000
AXPZ20 KNHC 131541
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED FEB 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH IS ALONG 09N84W TO 05N91W TO 05N107W. THE 
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N107W TO 
05N140W. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM NORTH AND 
90 NM SOUTH OF THE AXIS BETWEEN 119W AND 140W.

...DISCUSSION...
A POSITIVELY TILTED MIDDLE TO UPPER LEVEL TROUGH THAT EXTENDS 
FROM THE CENTRAL U.S. PLAINS THROUGH BAJA CALIFORNIA TO A BASE 
IN THE NE FORECAST WATERS NEAR 25N115W WILL SHIFT EAST TODAY AND 
GRADUALLY BE REPLACED BY UPPER LEVEL RIDGING ANCHORED OVER THE 
NW FORECAST WATERS BETWEEN 120W AND 135W. AT THE SURFACE...THE 
STRONG PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE OVER NE 
WATERS AND TROUGHING OVER NORTHERN MAINLAND MEXICO DUE TO THE 
COLD FRONT ASSOCIATED WITH THIS TROUGH ALOFT IS FORCING FRESH TO 
STRONG N-NW WINDS DOWN THE LENGTH OF THE GULF OF CALIFORNIA TO 
AS FAR SOUTH AS 18N BETWEEN 105W AND 109W. A RECENT EARLIER 
MORNING ASCAT PASS AROUND 13/0504 UTC CAPTURED THESE WINDS. THE 
LONG FETCH DOWN THE GULF HAS LIKELY ALLOWED SEAS TO BUILD TO 8 
FT. THE 1036 MB SUBTROPICAL HIGH CURRENTLY CENTERED NEAR 38N136W 
WILL REMAIN STATIONARY UNTIL THURSDAY WHEN IT IS FORECAST TO 
WEAKEN AND SHIFT NORTHEASTWARD. WINDS AND SEAS WILL DIMINISH IN 
THE GULF OF CALIFORNIA BY THURSDAY AFTERNOON AS THE PRESSURE 
GRADIENT RELAXES.

AN UPPER LEVEL LOW IS CENTERED WEST OF THE AREA NEAR 24N144W AND 
REFLECTS A SURFACE TROUGH ANALYZED FROM 28N147W TO 24N144W TO 
19N147W. EARLIER ASCAT PASSES SHOWED A LARGE AREA OF NE TO E 
TRADES GENERATED BY THE PRESSURE GRADIENT BETWEEN THE RIDGING 
GENERALLY FROM 07N TO 20N W OF 115W AND AREA OF LOWER PRESSURE W 
OF THE AREA MENTIONED ABOVE. THE LOWER PRESSURE AREA IS FORECAST 
TO DRIFT WESTWARD WHILE DISSIPATING LATER TODAY...DIMINISHING 
THE PRESSURE GRADIENT AND SHRINKING THE AREA OF TRADES FROM 06N 
TO 17N W OF 122W BY EARLY FRIDAY.

GAP WINDS...
GULF OF TEHUANTEPEC...NORTHERLY WINDS BEHIND A COLD FRONT MOVING 
THROUGH THE SW GULF OF MEXICO THU WILL SQUEEZE THROUGH THE 
CHIVELA PASS AND GENERATE FRESH TO STRONG N WINDS IN THE GULF OF 
TEHUANTEPEC BY EARLY FRI MORNING. 

$$
HUFFMAN