[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 090550
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...SPECIAL FEATURES...

HURRICANE OPHELIA IS CENTERED NEAR 28.9N 79.3W...OR ABOUT 70 NM
ENE OF CAPE CANAVERAL FLORIDA...AT 09/0600 UTC DRIFTING
NORTHWARD. ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. MAXIMUM
SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 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 INDICATES
THAT THE CENTER OF OPHELIA HAS COMPLETELY FILLED WITH RAIN
ECHOES. OPHELIA IS ON THE W EDGE OF AN UPPER RIDGE EXTENDING THE
UPPER MOISTURE WELL TO THE E TOWARD HURRICANE NATE. SCATTERED/
NUMEROUS STRONG CONVECTION IS FROM 28N-29.5N BETWEEN 79W-80.5W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS
THE REMAINDER OF THE AREA WITHIN 75/90 NM OF LINE FROM 30N75W
INLAND OVER FLORIDA TO NEAR 28N81.5W.

HURRICANE NATE IS CENTERED NEAR 33.0N 60.2W...OR 235 NM E OF
BERMUDA...AT 09/0300 UTC MOVING ENE AT 18 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 979 MB. MAXIMUM SUSTAINED WIND SPEED IS 80
KT WITH GUSTS TO 100 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. NATE
HAS MOVED CLOSE ENOUGH TO THE MID-LATITUDE WESTERLIES THAT THE
UPPER LEVEL MOISTURE IS SPREADING E AROUND THE N OF AN UPPER
LEVEL RIDGE OVER THE CENTRAL ATLC. SCATTERED MODERATE/STRONG
CONVECTION IS FROM 32N-33.5N BETWEEN 59W-62.5W. SCATTERED
MODERATE CONVECTION IS WITHIN 90/120 NM OF LINE 33.5N60W-26N55W.

HURRICANE MARIA WAS DOWNGRADED TO TROPICAL STORM AT 09/0300 UTC.
TROPICAL STORM MARIA IS CENTERED NEAR 39.7N 45.9W...OR 525 NM SE
OF CAPE RACE NEWFOUNDLAND...AT 09/0300 UTC MOVING NE AT 9 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 984 MB. MAXIMUM SUSTAINED
WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS. MARIA IS NOW OVER WATERS TOO COOL TO SUPPORT
TROPICAL CYCLONE. HOWEVER...MID-LATITUDE ENERGY HAS BEEN ABLE TO
MAINTAIN CONVECTION TO THE N OF THE EYE-LIKE CENTER. MARIA IS
EXPECTED TO BECOME A STRONG EXTRATROPICAL SYSTEM OVER THE NEXT
36 HOURS. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF LINE
FROM 28N43W NW TO 45N51W. LARGE AREA OF SIMILAR CONVECTION
LOOSELY TIED TO THE OUTFLOW OF MARIA WITHIN 150 NM OF LINE
31N43W-41N33W.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 22W/23W S OF 20N MOVING W 10 KT
WITH A 1012 MB LOW ALONG THE WAVE NEAR 13N. THE WAVE IS DRAWING
SAHARAN DUST S TO 8N AHEAD OF THE AXIS THUS LITTLE SIGNATURE
CURVATURE CAN BE OBSERVED ON INFRARED SATELLITE IMAGERY. NO
ASSOCIATED DEEP CONVECTION.

CENTRAL ATLC TROPICAL WAVE IS ALONG 8N49W 17N49W 25N46W MOVING
WNW 10-15 KT. WAVE HAS A SW/NE TILT AND A LARGE AMPLITUDE THAT
REACHES WELL INTO THE SUBTROPICS. WAVE IS EMBEDDED WITHIN
ANOTHER AREA OF SAHARAN DUST...SO ONLY ISOLATED LOW LEVEL
SHOWERS ARE PRESENT WITHIN 120 NM E OF THE WAVE AXIS FROM
17N-21N.

E CARIBBEAN TROPICAL WAVE IS ALONG 63W S OF 20N MOVING W 15 KT.
WAVE IS INTERACTING WITH A LARGE UPPER LEVEL LOW CENTERED OVER
THE VIRGIN ISLANDS AND IS PRODUCING SCATTERED SHOWERS/
THUNDERSTORMS FROM 16N-20N BETWEEN 61W-65W. THE UPPER LOW IS
EXPECTED TO MOVE TOWARDS THE BAHAMAS BY SAT MORNING TAKING THE
SHOWERS/THUNDERSTORMS WITH IT.

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 77W/78W S OF 20N MOVING
W 15 KT. MOST OF THE ENERGY ASSOCIATED WITH THIS WAVE IS BEING
PULLED N TOWARDS HURRICANES NATE AND OPHELIA AND IT IS 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 20N16W 15N21W...THEN ALONG 9N23W
7N31W 16N44W...THEN ALONG 13N50W 12N55W 13N59W. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 45 NM OF 18N FROM 18W TO
THE COAST OF MAURITANIA AFRICA. SCATTERED MODERATE CONVECTION IS
WITHIN 60 NM OF THE AXIS FROM 26W-32W AND FROM 53W-58W.

...DISCUSSION...

GULF OF MEXICO...
A TIGHTLY-WRAPPED UPPER LEVEL LOW IS MOVING ACROSS CENTRAL
MEXICO NEAR 24N104W 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 A LINE OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS FROM 27N92W TO OVER BROWNSVILLE
TEXAS. A WEAK 1011 MB LOW IS IN THE SW GULF NEAR 22N96W WITH A
SURFACE TROUGH EXTENDING N TO 27N96W AND SE TO THE BAY OF
CAMPECHE NEAR 18N93W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS INLAND AND WITHIN 30 NM ALONG THE COAST OF S
MEXICO FROM 92W-95W. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM
THE LOW N ALONG THE SURFACE TROUGH. 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. FARTHER
E...MODERATE NE FLOW EMANATING AWAY FROM HURRICANE OPHELIA IS
SPREADING HIGH CIRRUS CLOUDS OVER THE NE GULF AND N FLORIDA.

CARIBBEAN...
BROAD CUT OFF UPPER LOW EXTENDS FROM THE YUCATAN CHANNEL SE TO
THE GULF OF VENEZUELA OF THE COAST 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 SCATTERED
STRONG CONVECTION FROM THE BORDER OF COSTA RICA TO 13.5N W OF
81W TO INLAND OVER NICARAGUA AND S OF 10.5N TO THE COAST OF
PANAMA FROM 77W-79W. THE UPPER RIDGE IN THE W ATLC IS PRODUCING
DIFFLUENCE OVER HAITI AND CUBA GENERATING SCATTERED
SHOWERS/THUNDERSTORMS WITHIN 45 NM OF LINE 19N73W-21N78W.
DRIER AIR COVERS THE CENTRAL PORTION OF THE CARIBBEAN WITHIN 175
NM OF LINE FROM THE COLOMBIAN COAST NEAR 11N71W TO 21N83W. AN
UPPER LOW IS LOCATED TO THE E OVER THE VIRGIN ISLANDS AND IS
PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF
GUADELOUPE TO OVER THE VIRGIN ISLANDS.

WEST ATLANTIC...
AN UPPER HIGH IS LOCATED E OF OPHELIA AND NE OF THE NORTHERN
MOST BAHAMA ISLANDS NEAR 28N76W. THIS IS PUSHING NATE FURTHER TO
THE E AND IS BEING PICKED UP BY THE MID-LATITUDE WESTERLIES.
OPHELIA IS TO THE W OF THIS UPPER HIGH FLOW IS BEING ISOLATED
AND SO CONTINUES TO MEANDER JUST OFF THE COAST OF FLORIDA. THIS
UPPER HIGH IS PRODUCING SLIGHT SOUTHERLY SHEAR OVER OPHELIA...
BUT THE HURRICANE IS NOW PRODUCING ITS OWN UPPER LEVEL OUTFLOW
PATTERN WHICH IS SHIELDING ITSELF FROM THE RIDGE. SEE SPECIAL
FEATURES FOR FURTHER DISCUSSION ON EACH HURRICANE.

EAST/CENTRAL ATLANTIC...
THE UPPER LOW OVER THE VIRGIN ISLANDS IS MOVING TO THE W AND A
LARGE UPPER HIGH HAS BECOME ESTABLISHED NEAR 27N49W WITH A RIDGE
AXIS EXTENDING SW INTO THE TROPICS NEAR 15N50W. DRY AIR COVERS
MUCH OF THE ATLC WATERS FROM 30W-60W. A NEAR STATIONARY UPPER
TROUGH EXTENDS N OF THE CAPE VERDE ISLANDS BETWEEN AFRICA AND
30W WITH AN UPPER LOW NEAR 24N26W REINFORCING THE PATTERN. A
SMALL MID/UPPER LOW HAS SPUN UP ALONG THE COAST OF THE WESTERN
SAHARA/MAURITANIA BORDER NEAR 22N18W AND IS PROVIDING JUST
ENOUGH SUPPORT FOR THE CONVECTION FOUND WITHIN THE ITCZ. THE
LAST VISIBLE SATELLITE IMAGES SHOW THAT SAHARAN DUST CONTINUES
TO BE FORCE INTO THE E ATLC NOW EXTENDING TO 40W.

$$
WALLACE


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