000
AXPZ20 KNHC 170945
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON AUG 17 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 
0930 UTC.

...SPECIAL FEATURES...

TROPICAL STORM GUILLERMO CENTER JUST W OF AREA NEAR 20.8N 142.6W 
AT 0900 UTC MOVING W OR 285 DEG AT 13 KT. MAXIMUM SUSTAINED 
WINDS ARE 60 KT WITH GUSTS TO 75 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 990 MB. SCATTERED MODERATE CONVECTION IS NOTED FROM 
18N TO 22N W OF 138W. SEE THE LATEST FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADERS HFOTCMCP4/WTPA24 PHFO FOR MORE DETAILS. 

...TROPICAL WAVES...

A TROPICAL WAVE IS ANALYZED N OF 06N ALONG 92W WITH WESTWARD 
MOTION OF 15 KT OVER THE PAST 24 HOURS. ONLY SLIGHT CYCLONIC 
TURNING IS NOTED ALONG THE WAVE AT 09N WHERE A SMALL CLUSTER OF 
TSTMS ARE NOTED.

A TROPICAL WAVE IS ANALYZED N OF 06N ALONG 105W AND HAS BEEN 
MOVING W AT 15 KT OVER THE PAST 48 HOURS. ISOLATED MODERATE AND 
STRONG CONVECTION IS NOTED WITHIN 180 NM OF THE WAVE AXIS BUT IS 
CURRENTLY DECREASING IN INTENSITY.

A TROPICAL WAVE IS ANALYZED FROM 04N TO 16N ALONG 120W AND HAS 
BEEN MOVING W AT ABOUT 15 KT OVER THE PAST 48 HOURS. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS FLARING FROM 10N TO 13N 
WITHIN 30 NM E AND WITHIN 180 NM W OF THE WAVE AXIS.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED ALONG 08N82W TO 
12N120W TO 09N130W TO 12N140W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION IS NOTED TO THE N OF 04N E OF 88W. ISOLATED 
MODERATE AND STRONG CONVECTION IS NOTED OVER THE DISCUSSION AREA 
FROM 05N TO 15N FROM 88W TO BEYOND 140W.

...DISCUSSION...

A QUASI STATIONARY UPPER ANTICYCLONE IS CENTERED AT 26N128W WITH 
A RIDGE EXTENDING SW TO A SHARP CREST AT 26N143W. THE RIDGE JUST 
BRUSHED ACROSS TROPICAL CYCLONE GUILLERMO EARLIER AND THE DEBRIS 
MOISTURE IS ADVECTED NE TO NEAR 30N128W. 

A SECOND UPPER ANTICYCLONE IS OVER OLD MEXICO NEAR 27N105W WITH 
A RIDGE EXTENDING S OVER THE TROPICAL PACIFIC N OF 13N BETWEEN 
103W AND 113W. SQUEEZED BETWEEN THE ANTICYCLONES IS A WELL 
DEFINED UPPER CYCLONE AT 18N122W WHICH IS MOVING W WITH TIME.  
DRY UPPER AIR IS NOTED OVER THE W PERIPHERY OF THIS 
CYCLONE...ROUGHLY FROM 15N TO BEYOND 32N BETWEEN 118W AND 128W. 
DEBRIS MOISTURE FROM ITCZ CONVECTION BETWEEN 112W AND 120W IS 
SPREADING N OVER THE E SEMICIRCLE OF THE UPPER CYCLONE BUT SEEMS 
TO EVAPORATE BEFORE REACHING THE CYCLONE CENTER.   

AN UPPER CYCLONE IS NOTED NEAR 19N96W WITH A TROUGH EXTENDING 
SSW ACROSS THE ISTHMUS OF TEHUANTEPEC TO A BASE AT 13N94W. BROAD 
UPPER RIDGING IS ENHANCING CONVECTION OVER THE TROPICAL PACIFIC 
ELSEWHERE E OF 108W WITH THE DEBRIS MOISTURE REMAINING IN 
ROUGHLY THE SAME AREA.   

AT LOW LEVELS A SURFACE RIDGE EXTENDS INTO THE AREA AT 32N135W 
TO 10N115W. NW WINDS ARE AT 15 TO 20 KT ALONG THE W COAST OF THE 
BAJA PENINSULA. 

$$
NELSON