[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 100009
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUL 09 2008

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2345 UTC.

...SPECIAL FEATURE....

THE CENTER OF HURRICANE BERTHA AT 09/2100 UTC IS NEAR 24.8N
58.1W. BERTHA IS MOVING NORTHWEST OR 305 DEGREES AT 10 KT. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE NOW 90 KT WITH GUSTS TO 110 KT MAKING
BERTHA A CATEGORY 2 HURRICANE ON THE SAFFIR-SIMPSON SCALE.
BERTHA IS LOCATED 560 MILES...900 KM...NORTHEAST OF THE NORTHERN
LEEWARD ISLANDS AND ABOUT 660 MILES...1060 KM...SOUTHEAST OF
BERMUDA. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY
UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. THE OVERALL CLOUD
PATTERN HAS BECOME MUCH MORE ORGANIZED WITH A WELL DEFINED 20 NM
DIAMETER EYE EMBEDDED WITHIN A 45-60 NM WIDE RING OF STRONG
CONVECTION. CLOUD TOP TEMPERATURES HAVE WARMED SLIGHTLY OVER THE
PAST HOUR OR SO. HOWEVER THIS MAY BE TEMPORARY AS THE ATMOSPHERE
IS EXPECTED TO REMAIN FAVORABLE FOR ADDITIONAL STRENGTHENING AND
SEA SURFACE TEMPERATURES ARE SUFFICIENTLY WARM. THE LATEST
INTENSITY FORECAST CALLS FOR BERTHA TO BECOME A MAJOR HURRICANE
WITHIN THE NEXT 12 HOURS. INTERESTS IN BERMUDA SHOULD CLOSELY
MONITOR THE PROGRESS OF BERTHA.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 32W SOUTH OF 14N MOVING WEST NEAR 15 KT.
ALTHOUGH THE WAVE IS AT A FAIRLY LOW LATITUDE AND OF LOW
AMPLITUDE IT CONSISTS OF A WELL ORGANIZED LOW LEVEL CIRCULATION
WITH POCKETS OF MODERATE CONVECTION DEVELOPING.

TROPICAL WAVE ALONG 51W SOUTH OF 13N MOVING WEST 10 TO 15 KT.
CYCLONIC FLOW IN THE LOW CLOUDS ON VISIBLE SATELLITE IMAGERY AND
QUIK-SCAT DATA HELP TO CONFIRM THIS POSITION. NEARBY
PRECIPITATION IS IN THE ITCZ.

SOUTHWESTERN GULF OF MEXICO TROPICAL WAVE HAS MOVED INLAND ALONG
97W SOUTH OF 22N AND CONTINUES MOVING WEST AT 15 KT. THIS WAVE
IS MOVING THROUGH THE SOUTH SIDE OF AN UPPER LEVEL SHEAR AXIS
WITH MODERATE TO STRONG NORTHWESTERLY WIND FLOW CUTTING ACROSS
THE NORTHERN END OF THE WAVE. SHOWERS AND THUNDERSTORMS ARE
DEVELOPING ALONG THE SIERRA MADRE IN MEXICO...WITH STRONGER
ACTIVITY OVER THE ISTHMUS OF TEHUANTEPEC.

...THE ITCZ...
10N14W 9N30W 8N43W 7N59W. SCATTERED MODERATE TO STRONG SHOWERS
AND THUNDERSTORMS ARE FROM 4N TO 6N BETWEEN 22W AND 31W...AND
FROM 7N TO 11N BETWEEN 54W AND 60W. ISOLATED MODERATE SHOWERS
AND THUNDERSTORMS ARE NOTED FROM 6N TO 8N BETWEEN 40W AND 45W.
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS WERE MOVING OFF THE
WEST AFRICAN COAST FROM 11N TO 14N BETWEEN 15W AND 16W...IN
GUINEA AND GUINEA-BISSAU AND SENEGAL.

...DISCUSSION...

THE GULF OF MEXICO...
MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW EXTENDS FROM THE
NORTHWEST ATLANTIC OCEAN INTO THE NORTHERN GULF OF MEXICO TO THE
CENTRAL TEXAS GULF COAST. MIDDLE TO UPPER LEVEL TROUGH/SHEAR
AXIS EXTENDS FROM CUBA WESTWARD ACROSS THE SOUTHERN GULF OF
MEXICO. A WEAK CYCLONIC CIRCULATION WAS NOTED OVER THE BAY OF
CAMPECHE NEAR 22N94W. MODERATE TO STRONG NORTHWESTERLY FLOW ON
THE SOUTH SIDE OF THIS SHEAR AXIS WAS SWEEPING ACROSS THE
NORTHERN END OF THE TROPICAL WAVE ALONG 97W. AT THE SURFACE WEAK
RIDGE OF HIGH PRESSURE DOMINATED THE GULF. CLUSTERS OF MODERATE
TO STRONG THUNDERSTORMS WERE MOVING OFF THE SW FLORIDA COAST
BETWEEN MARCO ISLAND AND TAMPA BAY. ADDITIONAL ACTIVITY WAS
MOVING OFF THE NORTHWEST YUCATAN PENINSULA.

THE CARIBBEAN SEA...
A MIDDLE TO UPPER LEVEL SHEAR AXIS COVERED THE NORTHWESTERN
CORNER OF THE CARIBBEAN SEA. ISOLATED MODERATE SHOWERS AND SOME
THUNDERSTORMS ARE FROM 20N TO 22N BETWEEN 84W AND 85W...MOVING
FROM THE WESTERN TIP OF CUBA INTO THE YUCATAN CHANNEL. UPPER
LEVEL NORTHWESTERLY WIND FLOW S OF THE SHEAR AXIS CUTS ACROSS
THE YUCATAN PENINSULA...THE GULF OF HONDURAS TO THE GREATER
ANTILLES. ISOLATED MODERATE SHOWERS ARE FROM 17N TO 19N BETWEEN
66W AND 71W...FROM PUERTO RICO TO THE WATERS SOUTH OF THE
WESTERN DOMINICAN REPUBLIC IN AN AREA OF UPPER LEVEL DIFFLUENT
FLOW. A FLAT UPPER LEVEL RIDGE EXTENDS FROM 5N72W IN COLOMBIA TO
15N76W. SCATTERED MODERATE SHOWERS AND STRONG THUNDERSTORMS ARE
OCCURRING FROM 15N TO 17N BETWEEN 80W AND 85W ALSO IN UPPER
LEVEL DIFFLUENT FLOW IN THE FAR SOUTHWESTERN CARIBBEAN SEA.
STRONG SHOWERS AND THUNDERSTORMS ARE SOUTH OF 11N75W
13N84W...UNDER THE UPPER LEVEL RIDGE...NORTH OF THE ITCZ...WITH
BROAD MIDDLE LEVEL CYCLONIC WIND FLOW.

THE ATLANTIC OCEAN...
A STATIONARY MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
IS NEAR 28N69W. CYCLONIC FLOW AROUND THIS CENTER COVERS THE
ATLANTIC OCEAN FROM 22N TO 32N BETWEEN 65W AND 73W AND IS
PROVIDING SOME OF THE STEERING FLOW FOR HURRICANE BERTHA.
A MIDDLE TO UPPER LEVEL TROUGH IS DROPPING SOUTHWARD JUST TO THE
NORTHEAST OF HURRICANE BERTHA...WITH AXIS THROUGH 34N50W TO
32N54W. THIS TROUGH SUPPORTS A COLD FRONT THAT IS GRAZING THE
EXTREME NORTHERN PORTION OF THE AREA ALONG 32N AND 55W.
ISOLATED SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF 31N BETWEEN
40W AND 52W. A SURFACE RIDGE PASSES THROUGH A 1023 MB HIGH
PRESSURE CENTER NEAR 33N64W TO THE FLORIDA PANHANDLE NEAR 30N85W
INTO SOUTHERN LOUISIANA. A MIDDLE TO UPPER LEVEL TROUGH IS IN
THE EASTERN ATLANTIC OCEAN PASSING THROUGH 32N32W TO 22N39W. A
SURFACE RIDGE PASSES THROUGH 32N26W TO 29N32W TO 24N44W TO
16N52W. MID TO UPPER LEVEL EASTERLY FLOW COVERS THE DEEP TROPICS
E OF 50W.

$$
COBB





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