000
AXPZ20 KNHC 200321
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN AUG 20 2006

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...SPECIAL FEATURES...
HURRICANE HECTOR AT 19.0N 132.1W 982 MB AT 0300 UTC AUG 20 
MOVING WNW OR 300 DEG AT 11 KT. MAXIMUM SUSTAINED WINDS 70 KT 
GUSTS 85 KT. NUMEROUS STRONG CONVECTION IS NOTED WITHIN 90 NM OF 
CENTER WITH A FAINT 11 NM DIAMETER EYE OCCASIONALLY BREAKING 
THROUGH THE CENTRAL DENSE OVERCAST. HECTOR IS ENCOUNTERING NW 
SHEAR AND DRY AIR ENTRAINMENT OVER ITS SW QUAD. A STEADY 
WEAKENING IS FORECAST THROUGH TONIGHT THEN QUICKER WEAKENING IS 
EXPECTED ON SUN AS HECTOR MOVES OVER COOLER SEA SURFACE WATERS 
AND EXPERIENCES INCREASING W WIND SHEAR. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
FOR MORE DETAILS. 

...TROPICAL WAVES...
A TROPICAL WAVE ALONG 97W TO THE N OF 5N IS MOVING W AT AN 
ESTIMATED 15 KT. BROAD CYCLONIC TURNING IS NOTED WITH SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION ENHANCED NEAR 11.5N 
99.5W. GLOBAL MODELS GRADUALLY SPIN UP A CYCLONE ALONG THIS 
WAVE OVER THE NEXT FEW DAYS...BUT NO ORGANIZED BANDING CAN BE 
MEASURED AT THE MOMENT.    

A TROPICAL WAVE ALONG 121W FROM 3N TO 15N IS MOVING W AT AN 
ESTIMATED 12 KT. ONLY ISOLATED SHOWERS ACCOMPANY THE WAVE AT THE 
MOMENT.

...ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 9N78W 10N90W 9N120W 14N130W 
11N140W. SCATTERED MODERATE ISOLATED STRONG WITHIN 30 NM OF 
COAST OF COLOMBIA FROM 2N TO 8N AND WITHIN 180 NM EITHER SIDE OF 
LINE 6N83W 11N100W 8N122W.

...DISCUSSION...
A SHORTWAVE TROUGH IS SWING SE THROUGH THE UPPER LEVELS WITH ITS 
AXIS CURRENTLY BECOMING NEGATIVE TILT ALONG 32N135W 26N131W. NW 
WINDS TO THE W OF THE TROUGH IS PARTIALLY RESPONSIBLE FOR THE NE 
SHEAR THAT HURCN HECTOR IS EXPERIENCING. A SECOND SHORTWAVE IS 
NOTED ALONG 32N120W 25N118W. THE ANTICYCLONE ASSOCIATED WITH 
HECTOR...NEAR 18N125W...RIDGES N ALONG 125W TO A GENTLE CREST 
ALONG 26N BETWEEN 131W AND 123W...AND EFFECTIVELY SEPARATING THE 
TWO SHORTWAVE TROUGHS. THE TROUGH TO THE W APPEARS TO BE ERODING 
THE RIDGE.  

ANOTHER ANTICYCLONE IS NOTED JUST W OF THE DISCUSSION AREA NEAR 
17N147W RIDGING NE TO A CREST JUST W OF THE HURCN AT 19N138W... 
WITH THE ANTICYCLONIC FLOW MERGING WITH THE CYCLONIC FLOW NW OF 
THE UPPER TROUGH...ALL BECOMING THE NW SHEAR INTO HECTOR.
     
TO THE SE OF HECTOR...AN UPPER LEVEL CYCLONE IS OBSERVED NEAR 
14N114W AND IS SLIPPING W WITH TIME AS MODELS SUGGEST. AN UPPER 
INVERTED TROUGH EXTENDS N FROM THE CYCLONE TO NEAR 24N112W. 
ANOTHER SMALL UPPER CYCLONE IS OBSERVED NEAR 22N98W AND IS ALSO 
MOVING W WITH TIME...WITH AN UPPER TROUGH EXTENDING SE THROUGH 
20N92W TO ANOTHER UPPER CYCLONE OVER THE CARIBBEAN NEAR 18N82W.  
AN UPPER RIDGE SEPARATE THE PACIFIC CYCLONE FROM THE MEXICAN
CYCLONE...WITH THE SMALL ANTICYCLONIC CENTER QUASI-STATIONARY 
NEAR 20N105W. A RIDGE EXTENDS SE ALONG 15N96W TO ANOTHER UPPER 
ANTICYCLONE AT 14N95W.

UPPER MOISTURE...ORIGINATING FROM ITCZ CONVECTION THROUGHOUT THE 
DISCUSSION AREA AND FROM HURCN HECTOR...IS NOTED SE OF LINE 
14N140W 24N132W 30N113W. MODERATE DRY AIR UPPER IS NOTED NW OF 
THE SAME LINE. 
 
AT THE SURFACE...A RIDGE EXTENDS SE ALONG 32N133W TO 18N110W 
WITH NW WINDS SURGING TO 20 KT OVER THE WATERS N OF 25N ALONG 
THE W COAST OF THE BAJA PENINSULA. 

$$
NELSON