
PROPAGATE FURTHER DOWNWIND FROM THE GULF OF PAPAGAYO AND MERGE  
WITH THE AREA OF 8 FT SEAS DOWNWIND FROM THE GULF OF TEHUANTEPEC  
ON FRI AND SAT. AREAL COVERAGE OF THE STRONG WINDS WILL DECREASE  
ON SUN AND MON.  
 
ELSEWHERE N OF 09N, GENTLE TO MODERATE OFFSHORE FLOW WILL  
PREVAIL. MODERATE TO FRESH WINDS WILL PULSE TO STRONG DURING  
OVERNIGHT HOURS IN THE GULF OF PANAMA AS WELL THROUGH WED  
MORNING, BECOMING MODERATE TO FRESH THU AND FRI. OTHERWISE, LIGHT  
TO GENTLE S TO SW WINDS WILL GENERALLY PREVAIL S OF 09N THROUGH  
FRI NIGHT.  
 
REMAINDER OF THE AREA...  
 
THE RIDGE OF HIGH PRESSURE MENTIONED ABOVE ALSO EXTENDS S ACROSS  
THE NW PART OF THE DISCUSSION AREA THIS MORNING, AND WILL REMAIN  
IN PLACE DURING THE NEXT SEVERAL DAYS. NW SWELL GENERATED BY A  
FETCH OF WINDS TO THE W OF A NEARLY STATIONARY FRONTAL BOUNDARY  
CURRENTLY NW OF THE HAWAIIAN ISLANDS HAS SPREAD ACROSS THE W  
PORTION OF THE DISCUSSION AREA AND IS GENERATING SEAS OF 8 TO 9  
FT W OF A LINE FROM 23N124W TO 15N120W TO 00N137W. THE NW SWELL  
HAVE PEAKED AND WILL CONTINUE TO PROPAGATE SE AND DECAY. A  
RESIDUAL AREA OF 8 FT SEAS WILL LINGER FROM 08N TO 17N BETWEEN  
114W AND 120W WED EVENING. THE NEXT SIGNIFICANT PULSE OF NW  
SWELL IS NOT EXPECTED TO ENTER THE AREA WATERS UNTIL SAT NIGHT.  
 
WEATHER FOR THE REMAINDER OF THE WEEK LOOKS BENIGN WITH ONLY  
LIGHT TO MODERATE WINDS AND 4-7 FT SEAS ANTICIPATED BEYOND 250 NM  
OFFSHORE. A PERSISTENT SURFACE TROUGH CURRENTLY EXTENDING FROM  
23N118W TO 16N123W IS PRODUCING SCATTERED MODERATE CONVECTION  
FROM 17N TO 20N BETWEEN 120W AND 122W. THE SURFACE TROUGH IS  
SUPPORTED BY A BROAD UPPER-LEVEL CYCLONE CENTERED NEAR 21N122W.  
THE TROUGH WILL REMAIN NEAR ITS CURRENT LOCATION AND EVENTUALLY  
DISSIPATE BY SAT AS THE MID TO UPPER-LEVEL LOW WEAKENS AND THE  
ASSOCIATED CONVECTION GRADUALLY DIMINISHES IN COVERAGE.  
 

 
FORMOSA  
 
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