[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 030555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU SEP 03 2009

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
0345 UTC.

...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 16.2N 62.6W OR ABOUT 70 NM
W OF GUADELOUPE AND ABOUT 240 NM ESE OF SAN JUAN PUERTO RICO
MOVING WNW AT 4 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008
MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.
SEE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC AND THE FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. ERIKA IS BARELY
A TROPICAL STORM TONIGHT AND HAS BECOME DISORGANIZED. SCATTERED
MODERATE/STRONG CONVECTION COVERS THE AREA FROM 13N-16N BETWEEN
59W-63W AND FROM 16N-19N BETWEEN 58W-62W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 29W S OF 19N MOVING W 15-20 KT. THE WAVE
COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. HOWEVER...SATELLITE IMAGERY AND THE
TPW IMAGERY INDICATE DRY SAHARAN AIR LAYER IS BEING INTRODUCED
INTO THE WAVE. A SMALL LOWER LEVEL CYCLONIC CIRCULATION IS
OBSERVED ON INFRARED SATELLITE IMAGERY CENTERED NEAR 15N30.5W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 30 NM OF
17N FROM 29W-32W.

TROPICAL WAVE EXTENDS FROM 14N45W TO 7N42W MOVING W 10-15 KT.
WAVE REMAINS LOW-AMPLITUDE AND EMBEDDED WITHIN THE ITCZ AT THE
LEADING EDGE OF A MOISTURE MAXIMUM AS INDICATED BY TOTAL
PRECIPITABLE WATER IMAGERY. WAVE IS ALSO EMBEDDED WITHIN SAHARAN
DUST THUS LIMITING ANY SHOWERS OR CONVECTION.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 13N16W 9N30W 11N39W 7N49W 9N62W.
SCATTERED MODERATE/STRONG CONVECTION IS MOVING OFF W AFRICA FROM
11N-16N E OF 20W AND WITHIN 90 NM OF 18W FROM 7N-11N. LARGE
CLUSTERS OF SIMILAR CONVECTION ARE 6N-12N BETWEEN 25W-42W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH COVERS THE E HALF OF THE U.S. INTO THE N GULF N
OF 24N W OF 84W WITH THE ASSOCIATED DISSIPATING STATIONARY FRONT
ACROSS GULF FROM THE W ATLC OVER NE FLORIDA PENINSULA ENTERING
THE GULF WATERS NEAR CEDAR KEY CONTINUING SW ALONG 24N92W TO
25N96W. A WEAK SURFACE TROUGH EXTENDS OVER THE S FLORIDA
PENINSULA FROM 28N80W TO 25N82W. THE UPPER RIDGE ANCHORED IN THE
E PACIFIC EXTENDS ACROSS SOUTHERN MEXICO OVER THE SW GULF
THROUGH TUXPAN TO THE YUCATAN PENINSULA. CLUSTERS OF SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE ACROSS THE E
GULF E OF 88W WITH SCATTERED SHOWERS ARE REMAINDER OF THE S GULF
S OF THE FRONTAL BOUNDARY. A SURFACE RIDGE IS BUILDING OVER THE
N GULF WITH A 1016 MB HIGH OVER THE TEXAS/LOUISIANA BORDER
CLEARING SKIES N OF THE FRONTAL BOUNDARY ALONG THE GULF COAST
FROM MISSISSIPPI/LOUISIANA BORDER TO THE TEXAS/MEXICO BORDER.

CARIBBEAN SEA...
A BIG CONCERN TONIGHT FOR THE LESSER ANTILLES IS TROPICAL STORM
ERIKA. EVEN THOUGH ERIKA IS WEAK COULD BRING 2 TO 4 INCHES OF
RAIN OVER MUCH OF THE LESSER ANTILLES DURING THE NEXT COUPLE OF
DAYS...WITH ISOLATED MAXIMUM AMOUNTS OF 6 INCHES POSSIBLE AND
OVER PUERTO RICO...3 TO 5 INCHES OF RAIN ARE POSSIBLE DURING THE
NEXT FEW DAYS...WITH ISOLATED MAXIMUM AMOUNTS OF 8 INCHES. AN
UPPER LOW IS OVER THE W CARIBBEAN W OF THE CAYMAN ISLANDS NEAR
20N83W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
INLAND AND WITHIN 75 NM ALONG THE S COAST OF CUBA. OTHERWISE...
THE REMAINDER OF THE CARIBBEAN REMAINS UNDER RELATIVELY CLEAR
SKIES TONIGHT.

ATLANTIC OCEAN...
A DISSIPATING STATIONARY FRONT ENTERS THE REGION NEAR 32N77W
EXTENDING SW ACROSS THE FLORIDA PENINSULA NEAR ST. AUGUSTINE. A
WEAK SURFACE TROUGH EXTENDS OVER THE S FLORIDA PENINSULA FROM
28N80W TO 25N82W. A SECOND STRONGER SURFACE TROUGH IS TO THE E
EXTENDING FROM 28N76W ACROSS THE N BAHAMA ISLANDS TO THE COAST
OF CUBA NEAR 22N78W. BROAD UPPER RIDGE COVERS THE W ATLC
ANCHORED NEAR 28N72W PROVIDING DIFFLUENCE ALOFT TO GENERATE
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE
AREA W OF 72W TO OVER THE FLORIDA PENINSULA AND TO THE COAST OF
GEORGIA AND SOUTH CAROLINA. THE REMAINDER OF THE ATLC IS
DOMINATED BY RATHER BENIGN UPPER LEVEL FEATURES AND A BROAD
SURFACE RIDGE BETWEEN 20W-70W ANCHORED BY A 1030 MB HIGH N OF
THE REGION SW OF THE AZORES.

$$
WALLACE





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