000
AXPZ20 KNHC 182128
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI MAR 18 2011

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 IS CENTERED ALONG 04N98W TO 
03N103W TO 08N124W TO 04N137W TO 04N140W. SCATTERED MODERATE 
CONVECTION WAS NOTED WITHIN 60 NM N OF AXIS W OF 130W.

...DISCUSSION...

A 1032 MB HIGH PRESSURE CENTER ANALYZED WELL NW OF THE REGION 
NEAR 31N145W EXTENDS A RIDGE SE INTO THE FORECAST DISCUSSION 
AREA NEAR 30N140W EXTENDING TO NEAR 17N105W. THE PRESSURE 
GRADIENT BETWEEN THE RIDGE AND LOWER PRESSURE NEAR THE ITCZ IS 
MAINTAINING FRESH TO STRONG TRADE WINDS FROM 05N TO 23N W OF 
125W. THE PRESSURE GRADIENT BETWEEN THE RIDGE AND TROUGHING OVER 
THE SW UNITED STATES IS SUPPORTING FRESH 20 KT NW WINDS N OF 28N 
E OF 118W TO COAST OF BAJA CALIFORNIA. THE RIDGE WILL SHIFT 
SOUTH AND ENABLE A COLD FRONT TO MOVE INTO THE NW PORTION OF THE 
AREA LATE SAT NIGHT. WITH THE SURFACE RIDGE WEAKENING...COVERAGE 
OF THE FRESH TO STRONG TRADES WILL DECREASE IN AREAL EXTENT 
THROUGH THE WEEKEND. THE WEAKENING RIDGE WILL ALSO RELAX THE 
PRESSURE GRADIENT OFF THE COAST OF BAJA CALIFORNIA...DIMINISHING 
WINDS BELOW 20 KT LATE SAT NIGHT. 

THE SURFACE COLD FRONT MENTIONED IN THE PREVIOUS PARAGRAPH WILL 
BRING AN INCREASE IN SW-W WINDS AHEAD OF IT. THESE WINDS WILL 
BE IN THE RANGE OF 20-30 KT N OF 29N WITHIN 240 NM E OF THE 
FRONT...THEN INCREASE TO MINIMAL GALE FORCE STRENGTH BY EARLY 
SUN MORNING AS THE FRONT REACHES FROM 30N130W TO 27N140W WITH 
SEAS BUILDING...POSSIBLY UP TO 14 FT. WINDS BEHIND THE FRONT ARE 
FORECAST TO BE W-NW AT 20 TO 25 KT WITH SEAS TO 16 FT IN LONG 
PERIOD NW SWELL.

GAP WINDS...
GULF OF TEHUANTEPEC...FRESH TO STRONG N TO NE WINDS PREVAIL 
WITHIN 30 NM EITHER SIDE OF LINE FROM 16N95W TO 15N95W TO 
12N98W. THESE WINDS WILL BRIEFLY PEAK TO 30 KT SAT AND SUN 
MORNING WITH THE AID OF NOCTURNAL DRAINAGE FLOW.

FRESH TO STRONG WINDS OVER THE SW CARIBBEAN ARE FUNNELING 
THROUGH THE CENTRAL AMERICA PASSES INTO THE GULFS OF PAPAGAYO 
AND PANAMA. THESE WINDS WILL PREVAIL THROUGH THE FORECAST 
PERIOD. 

$$
AL