000
AXPZ20 KNHC 170351
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED JUN 17 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...SPECIAL FEATURE...

AN ELONGATED AREA OF LOW PRESSURE WAS EMBEDDED NEAR THE NE END OF A 
MONSOON TROUGH CIRCULATION OCCURRING BETWEEN 100W AND 118W. SATELLITE
IMAGERY DURING YESTERDAY AND EARLY THIS MORNING HAS REVEALED MULTIPLE
SMALL LOW LEVEL CENTERS ROTATING CYCLONICALLY WITHIN AN ELONGATED 
MEAN CIRCULATION...WITH THIS MEAN CENTER MOVING WNW NEAR 10 MPH. THE 
LOW LEVEL CENTERS HAVE APPEARED INTERMITTENTLY ALONG THE NRN EDGE OF 
DEEP CONVECTIVE CLUSTERS OCCURRING IN THE S AND SE QUADRANTS OUT TO 
120 NM FROM THE CENTER...SUGGESTING N TO NE WIND SHEAR. AT 18Z...A 
1008 MB LOW CENTER WAS ESTIMATED NEAR 14.5N105W...OR 285 MILES SW OF 
MANZANILLO MEXICO. SCATTEROMETER PASSES YESTERDAY REVEALED A BROAD 
ZONE OF SW TO S WINDS AT 20 TO 25 KT ON THE SOUTH AND EAST SIDES OF 
THIS SYSTEM... WHICH HAVE BEGUN TO SPIRAL IN TOWARDS THE CENTER. 
FURTHER DEVELOPMENT OF THIS SYSTEM IS POSSIBLE AND IT HAS THE 
POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO 
AS IT MOVES SLOWLY WEST-NORTHWESTWARD. THERE IS A HIGH CHANCE...
GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE 
DURING THE NEXT 48 HOURS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N76W 9N86W 11N102W 7N120W 6N140W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N
OF THE AXIS BETWEEN 96W-114W. SCATTERED MODERATE CONVECTION IS
WITHIN 120 NM EITHER SIDE S OF THE AXIS W OF 115W.

...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. 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 EARLIER THIS MORNING INDICATED AN AREA OF 20 KT NORTH 
NORTHWESTERLY 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 14.5N105W. DIVERGENT FLOW ALOFT 
HAS ALSO AIDED IN CONVECTIVE DEVELOPMENT DURING THE DAY. TO THE 
SOUTH OF THIS LOW...SCATTEROMETER AND EARLIER BUOY DATA SHOWED A 
BROAD AREA OF S TO SW CROSS EQUATORIAL FLOW...AT AND 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 SWELLS OF 15-16 SECONDS WITH WAVE HEIGHTS 
OF 3 TO 4 FT IS MOVING INTO PORTIONS OF THE SOUTHERN MEXICAN AND 
NORTHERN CENTRAL AMERICAN PACIFIC COASTLINES...BUT SHOULD BE 
DIMINISHING THROUGH TONIGHT. THIS WILL CONTINUE TO GENERATE MODERATE 
SURF ALONG EXPOSED COASTLINES...AS WELL AS STRONG RIP CURRENTS 
WITHIN THE SURF ZONE.

$$
STRIPLING/AGUIRRE