[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121153
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT JUL 12 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

...SPECIAL FEATURE....

A TROPICAL STORM WATCH REMAINS IN EFFECT FOR BERMUDA. IT IS
LIKELY THAT A TROPICAL STORM WARNING WILL BE ISSUED FOR BERMUDA
LATER TODAY. THE CENTER OF HURRICANE BERTHA AT 12/1200 UTC IS
NEAR 29.7N 62.6W. IT IS MOVING NORTH-NORTHWEST OR 340 DEGREES 4
KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 976 MB. THE
MAXIMUM SUSTAINED WIND SPEEDS ARE 80 KT WITH GUSTS TO 100 KT.
THIS POSITION ALSO IS 190 NM/360 KM SOUTH-SOUTHEAST OF BERMUDA.
THE CENTER OF BERTHA IS EXPECTED TO PASS SLOWLY TO THE SOUTHEAST
AND EAST OF BERMUDA DURING THE NEXT COUPLE OF DAYS...BUT THE
MOTION OCCASIONALLY MAY BE ERRATIC. PLEASE READ THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE
DETAILS. SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS
ARE FROM 28N TO 31N BETWEEN 60W AND 65W. THE INTENSITY FORECAST
WILL KEEP BERTHA AT 80 KT FOR THE FIRST 24 HOURS...WEAKENING
GRADUALLY AND FALLING BELOW HURRICANE-FORCE WINDS AFTER 72
HOURS.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 45W/46W SOUTH OF 15N
MOVING WEST 15 KT. A LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION
CENTER IS ALONG THE WAVE NEAR 10.5N. SCATTERED STRONG SHOWERS
AND THUNDERSTORMS IN INDIVIDUAL CLUSTERS FROM 10N TO 12N BETWEEN
46W AND 48W.

A CENTRAL CARIBBEAN SEA TROPICAL WAVE IS ALONG 73W/74W SOUTH OF
18N MOVING WEST 15 KT. THIS WAVE STRETCHES FROM THE SOUTHWESTERN
COAST OF HAITI TO THE NORTHERN COLOMBIA COAST. BROAD UPPER LEVEL
ANTICYCLONIC WIND FLOW IS ON TOP OF WEAK MIDDLE LEVEL CYCLONIC
FLOW IN THE AREA THROUGH WHICH THE WAVE IS MOVING. NO DEEP
CONVECTIVE PRECIPITATION.

...THE ITCZ...
14N17W 9N33W 11N45W 6N60W IN NORTHERN GUYANA. WIDELY SCATTERED TO
SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS IN
AN AREA BOUNDED BY THE LINE FROM THE EQUATOR AT 28N TO 6N24W TO
1N38W TO THE EQUATOR AT 38W...AND FROM 7N TO 12N BETWEEN AFRICA
AND 60W.

...DISCUSSION...

THE GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW COVERS THE ENTIRE
AREA. MIDDLE TO UPPER LEVEL MOISTURE IS EAST OF 90W AND
COMPARATIVELY MUCH DRIER AIR IN SUBSIDENCE IS WEST OF 90W.
THE MIDDLE LEVEL CYCLONIC CIRCULATION CENTER/TROUGH IN THE
COASTAL PLAINS OF TEXAS FROM 24 HOURS AGO HAS MOVED MORE AND
MORE WESTWARD...A CYCLONIC CENTER IS NEAR 27N104W IN MEXICO.
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS IN THE
NORTHWESTERN CORNER OF THE YUCATAN PENINSULA. A MIDDLE TO UPPER
LEVEL TROUGH PASSES THROUGH 32N80W IN COASTAL SOUTH CAROLINA
TO NORTHERN FLORIDA NEAR 30N83W. A SURFACE RIDGE RUNS FROM
A 1021 MB HIGH PRESSURE CENTER NEAR 27N85W TO EXTREME
NORTHEASTERN COASTAL MEXICO JUST SOUTH OF THE LOWER TEXAS COAST.

THE CARIBBEAN SEA...
BROAD UPPER LEVEL ANTICYCLONIC FLOW CUTS INTO THE NORTHWESTERN
CORNER ACROSS CUBA...FROM THE ATLANTIC OCEAN AND THE EASTERN
GULF OF MEXICO. A MIDDLE TO UPPER LEVEL TROUGH PASSES THROUGH
THE ATLANTIC OCEAN FROM A CYCLONIC CENTER NEAR 25N75W...ACROSS
CUBA TO 19N80W. SHOWERS DEVELOP AND ALTERNATELY DISSIPATE NEAR
THE TROUGH. ISOLATED MODERATE SHOWERS ARE IN THE WATERS NORTH OF
HONDURAS IN UPPER LEVEL DIFFLUENT FLOW. AN UPPER LEVEL RIDGE IS
ON TOP OF MIDDLE LEVEL CYCLONIC FLOW IN THE SOUTHWESTERN CORNER
OF THE AREA. STRONG SHOWERS AND THUNDERSTORMS ARE EAST OF
NICARAGUA AND IN SOUTHEASTERN NICARAGUA FROM 10N TO 13N BETWEEN
82W AND 85W...AND SOUTH OF 10N BETWEEN PANAMA AT 79W AND COSTA
RICA. SHOWERS ARE WEAKENING SOUTH OF 10N BETWEEN COLOMBIA AND
PANAMA AND IN THE GULF OF URABA.

THE ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH GOES FROM 32N72W TO A CYCLONIC
CIRCULATION CENTER NEAR 25N75W TO 23N76W...ACROSS CUBA TO 19N80W
A LITTLE BIT WEST OF JAMAICA. ISOLATED MODERATE SHOWERS ARE
WITHIN 120 NM TO 180 NM ON EITHER SIDE OF TROUGH. DRY AIR IN
SUBSIDENCE COVERS MUCH OF THE REST OF THE ATLANTIC WATERS NORTH
OF THE ITCZ CLOUDS AND PRECIPITATION TO 30N BETWEEN 30W AND 70W.
A DEEP LAYER TROUGH CONTINUES TO THE EAST-NORTHEAST OF HURRICANE
BERTHA...FROM A CYCLONIC CIRCULATION CENTER NEAR 34N45W TO
25N46W. BROAD MIDDLE TO UPPER LEVEL CYCLONIC FLOW COVERS THE
AREA NORTH OF 25N BETWEEN 34W AND 56W. A SURFACE TROUGH PASSES
THROUGH 33N46W TO 31N47W. SCATTERED MODERATE TO STRONG SHOWERS
AND THUNDERSTORMS FROM 30N TO 35N BETWEEN 44W AND 47W. A SURFACE
RIDGE EXTENDS FROM A 1022 MB HIGH PRESSURE CENTER NEAR 29N73W TO
THE NORTHEASTERN FLORIDA COAST NEAR 29N...AND EVENTUALLY TO THE
GULF OF MEXICO 1021 MB HIGH PRESSURE CENTER NEAR 27N85W. BROAD
SURFACE HIGH PRESSURE COVERS THE AREA NORTH OF 16N BETWEEN
AFRICA AND 57W.

$$

MT




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