000 AXPZ20 KNHC 140901 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU MAY 14 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 0845 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 08N84W TO 08N100W. THE ITCZ EXTENDS FROM 08N100W TO 11N110W. A WEAK MONSOON TROUGH THEN CONTINUES FROM 11N110W TO 10N127W WHERE THERE IS A BREAK WITH 1009 MB LOW PRES NEAR 09N131W THEN RESUMES ONCE AGAIN FROM 07N134W TO BEYOND 06N140W. SCATTERED MODERATE CONVECTION IS FROM 00N TO 05N BETWEEN 85W AND 90W...WITHIN 120 NM SE OF THE AXIS BETWEEN 91W AND 98W...WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 104W AND 110W...FROM 03N TO 10N BETWEEN 108W AND 110W...WITHIN 240 NM SE OF A LINE FROM 10N118W TO 05N126W... WITHIN 90 NM N OF THE AXIS BETWEEN 114W AND 127W...AND ALSO WITHIN 360 NM NW OF A LINE FROM 05N132W TO 01N140W. ...DISCUSSION... A 1027 MB SUBTROPICAL HIGH CENTERED NW OF THE AREA NEAR 34N149W EXTENDS A RIDGE SE THROUGH 26N133W TO NEAR 18N106W. THE PRESSURE GRADIENT BETWEEN THIS RIDGE AND LOW PRES EMBEDDED IN THE MONSOON TROUGH NEAR 09N131W IS GENERATING MODERATE TO FRESH NE TRADE WINDS DURING THE OVERNIGHT HOURS. THE SURFACE RIDGE IS EXPECTED TO SHIFT SW OVER THE NEXT 24-48 HOURS AS A COLD FRONT APPROACHES THE HIGH FROM THE NW AND A SERIES OF IMPULSES ON THE W SIDE OF THE UPPER TROUGH CENTERED ALONG 125W N OF 20N DIP INTO THE NE PORTION OF THE AREA. A TIGHTER PRESSURE GRADIENT WILL DEVELOP BETWEEN THE SUBTROPICAL RIDGE AND THE MONSOON TROUGH/ITCZ WHICH WILL ALLOW TRADES TO PICK UP TO A SOLID FRESH BREEZE BY THIS AFTERNOON. ONE OF THE IMPULSES IN THE AFOREMENTIONED UPPER TROUGH CENTERED NEAR 125W IS EXPECTED TO LIE OFF THE SOUTHERN CALIFORNIA COAST BY FRI MORNING. A STRONG SURFACE REFLECTION IS EXPECTED WITH THIS IMPULSE. NW SWELL ASSOCIATED WITH THE SYSTEM WILL BUILD SEAS TO 8 FT N OF 29N BETWEEN 126W AND 134W BY THIS EVENING. A COLD FRONT WILL MOVE INTO THE N CENTRAL WATERS FRI MORNING AND IS EXPECTED TO APPROACH THE COAST NEAR ENSENADA FRI AFTERNOON BEFORE MOVING INTO THE NORTHERN GULF OF CALIFORNIA. WINDS IN THE PACIFIC WILL REACH A FRESH TO STRONG BREEZE ON THE LEADING EDGE OF THE FRONT BY LATE TONIGHT THEN ALSO BEHIND THE FRONT BY EARLY FRI BEFORE DIMINISHING TO FRESH LEVELS LATER FRI. ASSOCIATED SEAS IN THE NW SWELL WILL BUILD TO 11 FT ALONG 30N. A VAST ANTICYCLONE ALOFT IS CENTERED NEAR 11N116W AND EXTENDS AN UPPER RIDGE AXES W TO BEYOND 11N140W AND TO THE E TO 12N99W. THE MONSOON TROUGH AND ITCZ ARE PARTICULARLY CONVECTIVELY ACTIVE IN THE VICINITY OF THIS ANTICYCLONE WHERE UPPER LEVEL DIVERGENCE IS ENHANCING LIFT OF THE MOIST LOW-LEVELS AROUND THE AXIS. THE ABUNDANT CONVECTION IN THIS AREA IS ASSOCIATED WITH A KELVIN WAVE PROPAGATING INTO THE REGION. FORECAST GUIDANCE SUGGESTS THAT THE ANTICYCLONE WILL SHIFT WNW TO NEAR 12N124W THROUGH FRI EVENING...CARRYING THE BULK OF THE CONVECTION W WITH IT. LONG-PERIOD CROSS-EQUATORIAL SOUTHERLY SWELL AT 17-20 SECONDS CONTINUES TO IMPACT THE MEXICAN AND CENTRAL AMERICAN COASTS WITH THE LONGEST PERIOD WAVES NOW PROPAGATING INTO THE SOUTHERN CALIFORNIA COASTAL WATERS. THIS LONG PERIOD SWELL IS PRODUCING HAZARDOUS SURF AND BEACH CONDITIONS WHICH SHOULD BEGIN TO IMPROVE THROUGH THE DAY TODAY. SEA HEIGHTS OF 8 FT OR GREATER IN THE SW SWELL ARE PRIMARILY IMPACTING THE AREA S OF A LINE FROM 03.4S85W TO 03N98W TO 00N120W EXCLUDING THE LEE OF THE GALAPAGOS ISLANDS. THESE SEAS OVER 8 FT WILL SUBSIDE N OF THE EQUATOR BY THIS EVENING. GAP WINDS... GULF OF CALIFORNIA...THE PRES GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND TROUGHING OVER THE SW UNITED STATES HAS INCREASED DURING THE OVERNIGHT HOURS AS A NEW IMPULSE ALOFT HAS MOVED INTO THE BASE OF THE MEAN UPPER TROUGH ALONG THE CALIFORNIA COAST. FRESH TO NEAR GALE FORCE S-SW WINDS ARE BLOWING IN THE GULF N OF 29.5N WITH THE STRONGEST WINDS FUNNELING THROUGH MOUNTAIN PASSES. THESE WINDS WILL CONTINUE DESPITE THE WEAKENING SUBTROPICAL RIDGE AS THIS IMPULSE TURNS THE UPPER TROUGH NEGATIVE TILT AND STRENGTHENS THE SURFACE TROUGHING. SEAS ARE EXPECTED TO REACH AS HIGH AS 8 FT. WINDS SHOULD BRIEFLY DIMINISH AROUND SUNRISE FRI AS THE SURFACE SYSTEM MOVES EASTWARD...BUT WILL RESUME AHEAD OF THE COLD FRONT MOVING INTO THE NORTHERN GULF OF CALIFORNIA LATE FRI. GULF OF TEHUANTEPEC...A SURFACE TROUGH MOVING W OFF THE YUCATAN PENINSULA INTO THE BAY OF CAMPECHE COMBINED WITH RIDGING ALONG THE SW GULF OF MEXICO COAST IS ALLOWING FOR FRESH TO STRONG NORTHERLY WINDS WHICH ARE FUNNELING THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC. THESE WINDS WILL DIMINISH TO LESS THAN 20 KT IN THE AFTERNOON AS HIGH PRESSURE NE OF THE AREA WILL SHIFT FARTHER AWAY LOOSENING THE PRESSURE GRADIENT. SEAS IN MIXED NE AND SW SWELL WILL SUBSIDE TO LESS THAN 8 FT BY THIS EVENING. GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN RIDGING OVER THE NW CARIBBEAN AND TROUGHING NEAR THE MONSOON TROUGH IS SUPPORTING FRESH TO NEAR GALE FORCE NE WINDS IN THE GULF OF PAPAGAYO WHICH WILL CONTINUE THROUGH THE EARLY AFTERNOON BEFORE DIMINISHING. WINDS MAY LOCALLY APPROACH THE STRONG LEVEL DURING THE LATE NIGHT AND EARLY MORNING HOURS THROUGH THE NEXT 48 HOURS WITH THE ASSISTANCE OF NOCTURNAL DRAINAGE FLOW. SEAS ARE UP TO 11 FT IN MIXED FRESH NE SWELL AND LONGER PERIOD SW SWELL WHICH WILL GRADUALLY SUBSIDE TO LESS THAN 8 FT BY 48 HOURS. GULF OF PANAMA...FRESH NORTHERLY FLOW IN THE GULF COMBINED WITH LONG PERIOD SW SWELL IS RESULTING IN COMBINED SEAS OF 8 FT JUST DOWNWIND OF THE IMMEDIATE GULF. THESE SEAS WILL SUBSIDE LATER THIS MORNING AS THE SW SWELL DECAYS AND WITH THE NORTHERLY FLOW WEAKENING TO MODERATE STRENGTH. $$ LEWITSKY