[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 080004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED SEP 07 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM OPHELIA IS CENTERED NEAR 28.8N 79.3W...OR 70 NM
ENE OF CAPE CANAVERAL FLORIDA...AT 08/0000 UTC AND NEARLY
STATIONARY. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO
55 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 994 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
AND THE PUBLIC ADVISORY UNDER HEADERS MIATCPAT1/WTNT31 KNHC FOR
MORE DETAILS. CONVECTION OPHELIA DOES NOT REALLY HAVE MUCH
ORGANIZATION AND IS CHARACTERIZED BY ONE BLOB NEAR THE CENTER
WITH OTHER SCATTERED CONVECTION TO THE NE. HOWEVER...RADAR
IMAGERY SHOWS A WELL-DEFINED CLEAR CENTER THAT COULD BE MISTAKEN
FOR AN EYE. SCATTERED MODERATE CONVECTION FROM 27N-31N BETWEEN
77W-82W. BANDS OF STRONG CONVECTION ARE PRIMARILY LOCATED N/NW
OF THE CENTER BUT REMAIN OFFSHORE. OTHER HEAVY RAINBANDS ARE
MOVING ONSHORE BETWEEN BRUNSWICK GEORGIA AND ST. AUGUSTINE
FLORIDA...ROTATING SWD ALL THE WAY TO LAKE OKEECHOBEE. THREE TO
FIVE INCHES OF RAIN ARE EXPECTED OVER PARTS OF FLORIDA AND
GEORGIA WITH ISOLATED AMOUNTS UP TO 8 INCHES WHERE BANDS
CONTINUOUSLY MOVE OVER THE SAME AREA.

HURRICANE NATE CENTERED NEAR 29.6N 65.6W...OR 170 NM SSW OF
BERMUDA...AT 08/0000 UTC MOVING NE 4 KT. MAXIMUM SUSTAINED WIND
SPEED IS 75 KT WITH GUSTS TO 90 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE 979 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/
WMO HEADERS MIATCMAT5/WTNT25 KNHC AND THE PUBLIC ADVISORY UNDER
HEADERS MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS. DEEP CONVECTION
AROUND NATE IS SOMEWHAT RAGGED AND HEAVILY WEIGHTED ON THE N/NE
SIDE OF THE CIRCULATION...BUT THE HURRICANE HAS STILL MANAGED TO
SUPPORT SOME SORT OF EYE-LIKE FEATURE. TWO OUTFLOW JETS EXTEND
EWD FROM THE NRN SEMICIRCLE AND SW FROM THE SE QUADRANT BUT IS
MORE LIMITED TO THE SW DUE TO DRIER AIR. THE STRONG CONVECTION
IS STILL LOCATED ABOUT 60 NM S OF BERMUDA BUT RADAR IMAGERY FROM
THE ISLAND DOES SHOW INTERMITTENT SHOWERS RACING WWD NEARBY.
NUMEROUS MODERATE/STRONG CONVECTION FROM 27.5N-31.5N BETWEEN
62W-67.5W. SCATTERED MODERATE ELSEWHERE FROM 23N-30N BETWEEN
56W-64W.

HURRICANE MARIA CENTERED NEAR 36.9N 50.4W...OR 1110 NM W OF THE
AZORES...AT 07/2100 UTC MOVING NE 12 KT. MAXIMUM SUSTAINED WIND
SPEED IS 70 KT WITH GUSTS TO 85 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE 980 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/
WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. WATER VAPOR
IMAGERY INDICATES THAT MARIA IS EMBEDDED IN THE HEART OF AN
UPPER LEVEL SHORTWAVE TROUGH AND NOW SOUTHERLY SHEAR IS EXPOSING
THE LOW-LEVEL CENTER OF THE SOUTHERN CUSP OF DEEPEST CONVECTION.
THE HURRICANE IS BEGINNING TO GO THROUGH EXTRATROPICAL
TRANSITION BY BECOMING INCORPORATED INTO THE UPPER TROUGH BUT IS
STILL MAINTAINING A CORE OF NUMEROUS MODERATE CONVECTION FROM
36N-42N BETWEEN 46W-52W. A BAND OF SCATTERED SHOWERS/TSTMS ALSO
EXTENDS DOWN THE SE SIDE OF MARIA WITHIN 75 NM OF A LINE 38N46W
35N46W 31N49W.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE ALONG 42W S OF 22N MOVING W 15-20
KT. THE WAVE CONTINUES TO DISPLAY A SHARP SIGNATURE BUT IS
TILTED SLIGHTLY SW/NE. DRY SAHARAN AIR SEEMS TO STILL BE CHOKING
THE DEVELOPMENT OF WIDESPREAD CONVECTION...SO ONLY ISOLATED
SHOWERS ARE FROM 19N-23N BETWEEN 38W-43W AND FARTHER S ALONG THE
ITCZ.

TROPICAL WAVE LOCATED ABOUT 300 NM E OF THE LESSER ANTILLES
ALONG 55W S OF 19N MOVING W 15 KT. THE WAVE IS LOCATED ALONG THE
LEADING EDGE OF THE SAHARAN DUST SURGE AND IS TRIGGERING
ISOLATED SHOWERS/TSTMS FROM 12N-16N BETWEEN 53W-60W WHERE THE
STRONG NELY FLOW IS CONVERGING WITH THE ITCZ.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 68W/69W S OF 21N MOVING W
10-15 KT. THE NORTHERN SEGMENT OF THE WAVE HAS DECELERATED A BIT
AS IT INTERACTS WITH THE FLOW AROUND HURRICANE NATE...BUT THE
SHARP CURVATURE IS STILL PRODUCING SCATTERED MODERATE CONVECTION
OVER PUERTO RICO AND HISPANIOLA AND THE ADJACENT WATERS FROM
15N-20N BETWEEN 66W-74W. THESE SHOWERS/TSTMS ARE EXPECTED TO
MOSTLY DISSIPATE OVER THE NEXT 24 HRS AS THE WAVE MOVES INTO A
MUCH DRIER ENVIRONMENT FARTHER TO THE W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 16N12W 6N19W 19N40W...THEN ALONG
13N43W 11N57W 19N63W. SCATTERED MODERATE CONVECTION FROM 6N-13N
BETWEEN 16W-25W ASSOCIATED WITH A TROPICAL WAVE MOVING OFF THE
AFRICAN COAST. ISOLATED SHOWERS/TSTMS FROM 10N-14N BETWEEN
42W-50W. WIDELY SCATTERED SHOWERS/TSTMS MOVING TOWARDS THE
ISLANDS OF GUADELOUPE...DOMINICA...AND MARTINIQUE.

...DISCUSSION...

GULF OF MEXICO...
THE LARGE UPPER LOW WHICH WAS OVER THE W/CENTRAL GULF YESTERDAY
HAS QUICKLY MOVED TO THE W AND IS NOW OVER THE MEXICAN PLATEAU
NEAR 22N100W. THE LOW IS WRAPPING DRY AIR OFF THE PLATEAU INTO
THE S SIDE OF THE CIRCULATION FROM MEXICO CITY TO VERACRUZ.
HOWEVER...A BROAD PLUME OF TROPICAL MOISTURE IS BEING ADVECTED
UP THE E SIDE OF THE LOW OVER THE ENTIRE W GULF. IN
ADDITION...AN ILL-DEFINED 1009 MB LOW HAS DEVELOPED OVER THE BAY
OF CAMPECHE NEAR 20N94W WITH A TROUGH EXTENDING NWD TO
26N96W...AND THIS IS INTERACTING WITH THE DEEP MOISTURE PLUME TO
PRODUCE SCATTERED SHOWERS/TSTMS FROM 18N-29N BETWEEN 89W-100W.
THIS SCENARIO IS PRODUCING AN ALMOST WINTER-LIKE POST-FRONTAL
SITUATION WHERE NORTHERLY FLOW IS BANKING LOW CLOUDS AGAINST THE
SLOPES OF THE SIERRA MADRES. FARTHER E...A SURFACE TROUGH NEAR
THE TAIL END OF T.S. OPHELIA EXTENDS FROM SOUTH FLORIDA WWD TO
25N92W AND IS PRODUCING ISOLATED SHOWERS ABOUT 100 NM SW OF FT.
MYERS FLORIDA.

CARIBBEAN...
A LARGE UPPER LEVEL TROUGH IS OBTAINING A SLIGHTLY STRONGER
CIRCULATION OVER THE CENTRAL CARIBBEAN WITH AN AXIS EXTENDING
FROM E CUBA TO THE N COAST OF COLOMBIA...AND IS ASSOCIATED WITH
A SUBSTANTIAL AREA OF MODERATE/STRONG SUBSIDENCE BETWEEN
73W-82W. W/NW FLOW FEEDING INTO THE TROUGH IS ADVECTING MOISTURE
EWD ACROSS CENTRAL AMERICA FROM THE PACIFIC WITH WIDELY
SCATTERED MODERATE CONVECTION EXTENDING FROM BELIZE SEWD TO
PANAMA EXTENDING UP TO 150 NM OFFSHORE. FARTHER E...A LARGE
UPPER LOW APPROACHING THE LEEWARD ISLANDS FROM THE ATLC IS
PRODUCING MODERATE NELY FLOW OVER THE E CARIBBEAN. THE BULK OF
THE MOISTURE ASSOCIATED WITH THE TROPICAL WAVE ALONG 68W/69W IS
MOVING WWD AWAY FROM PUERTO RICO TOWARDS HISPANIOLA AND THE
WINDWARD PASSAGE. THE CARIBBEAN WILL REMAIN MOSTLY DRY OVER THE
NEXT SEVERAL DAYS WITH ONLY ISOLATED AREAS OF SHOWERS EXPECTED
TO RUN ACROSS THE AREA. THE DEEPEST CONVECTION SHOULD BE HELD
PRIMARILY OVER THE FAR SW CARIBBEAN NEAR PANAMA AND COSTA RICA.

ATLANTIC...
A BROAD UPPER RIDGE EXTENDS ACROSS THE W ATLC WATERS FROM THE
FLORIDA/GEORGIA BORDER EWD TO 28N54W...SPANNING OVER BOTH T.S.
OPHELIA AND HURRICANE NATE. A LARGE PATCH OF DRY AIR EXTENDS
BETWEEN THE TWO SYSTEMS S OF 28N W OF 68W WITH THE OUTFLOW FROM
OPHELIA EXTENDING UP THE CAROLINA COAST...AND THAT OF NATE
STRETCHING E AND S TOWARDS THE ATLC AND GREATER ANTILLES. AN
UPPER LEVEL TROUGH EXTENDS ACROSS THE CNTRL ATLC FROM 32N40W
22N54W 10N56W WITH AN UPPER LOW NEAR 18N56W MOVING W 15 KT
TOWARDS THE LESSER ANTILLES. THE LOW IS DRAWING MOISTURE NWD TO
ITS E...AND SUPPORTING SCATTERED SHOWERS/TSTMS ALONG THE
TROPICAL WAVE NEAR 55W. A LARGE UPPER HIGH IS CENTERED NEAR
20N34W WITH A RIDGE EXTENDING SW TO 8N50W BUT IT IS BEING PUSHED
TO THE W BY A DIGGING UPPER TROUGH THAT EXTENDS N OF THE CAPE
VERDE ISLANDS E OF 28W. ONE SURGE OF SAHARAN DUST HAS CROSSED
THE ATLC TO ABOUT 58W...BUT A SECOND MORE CONCENTRATED SURGE IS
ALIGNED E OF A LINE FROM 30N39W 20N35W 5N22W. A WELL-DEFINED
CYCLONIC CIRCULATION IS CURRENTLY ALIGNED OVER SENEGAL AND
GUINEA-BISSAU AND IS THE PROBABLE HARBINGER OF THE NEXT TROPICAL
WAVE TO MOVE OFF THE AFRICAN COAST.

$$
BERG


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