[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061827 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...COR
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN SEP 06 2009

CORRECTION IN ORDER TO UPDATE THE TROPICAL WAVES...THE
CARIBBEAN SEA SECTION...AND THE ITCZ SECTION

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1745 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 39W/40W FROM 10N TO 15N
MOVING WEST 10 TO 15 KT. A TROUGH REMAINS ALONG 33W/34W FROM 16N
TO 24N. A 1012 MB LOW PRESSURE IS ALONG THE TROUGH NEAR 19N.
A SWIRL OF LOW CLOUDS IS AROUND THE 1012 MB LOW PRESSURE CENTER
WITHIN 240 NM OF THE CENTER IN THE NORTHERN SEMICIRCLE.
HIGH CLOUDS ARE BEING PUSHED BY UPPER LEVEL ANTICYCLONIC FLOW
FROM 20N42W TO 26N29W BEYOND 30N20W...TOWARD A MIDDLE LEVEL TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER THAT IS JUST TO THE
NORTHEAST OF THE CANARY ISLANDS NEAR 30N13W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 46W FROM 12N TO 19N
MOVING WEST 10 TO 15 KT. A 1011 MB LOW PRESSURE CENTER IS ALONG
THE WAVE NEAR 16N. ISOLATED MODERATE SHOWERS ARE WITHIN A 60 NM
RADIUS OF 16N47W. POSSIBLE SHOWERS FROM ELSEWHERE FROM 16N TO
20N BETWEEN 43W AND 52W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 66W/67W TO THE SOUTH OF
20N MOVING WESTWARD 15 KT. THIS WAVE WAS RE-POSITIONED IN ORDER
TO MAKE IT FIT A WIND SPEED SURGE ALONG 66W/67W AT SOME BUOYS.
IT IS POSSIBLE THAT WE WERE A LITTLE BIT SLOW IN MOVING IT ALONG
DURING THE LAST FEW DAYS. NO DEEP CONVECTIVE PRECIPITATION
ACCOMPANIES THIS WAVE.

...THE ITCZ...

12N16W 12N30W 13N37W 11N42W 9N50W 7N59W. POSSIBLE SHOWERS FROM
7N TO 14N BETWEEN 35W AND 60W. WIDELY SCATTERED MODERATE SHOWERS
TO ISOLATED STRONG THUNDERSTORMS FROM 6N TO 10N BETWEEN AFRICA
AND 25W. STRONG SHOWERS AND THUNDERSTORMS ARE FROM 12N TO 15N
BETWEEN 18W AND 20W...ACCOMPANYING WHAT IS EXPECTED TO THE NEXT
TROPICAL WAVE. COMPUTER MODELS DEVELOP A SURFACE LOW PRESSURE
CENTER DURING THE NEXT 24 HOURS ABOUT 300 NM MORE TO THE WEST.
THE HURRICANE SPECIALISTS ALREADY HAVE PROCLAIMED THAT THIS
AREA OF DISTURBED WEATHER HAS A MEDIUM CHANCE OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...DISCUSSION...

THE GULF OF MEXICO...
SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS
ARE WITHIN 60 NM TO 90 NM ON EITHER SIDE OF 30N87W 28N88W
26N90W 24N94W 21N97W. CLOUD TOP TEMPERATURES ARE WARMING AND
PRECIPITATION IS DISSIPATING TO THE SOUTH OF 21N BETWEEN 94W
AND 97W...INCLUDING ACROSS THE ISTHMUS OF TEHUANTEPEC.
UPPER LEVEL ANTICYCLONIC FLOW HAS BEEN INCREASING IN COVERAGE
DURING THE LAST 24 HOURS TO 48 HOURS...AND OVERTAKING WHAT
WAS AN AREA OF CYCLONIC FLOW FROM A TROUGH TO THE EAST OF 90W
ONLY 24 HOURS AGO. THE AREA OF MIDDLE LEVEL TO UPPER LEVEL
CYCLONIC FLOW THAT 24 HOURS AGO COVERED THE GULF OF MEXICO TO
THE EAST OF 90W NOW COVERS PARTS OF THE CARIBBEAN SEA...THE
GULF OF MEXICO...AND THE ATLANTIC OCEAN FROM 18N TO 27N BETWEEN
THE BAHAMAS ISLANDS AND 84W. SCATTERED MODERATE SHOWERS TO
ISOLATED STRONG THUNDERSTORMS ARE OVER THE WATERS AND REACHING
THE BAHAMAS WITHIN 30 NM TO 60 NM ON EITHER SIDE OF 21N73W
23N77W 24N79W 26N78W 29N77W. A SURFACE TROUGH CONTINUES FROM
A FRONTAL BOUNDARY...ALONG 31N79W TO NORTHERN FLORIDA...IN
THE NORTHEASTERN GULF OF MEXICO FROM FLORIDA TO SOUTHEASTERN
LOUISIANA...CURVING ALONG THE UPPER TEXAS COAST TO 25N96W IN
THE NORTHWESTERN GULF OF MEXICO.

THE CARIBBEAN SEA...
MIDDLE LEVEL TO UPPER LEVEL CYCLONIC FLOW COVERS THE
NORTHWESTERN CORNER OF THE AREA...INCLUDING IN THE SOUTHEASTERN
GULF OF MEXICO AND ON TOP OF THE BAHAMAS. BROAD UPPER LEVEL
ANTICYCLONIC FLOW COVERS PRETTY MUCH THE ENTIRE AREA THAT IS
AWAY FROM THE NORTHWESTERN CORNER. THE UPPER LEVEL WESTERLY
FLOW FROM THE ANTICYCLONIC PART COMBINES WITH UPPER LEVEL
WESTERLY FLOW FROM A BIT OF THE LARGE-SCALE ATLANTIC OCEAN
UPPER LEVEL CYCLONIC FLOW THAT IS AROUND THE 30N68W ATLANTIC
OCEAN CYCLONIC CENTER. SHOWERS AND THUNDERSTORMS ARE IN THE
SOUTHWESTERN CORNER OF THE AREA...NEAR MIDDLE LEVEL CYCLONIC
FLOW OVER FROM NICARAGUA TO COSTA RICA.

THE ATLANTIC OCEAN...
LARGE-SCALE UPPER LEVEL CYCLONIC FLOW COVERS THE CARIBBEAN SEA
AND THE ATLANTIC OCEAN FROM 19N TO 34N AROUND A 30N68W CYCLONIC
CENTER. THIS CYCLONIC FLOW HAS BEEN COVERING A LARGE PART OF THE
ATLANTIC OCEAN TO THE WEST OF 55W OR SO FOR THE LAST THREE OR
FOUR DAYS. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS WITHIN A 60 NM RADIUS OF 21N65W...FROM 25N TO
30N...AND FROM 28N TO 32N BETWEEN 66W AND 70W. A SURFACE TROUGH
IS ALONG 29N77W 26N78W 24N79W. A SURFACE TROUGH ALONG 26N68W
23N70W TO THE HAITI/DOMINICAN REPUBLIC BORDER NEAR 19N72W
REPRESENTS THE REMNANTS OF ERIKA. AN UPPER LEVEL TROUGH THAT IS
SURROUNDED BY DRY AIR/SUBSIDENCE EXTENDS FROM A CYCLONIC CENTER
NEAR 32N29W TO 26N41W TO 18N53W.

$$
MT




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