000
AXPZ20 KNHC 092115
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC THU APR 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1945 UTC. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              

THE PRIMARY ITCZ AXIS WAS ANALYZED FROM 08N83W TO 04N92W TO 
04N100W TO 02N110W TO 06N133W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 210 NM S OF THE PRIMARY AXIS BETWEEN 97W-102W. A TROUGH 
WAS ANALYZED FROM 12N134W TO 04N137W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION WAS WITHIN 270 NM E OF THE TROUGH AND 
450 NM W OF THE TROUGH FROM 04N-11N.

...DISCUSSION... 

A SURFACE RIDGE AXIS EXTENDS FROM A 1019 MB HIGH CENTER NEAR 
28N125W THROUGH 16N117W TO 14N98W. RECENT ASCAT DATA SHOW A 
SHRINKING AREA OF MODERATE TO FRESH TRADE WINDS SW OF THE RIDGE 
AXIS. THE SUBTROPICAL HIGH IS EXPECTED TO WEAKEN FURTHER AND 
SHIFT SE FRI BEFORE DISSIPATING SAT AS A PROGRESSIVE COLD FRONT 
OVER THE NW PART OF THE AREA ENCROACHES UPON IT. THIS SHOULD 
KEEP TRADE WINDS BELOW THE ADVISORY CRITERIA OF 20-25 KT THROUGH 
THE END OF THE FORECAST PERIOD SAT AFTERNOON. WINDS SHOULD 
REMAIN A SOLID FRESH BREEZE OVER W WATERS THROUGH TOMORROW AS A 
SURFACE TROUGH ENHANCES THE PRESSURE GRADIENT. THIS TROUGH 
CURRENTLY LIES FROM 12N134W TO 04N137W AND IS FORECAST TO SHIFT 
W OF THE AREA FRI AFTERNOON. THE FRESH BREEZE HERE SHOULD HELP 
MAINTAIN SEAS TO 9 FT OVER WATERS W OF 120W THROUGH FRI WHERE 
NW...NE AND SW SWELL ARE COMBINING. SEAS TO 8 FT ARE EXPECTED TO 
SHIFT TO WATERS FROM 10N-14N W OF 137W BY THE END OF THE 
FORECAST PERIOD SAT AFTERNOON. 

THE COLD FRONT ENCROACHING ON THE SUBTROPICAL HIGH STRETCHES 
FROM 32N133W TO 26N140W. SHOWERS LIE PRIMARILY WITHIN 210 NM SE 
OF FRONT FRONT. THE 1924 UTC ASCAT-B PASS SHOWS SW WINDS TO 
ADVISORY CRITERIA LIE WITHIN 120 NM AHEAD OF THE FRONT N OF 29N. 
SEAS WILL SLOWLY BUILD ABOVE 8 FT BEHIND THE FRONT OVERNIGHT 
TONIGHT. ALOFT...THE TROUGH SUPPORTING THIS COLD FRONT IS 
CUTTING OFF FROM THE NORTHERN STREAM. A DEEP LAYERED LOW WILL 
MOVE INTO WATERS N OF 30N BETWEEN 130W-135W TONIGHT INTO FRI. 
THUNDERSTORMS WILL ACCOMPANY THE LOW. WINDS W OF THE LOW WILL 
INCREASE TO A STRONG BREEZE AS SEAS BUILD AS HIGH AS 15 FT. THE 
SYSTEM WILL BREAK DOWN AT THE SURFACE...WITH THE WINDS 
DIMINISHING AND THE FRONT AND LOW DISSIPATING...BY SAT. 

SPLIT FLOW OVER THE CENTRAL PACIFIC HAS DIRECTED A 100 KT JET 
ACROSS THE AREA FROM 18N140W THROUGH 22N120W TO GUAYMAS MEXICO. 
THIS JET IS PROPELLING WANING TROPICAL MOISTURE ALOFT ACROSS THE 
FORECAST AREA. A BAND OF CIRRUS LIES WITHIN 450 NM SE OF THE JET 
AXIS FROM THE OUTFLOW ASSOCIATED WITH THE SURFACE TROUGH OVER SW 
WATERS NORTHEASTWARD INTO THE SOUTHERN GULF OF CALIFORNIA AND 
BEYOND INTO NW MEXICO. THIS UPPER JET IS EXPECTED TO BECOME MORE 
ZONAL AS THE TROUGH ASSOCIATED WITH THE COLD FRONT OVER NW 
WATERS PUSHES SE. THIS SHOULD FURTHER LIMIT THE MOISTURE ALOFT 
PROPELLED INTO MEXICO BY THE JET. 

GAP WINDS...                                                    
GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN RIDGING OVER 
THE WESTERN CARIBBEAN AND THE ITCZ TO THE S IS STRONG ENOUGH TO 
SUPPORT A PULSING FRESH TO STRONG NE BREEZE IN THE GULF OF 
PAPAGAYO WITH THE ASSISTANCE OF NOCTURNAL DRAINAGE FLOW. THE 
WINDS ARE BELOW ADVISORY CRITERIA AT THE MOMENT...BUT ARE 
EXPECTED TO RETURN IN THE EARLY MORNING HOURS FRI. WINDS WILL 
DROP OFF AGAIN FRI AFTERNOON AND RETURN TO ADVISORY CRITERIA SAT 
MORNING...EXCEPT HUG CLOSER TO THE COAST...BEFORE DROPPING OFF 
AGAIN SAT AFTERNOON. 

$$
SCHAUER