000
AXPZ20 KNHC 260332
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU SEP 26 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 10N85W TO LOW PRES NEAR 
16N100W TO 13N112W TO LOW PRES NEAR 14N123W TO 12N125W. THE ITCZ 
CONTINUES FROM 12N125W TO BEYOND 10N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 60 NM S OF CENTRAL AMERICA E OF 84W... 
WITHIN 75 NM IN THE NW SEMICIRCLE OF THE FIRST LOW...WITHIN 60 
NM S OF THE MONSOON TROUGH BETWEEN 113W AND 115W...FROM 13N TO 
15N BETWEEN 115W AND 118W...AND ALSO WITHIN 150 NM S OF THE ITCZ 
BETWEEN 132W AND 138W.

...DISCUSSION...

SATELLITE WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL ANTICYCLONE  
LOCATED NEAR SOUTHERN BAJA CALIFORNIA AT 23N111W WITH RIDGING 
COVERING MOST OF THE CENTRAL PORTION OF THE WATERS. MAINLY DRY 
AND STABLE CONDITIONS ARE PRESENT N OF 20N E OF 130W...AND N OF 
14N W OF 130W. TO THE SW OF THE ANTICYCLONE...AN INVERTED 
SHORTWAVE UPPER LEVEL TROUGH EXTENDS FROM NEAR 20N128W TO 
10N130W WITH ISOLATED TO WIDELY SCATTERED SHOWERS POSSIBLE 
WITHIN 180-300 NM E OF THE TROUGH. TO THE E OF THE TROUGH AND SE 
OF THE ANTICYCLONE...FAIRLY DEEP LAYERED EASTERLY FLOW IS NOTED. 
THIS FLOW PATTERN CONTINUES TO ADVECT UPPER LEVEL DEBRIS 
MOISTURE FROM CONVECTION ALONG THE COAST OF SOUTHERN MEXICO...AS 
WELL AS JUST INLAND AND S OF SOUTHEASTERN MEXICO AS IS DESCRIBED 
IN THE CONVECTION SECTION ABOVE. 
 
AT THE SURFACE...A NEARLY STATIONARY 1031 MB HIGH PRES IS WELL 
NW OF THE DISCUSSION AREA NEAR 39N147W WITH A RIDGE STRETCHING 
SE THROUGH 32N130W TO 28N122W. A WEAK TROUGH EXTENDS JUST SE OF 
THE RIDGE FROM NEAR 26N117W TO 23N128W. THE TIGHT PRES GRADIENT 
BETWEEN THE RIDGE AND TROUGH IS RESULTING IN NW 25-30 KT WINDS 
JUST N OF THE NE PART OF THE AREA. THESE WINDS ARE FORECAST TO 
STRENGTHEN TO MINIMAL GALE INTENSITY N OF 32N THIS EVENING. THE 
RESULTANT SWELLS WITH PERIODS OF 15-18 SECONDS WILL PROPAGATE SE 
INTO MUCH OF THE NE AND N CENTRAL SECTIONS OF THE AREA THROUGH 
THE NEXT 48 HOURS...PRODUCING SEAS OF 10-12 FT THIS EVENING N OF 
26N BETWEEN 119W AND 127W WITH 12-14 FT SEAS FROM 30N TO 32N. 
THE SURROUNDING AREA OF SEAS OF 8 FT OR GREATER COVERS THE 
REMAINDER OF THE WATERS N OF 20N W OF 116W. THE NW SWELLS WILL 
CONTINUE TO SEEP TO THE SE-S THROUGH FRI...GRADUALLY DECAYING.

1006 MB LOW PRES IS EMBEDDED IN THE MONSOON TROUGH NEAR 16N100W. 
THIS LOW IS UNDERNEATH AN AREA OF UPPER EASTERLY SHEAR WITH THE 
MAJORITY OF THE DEEP CONVECTION DISPLACED TO THE S-SW OF THE LOW 
LEVEL CIRCULATION. ASSOCIATED WINDS ARE MODERATE TO FRESH WITH 
SEAS CURRENTLY LESS THAN 8 FT. THE LOW IS FORECAST TO MOVE TO 
THE W-NW DURING THE NEXT 48 HOURS JUST S OF THE COAST OF MEXICO. 
ADDITIONAL HEAVY RAINS MAY SPREAD OVER AREAS OF SW MEXICO THAT 
ARE ALREADY WELL SATURATED DUE TO PREVIOUS TROPICAL SYSTEMS... 
WITH THE RISK OF FLASH FLOODING AND MUDSLIDES PARTICULARLY 
ACROSS SOUTHERN AND SOUTHWESTERN MEXICO THROUGH THE END OF THE 
WEEK.

1008 MB LOW PRES IS WELL TO THE W...ALSO EMBEDDED IN THE MONSOON 
TROUGH...NEAR 13.5N123W. REMNANT 8 FT SEAS ARE OCCURRING WITHIN 
120 NM OF THE LOW CENTER...INDUCED BY EARLIER FRESH TO STRONG 
WINDS AS WELL AS LONG PERIOD NW SWELL SPREADING ACROSS THE AREA. 
THE LOW IS FORECAST TO MOVE EASTWARD...GRADUALLY DISSIPATING 
DURING THE NEXT 24 HOURS.

CROSS-EQUATORIAL SE SWELL IS IMPACTING THE FAR SW WATERS WITH 8-
9 FT SEAS S OF A LINE FROM 00N110W TO 07N122W TO 07N129W TO 
04N140W. THIS AREA OF SE SWELL WILL GRADUALLY DECAY TO LESS THAN 
8 FT BY FRI MORNING.

$$
LEWITSKY