000 AXPZ20 KNHC 180351 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN JAN 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 UTC. ...SPECIAL FEATURES... GULF OF TEHUANTEPEC GALE WARNING...THE HIGH PRESSURE RIDGE EXTENDING ACROSS THE WESTERN GULF OF MEXICO AND ALONG MEXICO'S EAST COAST HAS WEAKENED DURING THE PAST 24 HOURS...WITH WINDS THERE DIMINISHING CONSIDERABLY. STRONG NORTHERLY WIND FORCING HAS ENDED TEMPORARILY THROUGH THE ISTHMUS OF TEHUANTEPEC WITH GALES ENDING THIS MORNING ACROSS AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC. WINDS THERE ARE CURRENTLY ESTIMATED AT 20-30 KT N OF 15N...AND WILL PERSIST SIMILARLY THROUGH SUN MORNING. HIGH PRES BUILDING INTO SOUTHERN TEXAS AND NE MEXICO ON SUNDAY WILL TIGHTEN THE PRESSURE GRADIENT ONCE AGAIN...WITH WINDS EXPECTED TO BEGIN TO INCREASE LATE SUN MORNING AND REACH MINIMAL GALE AROUND 1500-1800 UTC SUN. PEAK WINDS ARE EXPECTED AT 35 TO 40 KT SUN EVENING AND NIGHT...AND REMAIN AT GALE FORCE THROUGH MON MORNING BEFORE DIMINISHING BELOW GALE FORCE AGAIN. GALES ARE NOT INDICATED BY GLOBAL MODELS ACROSS TEHUANTEPEC DURING THE REMAINDER OF THE WEEK. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 07N75W TO 03N80W TO 08N87W TO 06N90W...THEN TRANSITIONS TO ITCZ CONTINUING ON TO 10N118W... WHERE IT BREAKS...THEN RESUMES FROM 08N123W TO BEYOND 06N140W. SCATTERED MODERATE CONVECTION NOTED FROM 05N TO 10N BETWEEN 83W AND 90W. SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION NOTED FROM 09N TO 19N BETWEEN 111W AND 120W. ...DISCUSSION... A 1012 MB LOW IS CENTERED NEAR 19.5N121.5W MOVING WESTWARD AROUND 10 KT. THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS LOW WAS NON EXISTENT DURING THE PAST SEVERAL HOURS...AND THE LOW CONTINUES TO SLOWLY WEAKEN. STRONG WINDS TO 25 KT WERE OCCURRING WITHIN 270 NM NE AND 210 NM NW QUADRANTS OF THE LOW...WHERE SEAS WERE 8 TO 11 FT...WHILE A BROADER AREA OF FRESH NE TRADEWINDS REMAINED DRAPED ACROSS N AND NW PORTIONS OF THE LOW FROM 16N TO 24N BETWEEN 122W AND 130W. THE LOW IS EXPECTED TO CONTINUE MOVING W THROUGH MON AND CONTINUE TO GRADUALLY WEAKEN...OPENING UP INTO A SURFACE TROUGH BY SUN. AN AREA OF ENHANCED SEAS TO 9- 10 FT WILL ACCOMPANY THE LOW AS IT TRACKS ACROSS WATERS W OF 120W. THESE SEAS WILL EVENTUALLY MERGE WITH LARGE AREA OF LONG PERIOD NW SWELL ACROSS NW CORNER OF DISCUSSION AREA. THE SUBTROPICAL RIDGE EXTENDS SOUTHWARD FROM A 1024 MB HIGH NEAR 32N128W SE TO 23N108W AND SW FROM THE HIGH TO 22N152W. THE PRES GRADIENT BETWEEN THE LOW CENTER MENTIONED ABOVE AND THE RIDGE IS PRODUCING A BROAD ZONE OF FRESH TRADE WINDS S OF 24N W OF 120W. ASSOCIATED WIND WAVES MERGING WITH FADING NW SWELL IS PRODUCING SEAS OF 8-10 FT ACROSS THIS AREA. TRADE WIND WAVES WILL DECAY SLIGHTLY AND PERSIST MAINLY W OF 125W SUN AND MON. A BROAD UPPER LEVEL TROUGH PERSISTS ACROSS CENTRAL PORTIONS OF THE AREA BETWEEN 112W AND 130W...WITH AN EMBEDDED MIDDLE TO UPPER CYCLONE NEAR 14N124W. THIS DEEP LAYERED CYCLONE CONTINUES TO PRODUCE A BROAD ZONE OF LOW TO MIDDLE LEVEL CONVERGENCE E OF 120W...WHERE SCATTERED SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION IS OCCURRING AS DESCRIBED ABOVE. THE CYCLONE WILL BEGIN TO WEAKEN AND SHIFT EASTWARD DURING THE NEXT 24-36 HOURS...WITH ASSOCIATED PERSISTENT CONVECTION GRADUALLY DIMINISHING TO ITS EAST. GULF OF PAPAGAYO...STRONG RIDGING ACROSS CENTRAL AMERICA IS SUPPORTING FRESH TO STRONG NE WINDS PULSING THROUGH PAPAGAYO. PEAK WINDS WILL CONTINUE TO PULSE IN EXCESS OF 25 KT DURING LATE NIGHT AND EARLY MORNING HOURS THROUGH MON...BRIEFLY REACHING 30 KT DURING MAXIMUM NOCTURNAL DRAINAGE FLOW BEFORE SUNRISE...WITH A LULL EACH DAY DURING THE AFTERNOON WITH WINDS LESS THAN 20 KT. SEAS WILL REACH 8-9 FT DOWNWIND OF THE GULF EACH MORNING. GULF OF PANAMA...FRESH TO LOCALLY STRONG N WINDS WILL PERSIST IN THE GULF OF PANAMA DUE TO THE PRESSURE GRADIENT ACROSS THE AREA. MAX SEAS TO 7 FT EXPECTED AT PEAK WINDS DURING THE EARLY MORNING. $$ STRIPLING