000
AXPZ20 KNHC 082116
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE SEP 08 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 
2100 UTC.

...SPECIAL FEATURES...

AT 08/2100 UTC...TROPICAL STORM LINDA IS LOCATED NEAR 15.5N 
128.4W MOVING NW OR 315 DEG AT 2 KT. MAXIMUM SUSTAINED WIND 
SPEED IS 50 KT WITH GUSTS TO 60 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 997 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. 
CONVECTION HAS DIMINISHED IN THE LAST SIX HOURS WITH SCATTERED 
MODERATE ISOLATED STRONG CONVECTION WITHIN 150 NM OF THE CENTER.
ADDITIONAL STRENGTHENING IS FORECAST THROUGH TONIGHT BUT THE 
FORECAST KEEPS LINDA AS A TROPICAL STORM. LINDA IS FORECAST TO 
GRADUALLY WEAKEN BEGINNING WEDNESDAY. SATELLITE IMAGERY SHOWS A 
SHARP WESTERN EDGE TO THE DEEP CONVECTIVE CLOUDS ASSOCIATED WITH 
LINDA...INDICATING THAT THE CYCLONE IS EXPERIENCING WESTERLY 
SHEAR.

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 05N77W TO 
08N105W TO 07N140W. SCATTERED MODERATE TO STRONG CONVECTION IS 
WITHIN THE AREA FROM 05N TO 07.5N EAST OF 87W. SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN THE AREA 120 
NM NORTH OF THE ITCZ AXIS FROM 99W TO 108W. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF THE POINT 
07.5N111.5W. SCATTERED MODERATE TO STRONG WITHIN 60 NM EITHER 
SIDE OF LINE FROM 06N117W TO 09N121W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS WITHIN THE AREA 45 NM EITHER SIDE 
OF THE ITCZ AXIS WEST OF 133W.

...DISCUSSION...

A DEEP LAYER ANTICYCLONE LOCATED W OF 140W HAS A RIDGE EXTENDING 
EWD OVER THE WESTERN PORTION OF THE FORECAST REGION. THE RIDGE 
AND THE ASSOCIATED DRY STABLE AIR IN THE MIDDLE AND UPPER LEVELS 
OF THE ATMOSPHERE COVERS THE AREA N OF 10N AND W OF 130W.

A SHARP DEEP LAYER TROUGH EXTENDS FROM SOUTHERN NEW MEXICO 
ACROSS CENTRAL BAJA CALIFORNIA TO 18N130W. ANOTHER UPPER LEVEL 
ANTICYCLONIC CIRCULATION IS CENTERED NEAR 15N116W. TROPICAL 
STORM LINDA IS MOVING AROUND THE WESTERN PERIPHERY OF THIS 
SYSTEM. THE THIRD MID/UPPER LEVEL HIGH IS OVER SOUTHERN MEXICO 
ALONG THE COAST OF THE BAY OF CAMPECHE AND IS ENHANCING 
CONVECTION N OF THE ITCZ BETWEEN 95W-110W. AN INVERTED UPPER 
LEVEL TROUGH WITH AXIS ALONG 111W SEPARATES THE ABOVE MENTIONED 
ANTICYCLONES. A TROUGH EXTENDS FROM THE WESTERN CARIBBEAN ACROSS 
CENTRAL AMERICA EAST OF 87W. ENHANCED CONVECTION IN THE ITCZ 
REGION SOUTH OF PANAMA AND COSTA RICA IS ASSOCIATED WITH THIS 
TROUGH.

A SURFACE RIDGE CONTINUES TO DOMINATE THE NORTHERN PORTION OF 
DISCUSSION AREA MAINLY N OF 20N W OF 115W. THE PRESSURE GRADIENT 
BETWEEN LINDA AND THE RIDGE IS PRODUCING A LARGE AREA OF NE 
WINDS 20 KT AND SEAS TO 9 FT PARTICULARLY FROM 15N TO 25N AND W 
OF 130W. THESE CONDITIONS ARE EXPECTED TO PERSIST DURING THE 
NEXT 48 HOURS. STRATOCUMULUS CLOUDS ARE OBSERVED N OF 15N W OF 
120W.

SWELLS FROM THE NW ARE IN THE NE PORTION OF THE AREA THROUGH 
TONIGHT. LATE IN THE WEEK...LONG PERIOD SWELLS OF 16 SECONDS  
WILL APPROACH THE NW PART OF THE AREA WITH SEAS TO 11 FT.

$$
LL