000 AXPZ20 KNHC 292218 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SUN NOV 29 2015 UPDATED TO INCLUDE CONVECTION OVER CENTRAL WATERS AND MENTION OF SURFACE TROUGHS 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 2130 UTC. ...SPECIAL FEATURES... GULF OF TEHUANTEPEC GALE WARNING...THE PRESENT SYNOPTIC SET-UP ACROSS THE REGION...WITH HIGH PRESSURE RIDGING SOUTHWARD ACROSS EASTERN MEXICO AND HIGH AMPLITUDE TROUGHING ACROSS THE CENTRAL CARIBBEAN SEA AND ADJACENT W ATLANTIC IS PROVIDING A VERY FAVORABLE ENVIRONMENT FOR THE ONGOING GAP WIND EVENT ACROSS THE NE TROPICAL PACIFIC. GALE FORCE NORTHERLY WINDS CONTINUE TO FUNNEL THROUGH THE GULF OF TEHUANTEPEC AND DOWNSTREAM THIS AFTERNOON...AND ARE EXPECTED TO CONTINUE THIS EVENING THROUGH AROUND NOON TIME ON MONDAY BEFORE DIMINISHING BELOW GALE FORCE MONDAY AFTERNOON. CURRENTLY N TO NE WINDS IN THE RANGE OF 30-35 KT ARE OCCURRING ACROSS THE GULF AND DOWNWIND TO NEAR 13.5N96W...WITH PEAK SEAS AROUND 13 FT. WINDS ARE EXPECTED INCREASE THERE TONIGHT TO 30-40 KT WITH SEAS REACHING 12-15 FT. THE PRESSURE GRADIENT IS FORECAST TO WEAKEN ON MON...WITH NOCTURNAL WINDS ONLY PEAKING AT 30 KT OVER A MUCH SMALLER AREA MONDAY AND TUESDAY NIGHTS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A MONSOONAL CIRCULATION IS NOT CURRENTLY EVIDENT ACROSS THE FAR TROPICAL NE PACIFIC. THE ITCZ EXTENDS FROM 04N92W TO 06N113W TO 09N125W TO 06N135W TO 03N140W. SCATTERED TO NUMEROUS STRONG CONVECTION NOTED WITHIN 270 NM NW OF AXIS BETWEEN 123W AND 140W. ...DISCUSSION... THE REMNANT LOW OF SANDRA IS DISSIPATING ACROSS SINALOA MEXICO AND ALONG THE WESTERN SLOPES OF THE SIERRA MADRE OCCIDENTALES THIS AFTERNOON NEAR 25N107.5W. IN ITS WAKE...STRONG HIGH PRESSURE OVER THE GREAT BASIN OF THE U.S. WILL INTERACT WITH TROUGHING NEAR THE BAJA CALIFORNIA PENINSULA AND INDUCING A QUICK SURGE OF NW-N WINDS OF 20-25 KT DOWN THE ENTIRE LENGTH OF THE GULF OF CALIFORNIA BY EARLY THIS EVENING. THESE WINDS WILL INCREASE TO 25-30 KT BY EARLY ON MON ACROSS CENTRAL PORTIONS OF THE GULF... WITH SEAS BUILDING 8 TO 10 FT. THE WINDS THEN DIMINISH SLIGHTLY BACK TO 20-25 KT EARLY TUE WITH SEAS OF 8-9 FT. A WEAK COLD FRONT EXTENDS ACROSS N PORTIONS OF THE AREA FROM 30N121W TO 27N133W...WHILE A 1023 MB HIGH CENTER IS WSW OF THE FRONT AT 27.5N138W WITH BROAD RIDGING N OF 22N W OF 128W. THE PRESSURE GRADIENT BETWEEN THE RIDGE AND OLD FRONTAL REMNANTS ALONG 12-13N IS SUPPORTING AN ELONGATED AREA OF 20-25 KT NE WINDS OCCURRING S OF 21N TO A LINE FROM 20N115W TO 10N126W TO 06.5N140W. THIS IS RESULTING IN A LARGE AREA OF 8-12 FT SEAS THERE WITH ISOLATED ZONES TO 13 AND 14 FT. THIS AREA OF STRONG NE TRADES IS EXPECTED TO SHIFT WSW AS RIDGING BUILDS SOUTHEASTWARD ACROSS THE NORTHERN FORECAST WATERS TONIGHT THROUGH TUESDAY. ANOTHER COLD FRONT IS ABOUT 120 NM NW OF THE FAR NW CORNER OF THE AREA. THE FRONT WILL BE ON THE WEAK AS IT ENTERS THE FAR NW PART OF THE AREA EARLY THIS EVENING. HOWEVER LARGE NW SWELL WITH RAISE SEAS IN THE RANGE OF 10-13 FT TO THOSE NW WATERS THROUGH MON MORNING. SCATTERED TO NUMEROUS STRONG CONVECTION IS OCCURRING FROM 04N TO13N W OF 123W...TO THE SE OF A STRONG UPPER LEVEL TROUGH MOVING INTO NW PORTIONS. RIPPLES OF UPPER LEVEL SHORTWAVE ENERGY EMBEDDED IN AN ACTIVE SUBTROPICAL JET STREAM BRANCH WILL PROPAGATE TO THE NE ACROSS THAT PORTION OF THE AREA AND AID IN MAINTAINING CONVECTION N OF THE ITCZ THERE. GAP WINDS... AS MENTIONED ABOVE...THE SYNOPTIC PRESSURE PATTERN CONDUCIVE FOR THE ONGOING GULF OF TEHUANTEPEC GALE EVENT IS ALSO VERY FAVORABLE FOR STRONG NE WINDS TO FUNNEL THROUGH THE GULF OF PAPAGAYO...THE GULF OF FONSECA...AND MOST OF THE OTHER GAP WIND PRONE AREAS OF CENTRAL AMERICA THROUGH MAINLY MON MORNING WITH POSSIBLE SMALLER AREAS OF GAP WINDS TO OCCUR LATE MON NIGHT INTO EARLY TUE MORNING. SEAS ASSOCIATED WITH THESE WINDS ARE FORECAST TO BE IN THE 8-9 FT RANGE...BUT SUBSIDE TO LESS THAN 8 FT EARLY ON TUE. FRESH TO BRIEFLY STRONG N WINDS WILL SURGE THROUGH THE GULF OF PANAMA TONIGHT AND EARLY ON MON...THEN DIMINISH TO MODERATE INTENSITY EARLY MON AFTERNOON BEFORE MATERIALIZING AGAIN LATE MON NIGHT WITH RESULTANT SEAS OF 5-7 FT. $$ STRIPLING