000
AXPZ20 KNHC 142134
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE APR 14 2009

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
2000 UTC.

...ITCZ...

ITCZ AXIS IS FROM 06N78W TO 05N86W TO 07N103W TO 06N120W TO 
08N140W. SCATTERED MODERATE CONVECTION LIES WITHIN 90 NM OF THE 
ITCZ AXIS BETWEEN 112W AND 121W. 

...DISCUSSION...

N OF 20N...
AN AMPLIFIED BUT PROGRESSIVE UPPER PATTERN IS IN PLACE ACROSS N 
WATERS...WITH A STRONG MID TO UPPER LEVEL TROUGH MOVING INTO THE 
WESTERN U.S. AND MAKING ITS WAY TOWARD BAJA CALIFORNIA. THE 
PRESSURE GRADIENT BETWEEN THE SURFACE LOW IN THE VICINITY OF THE 
GREAT SALT LATE AND THE HIGH PRES CENTERED NEAR 40N135W HAS 
INCREASED WINDS OVER N WATERS. THE ASCAT PASS FROM 1718 UTC AND 
THE QUIKSCAT PASSES FROM 1336 UTC AND 1516 UTC CONFIRM WINDS TO 
30 KT WHILE A LONE SHIP OBSERVATION...3FPR9...REPORTED WINDS TO 
33 KT NEAR 29N129W AT 1500 UTC. EXPECT THE AREA OF STRONG WINDS 
TO SLIDE S AND DIMINISH OVER THE NEXT TWO DAYS AS THE LOW 
PRESSURE SYSTEM MOVES INTO THE PLAINS AND THE RIDGE AXIS SETTLES 
SOUTHEASTWARD. N TO NW SWELL WILL CAUSE WAVES HEIGHTS TO BUILD 
TO THE 12 TO 18 FT RANGE ON WED OFF THE NORTHERN BAJA CALIFORNIA 
COAST AS FAR W AS 125W BEFORE SUBSIDING TO 8 TO 12 FT LATE THU.

THE STRONG PRESSURE GRADIENT OVER WESTERN NORTH AMERICA WILL 
ALSO KEEP SW WINDS TO 20 KT IN THE NORTHERN GULF OF CALIFORNIA 
THROUGH WED. ON THU...EXPECT THE SURFACE TROUGH ASSOCIATED WITH 
THE MID TO UPPER LEVEL SYSTEM PASSING FROM THE GREAT BASIN INTO 
THE PLAINS TO SWING THROUGH THE NORTHERN GULF OF CALIFORNIA AND 
FORCE WINDS TO BECOME NORTHERLY. THE AREA OF 20 KT WINDS SHOULD 
SHIFT FARTHER S IN THE GULF OF CALIFORNIA THU...BETWEEN 25N AND 
30N.

S OF 20N...
AN ASHFALL ADVISORY IS IN EFFECT FROM THE ONGOING ERUPTION OF 
THE FERNANDINA VOLCANO NEAR 0.4S91.5W. THE GOVERNMENT OF ECUADOR 
IS CURRENTLY FLYING A RECONNAISSANCE MISSION TO INVESTIGATE THE 
ERUPTION. ON THE RECOMMENDATION OF THE NESDIS SATELLITE ANALYSIS 
BRANCH...THE ASHFALL ADVISORY WAS EXTENDED THROUGH 48 HOURS DUE 
TO THE UNCERTAINTY IN THE TIMING OF THE END OF THE VOLCANIC 
ACTIVITY. WINDS ARE EXPECTED TO REMAIN EAST TO SE NEAR 10 KT IN 
THIS AREA DURING THAT TIME. MARINERS SHOULD EXERCISE CAUTION 
DOWNWIND OF THE VOLCANO FROM 01S TO 01N BETWEEN 91W AND 94W FOR 
AT LEAST THE NEXT FEW DAYS.

ELSEWHERE...SCATTERED MODERATE CONVECTION LIES WITHIN 90 NM OF 
THE ITCZ AXIS BETWEEN 112W AND 121W IN A REGION OF UPPER LEVEL 
DIFFLUENCE BETWEEN THE SE SIDE OF AN UPPER LEVEL ANTICYCLONE 
CENTERED NEAR 08N124W AND AN UPPER LEVEL TROUGH WHOSE AXIS LIES 
FROM 12N112W TO 00N120W. A WEAK REGION OF UPPER LEVEL DIFFLUENCE 
ALSO LIES OFF THE COAST OF COSTA RICA AND WESTERN PANAMA ON THE 
EASTERN EDGE OF ANOTHER WEAK ANTICYCLONE NEAR 06N86W.

TRADE WINDS...WITH NE TO E FLOW CURRENTLY IN THE 20 TO 25 KT 
RANGE PRIMARILY W OF 130W ACCORDING TO THE 1512 UTC QUIKSCAT 
PASS...SHOULD SPREAD EASTWARD OVER THE NEXT FEW DAYS AS THE 
RIDGE AXIS MOVES EASTWARD.

$$
SCHAUER CLARK