[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 120601
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

...SPECIAL FEATURE....

A TROPICAL STORM WATCH REMAINS IN EFFECT FOR BERMUDA. THE CENTER
OF HURRICANE BERTHA AT 12/0600 UTC IS NEAR 29.5N 62.6W. IT IS
MOVING NORTH-NORTHWEST OR 335 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
200 NM/370 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 30N
BETWEEN 61W AND 64W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND
OTHER POSSIBLE PRECIPITATION COVER THE AREA FROM 25N TO 32N
BETWEEN 54W AND 68W. 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. THE PROBABILITY OF
WINDS OF TROPICAL STORM FORCE OCCURRING IN BERMUDA WITHIN THE
NEXT FIVE DAYS...AS CONVEYED IN THE WIND SPEED PROBABILITY
PRODUCT INCLUDED IN EACH ADVISORY PACKAGE...HAS BEEN RISING
GRADUALLY DURING THE PAST COUPLE OF DAYS...AND NOW HAS
REACHED 58%.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 44W/45W SOUTH OF 15N
MOVING WEST 15 KT. A LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION
CENTER IS NEAR 10.5N45W. SCATTERED STRONG SHOWERS AND
THUNDERSTORMS IN INDIVIDUAL CLUSTERS FROM 8N TO 11N BETWEEN
46W AND 49W.

A CENTRAL CARIBBEAN SEA TROPICAL WAVE IS ALONG 71W/72W SOUTH OF
18N MOVING WEST 15 KT. THIS WAVE STRETCHES FROM THE SOUTHWESTERN
CORNER OF THE DOMINICAN REPUBLIC TO PENINSULA DE LA GUAJIRA OF
NORTHEASTERN COLOMBIA. 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...
15N18W 9N33W 11N45W 10N60W IN NORTHERN GUYANA. STRONG SHOWERS
AND THUNDERSTORMS SOUTH OF 3N BETWEEN 30W AND 32W. WIDELY
SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS
FROM 8N TO 12N BETWEEN 24W AND 40W. ISOLATED MODERATE SHOWERS
ELSEWHERE SOUTH OF 10N BETWEEN 10W 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 TROUGH PASSES THROUGH 32N80W IN COASTAL
SOUTH CAROLINA TO 31N88W SOUTHWESTERN ALABAMA. A SURFACE RIDGE
RUNS FROM A 1021 MB HIGH PRESSURE CENTER NEAR 27N86W 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 HAVE DEVELOPED AND ALREADY DISSIPATED
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 12N BETWEEN 81W AND 84W.

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 RIDGE EXTENDS
FROM A 1022 MB HIGH PRESSURE CENTER NEAR 30N72W TO THE
NORTHEASTERN FLORIDA COAST NEAR 29N...AND EVENTUALLY TO THE
GULF OF MEXICO 1021 MB HIGH PRESSURE CENTER NEAR 27N86W.
BROAD SURFACE HIGH PRESSURE COVERS THE AREA NORTH OF 16N
BETWEEN AFRICA AND 57W.

$$

MT




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