000
AXPZ20 KNHC 230248
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE OCT 23 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 ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

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

THE MONSOON TROUGH IS ALONG 13N87W TO 12N95W TO 15N106W TO 
07N126W TO 08N133W. THE INTERTROPICAL CONVERGENCE ZONE AXIS 
EXTENDS FROM 08N137W TO 09N140W. SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION IS WITHIN 75 NM N OF THE TROUGH AXIS BETWEEN 
96W AND 101W...WITHIN 180 NM S OF THE TROUGH AXIS BETWEEN 93W 
AND 95W...AND ALSO BETWEEN 97W AND 104W. SCATTERED MODERATE 
CONVECTION IS WITHIN 180 NM S OF THE TROUGH AXIS BETWEEN 113W 
AND 116W...WITHIN 120 NM N OF THE TROUGH AXIS BETWEEN 115W AND 
118W...AND ALSO BETWEEN 120W AND 126W.

...DISCUSSION...

A WEAK COLD FRONT EXTENDS INTO THE NW PORTION OF THE AREA FROM 
32N122W TO 24N140W. EARLIER SCATTEROMETER PASSES INDICATED LIGHT 
TO MODERATE WINDS AHEAD OF THE FRONT AND MODERATE TO LOCALLY 
FRESH WINDS BEHIND THE FRONT. NEARBY SHIP OBSERVATIONS HAVE BEEN 
REPORTING 4 TO 7 FT IN THE VICINITY OF THE FRONT. NO SIGNIFICANT 
DEEP CONVECTION IS CURRENTLY OBSERVED NEAR THE FRONT...ALTHOUGH 
SCATTERED SHOWERS ARE LIKELY WITHIN 60-120 NM OF THE FRONT AXIS. 
THE FRONT IS FORECAST TO DISSIPATE AS IT REACHES TO 27N TUE INTO 
WED.

DISORGANIZED SHOWERS AND THUNDERSTORMS ALONG THE MONSOON TROUGH 
BETWEEN 96W AND 104W ARE ASSOCIATED A LOW-LEVEL VORTICITY 
MAXIMUM. THIS FEATURE CONTINUES TO BE ROBUSTLY SPUN UP BY THE GFS
DETERMINISTIC GLOBAL MODEL...WITH THIS SOLUTION DEVELOPING A 
TROPICAL CYCLONE BY WED. HOWEVER...THE REMAINING GLOBAL MODELS 
INCLUDING THE GFS ENSEMBLE DELAY THE DEVELOPMENT OF A SYSTEM 
UNTIL FRIDAY...AT THE EARLIEST. THUS EMPHASIS CONTINUES TO BE 
PLACED UPON THE ECMWF...UKMET...NOGAPS...AND GFS ENSEMBLE 
SOLUTIONS FOR THE SURFACE WIND AND PRESSURE PREDICTIONS.  
LIKEWISE...THE OUTPUT FROM THE GFS-BASED WAVEWATCH MODEL IS 
SUBSTANTIALLY REDUCED IN THE GRIDDED OUTPUT. INSTEAD OF 12 FOOT 
SEAS BY 48 HOURS...THE SIGNIFICANT WAVE HEIGHTS ARE CAPPED AT 9 
FT IN THE SW MONSOONAL FLOW SOUTH OF 10N/11N. SIMILARLY...THE 
WAVEWATCH PEAK OF 26 FT BY FRIDAY MORNING IS REDUCED TO JUST 12 
FT.

BUILDING SURFACE HIGH PRESSURE SEVERAL HUNDRED MILES WEST OF THE 
UNITED STATES-MEXICO BORDER WILL ENHANCE THE PRESSURE GRADIENT 
AND THUS THE CORRESPONDING NW WINDS ALONG THE SOUTHERN 
CALIFORNIA AND NORTHERN BAJA CALIFORNIA COASTS. NW WINDS AT 20 
TO 25 KT ARE EXPECTED TO COMMENCE TUE EVENING WITH SEAS BUILDING 
TO 10 FT BY WED EVENING WHILE THIS AREA OF STRONGER WINDS 
SPREADS S REACHING TO 23N AND WESTWARD TO ACROSS THE AREA E OF 
120W. THESE WINDS ARE FORECAST TO THEN CONTINUE THROUGH FRI 
WHILE REMAINING BELOW GALE FORCE.

A WEAK GULF OF TEHUANTEPEC GAP WIND EVENT WILL CONTINUE TO PULSE 
MAINLY BETWEEN 20 AND 25 KT DURING THE NEXT 48 HOURS. THESE 
WINDS ARE FORECAST TO RE-INITIALIZE TONIGHT. THE WINDS WILL THEN 
BE WEAKER IN THE AFTERNOON AND EARLY EVENING HOURS...WITH 
STRONGER WINDS DURING THE LATE NIGHT AND EARLY MORNING HOURS 
WHILE THE CONDITIONS PERSIST THROUGH THU MORNING. WINDS TO 30 KT 
WILL BRIEFLY BE POSSIBLE LATE TUE NIGHT.

NO SIGNIFICANT LONG-PERIOD SWELL EVENTS OF 8 FT OR GREATER ARE 
EXPECTED IN OUR AREA OF RESPONSIBILITY OVER THE NEXT SEVERAL 
DAYS.

$$
LEWITSKY