000
AXPZ20 KNHC 130930
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI APR 13 2012

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

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

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 04N107W TO 
03N120W TO 02N130W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION IS WITHIN 60-75 NM N OF THE AXIS W OF 126W AND ALSO 
FROM 05N TO 06N BETWEEN 123W AND 129W.

...DISCUSSION...

A BROAD MID TO UPPER LEVEL TROUGH COVERS THE MAJORITY OF THE 
DISCUSSION AREA N OF 19N E OF 135W WITH A MID TO UPPER LEVEL 
RIDGE REACHING FROM 19N135W TO BEYOND 27N140W. A 70-90 KT UPPER 
JET ACCOMPANIES THE TROUGH N OF 28N. WATER VAPOR SATELLITE 
IMAGERY REVEALS STRONG SUBSIDENCE FROM 18N TO 26N E OF 140W TO 
THE COAST OF MEXICO. AN UPPER LEVEL ANTICYCLONE IS POSITIONED 
NEAR 08N110W. MAINLY SW-W/ZONAL FLOW ALOFT COVERS THE WATERS S 
OF 19N.

AT THE SURFACE...A COLD FRONT IS LOCATED FROM 32N130W TO 32N140W 
WITH A PRE-FRONTAL TROUGH FROM 30N130W TO 28N140W. A 0540 UTC 
ASCAT SCATTEROMETER PASS INDICATED FRESH W-NW WINDS IN THE 
VICINITY OF THE FRONT N OF 30N W OF 130W. NW SWELL OF 8-12 FT 
WITH PEAK WAVE PERIODS OF 15-17 SECONDS IS IN THE FAR NW CORNER 
OF THE DISCUSSION WATERS W OF A LINE FROM 30N125W TO 26N140W. 
THIS SWELL WILL PROPAGATE SE COVERING THE WATERS N OF 20N W OF 
110W BY SAT NIGHT. 

NUMEROUS 06 UTC SHIP OBSERVATIONS AND A 0108 UTC WINDSAT PASS 
CAPTURED FRESH NW-N WINDS N OF 23N W OF THE BAJA CALIFORNIA 
PENINSULA TO 117W ALONG WITH 8 FT SEAS. THESE WINDS WILL PERSIST 
OVER THE SAME GENERAL AREA THROUGH SAT NIGHT BETWEEN TROUGHING 
OVER MEXICO AND RIDGING TO THE W OF THE PENINSULA AND BEHIND THE
FRONT.

FRESH NE-E TRADES ARE LOCATED FROM 04N TO 17N W OF 115W AS 
INDICATED BY RECENT ASCAT AND WINDSAT PASSES...ALONG WITH SEAS 
TO 11 FT IN MIXED NE AND NW SWELL. AN AREA OF 8-9 FT CONFUSED 
SEAS SURROUNDS THE REMAINDER OF THE AREA S OF 20N W OF 110W...IN 
A BROAD MIX OF NE...SW...AND NW SWELL. THESE TRADES ARE FORECAST 
TO LINGER THROUGH SAT NIGHT WHILE BECOMING ORIENTED ACROSS THE 
WATERS FROM 05N TO 26N W OF 125W...WITH THE SURROUNDING AREA OF 
SWELL NOT CHANGING MUCH AS WELL.

A SURFACE TROUGH EXTENDS FROM 07N87W TO 04N94W TO 03N104W. 
SCATTERED MODERATE TO STRONG CONVECTION IS OCCURRING S OF THE 
TROUGH BETWEEN 96W AND 101W. THIS FEATURE IS EXPECTED TO REMAIN 
NEARLY STATIONARY THROUGH THE NEXT 48 HOURS.

THE COLD FRONT MENTIONED ABOVE WILL APPROACH THE GULF OF 
CALIFORNIA TONIGHT INCREASING S-SW WINDS TO 20-25 KT IN THE GULF 
N OF 29N. THESE WINDS WILL CONTINUE THROUGH SAT AFTERNOON UNTIL 
THE FRONT MOVES INLAND OVER MEXICO WHILE WEAKENING.

$$
LEWITSKY