[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091200
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI SEP 09 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...

HURRICANE OPHELIA WAS DOWNGRADED TO TROPICAL STORM AT 09/0900
UTC. TROPICAL STROM OPHELIA IS CENTERED NEAR 29.3N 79.1W...OR
ABOUT 115 SM ENE OF DAYTONA BEACH FLORIDA...AT 09/1200 UTC
DRIFTING NORTHWARD. ESTIMATED MINIMUM CENTRAL PRESSURE IS 991
MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC AND THE PUBLIC ADVISORY UNDER HEADERS
MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. WSR-88D RADAR IMAGERY
FROM MELBOURNE HAS DETERIORATE AND THE NOAA AIRCRAFT FOUND ONLY
TROPICAL STORM FORCE WINDS. OPHELIA REMAINS ON THE W EDGE OF AN
UPPER RIDGE EXTENDING THE UPPER MOISTURE WELL TO THE E TOWARD
HURRICANE NATE. SCATTERED MODERATE/STRONG CONVECTION COVERS THE
AREA WITHIN 90 NM OF LINE FROM 32N74W TO JUST INLAND OVER
FLORIDA NEAR 29N81.5W.

HURRICANE NATE IS CENTERED NEAR 33.6N 58.1W...OR 350 NM ENE OF
BERMUDA...AT 09/0900 UTC MOVING ENE AT 19 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 985 MB. MAXIMUM SUSTAINED WIND SPEED IS 70
KT WITH GUSTS TO 85 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.
NATE IS EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES AND
THEREFORE IS RAPIDLY WEAKENING AS RESULT. THE UPPER LEVEL
MOISTURE CONTINUES TO SPREAD E AROUND THE N OF AN UPPER LEVEL
RIDGE OVER THE CENTRAL ATLC. SCATTERED MODERATE CONVECTION
COVERS THE AREA WITHIN 175 NM OF LINE 28N60W-39N54W.

TROPICAL STORM MARIA IS CENTERED NEAR 40.2N 44.1W...OR 550 NM SE
OF CAPE RACE NEWFOUNDLAND...AT 09/0900 UTC MOVING NE AT 12 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. MAXIMUM SUSTAINED
WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS. MARIA CONTINUES TO BE RESILIENT...HOWEVER IT
HAS MAINTAINED DEEP CONVECTION SURROUNDING THE EYE-LIKE CENTER.
MARIA IS EXPECTED TO BECOME A STRONG EXTRATROPICAL SYSTEM OVER
THE NEXT 24 TO 36 HOURS. SCATTERED MODERATE CONVECTION IS
39N-42N BETWEEN 40W-45W...FROM 39N-42N BETWEEN 31W-35W...AND
FROM 30N-36N BETWEEN 28W-43W.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 24W/25W S OF 19N MOVING W 15 KT
WITH A 1012 MB LOW ALONG THE WAVE NEAR 13N. WAVE REMAINS
EMBEDDED WITHIN AFRICAN DUST THAT PRECEDES THE AXIS THUS NO
ASSOCIATED SHOWER ACTIVITY/CONVECTION.

CENTRAL ATLC TROPICAL WAVE IS ALONG 7N50W 16N50W 25N48W MOVING
WNW 10-15 KT. WAVE HAS A SW/NE TILT AND A LARGE AMPLITUDE THAT
REACHES WELL INTO THE SUBTROPICS. WAVE IS ALSO EMBEDDED WITHIN
ANOTHER AREA OF AFRICAN DUST...SO NO ASSOCIATED SHOWER
ACTIVITY/CONVECTION.

E CARIBBEAN TROPICAL WAVE IS ALONG 64W S OF 20N MOVING W 10 KT.
WAVE IS INTERACTING WITH A LARGE UPPER LEVEL LOW CENTERED OVER
THE N COAST OF PUERTO RICO AND IS PRODUCING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 15N-21N BETWEEN 63W-70W. THE UPPER
LOW IS EXPECTED TO BE OVER THE BAHAMAS BY SAT MORNING TAKING THE
SHOWERS/THUNDERSTORMS WITH IT.

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 79W/80W S OF 20N MOVING
W 5-10 KT. MOST OF THE ENERGY ASSOCIATED WITH THIS WAVE IS BEING
PULLED N TOWARDS HURRICANE NATE AND T.S. OPHELIA WHILE BEING
EMBEDDED IN A DRY ENVIRONMENT...SO ITS SIGNATURE IN THE
CARIBBEAN REMAINS POOR. WAVE MAY ENHANCE SHOWERS/THUNDERSTORMS
OVER PARTS OF CENTRAL AMERICAN THROUGH THE WEEKEND AS THE WAVE
MOVES WESTWARD.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 16N15W 17N19W 15N23W...THEN ALONG
10N26W 9N39W 14N52W 14N62W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 120 NM ALONG THE COAST OF MAURITANIA FROM
THE ITCZ AXIS N TO 20N AND WITHIN 45 NM OF LINE 7N18W-10N16W.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE AXIS
FROM 55W-60W.

...DISCUSSION...

GULF OF MEXICO...
A TIGHTLY-WRAPPED UPPER LEVEL LOW IS MOVING ACROSS CENTRAL
MEXICO NEAR 25N104W AND IS ADVECTING TROPICAL MOISTURE FROM THE
E PACIFIC NE ACROSS S MEXICO OVER THE W GULF. BROAD UPPER
DIFFLUENCE IN THE NE GULF IS GENERATING CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 21N28N W OF 94W TO THE
COAST OF SE TEXAS/NE MEXICO. A WEAK 1012 MB LOW IS IN THE SW
GULF NEAR 21N97W WITH A SURFACE TROUGH EXTENDING N TO 26N97W AND
SE TO THE BAY OF CAMPECHE NEAR 18N94W. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS INLAND AND WITHIN 30 NM ALONG THE
COAST OF S MEXICO FROM 92W-94W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE ALONG A WEAK SURFACE TROUGH THAT EXTENDS FROM
THE S SIDE OF T.S. OPHELIA ACROSS THE FLORIDA KEYS TO 27N93W.
UPPER LEVEL WINDS ARE EXPECTED TO INCREASE FROM THE N OVER THE
WEEKEND AS AN UPPER LOW FROM THE CARIBBEAN MOVES OVER THE
YUCATAN PENINSULA.

CARIBBEAN...
BROAD...ELONGATED...CUT OFF UPPER LOW EXTENDS FROM THE YUCATAN
CHANNEL SE TO THE GUAJIRA PENINSULA OF COLOMBIA...WITH A
LARGE SWATH OF NW FLOW ADVECTING MOISTURE ACROSS THE YUCATAN
FROM THE GULF OF MEXICO TO OVER CENTRAL AMERICA. UPPER MOISTURE
FROM THE E PACIFIC COMBINED WITH THE ITCZ AXIS IS GENERATING
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION FROM THE BORDER
OF COLOMBIA/PANAMA ALONG 12N82W TO THE COAST OF NICARAGUA NEAR
14N84W. THE UPPER RIDGE IN THE W ATLC IS PRODUCING DIFFLUENCE
OVER HAITI AND CUBA GENERATING SCATTERED SHOWERS/THUNDERSTORMS N
OF 17N FROM HAITI TO E CUBA INCLUDING JAMAICA. NARROWING BAND OF
DRIER AIR IS ACROSS THE CENTRAL PORTION OF THE CARIBBEAN WITHIN
120 NM OF LINE FROM THE COLOMBIAN COAST NEAR 11N73W TO 21N83W.
AN UPPER LOW IS LOCATED TO THE E ALONG THE N COAST OF PUERTO RICO
AND IS PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF
14N ASSOCIATED WITH THE TROPICAL WAVE.

WEST ATLANTIC...
AN UPPER HIGH IS LOCATED E OF T.S. OPHELIA AND NE OF THE
NORTHERN MOST BAHAMA ISLANDS NEAR 27N74W. THIS IS PUSHING NATE
FURTHER TO THE EAST. T.S OPHELIA IS TO THE NW OF THIS UPPER HIGH
FLOW AND IS NOW STARTING TO MOVE AROUND THE N PERIPHERY OF THE
FLOW. THIS UPPER HIGH IS PRODUCING SOUTHERLY SHEAR OVER T.S.
OPHELIA AND BEGINNING TO WEAK IT AS WELL. SEE SPECIAL FEATURES
FOR FURTHER DISCUSSION ON EACH HURRICANE.

EAST/CENTRAL ATLANTIC...
THE UPPER LOW ALONG THE N COAST OF PUERTO RICO IS MOVING TO THE
W AND A LARGE UPPER HIGH IS ANCHORED NEAR 26N50W WITH A RIDGE
AXIS EXTENDING SW INTO THE TROPICS NEAR 16N40W. DRY AIR COVERS
MUCH OF THE ATLC WATERS FROM 42W-60W. A NEAR STATIONARY UPPER
TROUGH EXTENDS N OF THE CAPE VERDE ISLANDS BETWEEN AFRICA AND
30W WITH AN UPPER LOW NEAR 22N27W REINFORCING THE PATTERN. THE
FIRST VISIBLE SATELLITE IMAGES SHOW THAT SAHARAN DUST CONTINUES
TO BE FORCE INTO THE E ATLC NOW EXTENDING TO 44W.

$$
WALLACE



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