000
AXPZ20 KNHC 181535
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI JAN 18 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...
MONSOON TROUGH EXTENDS FROM 05N77W TO 06N91W...THEN ITCZ TO 
08N107W TO 09N122W TO 07N140W...WITH NO SIGNIFICANT CONVECTION.

...DISCUSSION...
WATER VAPOR IMAGERY SHOWS UPPER LOW NEAR 30N129W WITH A SHARP 
TROUGH FROM THE LOW TO 26N127W LIFTING NORTHEASTWARD. AN OCCLUDED
SURFACE LOW NEAR 45N158W EXTENDS A FRONTAL BOUNDARY TO 30N144W TO
21N146W...WITH A LINE OF ACTIVE CONVECTION ASSOCIATED WITH THE 
FRONT LOCATED JUST W OF THE DISCUSSION AREA. STRONG HIGH PRES IN 
SOUTHERN MEXICO IS PRODUCING A TIGHT PRES GRADIENT ACROSS THE 
ISTHMUS OF TEHUANTEPEC. A SHEAR LINE EXTENDING FROM CENTRAL CUBA
TO THE GULF OF HONDURAS IS SUPPORTING STRONG TO NEAR-GALE WINDS 
DOWNSTREAM FROM THE GULF OF PAPAGAYO. 
 
SCATTEROMETER PASSES AT 0000...0400...AND 0640 UTC ALL SHOWED 
GALE FORCE WINDS EXTENDING TO 14N96W IN THE GULF OF TEHUANTEPEC 
WITH PEAK WINDS OVER 50 KT. CARGO SHIP HANJIN PHILADELPHIA CALL 
SIGN A8CN8 REPORTED 49 KT WINDS AND 21 FT SEAS NEAR 15.3N 95.5W 
AT 0600 UTC. EXPECT WINDS TO DIMINISH BELOW STORM FORCE LATER 
THIS MORNING...THEN GALE FORCE WINDS SHOULD CONTINUE THROUGH SUN 
MORNING FOLLOWED BY VERY STRONG TO NEAR-GALE CONDITIONS THROUGH 
TUE WITH PEAK WINDS REACHING MINIMAL GALE AROUND SUNRISE FROM 
DIURNAL EFFECTS. NO SIGNIFICANT CHANGE IS EXPECTED IN THE 
SYNOPTIC PATTERN...WITH NORTHERLY WINDS IN THE GULF OF MEXICO 
AND PERSISTENT STRONG PRES GRADIENT IN CENTRAL AMERICA. THE GULF 
OF PAPAGAYO WILL ALSO HAVE STRONG PERSISTENT NE WINDS THROUGH 
MON IN THIS SYNOPTIC PATTERN. FRESH TO STRONG E-NE WINDS WILL 
EXTEND FAR DOWNWIND FROM THE SOURCE REGIONS NEAR TEHUANTEPEC AND 
GULF OF PAPAGAYO...RESULTING IN VERY LARGE AREA OF ELEVATED SEA 
HEIGHTS IN NE SWELL THROUGH SAT NIGHT EXTENDING ROUGHLY FROM 05N 
TO 14N E OF 110W. N-NE WINDS OF 20-25 KT ARE FORECAST TO SURGE 
THROUGH THE GULF OF PANAMA TODAY AND CONTINUE INTO TUE.

WW3 MODEL GUIDANCE SHOWS 27 SEC LONG PERIOD NW SWELL REACHING NW 
PORTION EARLY SAT MORNING THEN SPREADING ACROSS WESTERN WATERS 
THROUGH TUE WITH LITTLE CHANGE IN WAVE PERIOD ALONG LEADING EDGE 
OF THE SWELL. COASTAL AREAS IN MEXICO...THE BAJA PENINSULA IN 
PARTICULAR...WITH NW EXPOSURE CAN EXPECT HAZARDOUS SURF FROM 
UNUSUALLY LARGE WAVE HEIGHTS AND BEACH EROSION DURING THIS LONG 
PERIOD SWELL EVENT.

GFS AND ECMWF MODELS SHOW AN AREA OF LOW PRES DEVELOPING NEAR 
35N155W SAT MORNING...FORECAST TO MOVE SE TO AROUND 17N142W BY 
TUE MORNING AS A MODERATELY INTENSE LOW. ASSOCIATED STATIONARY 
FRONT OR FRONTAL TROUGH ENTERING BASIN SUN WITH STRONG TO NEAR 
GALE FORCE SE WINDS WELL AHEAD OF BOUNDARY AND SIMILAR W-SW 
WINDS W OF FRONT.

$$
MUNDELL