000
AXPZ20 KNHC 091555
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI OCT 09 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 
1545 UTC.

...TROPICAL WAVE... 

A TROPICAL WAVE WAS ANALYZED ALONG 109W/110W FROM 09N TO 15N
AND ESTIMATED TO BE MOVING W 10 TO 15 KT OVER THE PAST 24 HOURS. 
AS NOTED PREVIOUSLY THE WAVE HAS BECOME RATHER DIFFICULT TO 
DISCERN AS IT IS SITUATED TO THE SOUTH OF A DEVELOPING AREA OF 
LOW PRESSURE NEAR 18N107W...180 NM SW OF CABO CORRIENTES. A HIGH 
RESOLUTION QUIKSCAT PASS FROM 1310 UTC INDICATED A BROAD AREA OF 
SOUTHWESTERLY MONSOONAL FLOW IN THE AREA WHERE THE WAVE IS 
SITUATED. THE WAVE MAY BE DROPPED ON THE 1800 UTC SFC ANALYSIS 
PENDING FURTHER EXAMINATION AND THE AVAILABILITY OF ADDITIONAL 
VISIBLE SATELLITE IMAGERY. AS FOR THE AREA OF LOW PRESSURE...
GLOBAL MODELS SHOW THE LOW LEVEL CENTER STALLING THROUGH TODAY 
AS THE UPPER TROUGH LIFTS OUT...THEN SHIFTING TO THE N AND NE 
LATE SAT AND SUN AS ANOTHER MID TO UPPER TROUGH DIGS INTO THE 
AREA. 

...ITCZ...

THE ITCZ AXIS WAS CENTERED ALONG 08N85W TO 10N97W TO 12N108W TO 
12N120W TO 07N140W. SCATTERED TO NUMEROUS MODERATE TO ISOLATED 
STRONG CONVECTION IS FROM 06N TO 10N BETWEEN 82W AND 86W...AND 
FROM 07N TO 11N BETWEEN 95W AND 102W. 

...DISCUSSION...

A RATHER SHARP MID TO UPPER LEVEL TROUGH EXTENDS FROM THE 
CENTRAL PLAINS TO NORTH-CENTRAL MEXICO. THIS FEATURE IS 
GRADUALLY ERODING AN AMPLIFIED RIDGE THAT EXTENDS FROM FLORIDA 
TO EAST-CENTRAL MEXICO. THE TROUGH CONTINUES WEST AS A SHEAR 
AXIS ACROSS THE EASTERN PACIFIC TO A BASE NEAR 20N115W. 

E OF 110W...SOUTH OF THE RIDGE AXIS...A LARGE UPPER LOW IS NOTED 
NEAR 12N91W...DRIFTING WEST. THIS UPPER LOW WILL ENHANCE A VAST 
AREA OF CONVECTION OVER MOST OF CENTRAL AMERICA...SPREADING TO  
THE PACIFIC COAST OVER THE NEXT COUPLE OF DAYS 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.  

W OF 110W...A MINOR MID TO UPPER LEVEL SHORT WAVE TROUGH SHIFT 
EASTWARD N OF THE RIDGE AXIS WILL DO LITTLE TODAY TO DIMINISH A 
SURFACE RIDGE DOMINATING THE AREA N OF 20N W OF 110W. 
SCATTEROMETER DATA SHOW AN AREA OF FRESH TO STRONG TRADE WINDS 
BETWEEN THIS SURFACE RIDGE AND A TROUGH ALONG 130W S OF 15N 
MOVING WESTWARD. A 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.

WAVEWATCH MODEL IS SHOWING SW LONG PERIOD SWELL REACHING THE 
CENTRAL AMERICAN AND MEXICAN COAST BY LATE SUNDAY...WITH 
COMBINED SEAS TO 6 FT.

$$
COBB