[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 15 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...
THE CENTER OF TROPICAL STORM OPHELIA AT 16/1800 UTC IS NEAR
36.1N 74.1W...OR ABOUT 90 NM EAST-NORTHEAST OF CAPE HATTERAS
NORTH CAROLINA AND ABOUT 360 NM SOUTH-SOUTHWEST OF NANTUCKET
MASSACHUSETTS. IT IS MOVING NORTH-NORTHEAST 7 KT. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 996 MB. THE MAXIMUM SUSTAINED WIND
SPEEDS ARE 50 KT WITH GUSTS TO 60 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. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE FOUND
FROM 36N TO 38N BETWEEN 73W AND 75W. OPHELIA LOOKS LIKE A
SHEARED SYSTEM. IT IS STARTING TO BE CAUGHT UP IN THE UPPER
LEVEL WESTERLIES. LITTLE CHANGE IN STRENGTH IS EXPECTED DURING
THE NEXT 24 HOURS AS OPHELIA REMAINS OVER RELATIVELY WARM
WATER.  AFTER 24 HR...COLDER WATER...INCREASING SHEAR...AND THE
ONSET OF EXTRATROPICAL TRANSITION SHOULD CAUSE WEAKENING.
OPHELIA IS EXPECTED TO LOSE TROPICAL CHARACTERISTICS IN
36 TO 48 HR.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 51W/52W SOUTH OF 17N
MOVING WEST 15 KT. A SURFACE 1012 MB LOW PRESSURE CENTER IS
ALONG THE WAVE NEAR 10.5N. IT IS POSSIBLE THAT THIS FEATURE MAY
BECOME A TROPICAL CYCLONE DURING THE NEXT 24 HOURS. BROKEN TO
OVERCAST MULTILAYERED CLOUDS COVER THE ATLANTIC OCEAN WATERS IN
THE AREA BOUNDED BY THE POINTS 8N57W 20N51W 18N41W 8N42W 8N57W.
WIDELY SCATTERED SHOWERS AND ISOLATED MODERATE TO STRONG
THUNDERSTORMS ARE WITHIN 30 TO 40 NM ON EITHER SIDE OF 10N44W
12N45W 16N47W...AND WITHIN 40 NM ON EITHER SIDE OF 13N48W
11N54W. BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA ON
TOP OF AND AROUND THIS WAVE FROM 10N TO 20N BETWEEN 30W AND 60W.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 25W/26W SOUTH OF 19N MOVING WEST 10 TO
15 KT. ISOLATED MODERATE SHOWERS FROM 12N TO 16N BETWEEN
25W AND 30W. OTHER ITCZ SHOWERS AND THUNDERSTORMS HAVE MOVED
NORTH OF 10N BETWEEN 20W AND 30W.

ATLANTIC OCEAN TROPICAL WAVE ALONG 61W SOUTH OF 20N MOVING WEST
10 KT HAS SLOWED DOWN...AND IT IS NOT EASY TO FIND. ISOLATED
MODERATE SHOWERS ARE FOUND FROM 15N TO 17N BETWEEN 57W AND 60W.

...ITCZ...

ITCZ 14N17W 9N26W 8N44W 9N50W 9N61W. NUMEROUS STRONG SHOWERS
AND THUNDERSTORMS WITHIN 30 NM ON EITHER SIDE OF 10N28W 8N30W
8N35W...AND FROM 5N TO 8N BETWEEN 35W AND 37W.

...DISCUSSION...

THE GULF OF MEXICO...
BROAD UPPER LEVEL ANTICYCLONICALLY FLOW HAS MOVED INTO THE
NORTHWESTERN HALF OF THE GULF WATERS. MIDDLE TO UPPER LEVEL
CYCLONIC FLOW WITH A TROUGH COVERS THE REST OF THE GULF OF
MEXICO. THE TROUGH RUNS FROM THE FLORIDA PANHANDLE TO THE
CENTRAL GULF TO A MIDDLE TO UPPER LEVEL LOW CENTER IN THE
SOUTHWESTERN GULF JUST WEST OF THE YUCATAN PENINSULA.
A SURFACE COLD FRONT IS MOVING THROUGH NORTHERN LOUISIANA...
CUTTING ACROSS TEXAS ON A NORTHEAST-TO-SOUTHWEST LINE.
ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND
THUNDERSTORMS ARE STILL IN TEXAS FROM 30N TO 32N BETWEEN
94W AND 98W.

THE CARIBBEAN SEA...
STRONG ITCZ SHOWERS AND THUNDERSTORMS ARE IN THE SOUTHWESTERN
CORNER OF THE AREA SOUTH OF 13N BETWEEN 76W AND THE EASTERN
COAST OF NICARAGUA. THE TWO MIDDLE TO UPPER LEVEL LOW CENTERS
WHICH ARE JUST NORTH OF AND/OR AT THE EDGE OF THE CARIBBEAN
SEA IN THE NORTHEASTERN CORNER OF THE AREA ARE HELPING TO
GENERATE CLOUDINESS AND PRECIPITATION FOR THE NORTHEASTERN
CORNER...NORTH OF 17N EAST OF 70W. MOST OF THE HEAVIER WEATHER
IS IMMEDIATELY NORTH OF THE NORTHEASTERN CORNER. UPPER LEVEL
ANTICYCLONIC FLOW IS ON TOP OF THE SOUTHWESTERN CORNER. UPPER
LEVEL SOUTHWESTERLY WINDS CUT ACROSS THE 60W/61W TROPICAL WAVE.

THE ATLANTIC OCEAN...
TROPICAL STORM OPHELIA EASILY IS THE MAIN FOCUS OF EVERYTHING
ALONG THE COAST OF NORTH CAROLINA AND NORTHWARD ALONG THE U.S.A.
EAST COAST. ONE COMPARATIVELY BIGGER MIDDLE TO UPPER LEVEL LOW
CENTER IS NEAR 22N68W ABOUT 180 NM EAST OF THE SOUTHERN BAHAMAS.
A SECOND COMPARATIVELY SMALLER LOW CENTER IS NEAR 20N65W ABOUT
120 NM NORTHEAST OF PUERTO RICO. SCATTERED MODERATE SHOWERS TO
ISOLATED STRONG THUNDERSTORMS COVER THE ATLANTIC OCEAN AND
CARIBBEAN SEA WATERS FROM 17N TO 24N BETWEEN 58W AND 70W. THIS
INCLUDES SOME PRECIPITATION AROUND AND ON TOP OF PUERTO RICO
AND THE VIRGIN ISLANDS AND EASTERN AND SOUTHERN DOMINICAN
REPUBLIC. A MIDDLE TO UPPER LEVEL TROUGH WHICH RAN FROM PORTUGAL
SOUTHWESTWARD FOR THE LAST FEW DAYS HAS BECOME STRETCHED OUT.
DIFFERENT PARTS OF IT NOW ARE MORE SEPARATED THAN THEY WERE
DURING AT LEAST THE LAST TWO DAYS. THE MIDDLE TO UPPER LEVEL
LOW CENTER HAS MOVED TOWARD SOUTHERN SPAIN. A MIDDLE TO UPPER
LEVEL TROUGH NOW STRETCHES THROUGH 30N24W TO 20N30W. A GOOD
AMOUNT OF MIDDLE TO UPPER LEVEL DRY AIR REMAINS NEAR THIS
TROUGH...NORTH OF 20N BETWEEN 25W AND 40W.

$$
MT


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