000 AXPZ20 KNHC 300319 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC MON NOV 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 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. N TO NE WINDS HAVE INCREASED SLIGHTLY TONIGHT TO 30-40 KT ACROSS THE GULF AND DOWNWIND TO NEAR 14N96W...WITH PEAK SEAS AROUND 13 FT. WINDS ARE EXPECTED TO REMAIN IN THIS RANGE OVERNIGHT WITH SEAS REACHING 12-15 FT...BEFORE WINDS DIMINISH TO MINIMAL GALES MON MORNING. THE PRESSURE GRADIENT IS FORECAST TO WEAKEN ON MON...WITH NOCTURNAL WINDS ONLY PEAKING AT 30 KT OVER A MUCH SMALLER AREA BOTH 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 04.5N90W TO 04.5N108W TO 09N118W TO 08.5N126W TO LOW PRES 1006 MB NEAR 06N137.5W TO BEYOND 04N140W. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION NOTED WITHIN 90 NM S AND 270 NM NW OF AXIS BETWEEN 122W AND 142W. ...DISCUSSION... THE REMNANT LOW OF SANDRA HAS DISSIPATED ACROSS SINALOA MEXICO ALONG THE WESTERN SLOPES OF THE SIERRA MADRE OCCIDENTALES THIS AFTERNOON. IN ITS WAKE...STRONG HIGH PRESSURE OVER THE GREAT BASIN OF THE U.S. WILL COMBINE WITH TROUGHING ACROSS WESTERN MEXICO AND THE SIERRA MADRES TO INDUCE A QUICK SURGE OF NW TO N WINDS OF 20-25 KT DOWN THE ENTIRE LENGTH OF THE GULF OF CALIFORNIA OVERNIGHT. 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 WILL THEN DIMINISH SLIGHTLY TO 20- 25 KT EARLY TUE WITH SEAS OF 8-9 FT ACROSS THE SOUTHERN HALF OF THE GULF. A WEAK COLD FRONT IS DISSIPATING ACROSS N PORTIONS OF THE AREA FROM 30N120W TO 24.5N133W...WHILE A 1021 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 12-14N AND W OF 125W IS SUPPORTING AN ELONGATED AREA OF 20- 25 KT NE WINDS OCCURRING S OF 21N TO A LINE FROM 20N114W TO 14N120W TO 05.5N140W. 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 JUST REACHING THE FAR NW CORNER OF THE AREA LATE THIS EVENING AND WILL DRAG EASTWARD ACROSS NW PORTIONS OF THE AREA TONIGHT AND MONDAY BEFORE DISSIPATING. THE PRESSURE GRADIENT NEAR THIS FRONT IS WEAK AND EXPECT WINDS OF 15 KT OR LESS ON EITHER SIDE OF THE FRONT. HOWEVER LARGE NW SWELL GENERATED BEHIND THE FRONT WITH RAISE SEAS IN THE RANGE OF 10-13 FT ACROSS THE NW WATERS THROUGH MON MORNING BEFORE GRADUALLY SUBSIDING TO 10-11 FT MON EVENING. SCATTERED TO NUMEROUS STRONG CONVECTION IS OCCURRING FROM 04N TO 14N 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 SUSTAINING DEEP CONVECTION NEAR 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 AND EXTEND SOUTHWARD TO AROUND 06N TONIGHT THROUGH EARLY ON MON...THEN DIMINISH TO 15-20 KT EARLY MON AFTERNOON BEFORE INCREASING TO AROUND 20 KT AGAIN LATE MON NIGHT...WITH RESULTANT SEAS OF 5-7 FT. $$ STRIPLING