000
AXPZ20 KNHC 122204
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI FEB 12 2010

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 03N77W 
TO 07N85W TO 03N98W TO 06N132W TO 04N140W. ISOLATED MODERATE 
CONVECTION CAN BE FOUND WITHIN 120 NM N OF AXIS BETWEEN 102W AND 
108W.

...DISCUSSION...
THE UPPER LEVEL PATTERN OVER THE FORECAST AREA HAS BECOME 
DECIDEDLY LESS AMPLIFIED OVER THE PAST 24 HOURS AS THE NORTHERN 
STREAM TROUGHING HAS MOVED E OF THE AREA AND IS CURRENTLY 
FORCING A SURFACE COLD FRONT THROUGH THE YUCATAN PENINSULA AND 
ISTHMUS OF TEHUANTEPEC. VISIBLE SATELLITE IMAGERY SINCE 1645 UTC 
CLEARLY SHOWS AN ARC CLOUD MOVING S AWAY FROM THE GULF OF 
TEHUANTEPEC ASSOCIATED WITH THE LEADING EDGE OF THE STRONG 
NORTHERLY FLOW BEHIND THE COLD FRONT. WINDS ARE EXPECTED TO 
REACH GALE FORCE HERE BY 0000 UTC. A BROAD DEEP LAYER OF 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 18N129W TO 09N133W. THERE IS NO 
SIGNIFICANT CONVECTION ASSOCIATED WITH THIS TROUGH. 
UNFORTUNATELY...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 1025 MB HIGH NEAR 
31N126W TO 18N110W. A BROAD AREA OF FRESH TRADES STILL LIES IN 
THE REGION W OF 115W FROM 09N TO 23N. THE UPPER PATTERN IS 
EXPECTED TO BECOME INCREASINGLY LESS AMPLIFIED OVER THE NEXT TWO 
DAYS AND THE SURFACE TROUGH IS EXPECTED TO DISSIPATE.  

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 28N 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 S OF 28N AS SEEN 
BY SHIP OBSERVATION 9VKQ3 NEAR 27N115W AT 1700 UTC. THE PRES 
GRADIENT WILL SLACKEN SLIGHTLY TOMORROW AS HIGH PRES BEHIND THE 
COLD FRONT SHIFTS E. EXPECT WINDS OFF THE W COAST OF BAJA 
CALIFORNIA AND IN THE MOUTH OF THE GULF OF CALIFORNIA TO 
DIMINISH...BUT 20 KT WINDS ARE EXPECTED TO CONTINUE IN THE GULF 
OF CALIFORNIA FOR THE NEXT 48 HOURS. ON SUN...LOOK FOR THE 
GRADIENT TO TIGHTEN YET AGAIN AS HIGH PRES OVER THE PACIFIC 
SHIFTS SOUTHWARD AHEAD OF A COLD FRONT NW OF THE FORECAST AREA 
AND STRONG HIGH PRES MOVES INTO THE PLAINS STATES AND NE MEXICO. 
N WINDS SHOULD BUILD TO 20 KT IN NORTH WATERS BETWEEN THE HIGH 
AND 120W AS A RESULT.

ELSEWHERE...A FRONTAL TROUGH IS DISSIPATED OVER NW WATERS. SHIP 
WECH REPORTED 20 KT S WINDS NEAR 29N135W AHEAD OF THE FRONTAL 
TROUGH. LONG PERIOD NW SWELL HAS MOVED AHEAD OF FRONTAL TROUGH 
WITH SIGNIFICANT WAVE HEIGHTS ALREADY TO 17 FT NW OF THE FRONT. 
THE LEADING EDGE OF THIS NW SWELL WILL CONTINUE SE WHILE A NEW 
SURGE OF NW SWELL MOVES INTO NW WATERS TONIGHT AND RAISES WAVE 
HEIGHTS TO 20 FT. ANOTHER COLD FRONT WILL APPROACH NW WATERS SAT 
EVENING WITH WINDS EXPECTED TO REACH 20 KT IN THE SW FLOW AHEAD 
OF THE FRONT..BUT THE CONT SHOULD WEAKEN BEFORE REACHING NW 
WATERS.

GAP WINDS...
GALE FORCE WINDS ARE EXPECTED IN THE GULF OF TEHUANTEPEC THIS 
EVENING AND WILL REACH JUST BELOW STORM FORCE EARLY SAT MORNING 
BEFORE DIMINISHING TO A MINIMAL GALE SAT EVENING. AS THE COLD 
FRONT PROGRESSES SOUTHWARD...EXPECT WINDS IN THE GULF OF 
PAPAGAYO SUN MORNING TO AGAIN INCREASE TO 25 KT.

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

$$
SCHAUER