000
AXPZ20 KNHC 061610
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE OCT 06 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 88W N OF 08N. AN ASCAT PASS 
FROM 02Z SHOWED 15 TO 20 KT SW FLOW CONVERGING INTO THE WAVE 
FROM THE SOUTH. THE WAVE IS WITHIN A BROAD AREA OF DEEP LAYER 
MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. GLOBAL 
MODELS SHOW THIS FEATURE MOVING WNW...POSSIBLY DEVELOPING A LOW 
PRES AS IT PARALLELS THE CENTRAL AMERICAN AND MEXICAN 
COASTLINES. EXPECT INCREASED CONVECTION OFFSHORE OVER THE NEXT 
COUPLE OF DAYS WITH WINDS TO 20 KT AND SEAS REACHING 8 FT 
ASSOCIATED WITH THIS FEATURE.

...ITCZ...

THE ITCZ AXIS WAS ALONG 11N86W TO 07N100W TO 10N110W TO 07N130W 
TO 11N140W. SCATTERED MODERATE TO STRONG WITHIN 180 NM S OF AXIS 
FROM 88W TO 93W. SCATTERED MODERATE WITHIN 60 NM S OF AXIS FROM 
115W TO 117W.

...DISCUSSION...
W OF 110W...AN UPPER LEVEL RIDGE EXTENDS FROM CENTRAL MEXICO 
THROUGH 13N135W CONTINUES TO SHIFT EAST AND WEAKEN...AHEAD OF A 
MID TO UPPER LEVEL TROUGH EXTENDING FROM CENTRAL CALIFORNIA TO 
30N130W TO 18N130W. AN ASCAT PASS FROM 06Z SHOWED EVIDENCE OF A 
WEAK SURFACE TROUGH ASSOCIATED WITH THE MID TO UPPER LEVEL 
TROUGH...EXTENDING FROM 30N126W TO 26N131W WITH NE WINDS TO 20 
KT MAINLY W OF THE TROUGH. FURTHER SOUTH...THE ASCAT PASS ALSO 
SHOWED PERSISTENT 20 TO 25 KT WINDS MAINLY FROM 14N TO 20N W OF 
135W...ON THE SOUTHERN PERIPHERY OF A 1032 MB SURFACE HIGH PRES 
AREA ANALYZED OVER THE NE PACIFIC. EAST OF THIS AREA...SPEED 
CONVERGENCE OF MODERATE TRADES ON THE SOUTHERN PERIPHERY OF THE 
SURFACE RIDGE IS ENHANCING A LINE OF WEAK CONVECTION RUNNING 
ROUGHLY EAST TO WEST ALONG 12N. THIS IS ARGUABLY A SECOND ITCZ 
SITUATED PARALLEL AND TO THE NORTH OF THE MAIN ITCZ THAT IS 
BASED ON CONFLUENCE OF SW CROSS-EQUATORIAL FLOW. AT ANY 
RATE...CONVECTION...WINDS AND SEAS REMAIN MODEST ALONG THIS LINE 
FOR THE TIME BEING. THESE TRADES WILL INCREASE SLIGHTLY OVER THE 
NEXT COUPLE OF DAYS AS THE RIDGE N OF THE AREA BUILDS. A 1010 MB 
LOW IS NOTED ALONG THE MAIN ITCZ NEAR 112W. THIS FEATURE WILL 
DRIFT SLOWLY WNW OVER THE NEXT COUPLE OF DAYS...AND ALTHOUGH 
WILL NOT DEVELOP SIGNIFICANTLY...IT MAY ENHANCE TRADE WIND FLOW 
TO THE NORTH. MEANWHILE...LONG PERIOD SWELL WITH SEAS TO 8 FT 
COVERS THE AREA MAINLY N OF 10N W OF 110W...BUT WAVEWATCH AND 
FNMOC WAVE MODELS SHOW THIS SWELL DECAYING THROUGH TODAY.

EAST OF 110W...MORNING DRAINAGE FLOW CONVECTION HAS BEEN ACTIVE 
FROM EL SALVADOR TO SOUTHERN MEXICO. SOME OF THIS CONVECTION CAN 
BE ATTRIBUTED TO THE TROPICAL WAVE ALONG 88W. FURTHER 
NORTH...WINDS OVER THE NORTHERN GULF OF CALIFORNIA HAVE 
DIMINISHED AS A TROUGH OVER THE SOUTHWEST U.S. HAS LIFTED OUT TO 
THE NE. 

$$
CHRISTENSEN