[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 060539
TWDAT

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

...SPECIAL FEATURES...

HURRICANE KATIA IS CENTERED NEAR 25.8N 64.4W AT 06/0300 UTC OR
ABOUT 390 NM S OF BERMUDA MOVING NW AT 9 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 946 MB. MAXIMUM SUSTAINED WIND SPEED IS 115
KT WITH GUSTS TO 140 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. SCATTERED MODERATE/STRONG
CONVECTION IS FROM 23N-28N 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 10N31W 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/ STRONG CONVECTION IS NW OF THE CENTER FROM
10N-14N BETWEEN 32W-38W. ORGANIZATION OF THIS SYSTEM HAS CHANGED
LITTLE DURING THE PAST SEVERAL HOURS. 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 IS MOVING INTO THE W TROPICAL ATLC EXTENDING FROM
19N49W THROUGH A 1012 MB LOW NEAR 15N48W TO 12N47W MOVING W NEAR
15 KT. THE WAVE N OF 13N INCLUDING THE LOW IS EMBEDDED WITHIN AN
AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY WITH DRIER AIR COMPLETELY
UNDERCUTTING THE WAVE. ISOLATED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS ARE WITHIN 150 NM W OF THE WAVE N OF 13N.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA ENTERING THE E
TROPICAL ATLC NEAR 16N16W ALONG 12N23W THROUGH THE 1009 MB LOW
IN THE SPECIAL FEATURES NEAR 10N31W TO 9N44W. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 9N-12N BETWEEN 15W-17W
INCLUDING THE COAST OF GUINEA-BISSAU. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-9N BETWEEN
10W-47W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH COVERS THE MISSISSIPPI VALLEY AND IS FINALLY
LIFTING THE REMNANTS OF LEE E-NE ACROSS CENTRAL ALABAMA. THIS
UPPER TROUGH EXTENDS OVER THE W GULF N OF 23N W OF A COLD FRONT
THAT AT 06/0300 UTC ENTERS THE GULF WATERS JUST W OF TALLAHASSEE
FLORIDA ACROSS APALACHICOLA BAY ALONG 25N88W TO MEXICO BETWEEN
TUXPAN AND VERACRUZ. A SURFACE TROUGH EXTENDS FROM THE GULF
WATERS NEAR 24N87W TO OVER THE YUCATAN PENINSULA NEAR MERIDA TO
17N93W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 27N E
OF THE FRONT TO JUST INLAND OVER THE FLORIDA PENINSULA WITH
SCATTERED/HEAVY SHOWERS AND SCATTERED/NUMEROUS THUNDERSTORMS
ASSOCIATED WITH THE SURFACE TROUGH S OF 23N TO INLAND OVER THE
YUCATAN BETWEEN 87W-90W. ISOLATED CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS DOT THE REMAINDER OF THE SW GULF S OF 23N
W OF 90W. DRY AIR ALOFT AND CLEARING SKIES DOMINATE THE NW GULF
TONIGHT. THE COLD FRONT WILL MOVE SE THROUGH CENTRAL GULF
TONIGHT AND BECOME STATIONARY FROM FLORIDA BIG BEND AREA TO
DEVELOPING LOW PRESSURE OVER THE E BAY OF CAMPECHE THROUGH WED.
FRONT WILL THEN MOVE S AND DISSIPATE THU AND FRI WHILE THE LOW
PRESSURE LINGERS IN BAY OF CAMPECHE.

CARIBBEAN SEA...
AN INVERTED UPPER TROUGH AXIS EXTENDS FROM AN UPPER LOW OVER
HONDURAS TO W CUBA AND THE ISLE OF YOUTH ENHANCING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS INLAND AND IN THE GULF OF
HONDURAS S OF 17N W OF 87W. DRY STABLE AIR ALOFT DOMINATES THE
CARIBBEAN E OF 80W. HOWEVER...AFTERNOON HEATING HAS DEVELOPED
SCATTERED THUNDERSTORMS INLAND OVER CUBA AND HAITI WHICH HAVE
DRIFTED INTO THE IMMEDIATE COASTAL WATERS. 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 12N79W TO 16N83W. THIS IS LEAVING
THE REMAINDER OF THE CARIBBEAN UNDER REMARKABLY CLEAR SKIES
TONIGHT. TROPICAL WAVE WILL MOVE N OF PUERTO RICO WED NIGHT. THE
BROAD LOW PRESSURE IN THE SPECIAL FEATURES WILL ENTER TROPICAL N
ATLC LATE THU AND MOVE INTO NE CARIBBEAN LATE FRI AND SAT.

ATLANTIC OCEAN...
NW UPPER FLOW DOMINATES THE W ATLC W OF HURRICANE KATIA WITH
MOSTLY DRY STABLE AIR. HOWEVER...SOME ISOLATED SHOWERS/
THUNDERSTORMS ARE POSSIBLE WITHIN 60 NM ALONG THE COAST OF
FLORIDA AND OVER THE N BAHAMA ISLANDS. THE UPPER RIDGE
ASSOCIATED WITH HURRICANE KATIA COVERS THE REMAINDER OF THE W
ATLC WITH GOOD OUTFLOW IN ALL QUADRANTS. AN UPPER LOW IS OVER
THE CENTRAL ATLC CENTERED NEAR 27N51W AND IS EMBEDDED WITHIN A
MUCH LARGER UPPER TROUGH THAT COVERS THE REMAINDER OF THE
CENTRAL AND INTO THE E ATLC AND S INTO THE TROPICS WITH THE AXIS
EXTENDING FROM AN UPPER LOW NEAR 33N25W SW TO 16N44W GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 18N-23N BETWEEN
47W-55W. A SURFACE RIDGE DOMINATES THE ATLC N OF 20N W OF 60W
AND ANCHORED BY A 1027 MB HIGH BETWEEN THE AZORES AND PORTUGAL
AND A 1026 MB HIGH NEAR 33N51W. HURRICANE KATIA WILL CONTINUE TO
MOVE THROUGH THE W ATLC THROUGH WED MOVING THEN N OF THE AREA
OVERNIGHT WED NIGHT.

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

$$
PAW




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