000 AXPZ20 KNHC 091001 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON MAR 09 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...SPECIAL FEATURES... GULF OF PAPAGAYO GALE WARNING...RAPIDSCAT DATA FROM 2110 UTC YESTERDAY SHOWED A 90 NM WIDE SWATH OF NE 20-30 KT DOWNWIND OF THE GULF OF PAPAGAYO TO NEAR 09N87W. THE LATEST SURFACE OBSERVATION FROM LIBERIA (MRLB) LOCATED IN NORTHERN COSTA RICA REPORTED SUSTAINED WINDS OF 20 KT WITH GUSTS TO 30 KT...WITH THE PAST SEQUENCE OF OBSERVATIONS SHOWING GUSTS TO GALE FORCE FROM 1700 UTC YESTERDAY TO 0100 UTC LAST NIGHT. THE INDUCED SEAS ARE IN THE 8-10 FT RANGE. MINIMAL GALE FORCE WINDS ARE OVER THE GULF AS NOCTURNAL DRAINAGE FLOW GETS UNDERWAY. THESE ARE EXPECTED TO LAST TILL ABOUT 1200 UTC THIS MORNING WITH SEAS TO 11 FT. THE GALE FORCE WINDS THEN DIMINISH TO 20-25 KT BY EARLY THIS AFTERNOON...AND TO 15-20 KT EARLY TONIGHT WITH SEAS TO 8 FT IN A NE SWELL. HOWEVER...RESPITE WILL BE SHORT-LIVED AS BOTH LATEST GFS AND NAM MODEL GUIDANCE SUGGEST THAT A PULSE OF 20-30 KT WINDS BLASTS OFF NORTHERN COSTA RICA AND ACROSS THE GULF LATE TONIGHT INTO EARLY TUE MORNING...AND QUICKLY SHUTS DOWN TO 15-20 KT BY EARLY TUE AFTERNOON BEFORE INCREASING TO 20-25 KT LATE TUE NIGHT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE ITCZ AXIS EXTENDS FROM 04N90W TO 02N100W TO 04N112W TO 03N123W TO 05N130W WHERE IT BRIEFLY ENDS. IT RESUMES AT 05N133W ...AND CONTINUES TO BEYOND 03N140W. A FRAGMENTED SECOND ITCZ REMAINS S OF THE EQUATOR FROM 03S109W TO 03S122W. NO SIGNIFICANT CONVECTION IS NOTED WITH THESE TWO ITCZ AXES. ...DISCUSSION... UPPER LEVELS...A LARGE UPPER LOW MOVING SW IS OBSERVED TO THE NW OF THE AREA NEAR 35N154W. THE LOW IS HELPING TO AMPLIFY BROAD MID/UPPER RIDGE TO ITS SE. THIS RIDGE COVERS THE AREA N OF 17N AND W OF 115W WITH A MEAN AXIS EXTENDING FROM 14N135W NNE TO N OF THE AREA AT 32N133W...AND CONTINUING NNE TO THE FAR NE PACIFIC REGION. A VERY ACTIVE SUBTROPICAL JET STREAM BRANCH ROUNDS THE CREST OF THE RIDGE...THEN DIVES SEWD WHERE IT ROUNDS THE BASE OF AN UPPER TROUGH THAT EXTENDS FROM NORTHERN MEXICO SSW TO 19N109W. THE JET THEN SHARPLY TURNS NE TO ACROSS CENTRAL TEXAS AND THE LOWER MID-WEST REGION. SATELLITE IMAGERY SHOWS AN EXTENSIVE PLUME OF MOSTLY OVERCAST MID/UPPER LEVEL DEBRIS CLOUDINESS...THAT ORIGINATES FROM THE CENTRAL PACIFIC ITCZ CONVECTION...WITHIN ABOUT 700 NM S OF THE JET. THESE CLOUDS ARE BEING ADVECTED EWD INTO THE AREA REACHING AS FAR E AS 118W. THE PLUME THEN DECREASES TO WITHIN 300 NM S OF THE JET E OF 118W FROM WHERE THEY THEN ADVECT EWD ACROSS CENTRAL MEXICO...AND NE FROM THERE TO THE SE CONUS WHERE THEY FAN OUT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE POSSIBLE UNDERNEATH THESE CLOUDS MAINLY W OF 130W...WHILE SCATTERED SHOWERS ARE POSSIBLE OVER THE FAR EASTERN PORTION NEAR THE UPPER TROUGH MENTIONED ABOVE. OVER THE FAR SE PORTION OF THE AREA...A SMALL ANTICYCLONE IS NOTED ON WATER VAPOR TO BE ALONG THE COAST OF ECUADOR WITH A RIDGE EXTENDING N TO THE WESTERN CARIBBEAN SEA. WITH AMPLE STRONG SUBSIDENCE AND DRY ALOFT S OF 18N AND E OF ABOUT 113W AS NOTED ON WATER VAPOR...THE ATMOSPHERE THERE REMAINS VERY STABLE NOT ALLOWING FOR CONVECTIVE ACTIVITY TO DEVELOP. CONFLUENT FLOW ALOFT INTO THE BASE OF THE TROUGH FROM NORTHERN MEXICO TO NEAR 19N109W IS RESULTING IN MODERATE TO STRONG SUBSIDENCE IN ITS WAKE LEADING TO GENERALLY CLEAR SKIES THERE. AT THE SURFACE...A RIDGE EXTENDS FROM A 1026 MB HIGH PRES CENTER POSITIONED WELL N OF THE AREA NEAR 40N131W SEWD TO 32N127W TO 25N122W AND TO NEAR 18N114W. HIGH PRES COVERS THE AREA N OF 16N W OF 114W. THE PRES DIFFERENCE BETWEEN THE RIDGE AND LOW PRES IN THE TROPICS TO ITS SW IS SUPPORTING NE TO E 20-25 KT TRADES FROM 06N TO 14N BETWEEN 122W AND 135W WITH SEAS 9-11 FT. THIS WINDS WERE CAPTURED IN BOTH RAPIDSCAT AND ASCAT FROM LAST NIGHT. THE PRES GRADIENT WILL GRADUALLY RELAX OVER THE NEXT COUPLE OF THE DAYS AS THE RIDGE BREAKS DOWN IN RESPONSE TO A COUPLE OF FRONTS THAT WILL BE IMPACTING THE FAR WESTERN PART OF THE FORECAST REGION. BY THIS EVENING...NE TO E 20-25 KT WINDS ARE FORECAST FROM 07N TO 10N W OF 135W WITH SEAS OF 9-11 FT. REINFORCING NE SWELLS...ORIGINATING FROM THE RECENT GULF OF TEHUANTEPEC STORM FORCE WINDS...AND STRONG TO GALE FORCE WINDS IN THE GULF OF PAPAGAYO WILL CONTINUE TO PROPAGATE WSW INTO THE TROPICAL WATERS REACHING AN AREA CONFINED TO S OF 08N BETWEEN 99W AND 124W BY EARLY ON TUE...THEN DIMINISH IN AREAL COVERAGE TO AN AREA FROM 06N TO 09N BETWEEN 100W AND 107W BY LATE TUE NIGHT WITH SEAS AT THAT TIME SUBSIDING TO 8 FT IN MIXED NE AND SWELL. CROSS EQUATORIAL SOUTHERLY SWELLS MERGING WITH NE SWELLS OVER THE SOUTHERN WATERS E OF 126W ARE BRINGING SEAS OF 8 FT THERE. AS THE SWELL ENERGY SLOWLY DISSIPATES THROUGH WED...THE SEAS WILL RESPOND BY LOWERING TO MOSTLY 6-7 FT AS INDICATED BY THE WAVEWATCH MODEL. AS THE FIRST OF THE TWO COLD FRONTS APPROACHES THE NW PORTION THIS EVENING THE PRES GRADIENT BETWEEN IT AND THE RIDGING MENTIONED ABOVE WILL SUPPORT WILL SUPPORT INCREASING SLY WINDS OF 20-25 KT N OF 24N W OF 138W WITH SEAS OF 9-11 FT. BY LATE TONIGHT...LOW PRES OF 1010 MB IS PROGGED TO NEAR 28N139W WITH THE ASSOCIATED COLD FRONT WEAKENING FROM IT TO 22N140W. WINDS OF 20-25 KT ARE EXPECTED WITHIN 120 NM OF THE LOW IN THE SE QUADRANT. SLY WINDS OF 15-20 KT ARE EXPECTED ELSEWHERE W OF A LINE FROM 32N138W TO 26N137W TO 20N140W BY LATE TONIGHT WITH SEAS 9 FT IN NW SWELLS. BY EARLY TUE AFTERNOON...THE LOW IS FORECAST TO BE NEAR 31N135W 1010 MB WITH THE DISSIPATING COLD FRONT TO 24N138W AND DISSIPATING STATIONARY TO 22N140W. WINDS AT THAT TIME ARE FORECAST TO DIMINISH TO 15-20 KT FROM 27N TO 29N BETWEEN 135W AND 137W WITH SEAS TO 8 FT IN NW SWELLS. BY LATE TUE NIGHT...A FRONTAL TROUGH IS FORECAST TO BE APPROACHING THE NW CORNER OF THE AREA. SEAS TO 9 FT IN NW SWELLS WILL BE ARRIVING IN THE FAR NW CORNER AT THAT TIME. A TROUGH PERSISTS NEAR THE COAST OF COLOMBIA AND CURRENTLY EXTENDS FROM THE COLOMBIAN/PANAMANIAN LOW OF 1004 MB SW TO 04N77W AND TO 01N81W. ISOLATED SHOWERS ARE POSSIBLE NEAR THIS TROUGH. GAP WINDS... GULF OF TEHUANTEPEC...RAPIDSCAT DATA FROM YESTERDAY EVENING AND ASCAT AND ASCAT HIGH RESOLUTION DATA FROM LATE LAST NIGHT BOTH HIGHLIGHTED N WINDS OF 25-30 KT ACROSS THE GULF OF TEHUANTEPEC. THE VERY TIGHT PRES GRADIENT OVER MEXICO AND THE ISTHMUS OF TEHUANTEPEC FROM THE PAST FEW DAYS IS CONTINUING TO SLACKEN. THE 25-30 KT WINDS WILL DIMINISH TO 20-25 KT LATER THIS MORNING ...AND TO 15-20 KT THIS AFTERNOON AS SEAS SUBSIDE FROM 8-11 FT TO 9 FT IN MIXED SWELL TONIGHT. LOOKING AHEAD...THE NEXT TEHUANTEPEC GAP WIND EVENT IS EXPECTED TO BEGIN WITH 20-25 KT NORTHERLY WINDS LATE TUE NIGHT AS REINFORCING HIGH PRES BUILDS ACROSS THE WESTERN GULF OF MEXICO IN THE WAKE OF A NEW COLD FRONT. MODEL GUIDANCE HAS BEEN CONSISTENTLY FORECASTING THESE WINDS TO INCREASE TO MINIMAL GALE FORCE LATE WED NIGHT INTO THU MORNING. GALE CONDITIONS WILL LIKELY PERSIST THROUGH FRI MORNING. GULF OF PANAMA...N TO NE WINDS OF 20-25 KT WILL QUICKLY DIMINISH TO 15-20 KT THIS AFTERNOON. SEAS TO 9 FT WILL LOWER TO LESS THAN 8 FT THIS AFTERNOON. $$ AGUIRRE