000
AXPZ20 KNHC 130959
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON APR 13 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0930 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED 06N77W TO 06N98W TO 02N115W TO 07N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 120 NM OF 
AXIS BETWEEN 82W AND 84W. SCATTERED MODERATE CONVECTION FROM 04N 
TO 08N W OF 112W.

...DISCUSSION...

N OF 20N...A MID/UPPER TROUGH ALONG ROUGHLY 140W WILL BECOME 
MORE AMPLIFIED OVER THE NEXT COUPLE OF DAYS AS IT PUSHES 
EASTWARD AND ONSHORE ALONG THE CALIFORNIA COAST. AN ASSOCIATED 
FRONT STAYS N OF 30N AND WASHES OUT SOUTH OF 30N. QUIKSCAT DATA 
INDICATE A SWATH OF 20 KT WINDS MAINLY ALONG THE WESTERN BAJA 
COAST...BUT ALSO IN THE SOUTHERN GULF OF CALIFORNIA ON THE 
EASTERN SIDE OF A SURFACE HIGH PRES RIDGE EXTENDING FROM 33N132W 
TO ROUGHLY 20N110W. THIS HIGH PRES RIDGE WILL BECOME REINFORCED 
BEHIND THE FRONT AND WILL ALLOW NORTHERLY WINDS TO INCREASE 
ALONG THE COAST TO THE NORTHERN BAJA COAST. THESE WINDS MAY 
REACH AS HIGH AS 30 KT BY EARLY WEDNESDAY N OF 28N OFF THE BAJA 
COAST...BEFORE DIMINISHING LATER IN THE DAY AS THE HIGH PRES 
MOVES EASTWARD. NORTHERLY SWELL OF 10 TO 15 FT WILL ACCOMPANY 
THE INCREASED WINDS WEST OF NORTHERN BAJA BY LATE TUESDAY.

S OF 20N...AN AMPLIFIED UPPER PATTERN REMAINS IN PLACE WITH AN 
UPPER RIDGE CENTERED NEAR 06N140W...AND A SHARP MID/UPPER TROUGH 
ALONG 125W. DIVERGENT FLOW BETWEEN THESE TWO UPPER SYSTEMS IS 
PROMOTING CONVECTION NORTH OF THE ITCZ. SCATTEROMETER DATA HAVE 
BEEN SHOWING A WEAK TROUGH FROM 05N137W TO 10N130W IN THE 
VICINITY OF THE CONVECTION.SCATTEROMETER DATA ALSO INDICATE A 
BROAD SWATH OF 20 TO 25 KT TRADE WINDS BETWEEN SURFACE HIGH PRES 
N OF AREA AND THE SURFACE TROUGH. THE UPPER TROUGH WILL DAMPEN 
OUT THROUGH TODAY...ALLOWING THE SURFACE TROUGH TO WEAKEN AS 
WELL...AND WILL ALLOW THE TRADES TO DIMINISH OVER THE NEXT 48 
HOURS AS WELL. SEAS WILL BE DOMINATED BY A MIX OF NW AND SW 
SWELL THROUGH MID WEEK MAINLY W OF 120W. FURTHER EAST...STRONG 
NOCTURNALLY ENHANCED CONVECTION HAS BEEN FLARING SOUTH OF 
WESTERN PANAMA AND NORTH OF THE ITCZ FOR A FEW HOURS...BUT IS 
STARTING TO WEAKEN. LIGHT TO MODERATE CROSS-EQUATORIAL SOUTHERLY 
FLOW ALONG WITH ABUNDANT MOISTURE AND WEAK DIVERGENCE ALOFT WILL 
MAINTAIN SCATTERED CLUSTERS CONVECTION BETWEEN THE ITCZ AND THE 
SOUTHERN CENTRAL AMERICAN COAST THROUGH MID WEEK.

$$
CHRISTENSEN