000
AXPZ20 KNHC 090958
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT AUG 09 2008

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 
0945 UTC.

...SPECIAL FEATURE...

HURRICANE HERNAN IS CENTERED NEAR 15.5N 122.6W AT 0900 UTC 
MOVING W NW AT 09 KT. MAXIMUM SUSTAINED WINDS ARE 85 KT WITH 
GUSTS TO 105 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 973 MB.  
HERNAN HAS AN INTERMITTENT 10 NM OPEN EYE WITH NUMEROUS STRONG 
CONVECTION NOTED WITHIN 60 NM OF CENTER. SCATTERED MODERATE TO 
STRONG CONVECTION IS NOTED ELSEWHERE WITHIN 75 NM NW SEMICIRCLE 
AND WITHIN 180 NM OVER THE SE SEMICIRCLE. HERNAN IS FORECAST TO 
REMAIN A HURRICANE THROUGH THE NEXT 36 HOURS BEFORE ENCOUNTERING 
COOLER SEA SURFACE TEMPERATURES CAUSING IT TO UNDERGO WEAKENING. 
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER 
MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.

...TROPICAL LOWS...

.BROAD LOW PRES IS ANALYZED A SURFACE NEAR 10N93W 1008 MB. 
SCATTERED MODERATE TO STRONG CONVECTION IS ENHANCED W OF THE 
SURFACE LOW...WITHIN 60 NM EITHER SIDE OF LINE FROM 16N94W TO 
09N97W.

...TROPICAL WAVES... 

A TROPICAL WAVE IS N OF 04N ALONG 84W AND HAS BEEN MOVING W AT 
ABOUT 12 KT THE PAST 24 HOURS. CONVECTION IS FLARING OVER THE
TROPICAL PAC WITHIN 60 NM OF 06N87W.

A TROPICAL WAVE IS ALONG 108W FROM 05N TO 16N MOVING W AT ABOUT 
12 KT THE PAST 24 HOURS. A SURFACE LOW IS ANALYZED ALONG THE 
WAVE AT AXIS AT 11N ESTIMATED AT 1009 MB. ONLY MODERATE 
CONVECTION IS CURRENTLY OBSERVED WITHIN 75 NM OF 11N107W.

...ITCZ...

THE ITCZ AXIS IS ALONG FLUCTUATES FROM 08N TO 10N BETWEEN 85W 
AND 110W AND FROM 10N TO 12N BETWEEN 110W AND 140W. SCATTERED 
MODERATE ISOLATED ISOLATED STRONG CONVECTION IS NOTED FROM 04N 
TO 08N E OF 87W...AND ALSO WITHIN 30 NM EITHER SIDE OF LINE FROM 
11N111W TO 15N114W AND LINE 11N128W TO 11N135W TO 09N140W.

...DISCUSSION...

A LONGWAVE UPPER LEVEL TROUGH LIES OVER THE NE PACIFIC ALONG 
ROUGHLY 130W...AND EXTENDS S INTO THE DISCUSSION AREA FROM 
32N128W TO 19N137W. A REINFORCING SECONDARY TROUGH HAS ALMOST 
OVERCOME THE INITIAL TROUGH ALONG 32N1288W TO 22N140W. AN 
UPPER LEVEL ANTICYCLONE IS CENTERED OVER NEW MEXICO NEAR 35N106W 
WITH A RIDGE SW TO 18N133W. DRY UPPER AIR IS INDICATED N OF 18N 
W OF 119W. UPPER DEBRIS MOISTURE FROM HERNAN AND ITCZ CONVECTION 
BETWEEN 118W AND 145W REMAINS S OF 19N...BUT SOME OF THE 
MOISTURE IS ADVECTED S ACROSS THE EQUATOR BETWEEN 128W AND 143W. 
AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N140W TO 24N115W. 
LOCALLY OVERCAST STRATOCUMULUS IS NOTED N OF 18N W OF 117W.  

AN ATLC UPPER TROUGH EXTENDS W ACROSS THE CARIBBEAN ALONG 20N 
THROUGH UPPER CYCLONES AT 21N98W AND 21N114W. AN UPPER 
ANTICYCLONE IS ESTIMATED NEAR 13N80W RESULTING IN NE FLOW OVER 
THE TROPICAL PACIFIC S OF THE ITCZ.

GAP WINDS...FRESH NE WINDS OVER THE W CARIBBEAN ARE SURGING 
ACROSS CENTRAL AMERICA INTO...AND WITHIN 420 NM DOWNSTREAM OF 
THE GULF OF PAPAGAYO AT 20 KT. LITTLE CHANGE EXPECTED FOR 
ANOTHER DAY THEN CONDITIONS DIMINISH.

$$
NELSON