000 AXPZ20 KNHC 071604 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU AUG 07 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 1545 UTC. ...SPECIAL FEATURE... TROPICAL STORM HERNAN IS CENTERED NEAR 14.8N 115.1W OR ABOUT 655 NM...1055 KM SOUTH-SOUTHWEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA AT 07/1500 UTC MOVING WNW AT 10 KT. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. THIS SYSTEM HAS CONTINUED TO BECOME BETTER DEFINED AS OBSERVED IN ITS MORE EVIDENT BANDING FEATURES AND VERY PRONOUNCED BURSTS OF DEEP CONVECTION OVER AND WITHIN ALL QUADRANTS OF THE CENTER. THIS CONVECTION CONSISTS OF NUMEROUS STRONG WITHIN 100 NM OF THE CENTER OVER THE SW SEMICIRCLE. SCATTERED STRONG CONVECTION IS ELSEWHERE WITHIN 240 NM OF THE CENTER IN THE SW QUADRANT AND 180 NM OF THE CENTER IN THE W QUADRANT. SCATTERED MODERATE TO STRONG CONVECTION DENOTING A WELL-DEFINED BAND IS WITHIN 30 NM EITHER SIDE OF A LINE FROM 17N115W TO 15N117W. AN OUTER BAND CONSISTING OF SCATTERED/MODERATE ISOLATED STRONG CONVECTION IS WITHIN 30 NM EITHER SIDE OF LINE 10N117W 10N119W 10N123W. A QUIKSCAT PASS FROM 1322 UTC THIS MORNING SHOWED THE CENTER OF HERNAN BEING LOCATED OVER THE NE PART OF THE CONVECTION WITH 20 KT WINDS EXTENDING AS FAR S AS 8N...AND AS FAR N AS 18N. WATER VAPOR SATELLITE-DERIVED WINDS ARE STRONGEST OVER THE W SEMICIRCLE OF HERMAN AS IT MOVES AROUND THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE. HERMAN IS FORECAST TO BRIEFLY STRENGTHEN INTO A HURRICANE IN ABOUT 36 HOURS...BEFORE MOVING OVER COOLER WATER AND WEAKENING. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 102W FROM 7N TO 17N MOVING W ABOUT 10 KT. SCATTERED MODERATE ISOLATED/STRONG CONVECTION IS WITHIN 120 NM W OF THE AXIS FROM 9N TO 12N...AND FROM 14N TO 17N. A WEAK MID-LEVEL CIRCULATION IS WITHIN 120 NM W OF THE WAVE MORE TIED INTO THE ITCZ NEAR 10N104W. THIS WAVE REMAINS UNDER VERY FAST UPPER LEVEL WINDS NOT ALLOWING FOR IT TO ORGANIZE AT LEAST THROUGH THE NEXT 48 HOURS. A TROPICAL WAVE ALONG 132W/133W FROM 05N TO 16N IS MOVING W ABOUT 10-15 KT. THE WAVE REMAINS RATHER WEAK WITH ONLY ISOLATED SHOWERS WITHIN 60 NM OF THE AXIS. ...ITCZ... ITCZ AXIS ALONG 7N79W 6N90W 15N115W 9N132W 9N140W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 93W-105W ...AND E OF 85W. ...DISCUSSION... W OF 120W... A MIDDLE/UPPER LEVEL TROUGH EXTENDS SW INTO THE AREA FROM 32N125W TO 27N129W WHERE IT BECOMES A SHEAR AXIS TO 25N132W TO 24N140W. THE TROUGH IS MOVING E ABOUT 17 KT. MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR IS OBSERVED WITHIN 300 NM SE OF THE TROUGH ...AND WITHIN 240-300 NM SE AND S OF THE SHEAR AXIS. UPPER LEVEL MOISTURE IS SEEN PUSHING SEWD INTO THE NORTHERN PORTION OF THE AREA BEHIND THE TROUGH. SLIGHT DIFFLUENCE TO THE SE OF THE TROUGH IS ENHANCING ITCZ CONVECTION SOME BETWEEN 130W-135W. THE TROUGH IS FORECAST TO LIFT NE AND DAMPEN OUT OVER THE NEXT 36-48 HOURS AS MID/UPPER LEVEL RIDGING BUILDS SOUTHWESTWARD TO NEAR 130W AND N OF 20N. A NEARLY STATIONARY ELONGATED MID/UPPER LEVEL ANTICYCLONE IS LOCATED JUST W OF THE REGION NEAR 16N142W. STRONG EASTERLY UPPER LEVEL WINDS ARE NOTED FROM 3N-15N. AT THE SURFACE...A RIDGE EXTENDS SE FROM 32N138W TO 26N130W TO 23N120W. HIGH PRES COVERS THE AREA N OF 15N W OF 124W. BROKEN TO SCATTERED STRATOCUMULUS CLOUDS MOVING SW TO W WITH POSSIBLE ISOLATED SHOWERS ARE PRESENT NW OF A LINE FROM 21N120W TO 15N140W. E OF 120W... THE UPPER FLOW THROUGHOUT THIS AREA IS PRIMARILY BEING STEERED BY A LARGE UPPER LEVEL ANTI-CYCLONE CENTERED OVER THE GREAT PLAINS...AND AN ELONGATED UPPER LEVEL CYCLONIC OVER THE NW CARIBBEAN SEA S OF WESTERN CUBA. RIDGING FROM THE ANTICYCLONE EXTENDS SOUTHWARD TO NORTHERN MEXICO...WHILE THE UPPER FLOW TO THE W OF THE UPPER LEVEL CYCLONIC CIRCULATION EXTENDS W TO OVER THE YUCATAN PENINSULA...GUATEMALA AND BELIZE AND HONDURAS. UPPER LEVEL DEBRIS MOISTURE FROM ITCZ CONVECTION IS BEING CHANNELED WESTWARD UNDER THE UPPER ELY FLOW TOWARDS AND OVER HERNAN. A MID/UPPER LEVEL RIDGE ALONG 86W IS NEARLY STATIONARY. AT THE SURFACE A WEAK PRES EXISTS...WITH THE EXCEPTION OF THE GULF OF PAPAGAYO AND AREA FROM 10N TO 12N E OF 92W WHERE E WINDS OF 20 KT AND SEAS TO 8 FT CONTINUE. ANOTHER TROPICAL WAVE E OF THE AREA OVER THE WESTERN CARIBBEAN SEA ALONG 78W WILL FURTHER ENHANCE THE LIFE SPAN OF THESE WINDS THROUGH THE NEXT 3 DAYS AS IT MOVES WESTWARD AT 15 KT ACROSS CENTRAL AMERICA AND INTO THE E PACIFIC WATERS. $$ AGUIRRE