000
AXPZ20 KNHC 171525
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU JAN 17 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 08N77W TO 09N86W TO 07N93W THEN CONTINUES AS 
THE ITCZ TO 08N125W TO 06N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...
BROAD RIDGE OF HIGH PRES EXTENDS ACROSS MOST OF THE DISCUSSION 
AREA N OF THE CONVERGENCE ZONE. HIGH PRES RIDGE OVER CENTRAL AND 
SOUTHERN MEXICO IS PRODUCING A TIGHT PRES GRADIENT ACROSS THE 
ISTHMUS OF TEHUANTEPEC. LOW PRES TROUGH ALONG THE WEST COAST OF 
MEXICO ENHANCING NW WINDS IN GULF OF CALIFORNIA...WITH WINDS TO 
25 KT AND SEAS TO 7 FT NEAR 26N110W. ASCAT SCATTEROMETER SHOWS 
MODERATE TO FRESH E-NE TRADE WINDS FROM 11N TO 25N W OF 115W.

OSCAT PASS AT 0550 UTC AND WINDSAT PASS AT 0015 UTC SHOWED 35-45 
KT N WINDS IN THE GULF OF TEHUANTEPEC LAST NIGHT. EXPECT TIGHT 
PRES GRADIENT TO PERSIST SEVERAL MORE DAYS...PRODUCE STORM FORCE 
WINDS THROUGH FRI MORNING...GALE FORCE WINDS THROUGH SUN MORNING 
THEN 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 BEGIN
TO EXPERIENCE STRONG PERSISTENT NE WINDS FRI THROUGH MON IN THIS 
SYNOPTIC PATTERN. FRESH TO STRONG E-NE WINDS WILL EXTEND FAR 
DOWNWIND FROM THE SOURCE REGIONS NEAR TEHUANTEPEC AND PAPAGAYO...
RESULTING IN VERY LARGE AREA OF ELEVATED SEA HEIGHTS IN NE SWELL 
THU THROUGH LATE SAT EXTENDING ROUGHLY FROM 05N TO 14N E OF 115W.

WINDS WILL DIMINISH BELOW 20 KT IN THE GULF OF CALIFORNIA BY 
TONIGHT. MODERATE TRADE WINDS WILL PREVAIL ACROSS THE REMAINDER 
OF THE DISCUSSION AREA THROUGH SUN. 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 WITH NW EXPOSURE CAN EXPECT HAZARDOUS SURF FROM 
UNUSUALLY LARGE WAVE HEIGHTS AND BEACH EROSION DURING THIS LONG 
PERIOD SWELL EVENT.

AN OCCLUDED LOW CENTERED NEAR 34N152W WILL DRIFT N-NW THROUGH 
FRI NIGHT AND DRAG A FRONTAL BOUNDARY...CURRENTLY EXTENDING FROM 
THE LOW TO 30N145W TO 21N150W...SLOWLY NORTHEASTWARD AND APPROACH
140W FRI NIGHT AND SAT. THIS WILL CAUSE SE WINDS TO INCREASE TO 
20-25 KT NW OF A LINE FROM 30N135W TO 22N140W AND BUILDING SEA 
HEIGHTS TO 13-14 FT IN NW SWELL THROUGH THE WEEKEND. GFS AND 
ECMWF MODELS SHOW AN AREA OF LOW PRES DEVELOPING NEAR 35N155W 
EARLY SAT MORNING THEN MOVES SE TO AROUND 17N142W BY TUE MORNING 
AS A 1004-1006 MB LOW. WINDS AND SEAS WILL INCREASE W OF 130W 
SAT THROUGH MON AS THE LOW INTENSIFIES W OF THE DISCUSSION AREA.

$$
MUNDELL