000
AXPZ20 KNHC 091550
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT AUG 09 2008

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 
1500 UTC.

...SPECIAL FEATURE...

HURRICANE HERNAN IS CENTERED NEAR 15.7N 123.3W AT 1500 UTC 
MOVING W-NW AT 8 KT. MAXIMUM SUSTAINED WINDS ARE 105 KT WITH 
GUSTS TO 130 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 956 MB.  
HERNAN HAS INTENSIFIED SIGNIFICANTLY IN THE LAST 24 HOURS AND 
HAS A WELL DEFINED 20 NM DIAMETER EYE WITH NUMEROUS STRONG 
CONVECTION NOTED WITHIN 60 NM OF CENTER. SCATTERED MODERATE TO 
STRONG CONVECTION IS NOTED ELSEWHERE WITHIN 80 NM NW SEMICIRCLE 
AND WITHIN 180 NM OVER THE SE SEMICIRCLE. HERNAN IS FORECAST TO 
REMAIN A MAJOR HURRICANE THROUGH THE NEXT 24 HOURS BEFORE 
ENCOUNTERING SLIGHTLY COOLER SEA SURFACE TEMPERATURES THEN IN 48 
HOURS COOLER SEA WATER TEMPERATURES CAUSING IT TO UNDERGO 
WEAKENING AFTER 48 HOURS. SEE LATEST NHC FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADER MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.

...TROPICAL LOWS...

.LOW PRES IS ANALYZED NEAR 11N94W 1008 MB. CONVECTION HAS 
DECREASED OVERALL DURING THE LAST SIX HOURS HOWEVER NEWLY FORMED 
CONVECTION NEAR THE CENTER INDICATES THAT ORGANIZATION OF THE 
CONVECTION PERSISTS. THE LOW IS FORECAST TO POSSIBLY BECOME A 
TROPICAL CYCLONE IN THE NEXT 24 TO 48 HOURS. SCATTERED MODERATE 
TO STRONG CONVECTION IS NOTED WITHIN 240 NM IN THE NORTHEAST 
SEMICIRCLE. OTHER CONVECTION MOVING AWAY FROM THE CENTER IS 
NOTED WITHIN 60 NM EITHER SIDE OF A LINE FROM 16N96W TO 11N99W.
THE TROPICAL WAVE THAT HAS BEEN ANALYZED EAST OF THE LOW IS NOW 
DETERMINED TO BE ASSOCIATED WITH THE LOW AND IS ANALYZED FROM 
16N94W THROUGH THE LOW TO 05N94W. BOTH THE LOW AND THE WAVE ARE 
MOVING WEST ABOUT 10 KNOTS.

...TROPICAL WAVES... 

THE TROPICAL WAVE PREVIOUSLY ALONG 84W HAS BEEN ADJUSTED AS 
NOTED ABOVE.

A TROPICAL WAVE IS ALONG 107W 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. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION IS CURRENTLY OBSERVED WITHIN 60 
NM OF THE POINT 13N107.5W. THE CONVECTION IS WEAKLY ORGANIZED BY 
THE CYCLONIC CIRCULATION. THE SYSTEM IS EXPECTED TO CONTINUE TO 
MOVE WEST AND NOT TO DEVELOP.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE FROM 09N84W TO 
11N100W TO 13N103W TO 13N115W TO 16N123W TO 11N140W. SCATTERED 
MODERATE CONVECTION IS WITHIN THE AREA FROM 04N TO 06N BETWEEN 
78W TO 89W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF 
THE AXIS BETWEEN 112W AND 115W. SCATTERED MODERATE CONVECTION IS 
WITHIN 90 NM OF THE AXIS W OF 135W.

...DISCUSSION...

A LONGWAVE DEEP LAYER TROUGH LIES OVER THE NE PACIFIC ALONG A 
LINE FROM NEAR 35N120W TO 20N140W. A REINFORCING SECONDARY 
TROUGH HAS STRENGTHENED THE NORTHERN PART OF THE TROUGH NORTH OF 
27N. AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER NEW MEXICO NEAR 
34N106W. SOUTHERLY FLOW BETWEEN THE TROUGH AXIS AND THE 
ANTICYCLONE DOMINATES THE MIDDLE AND UPPER FLOW NORTH OF 17N 
WEST OF A LINE FROM NEAR 32N113W TO 18N122W TO 15N140W. THIS 
AREA IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS.IN 
THE LOWER LAYERS OVERCAST STRATOCUMULUS IS NOTED NORTH OF 24N 
BEGINNING ABOUT 200 NM WEST OF THE COAST OF BAJA CALIFORNIA OUT 
TO NEAR 130W WHERE THE CLOUDS BECOME BROKEN TO OVERCAST WEST OF 
130W AND SOUTH OF 25N. MOST MOISTURE ASSOCIATED WITH HERNAN 
CONVECTION IS NOT BEING ADVECTED NORTHWARD BUT IS REMAINING 
SOUTH OF 17N AND SOME IS BEING ADVECTED SOUTH OF THE ITCZ.

NORTH OF THE ITCZ EAST OF ABOUT 115W THE ATMOSPHERE IS MOIST IN 
THE MIDDLE AND UPPER LEVELS WITH AREAS OF MULTI LEVEL CLOUDINESS 
AND EMBEDDED AREAS OF CONVECTION.

WEAKENING COLD FRONT IS THROUGH 32N130W TO 27.5N140W. A WEAK 
RIDGE IS NORTHWEST OF HERNAN. ELSEWHERE EXCEPT FOR THE LOWS 
MENTIONED ABOVE A BROAD TROUGH IS ANALYZED.

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.

$$
LL