000
AXPZ20 KNHC 230940
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI OCT 23 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.

...TROPICAL LOW...
AN ELONGATED LOW TO MID LEVEL TROUGH PERSIST THIS MORNING FROM W 
PORTIONS OF THE SW CARIBBEAN ACROSS COSTA RICA AND NICARAGUA AND 
INTO THE FAR TROPICAL EPAC NEAR 09N92W. DURING THE PAST 24 HOURS 
THIS FEATURE HAS BECOME LINKED WITH A MID TO UPPER LOW DIGGING S 
FROM FLORIDA AND THE NW BAHAMAS INTO THE NW CARIBBEAN. THIS AREA 
SHOWED SOME POTENTIAL FOR AN ORGANIZED LOW TO DEVELOP A FEW DAYS 
AGO...BUT SINCE THAT TIME MUCH MOISTURE HAS CONTINUALLY BEEN 
SHEARED OFF TO THE NE...WHILE IN THE PAST 12 HOURS STRONG UPPER 
WINDS IN THE BASE OF THE UPPER LOW HAVE BEEN SHEARING CONVECTION 
THAT HAD BEGUN TO CLUSTER OVER A SURFACE LOW OFF THE COAST OF 
NICARAGUA. ANOTHER LOW WAS ANALYZED OVER THE EPAC NEAR 10N86.2W 
AT 1005 MB. ALTHOUGH MODEST MID LEVEL CYCLONIC ROTATION HAS BEEN 
NOTED IN SATELLITE IMAGERY...CONVECTION REMAINS GENERALLY 
ISOLATED NEAR THIS LOW...WHICH HAS PULSED UP AND DOWN OVERNIGHT. 

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS FROM 08N76W TO 10N82W TO 
10N101W TO 12N106W TO 10N116W TO 10N137W TO 07N145W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 120 NM S 
AND 180 NM N OF AXIS W OF 126W. ISOLATED MODERATE CONVECTION WAS 
NOTED ELSEWHERE WITHIN 150 NM OF AXIS. 

...DISCUSSION...
UPPER LEVEL ANTICYCLONES BOUNDED THE AREA TO THE W AND E...ONE 
NEAR 20N94W EXTENDING NE ALONG THE SE U.S. COASTLINES...AND 
ANOTHER NEAR 31N137W EXTENDING NNE INTO BRITISH COLOMBIA. 
BETWEEN THESE HIGHS WAS A L/W TROUGH EXTENDING FROM THE HIGH 
PLAINS OF THE U.S. SW THROUGH THE NW STATES OF MEXICO...ACROSS 
BAJA CALIFORNIA...AND TO A BROAD AND FLAT BASE ALONG ABOUT 16N 
BETWEEN 110W AND 130W. CONNECTED TO THE SW OF THIS UPPER TROUGH 
WAS AN UPPER LOW AT 20N143W THAT WAS AIDING IN PRODUCING A 
NARROW TROPICAL RIDGE EXTENDING S OF THE BASE OF THIS L/W 
TROUGH...TO AN INVERTED MID LEVEL TROUGH NEAR 12N112W. THIS 
TROPICAL RIDGE WAS ENHANCING CONVECTION ALONG THE ITCZ AS 
DESCRIBED ABOVE. AS WOULD BE EXPECTED...SOME OF THE DEBRIS 
MOISTURE BEING SWEPT E AND NE ALONG THE BASE OF THE TROUGH WAS 
LIFTING NE INTO CENTRAL MEXICO...OVER AN UPPER HIGH IN THE FAR 
SOUTHERN GULF OF MEXICO. 

AT THE LOW LEVELS HIGH PRES WAS CENTERED AT 33N136W WITH A RIDGE 
EXTENDING SE TO NEAR 15N111W. THE GRADIENT NE OF THE RIDGE WAS 
SUPPORTING NORTHERLY WINDS OF 20-25 FOR SEVERAL DEGREES OFF THE 
COAST OF CALIFORNIA TO 28N..WHILE THE GRADIENT S OF THE RIDGE 
AND N OF THE ITCZ WAS SUPPORTING NELY TRADES OF 20-25 KT VEERING 
SE ACROSS THE HAWAIIAN ISLANDS. E OF 110W...MONSOONAL FLOW 
PREVAILED WITH W TO NW WINDS N OF 10N CONVERGING WITH 
ANTICYCLONIC SWLY FLOW S OF THE ITCZ.

PULSES OF NW SWELL WERE MIXING OVER THE SUBTROPICAL WATERS WITH 
SRN HEMI SW SWELL AND SE WIND SWELL...WITH A BROAD SPECTRAL MIX 
BETWEEN 110W AND 130W. LITTLE CHANGE IN THIS SCENARIO IS 
EXPECTED OVER THE NEXT FEW DAYS AS SEA HEIGHTS REMAIN WITHIN 
SEASONAL NORMS. 

$$

STRIPLING