000
AXPZ20 KNHC 130331
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT FEB 13 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0115 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS 03N77W TO 07N85W TO 
03N97W TO 06N134W TO 04N140W. SCATTERED MODERATE CONVECTION LIES 
WITHIN 90 NM N OF THE ITCZ AXIS BETWEEN 84W AND 87W.

...DISCUSSION...
THE UPPER LEVEL PATTERN OVER THE FORECAST AREA HAS BECOME 
DECIDEDLY LESS AMPLIFIED OVER THE PAST DAY OR TWO AS THE 
NORTHERN STREAM TROUGHING MOVED E OF THE AREA AND IS CURRENTLY 
FORCING A SURFACE COLD FRONT THROUGH THE YUCATAN PENINSULA AND 
ISTHMUS OF TEHUANTEPEC. WINDS ARE BELIEVED TO HAVE REACHED GALE 
FORCE HERE BASED ON MODEL GUIDANCE AND THE ARC CLOUD THAT WAS 
EVIDENT ON VISIBLE IMAGERY RACING S OF THE REGION FROM 1645 UTC 
TO 2315 UTC. UNFORTUNATELY...THERE HAS NOT BEEN AN OBSERVATION 
IN THE REGION THIS EVENING TO CONFIRM THIS. A BROAD DEEP LAYER 
LOW PRES SYSTEM LEFT BEHIND BY THE NORTHERN STREAM TROUGH 
LINGERS OVER CENTRAL WATERS. A SURFACE REFLECTION OF THIS MID TO 
UPPER TROUGHING CAN BE FOUND FROM 18N126W TO 12N131W. THERE IS 
NO SIGNIFICANT CONVECTION ASSOCIATED WITH THIS TROUGH. THE 
TROUGH FELL BETWEEN THE 1732 AND 1912 UTC ASCAT PASSES. THESE 
PASSES SHOW THE STRONGEST WINDS ARE TO 25 KT AND NOW LIE E OF 
THE TROUGH FROM 16N TO 18N...BETWEEN THE TROUGH AND THE RIDGE OF 
HIGH PRES EXTENDING FROM A 1024 MB HIGH NEAR 31N125W TO 17N110W. 
A BROAD AREA OF FRESH TRADES STILL LIES IN THE REGION W OF 118W 
FROM 14N TO 22N AND W OF 132W FROM 07N TO 14N. THE UPPER PATTERN 
IS EXPECTED TO BECOME INCREASINGLY LESS AMPLIFIED OVER THE NEXT 
TWO DAYS AND THE SURFACE TROUGH IS EXPECTED TO 
DISSIPATE...REDUCING THE PRES GRADIENT AND SHRINKING THE AREA OF 
THESE TRADE WINDS WESTWARD.  

A TIGHT PRES GRADIENT BETWEEN THE AFOREMENTIONED SURFACE RIDGE 
EXTENDING SE ALONG THE MEXICAN COAST AND THE TROUGH OF LOW PRES 
BUILDING ON THE EASTERN SIDE OF THE SIERRA MADRE OCCIDENTAL TO 
THE W OF THE HIGH PRES BEHIND THE COLD FRONT OVER THE ISTHMUS OF 
TEHUANTEPEC HAS BROUGHT 20 TO 25 KT NORTHERLY WINDS TO THE GULF 
OF CALIFORNIA AND ITS MOUTH FROM 19N TO 26N E OF 110W. IN 
ADDITION...THIS GRADIENT IS RESPONSIBLE FOR 20 TO 25 KT N WINDS 
WITHIN 90 NM OF THE W COAST OF BAJA CALIFORNIA AS SEEN BY SHIP 
OBSERVATION 9VKQ3 NEAR 27N115W AT 1700 UTC AND ZCDG7 NEAR 
29N116W AT 2100 UTC. THE PRES GRADIENT WILL SLACKEN SLIGHTLY 
TOMORROW AS HIGH PRES BEHIND THE COLD FRONT SHIFTS E AND THE 
HIGH IN THE PACIFIC SHIFTS W. EXPECT WINDS IN THE SOUTH OF THE 
MOUTH OF THE GULF OF CALIFORNIA DIMINISH OVERNIGHT WHILE WINDS 
OFF THE W COAST OF BAJA CALIFORNIA SHIFT WESTWARD WITH THE HIGH. 
20 KT WINDS WILL CONTINUE IN THE GULF OF CALIFORNIA FOR THE NEXT 
48 HOURS...BUT THEIR EXTENT WILL SHRINK TO N OF 28N BY SUN NIGHT.

ELSEWHERE...A FRONTAL TROUGH HAS DISSIPATED OVER NW WATERS. LONG 
PERIOD NW SWELL ASSOCIATED WITH THE FORMER FRONT HAS MOVED SE 
THROUGH THE NW THIRD OF THE FORECAST AREA W OF 110W. THE 
WAVEWATCH MODEL APPEARS TO BE SLOW BRINGING THE HIGHEST WAVES 
EASTWARD BETWEEN 25N AND 30N COMPARED TO SHIP OBSERVATIONS AND 
THE 2000 UTC JASON1 PASS. WAVEWATCH ALSO BRINGS HIGHER WAVE 
HEIGHTS FARTHER S THAN THE SIGNIFICANT WAVE HEIGHT ANALYSIS 
SHOWS. SIGNIFICANT WAVE HEIGHTS ARE CURRENTLY AS HIGH AS 20 FT 
OVER FAR NW WATERS. THIS NW SWELL WILL CONTINUE MOVING 
SE...RAISING WAVE HEIGHTS TO 8 TO 15 FT ACROSS MUCH OF THE AREA 
W OF 110W BY SUN EVENING. ANOTHER COLD FRONT WILL APPROACH NW 
WATERS SAT EVENING...BUT THE FRONT WILL STALL SUN BEFORE 
REACHING THE FORECAST AREA AND THEN DISSIPATE.

GAP WINDS...
GALE FORCE WINDS IN THE GULF OF TEHUANTEPEC WILL REACH JUST 
BELOW STORM FORCE EARLY SAT MORNING BEFORE DIMINISHING TO A 
MINIMAL GALE SAT EVENING. AS THE COLD FRONT THAT BROUGHT THE 
GALE TO TEHUANTEPEC PROGRESSES SOUTHWARD THROUGH CENTRAL 
AMERICA...EXPECT WINDS IN THE GULF OF PAPAGAYO EARLY SUN MORNING 
TO INCREASE TO 25 KT NW OF THE FRONT.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
SCHAUER