043  
AXPZ20 KNHC 200915  
TWDEP  
 
TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
1005 UTC MON OCT 20 2025  
 
TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM  
03.4S TO 30N, EAST OF 120W INCLUDING THE GULF OF CALIFORNIA, AND  
FROM THE EQUATOR TO 30N, BETWEEN 120W AND 140W. THE FOLLOWING  
INFORMATION IS BASED ON SATELLITE IMAGERY, WEATHER OBSERVATIONS,  
RADAR, AND METEOROLOGICAL ANALYSIS.  
 
BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH  
0900 UTC.  
   
..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH  
 
THE MONSOON TROUGH EXTENDS FROM 08N83W TO 13N102W TO A 1010 MB  
LOW PRESSURE LOCATED NEAR 10N122W. THE ITCZ CONTINUES FROM  
10N122W TO ANOTHER 1010 MB LOW PRESSURE SITUATED NEAR 10N138W TO  
BEYOND 10N140W. A CLUSTER OF MODERATE TO STRONG CONVECTION IS  
OVER THE TEHUANTEPEC REGION COVERING THE WATERS N OF 14N BETWEEN  
94W AND 97W. SIMILAR CONVECTIVE ACTIVITY IS ALSO NOTED NEAR THE  
ENTRANCE TO THE GULF OF FONSECA N OF 12N BETWEEN 87.5W AND 89W.  
SCATTERED MODERATE ISOLATED STRONG CONVECTION CAN BE FOUND FROM  
05N TO 10N E OF 86W TO THE COAST OF COLOMBIA, AND FROM 10N TO  
12N BETWEEN 92W AND 110W.  
   
..OFFSHORE WATERS WITHIN 250 NM OF MEXICO  
 
A RIDGE DOMINATES THE OFFSHORE FORECAST WATERS OF BAJA CALIFORNIA,  
SUPPORTING MAINLY GENTLE TO MODERATE NW TO N WINDS WITH MODERATE  
SEAS. GENTLE TO MODERATE NW WINDS ARE ALSO FOUND IN THE CENTRAL  
AND SOUTHERN GULF OF CALIFORNIA WHILE WINDS ARE LIGHT AND VARIABLE  
IN THE NORTHERN PART OF THE GULF. ELSEWHERE ACROSS THE MEXICAN  
OFFSHORE WATERS, INCLUDING THE GULF OF TEHUANTEPEC, LIGHT TO GENTLE  
WINDS AND MODERATE SEAS, PRIMARILY IN SW SWELL, PREVAIL.  
 
FOR THE FORECAST, BUILDING HIGH PRESSURE ACROSS THE EASTERN SLOPES  
OF THE SIERRA MADRE MOUNTAINS IN MEXICO WILL SUPPORT A GAP WIND  
EVENT ACROSS THE TEHUANTEPEC REGION BEGINNING THIS MORNING. FRESH  
TO STRONG NORTHERLY WINDS AND MODERATE TO ROUGH SEAS ARE EXPECTED  
WITH THIS EVENT MOST OF THE WEEK. LONG PERIOD NW SWELL WILL  
PROPAGATE ACROSS THE OFFSHORE WATERS OF BAJA CALIFORNIA THROUGH  
THE FORECAST PERIOD, SUPPORTING MODERATE TO ROUGH SEAS. WINDS  
WILL FRESHEN UP IN THE OFFSHORE WATERS OF BAJA CALIFORNIA BY  
MIDWEEK AND CONTINUE THROUGH THE END OF THE WEEK AS THE PRESSURE  
GRADIENT TIGHTENS SOME ACROSS THE AREA BETWEEN THE RIDGE TO THE  
WEST AND LOWER PRESSURES OVER NORTH-CENTRAL MEXICO. LOOKING AHEAD,  
A SURFACE TROUGH LOCATED A FEW HUNDRED MILES SOUTH OF THE GULF  
OF TEHUANTEPEC IS PRODUCING DISORGANIZED SHOWERS AND THUNDERSTORMS.  
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR GRADUAL  
DEVELOPMENT OF THE SYSTEM, AND A TROPICAL DEPRESSION COULD FORM  
BY LATE THIS WEEK AS IT MOVES GENERALLY WESTWARD AT 10 TO 15 KT.  
 
CLIMATOLOGICALLY, THE FIRST GALE-FORCE EVENT OF THE SEASON OCCURS  
IN MID-OCTOBER, WITH THE FINAL GALE-FORCE EVENT OCCURRING IN  
LATE MARCH OR EARLY APRIL. OCCASIONALLY, GALE-FORCE EVENTS MAY  
OCCUR AS EARLY AS SEPTEMBER, AND AS LATE AS MAY.  
 
...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA,  
AND WITHIN 750 NM OF ECUADOR...  
 
SCATTERED SHOWERS AND THUNDERSTORMS ARE SEEN ACROSS THE OFFSHORE  
WATERS OF CENTRAL AMERICA AND COLOMBIA, INCLUDING ALSO PARTS OF  
THE GULF OF PANAMA. RECENT SATELLITE DERIVED WIND DATA INDICATE  
MODERATE S TO SW WINDS SOUTH OF THE MONSOON TROUGH, AND LIGHT TO  
GENTLE WINDS TO THE NORTH OF IT. SEAS IN THESE WATERS ARE  
MODERATE IN SW SWELL.  
 
FOR THE FORECAST, FRESH TO STRONG WINDS WILL PULSE IN THE GULF  
OF PAPAGAYO TONIGHT THROUGH TUE NIGHT. MODERATE SOUTHERLY WINDS  
AND MODERATE SEAS ARE EXPECTED SOUTH OF THE MONSOON TROUGH  
THROUGH THE FORECAST PERIOD. WINDS MAY BRIEFLY INCREASE TO FRESH  
SPEEDS BY THU.  
   
..REMAINDER OF THE AREA  
 
A 1031 MB HIGH PRESSURE IS LOCATED N OF AREA NEAR 39N140W. ITS  
ASSOCIATED RIDGE COVERS THE FORECAST WATERS N OF 15N AND W OF  
110W. THE PRESSURE GRADIENT BETWEEN THE RIDGE AND A 1010 MB LOW  
PRESSURE SITUATED ALONG THE MONSOON TROUGH NEAR 10N122W SUPPORTS  
AN AREA OF FRESH TO STRONG WINDS WITHIN ABOUT 150 NM N SEMICIRCLE  
OF THE LOW CENTER. MODERATE TO ROUGH SEAS ARE WITHIN THESE WINDS.  
MODERATE TO FRESH WINDS DOMINATE THE NW CORNER OF THE FORECAST  
REGION. SIMILAR WIND SPEEDS ARE ALSO NOTED FROM 13N TO 20N W OF  
130W. MODERATE SOUTHERLY WINDS AND MODERATE SEAS ARE FOUND SOUTH  
OF THE MONSOON TROUGH. ELSEWHERE, MODERATE OR WEAKER WINDS AND  
MODERATE SEAS ARE PREVALENT.  
 
FOR THE FORECAST, A RIDGE WILL REMAIN IN CONTROL OF THE WEATHER  
PATTERN ACROSS THE N WATERS, PARTICULARLY N OF 10N AND W OF 120W  
WHERE MODERATE TO LOCALLY FRESH NE TO E WINDS ARE EXPECTED EARLY  
THIS WEEK. A TIGHTENING PRESSURE GRADIENT BETWEEN THE RIDGE AND  
A WESTWARD-MOVING LOW PRESSURE ALONG THE MONSOON TROUGH WILL  
SUPPORT FRESH TO STRONG WINDS AND ROUGH SEAS NEAR THE LOW CENTER  
THROUGH AT LEAST THE MIDDLE PORTION OF THIS WEEK.  
 
 
GR  
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