000
AXPZ20 KNHC 081530
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN SEP 08 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.

...TROPICAL WAVES...

THE FAR SOUTHERN EXTENT OF A TROPICAL WAVE IS FORECAST TO MOVE 
OFF THE COAST OF NICARAGUA TODAY. THE TROPICAL TROPICAL WAVE IS 
POORLY DEFINED AND WILL DIMINISH FURTHER AS IT SHIFTS W TROUGH 
NORTHERN CENTRAL AMERICA AND THE ADJACENT PACIFIC WATERS. WHILE 
THERE IS NO INDICATION IT WILL ENHANCE GAP WIND FLOW INTO THE 
GULF OF TEHUANTEPEC...IT MAY RESULT IN AN INCREASE IN CONVECTION 
OVER NORTHERN CENTRAL AMERICA...SOUTHERN MEXICO AND ADJACENT 
COASTAL WATERS OVER THE NEXT COUPLE OF DAYS.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM 12N87W TO 15N110W TO 
12N130W TO 09N140W. SCATTERED MODERATE CONVECTION IS NOTED 
WITHIN 90 NM S OF AXIS BETWEEN 105W AND 110W. SCATTERED MODERATE 
CONVECTION NOTED FROM 10N TO 13N BETWEEN 110W AND 125W. 

...DISCUSSION... 

THE REMNANTS OF LORENA APPEAR TO BE LARGELY DISSIPATED OFF THE 
COAST OF BAJA CALIFORNIA SUR...ALTHOUGH AT 12 UTC A SHIP 
REPORTED SW WINDS AT 25 KT ON THE SE SIDE OF THE REMNANT LOW. AN 
ALTIMETER PASS FROM 07 UTC DIRECTLY OVER THE LOW PRES AREA 
SHOWED SEAS ONLY TO 5 FT...BUT SLIGHT HIGHER SEAS ARE STILL 
LIKELY THROUGH THE REMAINDER OF THE DAY. DESPITE A MODEST BURST 
OF CONVECTION DURING THE DIURNAL MAXIMUM THIS 
MORNING...CONVECTION HAS BEEN ALMOST NON EXISTENT OVER THE PAST 
24 HOURS. THE LOW WILL OPEN INTO TO TROUGH LATER TODAY.

A SURFACE TROUGH IS ANALYZED FROM THE COAST OF MEXICO NEAR CABO 
CORRIENTES SOUTHWARD TO 13N105W. SOME CYCLONIC TURNING IS NOTED 
ON SATELLITE IMAGERY MOSTLY IN THE LOWER TO MID LEVELS OF THE 
ATMOSPHERE WHERE A TROUGH EXTENDS FROM OFF THE COAST OF THE 
SOUTHERN BAJA PENINSULA TO 14N103W. THERE IS BROAD CONSENSUS 
AMONG GLOBAL MODELS SHOWING LOW PRES DEVELOPING OVER THE NEXT 24 
HOURS ALONG THE MONSOON TROUGH OFF THE COAST OF CENTRAL MEXICO 
NEAR 16N107W. SW FLOW INTO THE MONSOON TROUGH S OF THE LOW WILL 
INCREASE AS THE LOW FORMS...ALLOWING FOR INCREASED CONVECTION 
AND ENHANCING THE LOW PRES. EXPECT SW WINDS AT LEAST TO 20 KT 
WITH SEAS BUILDING TO 8 FT WITH THE NEXT 36 TO 48 HOURS FROM 08N 
TO 12N BETWEEN 100W AND 115W. THE WEAKENING TROPICAL WAVE MOVING 
THROUGH CENTRAL AMERICA WILL DRIFT INTO THE AREA BY MID WEEK. 
MAJOR MODELS INCLUDING THE GFS...ECMWF...AND UKMET SHOW LOW PRES 
AREAS DEEPENING LATER IN THE WEEK...POSSIBLY DUE TO THE 
INTERACTION OF THE TROPICAL WAVE AND THE MONSOON TROUGH NEAR THE 
LOW PRES.

AREAS OF CONVECTION HAD BEEN FLARING SOUTH OF THE MONSOON TROUGH 
BETWEEN 105W AND 125W...ALTHOUGH IS HAS MOSTLY DIMINISHED OVER 
THE PAST SEVERAL HOURS. THIS IS A RESULT OF SW FLOW ALREADY 
INCREASING. A 05 UTC ASCAT PASS INDICATED WINDS TO 20 KT IN THIS 
AREA. ANOTHER AREA OF LOW PRES IS EXPECTED TO FORM ALONG THE 
MONSOON TROUGH FARTHER W ALONG THE MONSOON TROUGH BETWEEN 125W 
AND 130W OVER THE NEXT 24 TO 48 HOURS. THIS IS THE RESULT OF A 
LOBE OF MID LEVEL TROUGHING MIGRATING WSW AND INTERACTING WITH 
THE MONSOON TROUGH. 

CROSS-EQUATORIAL SOUTHERLY SWELL WITH 8 TO 9 FT SEAS WILL PUSH 
AS FAR N AS 02N BETWEEN 105W AND 120W BY LATE MON NIGHT. 
OTHERWISE...1024 MB HIGH PRES CENTERED WELL N OF THE BASIN NEAR 
42N135W IS MAINTAINING A FLAT PRES GRADIENT ACROSS THE REMAINDER 
OF THE WATERS WITH MODERATE WINDS AND SEAS THROUGH THE NEXT 48 
HOURS.

$$
CHRISTENSEN