000
AXPZ20 KNHC 170927
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI APR 17 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 
0900 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 05N77W TO 05N82W TO 06N90W TO 
05N104W TO 06N119W TO 05N140W. SCATTERED MODERATE CONVECTION S 
OF THE AXIS WITHIN 60 NM OF 05N90W.

...DISCUSSION...

N OF 20N...SCATTEROMETER DATA SHOW 20 TO 25 KT NORTHERLY WINDS 
BETWEEN 1032 MB HIGH PRES NEAR 32N130W AND THE BAJA COAST. 
SIMILARLY 20 KT WINDS ARE NOTED THROUGH THE SOUTHERN HALF OF THE 
GULF OF CALIFORNIA...AS WELL OFF CABO CORRIENTES. SCATTEROMETER 
SHOWS FRESH TRADE WINDS SOUTH OF 22N TO THE SOUTH OF THE SURFACE 
HIGH PRES. LONG PERIOD NORTHERLY SWELL UP TO 10 FT ACCOMPANIES 
THE STRONG NORTHERLY FLOW OFF THE NORTHERN BAJA COAST. 
MEANWHILE...RIDGING ALOFT AMPLIFIES OVER THE U.S. COAST THROUGH 
THE WEEKEND AHEAD OF AN UPPER TROUGH DIGGING THROUGH THE NORTH 
CENTRAL PACIFIC. THE SURFACE HIGH PRES SHIFTS NORTH AS THE UPPER 
RIDGE BUILDS OVER THE WEST COAST...ALLOWING THE WINDS TO 
DIMINISH. SWELL DECAYS TO LESS THAN 8 FT BY LATE SAT.

S OF 20N...A BROAD SWATH OF NE TRADES GENERALLY N OF 07N W OF 
110W SHOWS UP ON SCATTEROMETER IMAGERY ON THE SOUTHERN PERIPHERY 
OF HIGH PRES CENTERED NEAR 32N130W. THE TRADES DIMINISH THROUGH 
THE WEEKEND AS THE HIGH PRES SHIFTS FURTHER NORTH. THE TRADE 
WIND CONVERGENCE COUPLED WITH WEAK DIVERGENCE ALOFT IS 
SUPPORTING MODEST CONVECTION TO THE NORTH OF THE ITCZ. THIS WILL 
DISSIPATE AS THE TRADE WINDS DIMINISH. FURTHER EAST...WINDS 
THROUGH THE GULF OF PAPAGAYO WILL INCREASE TO 20 KT THROUGH THE 
EARLY MORNING DUE TO DRAINAGE FLOW CONVERGENCE OFF THE LAND. 
DRAINAGE FLOW IS ALSO RESPONSIBLE FOR AN AREA OF WEAK NOCTURNAL 
CONVECTION OFF THE WEST COAST OF PANAMA...AND ALONG THE 
COLOMBIAN COAST. A COMBINATION OF SOUTHERLY CROSS EQUATORIAL 15 
KT FLOW AND WEAK DIVERGENCE ALOFT IS AIDING A SMALL AREA OF 
CONVECTION ALONG THE ITCZ NEAR 90W. MODEL GUIDANCE SUGGESTS A 
WEAK TROUGH MAY BE FORMING IN THIS AREA THAT WILL PUSH WEST 
ALONG THE ITCZ THROUGH THE WEEKEND...ACCOMPANIED BY SMALL 
CLUSTERS OF CONVECTION. 

GALAPAGOS VOLCANO...
WHILE THE LA CUMBRE VOLCANO ON ISLA FERNANDINA IN THE GALAPAGOS 
ISLANDS LOCATED AT 00.4S91.5W CONTINUES TO ERUPT...THE 
GOVERNMENT OF ECUADOR REPORTS THAT THE RESULTING PLUME CONTAINS 
VAPOR AND GASES WITH NO SIGNIFICANT ASH. THE WASHINGTON VAAC HAS 
DISCONTINUED ASHFALL ADVISORIES. HOWEVER...MARINERS SHOULD STILL 
EXERCISE CAUTION AS GASES...INCLUDING SULFUR DIOXIDE...EXTEND AS 
MUCH AS 1200 NM TO THE W OF THE VOLCANO. NASA/OMI IMAGERY FROM 
2254 UTC SHOWS ELEVATED LEVELS OF SULFUR DIOXIDE IN THE AREA 
FROM FROM 01N TO 03S BETWEEN 91W AND 105W WITH A SECOND PLUME 
FROM 03N TO 02S BETWEEN 111W AND 117W. EXPOSURE TO THIS GAS CAN 
BE DANGEROUS...CAUSING IRRITATION TO EYES AND SKIN.


$$
CHRISTENSEN