000
AXPZ20 KNHC 161539
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE JUN 16 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.

...SPECIAL FEATURE...

AN AREA OF LOW PRESSURE 1009 MB IS LOCATED NEAR 14.4N104.4W...OR 290 
MILES SOUTH OF MANZANILLO MEXICO. A CLUSTER OF MODERATE TO STRONG 
CONVECTION IS SHEARED TO THE SW WITHIN 90 NM OF THE WELL EXPOSED 
SURFACE CENTER. AN ASCAT PASS FROM 05Z INDICATED 20 TO 25 KT WINDS 
ON THE EAST SIDE OF THE SYSTEM CENTER. SOME DEVELOPMENT OF THIS 
SYSTEM IS POSSIBLE AS IT MOVES SLOWLY WEST-NORTHWESTWARD OVER THE 
NEXT DAY OR TWO. 

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 07N77W TO 07N90W TO 09N100W TO 06N140W. 
SCATTERED MODERATE ISOLATED STRONG NOCTURNAL CONVECTION IS ACTIVE S 
OF THE ITCZ AXIS WITHIN 60 NM OF THE COLOMBIAN COAST. SCATTERED 
MODERATE CONVECTION IS WITHIN 60 NM N OF AXIS BETWEEN 94W AND 96W. 
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM S OF AXIS BETWEEN 100W 
AND 105W. 

...DISCUSSION...

THE UPPER PATTERN IS BECOMING A LITTLE MORE AMPLIFIED W OF 110W AS 
DEEP LAYER TROUGH DIGS INTO SOUTHERN CALIFORNIA. THE UPPER TROUGH 
EXTENDS FROM SOUTHERN CALIFORNIA SW TO 12N140W. THE UPPER TROUGH 
CONTINUES TO SUPPORT A SURFACE TROUGH FROM 30N119W TO 26N125W...THAT 
WAS WELL DEFINED ON A 05Z ASCAT PASS...AND A RECENT SHIP 
OBSERVATION. THIS TROUGH IS IMPINGING ON A SURFACE RIDGE THAT 
EXTENDS FROM A 1025 MB HIGH PRES CELL NEAR 31N145W TO SOUTH OF THE 
SURFACE TROUGH TO ROUGHLY 25N114W. THE INTERACTION BETWEEN THE 
TROUGH AND RIDGE IS ENHANCING THE PRESSURE GRADIENT ALONG THE BAJA 
COAST. A QUIKSCAT PASS FROM YESTERDAY EVENING ALONG WITH SHIP 
OBSERVATIONS FROM EARLIER THIS MORNING INDICATED AN AREA OF 20 KT 
NORTHERLY WINDS PERSISTING BETWEEN THE SURFACE RIDGE AND THE BAJA 
COAST. THE FRESH NORTHERLY WINDS WILL LIKELY PERSIST THROUGH THE 
NEXT SEVERAL DAYS AS THE RIDGE MAINTAINS ITS STRENGTH. SOUTH OF THE 
RIDGE...AN AREA OF FRESH TRADES PERSISTS MAINLY W OF 135W. THE 
SURFACE TROUGH WILL PERSIST BUT WEAKEN THROUGH THE NEXT COUPLE OF 
DAYS AS THE UPPER TROUGH CUTS OFF JUST OFF THE NORTHERN BAJA COAST.

FURTHER TO THE EAST...AN UPPER ANTICYCLONE REMAINS ANCHORED OVER 
NORTH CENTRAL MEXICO...AND AN UPPER CYCLONE IS CENTERED ABOVE 
12N100W. THE DEEP LAYER NE FLOW BETWEEN THESE TWO SYSTEMS IS 
RESPONSIBLE FOR THE STRONG SHEARING OF THE CONVECTION ASSOCIATED 
WITH THE SURFACE LOW PRES AREA NEAR 14N104W. DIVERGENT FLOW ALOFT IS 
HAS ALSO AIDED THE CONVECTIVE DEVELOPMENT DURING THE OVERNIGHT 
DIURNAL MAXIMUM CONVECTIVE PERIOD. TO THE SOUTH OF THIS 
LOW...SCATTEROMETER AND EARLIER BUOY DATA SHOWED A BROAD AREA OF S 
TO SW CROSS EQUATORIAL FLOW...MAINLY BELOW 20 KT. THIS FLOW...ALONG 
WITH THE NE FLOW ASSOCIATED WITH THE RIDGE AXIS TO THE NORTH...MAY 
BE ENHANCING THE ROTATION ASSOCIATED WITH THE LOW CENTER. GLOBAL 
MODELS INDICATE THAT THIS CROSS-EQUATORIAL FLOW WILL INCREASE 
SLIGHTLY THROUGH LATE WEEK...ESPECIALLY IF THE LOW PRES AREA 
DEEPENS. THIS FLOW WILL WILL INCREASE THE LOW LEVEL CONVERGENCE FROM 
THE SOUTH...ENHANCING CONVECTION ALONG THE ITCZ THROUGH LATE WEEK 
MAINLY BETWEEN 95W AND 125W.

MEANWHILE...LONG PERIOD SW SWELL TO 16 SECONDS WITH WAVE HEIGHTS TO 
6 FT IS MOVING INTO PORTIONS OF THE SOUTHERN MEXICAN AND NORTHERN 
CENTRAL AMERICAN PACIFIC COASTLINES...BUT SHOULD BE DIMINISHING 
THROUGH TONIGHT.

$$
CHRISTENSEN