000 AXPZ20 KNHC 071005 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT MAR 07 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 FEATURE... A STORM WARNING REMAINS IN EFFECT FOR THE GULF OF TEHUANTEPEC. A VERY STRONG EARLY MARCH HIGH PRES RIDGE ENTRENCHED OVER CENTRAL AND SOUTHERN MEXICO CONTINUES TO MAINTAIN A TIGHT PRES GRADIENT THROUGH THE CHIVELA PASS AND GULF OF TEHUANTEPEC. THIS IS SUPPORTING MINIMAL STORM FORCE WINDS FLUCTUATING 40-50 KT THROUGH THE GULF OF TEHUANTEPEC...WITH GALE FORCE WINDS EXTENDING DOWNWIND SOME 220-240 NM. SCATTEROMETER DATA FROM LATE LAST NIGHT NICELY CAPTURED THE SWATH OF THESE ONGOING WINDS ACROSS THE GULF. LARGE SEAS OF 18-26 FT ARE FORECAST WITH THE STORM WINDS WHILE SEAS OF 14-20 FT ARE FORECAST WITH THE GALE FORCE WINDS. THE PRES GRADIENT WILL SLACKEN SLIGHTLY THIS AFTERNOON...WITH THE STORM FORCE WINDS DIMINISHING TO A STRONG GALE AROUND 1800 UTC...THEN CONTINUE TO WEAKEN THROUGHOUT THE DAY SAT INTO TONIGHT WITH ONLY MINIMAL GALE CONDITIONS EXPECTED EARLY SUN MORNING...AND BELOW GALE FORCE WINDS BY SUN AFTERNOON. THIS WILL BE THE THIRD STORM EVENT TO OCCUR ACROSS THE GULF OF TEHUANTEPEC DURING THIS COLD SEASON. THE NEXT TEHUANTEPEC EVENT IS EXPECTED TO BEGIN WITH 20-25 KT NORTHERLY WINDS ON TUE NIGHT...GRADUALLY INCREASING TO A MINIMAL GALE ON WED EVENING THROUGH SUNRISE ON THU. A GALE WARNING IS IN EFFECT FOR THE GULF OF PAPAGAYO. THE SAME STRONG PRES GRADIENT IS COMBINING WITH STRONG TRADE WINDS ACROSS THE CENTRAL AND SW CARIBBEAN TO SUPPORT STRONG GAP WINDS ACROSS THE GULF OF PAPAGAYO. WINDS ARE EXPECTED TO PULSE TO MINIMAL GALE FORCE WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW THROUGH REST OF TONIGHT AND EARLY MORNING...AND START UP AGAIN TONIGHT INTO EARLY SUN MORNING...WITH WINDS OF 20-30 KT EXTENDING DOWNWIND TO NEAR 95W WITH SEAS IN THE 9-14 FT RANGE WITH HIGHER SEAS OF 10-16 FT BETWEEN 91W AND 94W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE ITCZ AXIS EXTENDS FROM 06N87W TO 02N100W TO 03N108W...THEN RESUMES AT 03N112W TO 03N122W WHERE IT ENDS. ANOTHER ITCZ SEGMENT EXTENDS FROM 04N135W TO W OF THE AREA AT 02N140W. A SECOND ITCZ AXIS IS NOTED S OF THE EQUATOR...AND EXTENDS FROM 01S120W TO 03S131W TO 03S140W. THE CLIMATOLOGICAL PATTERN OF THE ITCZ DURING MONTHS OF MARCH AND APRIL TYPICALLY EXHIBITS DUAL ITCZ...ONE N OF THE EQUATOR AND THE OTHER ONE TO THE S OF THE EQUATOR AS PRESENTLY OBSERVED. SATELLITE IMAGERY SHOWS NO SIGNIFICANT CONVECTION WITH BOTH ITCZ FEATURES. ...DISCUSSION... UPPER LEVELS...A BROAD ZONAL FLOW PATTERN COVERS THE AREA W OF 130W AS BROAD RIDGING EXISTS S OF 29N BETWEEN 120W AND 130W. A RATHER PRONOUNCED JET STREAM BRANCH IS ADVECTING EXTENSIVE MOISTURE IN THE FORM OF OVERCAST TO BROKEN MID/HIGH CLOUDS EASTWARD ACROSS MUCH OF THE WESTERN AND CENTRAL PORTIONS FROM 13N TO 29N W OF 121W. PATCHES OF LOW BROKEN CLOUDS WITH POSSIBLE SCATTERED SHOWERS AND ISOLATED TSTMS ARE UNDERNEATH THESE CLOUDS PRIMARILY W OF 130W. AN UPPER CYCLONE IS OVER FAR SW ARIZONA WITH A TROUGH EXTENDING FROM ITS S TO ACROSS BAJA CALIFORNIA ...AND SSW TO 17N113W TO S OF THE EQUATOR AT 113W. WATER VAPOR SHOWS MODERATE SUBSIDENCE WITH ASSOCIATED DRY AIR WRAPPING AROUND THE UPPER CYCLONE...WHILE THE AFOREMENTIONED UPPER MOISTURE STREAMING EASTWARD IS SHUNTED NEWD TOWARDS NORTHERN MEXICO AND WESTERN TEXAS IN SW FLOW AHEAD OF THE TROUGH. MODERATE TO STRONG SUBSIDENCE IS PRESENT ELSEWHERE S OF 15N AND E OF 121W KEEPING MOISTURE AND INSTABILITY THERE SUPPRESSED. AT THE SURFACE...A STRONG RIDGE EXTENDS SE THROUGH 32N127W TO 23N118W AND TO NEAR 17N109W. HIGH PRES COVERS THE AREA N OF 14N W OF 110W. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES IN THE TROPICAL REGION IS ALLOWING FOR NE-E WINDS OF 20-25 KT FROM 13N TO 16N AND BETWEEN 119W AND 124W WITH SEAS TO 9 FT. WITH THE GRADIENT FORECAST TO STRENGTHEN SLIGHTLY AS THE RIDGE IS NUDGED EASTWARD WITH THE APPROACH OF A FRONTAL SYSTEM CURRENTLY W OF THE AREA...EXPECT THE AREA OF NE-E 20-25 KT TO EXIST FOUND FROM 05N TO 10N BETWEEN 108W AND 120W BY LATE TONIGHT...THEN EXPAND FROM 06N TO 16N W OF 125W AND FROM 06N TO 10N BETWEEN 115W AND 125W BY SUN AFTERNOON...BEFORE SHRINKING TO WITHIN AREA DEFINED FROM 06N TO 14N BETWEEN 122W AND 134W BY LATE SUN NIGHT WITH SEAS BUILDING TO 8-11 FT. REINFORCING NE SWELL...ORIGINATING FROM A STORM EVENT IN THE GULF OF TEHUANTEPEC AND A GALE EVENT IN THE GULF OF PAPAGAYO...WILL PROPAGATE WSW INTO THE TROPICAL WATERS TO THE S OF 13N...AND WILL SPREAD WESTWARD ACROSS THE WATERS BETWEEN 110-120W WELL INTO NEXT WEEK MIXING WITH THE NE TRADE WIND SWELL. A COLD FRONT IS FORECAST TO APPROACH THE FAR NW CORNER OF THE AREA THIS MORNING. A TIGHTENING PRES GRADIENT BETWEEN THE FRONT AND THE ABOVE MENTIONED RIDGE WILL LEAD TO SE-S 20-25 KT WINDS E OF THE FRONT N OF 27N W OF 135W WITH SEAS OF 8-11 FT. THE FRONT IS FORECAST TO BE VERY NEAR 30N140W BY EARLY THIS AFTERNOON...THEN REACH A POSITION FROM 31N139W TO 26N140W BY EARLY TONIGHT AS IT WEAKENS AND BECOME A NEARLY STATIONARY WEAKENING FRONT OVERNIGHT TONIGHT BEFORE IT BEGINS TO DISSIPATE SUN. NW SWELLS WILL FILTER INTO THE NW PART OF THE AREA IN THE WAKE OF THE FRONT...BUT WILL CONTAIN LESS ENERGY WITH THE ONGOING ONES. SEAS WILL THEN LOWER TO AROUND 9 FT N OF 25N AND W OF 136W BY EARLY ON SUN. A FRONTAL TROUGH WILL BE W OF THE AREA LATE SUN. THE SE-S 20-25 KT WINDS WILL DIMINISH TO 20 KT OR LESS BY EARLY ON SUN. GAP WINDS... THE ENHANCED NE WINDS ACROSS THE GULF OF PAPAGAYO WILL ALSO SPREAD N ALONG THE COAST OF NICARAGUA TO THE GULF OF FONSECA MAINLY DURING THE OVERNIGHT AND EARLY MORNING HOURS LIKELY THROUGH MON MORNING. GULF PANAMA...N WINDS OF 20-25 KT ARE FORECAST TO MATERIALIZE NEAR DAYBREAK THIS MORNING BEFORE DIMINISHING TO 15-20 KT EARLY THIS AFTERNOON. THIS WINDS THEN START UP AGAIN LATE TONIGHT N OF 06N BETWEEN 78W AND 80W...AND SPREAD AS FAR S AS 04N BETWEEN 79W AND 81.5W BY EARLY ON SUN WITH SEAS TO 9 FT. BY LATE SUN NIGHT...THIS WINDS ARE FORECAST TO BE N OF 06N BETWEEN 78W AND 80W WITH SEAS LESS THAN 8 FT. $$ AGUIRRE