000
AXPZ20 KNHC 222144
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON OCT 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

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

THE MONSOON TROUGH IS ALONG 12N87W TO 14N91W TO 12N100W TO 
10N110W TO 08N125W TO 10N133W. THE INTERTROPICAL CONVERGENCE 
ZONE AXIS EXTENDS FROM 08N137W TO 07N140W. SCATTERED MODERATE 
AND ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF THE TROUGH 
AXIS BETWEEN 87W AND 95W...AND FROM 09N TO 15N BETWEEN 97W AND 
102W. SCATTERED MODERATE WITHIN 120 NM S OF THE TROUGH AXIS 
BETWEEN 112W AND 118W...AND BETWEEN 121W AND 126W...AND ALSO 
WITHIN 120 NM N OF THE TROUGH AXIS BETWEEN 118W AND 122W.

...DISCUSSION...

A WEAK COLD FRONT EXTENDS INTO THE NW PORTION OF THE AREA FROM 
32N124W TO 29N137W. RECENT SCATTEROMETER PASSES INDICATE 
MODERATE TO FRESH WINDS BOTH AHEAD OF AND BEHIND THE FRONT WHILE 
NEARBY SHIP OBSERVATIONS REPORT 5 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 97W AND 102W 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 AFTERNOON WITH SEAS 
BUILDING TO 10 FT BY WED AFTERNOON WHILE THIS AREA OF STRONGER 
WINDS SPREADS S REACHING TO 25N. 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 
BETWEEN 20 AND 30 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.

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

$$
LEWITSKY