000
AXPZ20 KNHC 092204
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI OCT 09 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 
1545 UTC.

...SPECIAL FEATURE... 

THE TROPICAL WAVE WHICH WAS ANALYZED EARLIER ALONG 109W/110W
HAS BEEN DROPPED FROM THE SURFACE ANALYSIS. EARLIER DISCUSSIONS 
NOTED THAT THE WAVE WAS DIFFICULT TO DISCERN AS IT WAS SITUATED 
TO THE SOUTH OF A DEVELOPING AREA OF LOW PRESSURE. THIS AREA OF 
LOW PRESSURE IS NOW LOCATED NEAR 18N106W...OR ABOUT 120 NM SW OF
CABO CORRIENTES. THE LOW HAS BECOME BETTER DEFINED IN VISIBLE 
SATELLITE IMAGERY WITH SOME BANDING FEATURES NOTED IN THE E 
SEMICIRCLE OF THE LOW WITH SCATTERED MODERATE TO STRONG 
CONVECTION NOTED ALONG THE COAST OF MEXICO FROM TECOMAN THROUGH 
MANZANILLO TO NEAR CABO CORRIENTES. SOME OF THESE STORMS MAY 
PRODUCE LOCALLY HEAVY RAINFALL IN THOSE AREAS. CONDITIONS APPEAR 
FAVORABLE FURTHER DEVELOPMENT OF THIS AREA OF LOW PRESSURE AND 
THERE IS A MEDIUM POTENTIAL FOR TROPICAL CYCLONE FORMATION 
WITHIN THE NEXT 48 HOURS. 

...ITCZ...

THE ITCZ AXIS WAS CENTERED ALONG 09N85W TO 09N93W TO 12N105W TO 
12N115W TO 12N130W TO 07N140W. SCATTERED STRONG WITHIN 45 NM OF 
12N109W AND 12N134W. SCATTERED MODERATE TO STRONG WITHIN 180 NM 
S OF AXIS BETWEEN 82W AND 87W. SCATTERED MODERATE ISOLATED 
STRONG FROM 07N TO 12N BETWEEN 98W AND 105W...WITHIN 120 NM S OF 
THE AXIS BETWEEN 89W AND 94W AND 126W AND 130W. SCATTERED 
MODERATE WITHIN 120 NM S OF THE AXIS BETWEEN 122W AND 126W...AND 
180 NM S OF THE AXIS BETWEEN 130W AND 135W.

...DISCUSSION...

W OF 100W...
A SHEARING SHARP MID TO UPPER LEVEL TROUGH EXTENDS FROM THE 
CENTRAL PLAINS TO NORTH-CENTRAL MEXICO. THIS FEATURE IS 
GRADUALLY ERODING AN HIGHLY AMPLIFIED RIDGE THAT EXTENDS FROM 
FLORIDA TO THE GULF OF MEXICO. THE TROUGH CONTINUES TO THE SOUTH 
WEST AS A SHEAR AXIS ACROSS THE EASTERN PACIFIC TO A BASE NEAR 
20N115W. THIS SHEAR AXIS WAS LOCATED NE OF AN E-W ELONGATED 
ANTICYCLONE NEAR 18N115W COVERS THE TROPICAL PACIFIC S OF 23N 
AND EXTENDS WWD THROUGH 140W. 

ANOTHER MID TO UPPER LEVEL TROUGH WAS MOVING INTO THE NE PORTION 
OF THE DISCUSSION AREA WITH AXIS THROUGH 32N131W TO 21N140W. 
AN EXPANDING AREA OF HIGH LEVEL MOISTURE WAS MOVING EWD ACROSS 
THE DISCUSSION AREA N OF 23N TOWARD SOUTHERN CALIFORNIA. 

AT THE SURFACE...RIDGE OF HIGH PRESSURE DOMINATES THE AREA N OF 
18N W OF 110W. A 1448 UTC QUIKSCAT PASS SHOWED AN AREA OF FRESH 
TRADE WINDS BETWEEN THIS SURFACE RIDGE AND A TROUGH ALONG 131W S 
OF 15N MOVING WESTWARD. AN EARLIER 1310 UTC QUIKSCAT PASS 
INDICATED FRESH NORTHERLY FLOW ALONG THE NORTHERN BAJA 
COAST...ON THE EASTERN EDGE OF THE SURFACE RIDGE. THESE WINDS AS 
WELL AS TRADES WILL DIMINISH THROUGH AS THE SURFACE RIDGE SHIFTS 
SE AHEAD OF A DEEP LAYER TROUGH DIGGING INTO THE AREA FROM THE N 
CENTRAL PACIFIC...AND SHIFTS EASTWARD N OF 25N FROM LATE SAT 
THROUGH MON. MEANWHILE...SW CROSS-EQUATORIAL FLOW WILL INCREASE 
SLIGHTLY...INCREASING CONVECTION SLIGHTLY ALONG THE ITCZ.

E OF 100W...
A LARGE UPPER LOW IS NOTED NEAR 13N93W WAS MOVING W AT 10 KT. 
THIS UPPER LOW IS ENHANCING A VAST AREA OF CONVECTION OVER MOST 
OF CENTRAL AMERICA...SPREADING TO THE PACIFIC COAST OVER THE 
NEXT 24 HOURS AS THE DIVERGENT AREA ON THE EAST OF THE UPPER LOW 
TRANSITS OVER THE REGION. AT THE SURFACE...AN 1122 UTC HIGH 
RESOLUTION QUIKSCAT PASS SHOWED 20 KT FLOW SEEPING THROUGH THE 
GULF OF PAPAGAYO.  

WAVEWATCH MODEL IS SHOWING SW LONG PERIOD SWELL REACHING THE 
CENTRAL AMERICAN AND MEXICAN COAST BY LATE SUNDAY...WITH 
COMBINED SEAS TO 6 FT. DESPITE THE LOW OPEN SEA HEIGHTS...THERE 
REMAINS THE POTENTIAL FOR LARGE BREAKING SURF ALONG THE COAST OF 
BAJA CALIFORNIA DUE TO THE EXPECTED LONG PERIOD SWELLS OF 20 
SECONDS.  
 
$$
COBB