[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061148
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE SEP 05 2011

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...

HURRICANE KATIA IS CENTERED NEAR 26.5N 65.1W AT 06/0900 UTC OR
ABOUT 350 NM S OF BERMUDA MOVING NW AT 9 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 950 MB. MAXIMUM SUSTAINED WIND SPEED IS 110
KT WITH GUSTS TO 135 KT. PLEASE SEE THE LATEST INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT2/WTNT32 KNHC AND
THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT2/
WTNT22 KNHC FOR MORE DETAILS. SCATTRED/NUMEROUS STRONG
CONVECTION IS WITHIN 75 NM OF THE CENTER OVER THE W SEMICIRCLE
AND WITHIN 150 NM OVER THE SE SEMICIRCLE. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION COVERS THE REMAINDER OF THE AREA FROM
23N-30N BETWEEN 61W-67W. LARGE SWELLS GENERATED BY HURRICANE
KATIA ARE EXPECTED TO AFFECT MOST OF THE EAST COAST OF THE
UNITED STATES...BERMUDA...THE GREATER ANTILLES...AND EAST FACING
BEACHES OF THE BAHAMAS DURING THE NEXT FEW DAYS. THESE SWELLS
ARE LIKELY TO CAUSE LIFE THREATENING SURF AND RIP CURRENT
CONDITIONS. PLEASE CONSULT PRODUCTS ISSUED BY LOCAL NATIONAL
WEATHER SERVICE OFFICES FOR MORE INFORMATION.

A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH 1009 MB LOW IS
CENTERED SW OF THE CAPE VERDE ISLANDS NEAR 10N32W MOVING W 10-15
KT. THIS FEATURE IS EMBEDDED WITHIN AN BROAD AREA OF DEEP LAYER
MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MOSTLY NW OF
THE CENTER FROM 10N-15N BETWEEN 31W-41W. SHOWER ACTIVITY
ASSOCIATED WITH THIS FEATURE GRADUALLY IS BECOMING BETTER
ORGANIZED. ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR A
TROPICAL DEPRESSION TO FORM DURING THE NEXT DAY OR TWO. THIS
SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS.

...TROPICAL WAVES...
TROPICAL WAVE IN THE W TROPICAL ATLC EXTENDS FROM 19N50W ALONG
16N50W TO 12N48W MOVING W NEAR 15 KT. THE 1012 MB LOW IS NO
LONGER A CLOSED CIRCULATION. THE WAVE N OF 13N IS EMBEDDED
WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY WITH DRIER AIR UNDERCUTTING THE WAVE.
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE W OF
THE WAVE FROM 13N-18N BETWEEN 51W-55W.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA ENTERING THE E
TROPICAL ATLC NEAR 17N16W ALONG 13N21W TO E OF THE 1009 MB LOW
IN THE SPECIAL FEATURES NEAR 11N27W. CLUSTERS OF SCATTERED
MODERATE/STRONG CONVECTION ARE FROM 4N-10N BETWEEN 15W-23W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 4N-10N BETWEEN 30W-49W. ISOLATED SHOWER/THUNDERSTORMS ARE
WITHIN 90/120 NM ALONG THE COAST OF W AFRICA S OF 9N W OF 10W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH IS MOVING E OF THE MISSISSIPPI VALLEY AND
CONTINUES TO LIFT THE REMNANTS OF LEE NE ACROSS NE ALABAMA AND
NW GEORGIA. THIS UPPER TROUGH EXTENDS OVER THE GULF W OF A LINE
FROM THE BIG BEND AREA OF FLORIDA TO VERACRUZ MEXICO SUPPORTING
A COLD FRONT THAT AT 06/0900 UTC ENTERS THE GULF WATERS NEAR
CEDAR KEY FLORIDA ALONG 26N86W WHERE IT PULLS UP STATIONARY
ALONG 22N94W THEN S TO THE COAST OF MEXICO BETWEEN VERACRUZ AND
THE ISTHMUS OF TEHUANTEPEC. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE WITHIN 45/60 NM EITHER SIDE OF THE COLD
FRONT...WITHIN 90 NM W OF THE STATIONARY BOUNDARY...AND WITHIN
75 NM ALONG THE COAST OF MEXICO IN THE BAY OF CAMPECHE S OF 20N.
DRY AIR ALOFT AND CLEARING SKIES DOMINATE THE NW AND SE GULF
WATERS THIS MORNING. THE COLD FRONT WILL BECOME STATIONARY FROM
FLORIDA BIG BEND AREA TO DEVELOPING LOW PRESSURE OVER THE E BAY
OF CAMPECHE AND WEAKEN THROUGH WED. FRONT WILL THEN MOVE S AND
DISSIPATE THU AND FRI WHILE THE LOW PRESSURE LINGERS IN THE SW
GULF.

CARIBBEAN SEA...
AN ELONGATED UPPER LOW COVERS THE NW CARIBBEAN EXTENDING FROM
CENTRAL HONDURAS TO W CUBA AND THE ISLE OF YOUTH ENHANCING
SCATTERED SHOWERS/THUNDERSTORMS IN THE GULF OF HONDURAS S OF 19N
W OF 86W. THE SW UPPER FLOW OVER THE SW CARIBBEAN IS CONVERGING
WITH LOW LEVEL EASTERLY FLOW TO GENERATE A BAND OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 45/60 NM OF LINE FROM
14N83W TO 17N84W. THE MONSOON TROUGH EXTENDS CROSS THE SW
CARIBBEAN FROM COLOMBIA NEAR 10N75W ALONG 12N80W TO OVER
NICARAGUA NEAR 12N84W WITH SCATTERED SHOWERS/THUNDERSTORMS S OF
THE MONSOON TROUGH TO THE COAST OF PANAMA BETWEEN 78W-82W. DRY
STABLE AIR ALOFT DOMINATES THE CARIBBEAN E OF 80W. THIS IS
LEAVING THE REMAINDER OF THE CARIBBEAN UNDER REMARKABLY CLEAR
SKIES THIS MORNING. TROPICAL WAVE WILL MOVE NW THROUGH PUERTO
RICO THU. THE BROAD LOW PRESSURE IN THE SPECIAL FEATURES WILL
ENTER TROPICAL N ATLC LATE THU AND APPROACH LESSER ANTILLES ON
SAT.

ATLANTIC OCEAN...
NW UPPER FLOW WITH MOSTLY DRY STABLE AIR DOMINATES THE W ATLC W
OF HURRICANE KATIA. THE UPPER RIDGE ASSOCIATED WITH HURRICANE
KATIA COVERS AN AREA FROM 19N-32N BETWEEN 58W-73W. AN UPPER LOW
IS OVER THE CENTRAL ATLC CENTERED NEAR 28N52W AND IS EMBEDDED
WITHIN A MUCH LARGER UPPER TROUGH THAT COVERS THE REMAINDER OF
THE CENTRAL AND E ATLC INTO THE TROPICS WITH THE AXIS EXTENDING
THROUGH 32N27W SW TO 16N45W GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS N OF 30N BETWEEN 32W-37W. A SURFACE RIDGE
DOMINATES THE ATLC N OF 20N W OF 60W AND ANCHORED BY A 1026 MB
HIGH BETWEEN THE AZORES AND PORTUGAL AND A 1025 MB HIGH N OF THE
DISCUSSION AREA ABOUT 700 NM E-NE OF BERMUDA. HURRICANE KATIA
WILL CONTINUE TO MOVE THROUGH THE W ATLC THROUGH WED MOVING THEN
N OF THE AREA OVERNIGHT WED NIGHT. WEAK COLD FRONT WILL ENTER
FAR NW ATLC WATERS TONIGHT AND DISSIPATE BY THU. SURFACE RIDGE
WILL THEN BUILD ACROSS THE W ATLC IN WAKE OF KATIA THU THROUGH
SAT.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW





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