000
AXPZ20 KNHC 111016
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON AUG 11 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 18.7N 129.3W AT 0900 UTC 
MOVING W OR 280 DEG AT 09 KT. MAXIMUM SUSTAINED WINDS ARE 70 KT 
WITH GUSTS TO 85 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 983 
MB. HERNAN HAS A SMALL...ABOUT 8 NM WIDE EYE WITH SCATTERED 
MODERATE CONVECTION NOTED WITHIN 90 NM OF CENTER WITH THE 
STRONGEST BAND OVER THE SE QUADRANT AT THE MOMENT. HERNAN IS 
FORECAST TO GRADUALLY WEAKEN TO A TROPICAL STORM BY 24 HOURS. 
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER 
MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.

...TROPICAL LOWS...

.LOW PRES IS ANALYZED NEAR 15N113W AND ESTIMATED AT 1008 MB. 
SCATTERED MODERATE TO STRONG CONVECTION IDS OBSERVED WITHIN 180 
NM OVER ITS NW SEMICIRCLE. THE LOW IS FORECAST TO MOVE INITIALLY 
NW THEN TURN MORE WESTERLY IN ABOUT 48 HOURS WITH THE 
POSSIBILITY OF TROPICAL CYCLONE DEVELOPMENT.

.BROAD LOW PRES IS ANALYZED AS SURFACE LOW NEAR 13N98W AND 
ESTIMATED AT 1008 MB. SCATTERED MODERATE TO STRONG CONVECTION IS 
OBSERVED WITHIN 30 NM EITHER SIDE OF LINE FROM 15.5N94.5W TO 
13N99W.

...TROPICAL WAVES... 

A TROPICAL WAVE IS ALONG 78W AT THE MOMENT AND HAS BEEN MOVING W 
AT ABOUT 13 KT THE PAST 24 HOURS. INTENSE CONVECTION IS ENHANCED 
OVER INTERIOR COLOMBIA AND OVER THE SW CARIBBEAN...AND WILL 
LIKELY SPREAD OFFSHORE OVER THE PACIFIC WATERS S OF PANAMA EARLY 
TODAY.

...ITCZ...

THE ITCZ AXIS IS ALONG 10N80W TO 10N110W TO 14N120W TO 11N120W 
TO 14N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
NOTED WITHIN 120 NM EITHER SIDE OF LINE FROM 06N91W TO 07N113W.

...DISCUSSION...

AN UPPER LEVEL TROUGH LIES OVER THE SUBTROPICAL PACIFIC ALONG 
140W WITH AN ASSOCIATED SHORT WAVE TROUGH NOW APPROACHING THE NW 
PORTION OF THE DISCUSSION AREA ALONG 33N140W 25N145W. AN UPPER 
LEVEL ANTICYCLONE IS CENTERED NEAR 32N108W WITH A RIDGE 
EXTENDING SW TO A SHARP CREST NEAR 20N138W. DIFFLUENCE UNDER THE 
RIDGE ENHANCED CONVECTION OVER NW OLD MEXICO ON SUN WITH SOME OF 
THE DEBRIS MOISTURE NOW SPREADING SW ACROSS THE GULF OF 
CALIFORNIA AND THE BAJA PENINSULA. AN ATLC UPPER TROUGH EXTENDS 
W ACROSS THE CARIBBEAN AND OLD MEXICO ALONG 20N INTO THE E 
PACIFIC THROUGH UPPER CYCLONES AT 21N108W AND 22N120W. THE UPPER 
LEVELS SEEM MOIST EVERYWHERE N OF 20N BETWEEN 105W AND 110W. THE 
UPPER LEVELS APPEAR VERY DRY W OF A LINE FROM 32N113W TO 20N132W 
WITH SOME OF THIS DRY AIR ENTRAINING INTO THE NW QUADRANT OF 
HURRICANE HERNAN. AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N137W 
TO 20N110W. LOCALLY OVERCAST STRATOCUMULUS IS NOTED N OF 18N W 
OF 115W.  

A E TO W UPPER RIDGE DOMINATES THE TROPICAL PACIFIC E OF 110W 
WITH THE ASSOCIATED UPPER DIFFLUENCE ENHANCING THE CONVECTION 
DESCRIBED ABOVE. THE DEBRIS MOISTURE REMAINS S OF 20N E OF 105W 
WITH SOME OF THE MOISTURE SPREADING S OF THE EQUATOR BETWEEN 80W 
AND 105W.

$$
NELSON