000
AXPZ20 KNHC 311551
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI JUL 31 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 
1400 UTC.

...TROPICAL WAVES...
TROPICAL WAVE FROM 03N TO 18N ALONG 103W MOVING W 15 KT. 
ISOLATED MODERATE CONVECTION LIES WITHIN 180 NM W OF TROPICAL 
WAVE ALONG 103W FROM 09N TO 12N AND WITHIN 150 NM EITHER SIDE OF 
TROPICAL WAVE N OF 16N TO MEXICAN COAST. THIS TROPICAL WAVE IS 
TRACKING ON THE E SIDE OF THE UPPER LEVEL LOW LOCATED NEAR 
15N115W AND LIES IN A REGION OF UPPER LEVEL DIFFLUENCE 
ASSOCIATED WITH A RIDGE AXIS EXTENDING SOUTHWARD ALONG 102W FROM 
THE BROAD UPPER LEVEL ANTICYCLONE CENTERED OVER NORTHERN MEXICO.

TROPICAL WAVE FROM 04N TO 11N ALONG 122W MOVING W 10 KT. 
SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 180 NM W OF 
THE TROPICAL WAVE ALONG 122W FROM 12N TO 17N. THIS WAVE IS 
TRACKING ON THE E SIDE OF A MID TO UPPER LEVEL LOW NEAR 12N129W. 
PRECIPITABLE WATER VALUES ARE WELL IN EXCESS OF 2 INCHES IN THIS 
REGION OF DEEP SOUTHERLY FLOW. HOWEVER...THE WAVE ALSO LIES IN A 
REGION OF MEAN UPPER LEVEL CONFLUENCE BETWEEN THE UPPER LOWS TO 
ITS E AND W.

...ITCZ...
THE ITCZ LIES ALONG AN AXIS FROM 10N84W TO 08N108W TO 11N129W TO 
11N134W TO 13N140W. SCATTERED MODERATE CONVECTION LIES WITHIN 
120 NM OF THE ITCZ AXIS BETWEEN 110W AND 115W AND WITHIN 120 NM 
S OF THE ITCZ AXIS BETWEEN 89W AND 91W. 

...DISCUSSION...
THE EFFECTS OF T.S. LANA CONTINUE TO BE FELT OVER FORECAST 
WATERS W OF 137W FROM 12N TO 20N WHERE WINDS OF 20 KT AND SEAS 
TO 9 FT CAN BE FOUND. EXPECT THE IMPACTS FROM LANA TO DECREASE 
OVER THE NEXT 36 HOURS AS THE SYSTEM MOVES WESTWARD. FOR FURTHER 
INFORMATION ON T.S. LANA...PLEASE SEE THE LATEST PUBLIC ADVISORY 
FROM THE CENTRAL PACIFIC HURRICANE CENTER UNDER AWIPS/WMO 
HEADERS MIATCPEP1/WTPZ31.

ELSEWHERE OVER N WATERS...A SURFACE RIDGE CAN BE FOUND WITH AN 
AXIS FROM 29N140W TO 21N108W. MODERATE TO STRONG SUBSIDENCE WITH 
DRY STABLE AIR AT THE MIDDLE AND UPPER LEVELS OF THE ATMOSPHERE 
IS WITHIN 300 NM EITHER SIDE OF THE RIDGE AXIS W OF 120W. BROKEN 
TO OVERCAST STRATOCUMULUS CLOUDS BLANKET THE AREA N OF 20N W OF 
125W AND FROM 20N125W N TO THE CENTRAL COAST OF BAJA CALIFORNIA 
WITH THE EXCEPTION OF THE FAR NW CORNER WHERE AN UPPER LEVEL 
TROUGH EXTENDS FROM A CYCLONIC CIRCULATION N OF THE AREA TO 
30N128W 27N130W AND BREAKS UP THE OVERCAST STRATOCUMULUS.

THE HIGH RESOLUTION QUIKSCAT RETRIEVALS FROM 1144 UTC SHOW THE 
AREA OF 20 KT WINDS IN THE GULF OF PAPAGAYO IS DIMINISHING AND 
BEGINNING TO SHIFT W AWAY FROM SHORE. BY SUNDAY...THE TROPICAL 
WAVE CURRENTLY OVER THE CARIBBEAN ALONG 71W WILL PASS THROUGH 
PAPAGAYO AND BRING A RESURGENCE OF GAP WINDS ABOVE 20 KT NEAR 
THE COAST.

THE NEXT ROUND OF SOUTHWESTERLY SWELL HAS CROSSED THE EQUATOR 
WITH SIGNIFICANT WAVE HEIGHTS TO 8 FT IN THE CENTRAL PORTION OF 
THE FORECAST AREA S OF 05N. LONGER PERIOD SW SWELL IS CURRENTLY 
MOVING INTO THE WESTERN PORTION OF THIS AREA AND WILL CONTINUE 
NORTH...MOVING FIRST ONTO THE SOUTHERN BAJA AND CENTRAL MEXICAN 
COASTS SUN MORN.

$$
SCHAUER CLARK