000 AXPZ20 KNHC 281559 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU FEB 28 2013 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS NW FROM THE COLOMBIAN COAST AT 03N79W TO 08N86W...THEN TURNS SW TO 03N97W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ THEN WIGGLES W TO 02N130W...THEN TURNS NW THROUGH AN EMBEDDED TROUGH AT 05N135W... WITH THE ITCZ THEN CONTINUING W TO BEYOND 02N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION HAS FLARED WITHIN 90 NM OF THESE POINTS...05.5N78W...04N83W...AND 05N90W. ISOLATED MODERATE CONVECTION IS FLARING ALONG THE ITCZ BETWEEN 122W AND 132W. ...DISCUSSION... GULF OF TEHUANTEPEC...POST FRONTAL NORTHERLY SURGES AT 20 TO 25 KT HAVE ARRIVED IN THE GULF OF TEHUANTEPEC THIS MORNING. THESE N WINDS WILL BE REINFORCED TONIGHT INCREASING TO MINIMAL GALE FORCE AFTER MIDNIGHT. THE GRADIENT WILL CONTINUE TO TIGHTEN SUPPORTING A STRONG GALE AROUND SUNRISE SAT...AND MINIMAL STORM FORCE BY MIDDAY SAT AND CONTINUING THROUGH SUNRISE ON SUN. SEAS ARE EXPECTED TO MAX AROUND 25 FT SAT NIGHT. GULF OF CALIFORNIA...NW TO N WINDS CONTINUE AT 20 TO 30 KT RESULTING IN SEAS TO 11 FT ACROSS THE LONG FETCH AREAS IN THE CENTRAL GULF WATERS. WINDS WILL GRADUALLY DIMINISH TO 20 TO 25 KT ACROSS THE WATERS S OF 29N ON SAT. A NARROW UPPER TROUGH EXTENDS FROM 32N136W TO 26N140W...THEN S INTO AN UPPER CYCLONE AT 16N143W. DRY UPPER AIR IS INDICATED WITHIN 180 NM N AND W OF THE TROUGH AXIS. AN UPPER ANTICYCLONE IS CENTERED AT 13N104W WITH AN UPPER RIDGE EXTENDING NW TO A BROAD CREST AT 28N136W. UPPER DIFFLUENCE IS ENHANCING SCATTERED CONVECTION E OF THE UPPER CYCLONE...ROUGHLY WITHIN 120 NM OF A LINE FROM 12N133W TO 18N136W. DENSE UPPER LEVEL MOISTURE IS NOTED UNDER THE RIDGE FROM 13N TO 25N BETWEEN 120W AND 138W. THE MOISTURE PLUME TURNS E CONTINUING ACROSS NORTHERN MEXICO WITHIN 360 NM EITHER SIDE OF A LINE FROM 23N120W TO 27N95W. AN UPPER RIDGE ALSO DOMINATES THE DEEP TROPICS TO THE E OF 104W MERGING WITH THE ANTICYCLONE AT 13N140W...WITH THE ASSOCIATED UPPER DIFFLUENCE ENHANCING THE SMALL AREAS OF CONVECTION ALONG THE MONSOON TROUGH AND ITCZ AS PREVIOUSLY DESCRIBED. A SURFACE RIDGE EXTENDS FROM 32N130W TO 14N105W WITH A LOW LEVEL TROUGH EMBEDDED IN THE ITCZ FROM 04N136W TO 10N133W. THE PRESSURE GRADIENT SW OF THE RIDGE IS SUPPORTING NE TO E 20 TO 25 KT TRADES IN THE AREA FROM 12N TO 22N TO THE W OF 125W WITH SEAS 9 TO 11 FT. MIXED NE AND NW LONG PERIOD SWELL RESULTS IN COMBINED SEAS OF 7 TO 10 FT ELSEWHERE TO THE N OF 09N W OF 112W. THE TROUGH WILL SHIFT W OF OF 140W ON SAT AS THE AREA OF 20 TO 25 KT TRADES SHIFTS TO THE W OF 130W ON FRI...WITH THE PRESSURE GRADIENT WEAKENING AND ONLY SUPPORTING NE 15 TO 20 KT TRADES ON SAT. $$ NELSON