000
AXPZ20 KNHC 191505
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU APR 19 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

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

ITCZ AXIS EXTENDS FROM 08N110W TO 04N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WITHIN 60 NM EITHER SIDE OF THE AXIS.

...DISCUSSION...

NEARLY STATIONARY HIGH PRES NEAR 30N138W WILL PERSIST THROUGH 
FRI NIGHT THEN WEAKEN AND SHIFT NE AS A COLD FRONT ADVANCES INTO 
NW PORTION OF THE DISCUSSION AREA THIS WEEKEND. COLD FRONT WILL 
EXTEND FROM 35N137W TO 27N150W SAT...FROM 35N135W THROUGH 30N140W
TO 27N145W SAT NIGHT...THEN WEAKEN AND BECOME STATIONARY FROM 35N
131W TO 28N137W TO 24N145W SUN. LOW PRES TROUGH IS ALSO EXPECTED 
TO DEVELOP SW OF CALIFORNIA THIS WEEKEND...EXTENDING FROM SANTA 
BARBARA TO AROUND 26N123W. THIS SYNOPTIC PATTERN WILL WEAKEN THE 
TYPICAL PRES GRADIENT THAT USUALLY EXISTS ACROSS THE REGION...AND
THE 15-20 KT TRADE WINDS NORMALLY FOUND S OF 20N W OF 110W WILL 
DIMINISH CONSIDERABLY...TO AROUND 10 KT OR LESS OVER MOST OF THIS
AREA. AS A RESULT...SEAS WILL BE 5 FT OR LESS OVER NEARLY ALL OF 
THE DISCUSSION AREA BY MON. TWO NOTABLE EXCEPTIONS WILL BE IN THE
GULF OF TEHUANTEPEC AND AN EXPANDING AREA OF LONG PERIOD NW SWELL
ASSOCIATED WITH THE WEAKENING COLD FRONT AS IT TRANSITIONS INTO 
A SHEAR LINE SUN AND MON.

AN ASCAT SCATTEROMETER PASS AT 0330 UTC SHOWED 25 KT N-NE WINDS 
EXTENDING TO AROUND 14N95W INCLUDING THE GULF OF TEHUANTEPEC. IT 
APPEARS THE PEAK WINDS HAVE ALREADY OCCURRED...AND BASED ON GFS 
MODEL GUIDANCE EXPECT WINDS TO DIMINISH BELOW 20 KT BY EARLY FRI 
AS LOW PRES DEVELOPS ALONG THE EASTERN COAST OF MEXICO. SUITE OF 
GLOBAL MODELS SHOW UNUSUALLY STRONG LATE SEASON LOW PRES SYSTEM 
IN THE GULF OF MEXICO SAT AND SUN. HIGH PRES BUILDING BEHIND THE 
LOW WILL TIGHTEN THE GRADIENT ACROSS THE CHIVELA PASS AND INDUCE 
VERY STRONG WINDS IN THE GULF OF TEHUANTEPEC BY LATE SAT OR EARLY
SUN. LATEST GFS MODEL SHOWS GALE FORCE WINDS POSSIBLE SUN MORNING
THROUGH TUE MORNING. A SUSTAINED PERIOD OF HIGH WINDS WILL ALLOW 
SEAS TO BUILD TO 12-13 FT DOWNSTREAM OF TEHUANTEPEC MON AND TUE.

$$
MUNDELL