[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031151
TWDAT

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

...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 16.9N 63.1W OR ABOUT 35 NM
SW OF ST. KITTS AND ABOUT 190 NM ESE OF SAN JUAN PUERTO RICO
MOVING WNW AT 6 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
POORLY-DEFINED AND MAY BE OPENING UP INTO A TROUGH ORIENTED FROM
SOUTH-SOUTHWEST TO NORTH-NORTHEAST. SCATTERED MODERATE/STRONG
CONVECTION COVERS THE AREA WITHIN 120 NM OF LINE FROM 19N60W
ACROSS THE LESSER ANTILLES TO 13N63W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 30W/31W S OF 19N MOVING W NEAR 15 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 HAS BEING
INJECTED INTO THE WAVE. A SMALL LOWER LEVEL CYCLONIC CIRCULATION
IS OBSERVED ON INFRARED SATELLITE IMAGERY CENTERED REMAINING
NEAR 15N30.5W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 45 NM OF 017N FROM 29W-32W.

TROPICAL WAVE EXTENDS FROM 15N45W TO 7N43W 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 CONVECTION TO ISOLATED SHOWERS FROM
11N-13N BETWEEN 43W-47W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N13W 10N20W 11N29W 9N33W
11N46W 9N55W 10N65W. THE NEXT WAVE APPEARS TO BE EMERGING OFF
THE COAST OF W AFRICA WITH SCATTERED MODERATE/ISOLATED STRONG
WITHIN 75/90 NM OF OF LINE FROM 7N17W ACROSS THE ITCZ TO
15N22W...WITHIN 90 N M OF LINE FROM 6N27W TO 9N36W...AND WITHIN
45 NM OF 9N38W TO 10N42W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH COVERS THE E HALF OF THE U.S. INTO THE N GULF N
OF 22N W OF 83W WITH THE ASSOCIATED DISSIPATING STATIONARY FRONT
ACROSS GULF FROM THE W ATLC OVER THE FLORIDA PENINSULA ENTERING
THE GULF WATERS NEAR FORT MYERS CONTINUING WSW ALONG 24N89W TO
25N97W. THE UPPER RIDGE ANCHORED IN THE E PACIFIC EXTENDS ACROSS
S MEXICO TO THE YUCATAN PENINSULA NEAR GUATEMALA. CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ACROSS THE E GULF E
OF 89W AND IN THE BAY OF CAMPECHE WITHIN 75 NM OF COAST. A
SURFACE RIDGE IS BUILDING OVER THE N GULF WITH A 1020 MB HIGH
OVER S ARKANSAS CLEARING SKIES N OF THE FRONTAL BOUNDARY ALONG
THE GULF COAST W OF 90W TO THE TEXAS/MEXICO BORDER.

CARIBBEAN SEA...
A MAIN CONCERN THIS MORNING CONTINUES TO BE TROPICAL STORM ERIKA
OVER THE LESSER ANTILLES. EVEN THOUGH ERIKA IS WEAK IT COULD
STILL 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. A WEAKENING UPPER LOW IS
OVER THE W CARIBBEAN W OF THE CAYMAN ISLANDS NEAR 20N82W
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND AND
WITHIN 60 NM ALONG THE S COAST OF CUBA. OTHERWISE...THE
REMAINDER OF THE CARIBBEAN REMAINS UNDER RELATIVELY CLEAR SKIES
THIS MORNING WITH THE EXCEPTION OF THE GULF OF URABA WHERE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF S OF 10N E OF
78W TO INLAND OVER COLOMBIA.

ATLANTIC OCEAN...
A DISSIPATING STATIONARY FRONT ENTERS THE REGION NEAR 32N76W
EXTENDING SW ACROSS THE FLORIDA PENINSULA NEAR MELBOURNE INTO
THE GULF OF MEXICO WITH SCATTERED SHOWERS ARE N OF THE FRONTAL
BOUNDARY TO 80W. A SURFACE TROUGH EXTENDS FROM 29N76W ACROSS THE
N BAHAMA ISLANDS TO CUBA NEAR 21N78W. BROAD UPPER RIDGE COVERS
THE W ATLC ANCHORED NEAR 28N72W PROVIDING DIFFLUENCE ALOFT TO
GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
WITHIN 120 NM OF LINE FROM OFF CUBA NEAR 22N76W ACROSS THE
CENTRAL BAHAMAS TO BEYOND 32N74W. THE REMAINDER OF THE ATLC IS
DOMINATED BY RATHER BENIGN UPPER LEVEL FEATURES AND A BROAD
SURFACE RIDGE BETWEEN 20W-70W ANCHORED BY A 1027 MB HIGH N OF
THE REGION SW OF THE AZORES.

$$
WALLACE



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