000
AXPZ20 KNHC 300848
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC WED SEP 30 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 
0830 UTC.               

...SPECIAL FEATURES...

DOWNGRADED TROPICAL DEPRESSION MARTY CENTERED NEAR 16.1N 102.0W 
AT 30/0900 UTC OR 100 NM SSW OF ZIHUATANEJO MEXICO AND 217 NM SE 
OF MANZANILLO MEXICO MOVING W AT 4 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 1002 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH 
GUSTS TO 40 KT. SCATTERED MODERATE CONVECTION IS BETWEEN 45 NM 
AND 240 NM IN THE NE QUADRANT OF MARTY...PRIMARILY OVER LAND. 
MARTY WILL CONTINUE TO PRODUCE HEAVY RAINFALL IN THE MEXICAN 
STATE OF GUERRERO FROM THE SIERRA MADRE DEL SUR MOUNTAINS 
TOWARDS THE COAST WITH LIFE-THREATENING FLASH FLOODS AND 
MUDSLIDES POSSIBLE. A STORM SURGE IS EXPECTED TO PRODUCE COASTAL 
FLOODING IN AREAS OF ONSHORE FLOW AND SWELLS GENERATED BY MARTY 
WILL CAUSE LIFE-THREATENING SURF AND RIP CURRENTS ALONG PORTIONS 
OF SOUTHERN MEXICO. MARTY IS FORECAST TO CONTINUE TO WEAKEN AND 
WILL BECOME A REMNANT LOW BY 24 HOURS. SEE LATEST NHC FORECAST/ 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR   
MORE DETAILS.

A 1008 MB LOW IS EMBEDDED IN THE MONSOON TROUGH NEAR 12.5N119W. 
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 240 
NM IN THE S QUADRANT OF THE LOW. THE LOW IS EXPECTED TO DRIFT NE 
IN ENHANCED MONSOONAL FLOW THROUGH TODAY AS IT SLOWLY DEEPENS. 
BY THU...ENVIRONMENTAL CONDITIONS WILL BECOME MORE FAVORABLE FOR 
TROPICAL CYCLONE DEVELOPMENT. CROSS-EQUATORIAL SOUTHERLY SWELL 
MIXING WITH SW WIND WAVES S OF THE MONSOON TROUGH AXIS WILL 
PRODUCE 8-10 FT SEAS S OF THE LOW ACROSS S CENTRAL WATERS 
DURING THE NEXT COUPLE OF DAYS. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            

THE MONSOON TROUGH AXIS EXTENDS FROM 09N79W TO 12N98W THEN 
RESUMES FROM 14N108W TO LOW PRES NEAR 12.5N119W 1008 MB TO 
07N130W TO 12N140W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION IS WITHIN 180 NM S OF THE COAST OF CENTRAL AMERICA E 
OF 88W...WITHIN 180 NM S OF THE AXIS BETWEEN 108W AND 114W...AND 
ALSO WITHIN 180-240 NM SE OF THE AXIS BETWEEN 122W AND 132W. 
ISOLATED MODERATE CONVECTION IS WITHIN 300 NM SW OF THE AXIS W 
OF 132W.

...DISCUSSION...

A SURFACE RIDGE EXTENDS ACROSS THE AREA FROM 1021 MB HIGH PRES  
W OF THE DISCUSSION WATERS NEAR 32N151W THROUGH 28N137W TO 
23N120W. THE RIDGE IS BEING COMPROMISED BY A STATIONARY FRONT 
WHICH EXTENDS FROM 1011 MB LOW PRES NEAR 35N131W THROUGH 32N126W 
TO 28N130W TO 20N140W. THE FRONT IS FORECAST TO BECOME DIFFUSE 
DURING THE NEXT 24 HOURS WHILE SEAS UP TO 7 FT W OF IT GRADUALLY 
SUBSIDE. THE RIDGE WILL GRADUALLY STRENGTHEN BY THE END OF THE 
WEEK ALLOWING FOR FRESH WINDS TO DEVELOP OFF OF THE CALIFORNIA 
COAST AND ALONG THE NORTHERN PORTION OF THE BAJA CALIFORNIA 
PENINSULA. THESE WINDS WILL BUILD SEAS TO 8 FT N OF 28N E OF 
118W BY 48 HOURS.

GAP WINDS...                                                     
GULF OF TEHUANTEPEC...HIGH PRES BUILDING OVER THE WESTERN GULF 
OF MEXICO WILL INCREASE THE PRES GRADIENT ACROSS THE CHIVELA 
PASS BY EARLY THU. A SURGE OF STRONG TO NEAR GALE FORCE N-NE 
WINDS IS EXPECTED TO STRETCH THROUGH THE GULF OF TEHUANTEPEC 
DURING THE OVERNIGHT HOURS BY 00 UTC THU...WITH THE STRONGEST 
WINDS EXPECTED IN THE EARLY MORNING HOURS WHEN NOCTURNAL 
DRAINAGE FLOW OCCURS. SEAS ARE FORECAST BY THE LATEST TAFB-NWPS 
WAVE MODEL RUN TO BUILD UP TO 10-11 FT BY THU MORNING WITH SEAS 
UP TO 12 FT BY FRI MORNING.
  
$$
LEWITSKY