[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 070542
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED SEP 07 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 28.4N 67.5W AT 07/0600 UTC OR
ABOUT 275 NM S-SW OF BERMUDA MOVING NW AT 8 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 963 MB. MAXIMUM SUSTAINED WIND SPEED
IS 90 KT WITH GUSTS TO 110 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/ISOLATED STRONG CONVECTION COVERS THE AREA
FROM 24N-30N BETWEEN 63W-69W. LARGE SWELLS GENERATED BY
HURRICANE KATIA WILL CONTINUE 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.

TROPICAL DEPRESSION FOURTEEN IS CENTERED NEAR 11.6N 38.1W AT
07/0300 UTC OR ABOUT 865 NM W-SW OF THE CAPE VERDE ISLANDS AND
ABOUT 1375 NM E OF THE LESSER ANTILLES MOVING W AT 16 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. PLEASE SEE THE LATEST
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER
MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 300 NM OF THE CENTER IN THE NW QUADRANT. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 75 NM OF LINE FROM
9N41W TO 12N45W.

THE 1008 MB SURFACE LOW IS CENTERED IN THE S GULF OF MEXICO
NEAR 20N94W AT 07/0300 UTC AND REMAINS AT THE TAIL END OF A
FRONTAL BOUNDARY THAT HAS BECOME QUASI-STATIONARY. THIS SYSTEM
HAS CHANGED LITTLE IN ORGANIZATION OVER THE PAST FEW HOURS...BUT
SOME GRADUAL DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE
NEXT COUPLE OF DAYS. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING
A TROPICAL CYCLONE AS IT MOVES LITTLE DURING THE NEXT 48 HOURS.
AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO
INVESTIGATE THIS SYSTEM TODAY...IF NECESSARY. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE S OF 22N TO
INLAND OVER S MEXICO BETWEEN 91W-96W.

...TROPICAL WAVES...
TROPICAL WAVE IN THE E TROPICAL ATLC IS ALONG 20W S OF 13N
MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYER
MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS W OF THE WAVE
AXIS WITHIN 45/60 NM OF LINE FROM 12N23W TO 8N22W AND WITHIN 120
NM E OF THE WAVE FROM 11N-13N.

TROPICAL WAVE IN THE W TROPICAL ATLC IS ALONG 55W/56W S OF 19N
MOVING W NEAR 15 KT. 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.
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM
14N-19N BETWEEN THE WAVE AXIS AND 60W.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA BUT DOES NOT ENTER
THE E TROPICAL ATLC. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 3N-7N BETWEEN 24W-28W AND WITHIN 120
NM ALONG THE COAST OF W AFRICA S OF 10N W OF 10W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH IS MOVING ACROSS THE E CONUS COVERING THE
GULF W OF A LINE FROM THE BIG BEND AREA OF FLORIDA TO VERACRUZ
MEXICO SUPPORTING A FRONTAL BOUNDARY THAT HAS BECOME
QUASI-STATIONARY AT 07/0300 UTC. THE FRONT ENTERS THE GULF
WATERS NEAR TAMPA FLORIDA ALONG 25N87W SW TO THE 1008 MB LOW
NEAR 20N94W THAT WAS DISCUSSED IN THE SPECIAL FEATURES SECTION
ABOVE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 45/60
NM EITHER SIDE OF THE FRONT. AN UPPER RIDGE IS TO THE SE OF THE
FRONT ENHANCING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 75 NM OF
LINE FROM FLORIDA BAY THROUGH THE YUCATAN CHANNEL INCLUDING THE
LOWER FLORIDA KEYS. DRY AIR ALOFT AND REMARKABLE CLEAR SKIES
DOMINATE THE GULF WATERS NW OF A LINE FROM PANAMA CITY FLORIDA
ALONG 27N87W TO TAMPICO MEXICO. FRONT WILL REMAIN STATIONARY
TODAY AND DISSIPATE THU AND FRI WHILE THE LOW LINGERS IN THE SW
GULF THROUGH SUN...WITH THE POTENTIAL TO BECOME A TROPICAL
CYCLONE.

CARIBBEAN SEA...
A WEAK UPPER LOW COVERS THE NW CARIBBEAN CENTERED NEAR THE
CAYMAN ISLANDS ENHANCING SCATTERED SHOWERS/THUNDERSTORMS IN THE
YUCATAN CHANNEL N OF 20N BETWEEN 84W-87W. THE MONSOON TROUGH
EXTENDS ACROSS THE SW CARIBBEAN FROM COLOMBIA NEAR 10N75W INTO
THE E PACIFIC REGION NEAR THE PANAMA/COSTA RICA BORDER WITH
SCATTERED SHOWERS/THUNDERSTORMS MOSTLY INLAND OVER COLOMBIA AND
E PANAMA WITH ISOLATED SHOWERS DRIFTING INTO THE FAR SW
CARIBBEAN IN THE GULF OF URABA. DRY STABLE AIR ALOFT DOMINATES
THE CARIBBEAN E OF 80W. THIS IS LEAVING THE REMAINDER OF THE
CARIBBEAN UNDER REMARKABLY CLEAR SKIES AGAIN TONIGHT WITH THE
EXCEPTION OF SOME ISOLATED SHOWERS OVER THE FAR E CARIBBEAN AND
THE LESSER ANTILLES DUE TO THE APPROACHING TROPICAL WAVE. THE
TROPICAL DEPRESSION IS EXPECTED TO REACH THE W TROPICAL ATLC FRI
AS A TROPICAL STORM AND APPROACH THE LEEWARD ISLANDS SAT. THE W
ATLC TROPICAL WAVE WILL MOVE NW TOWARD PUERTO RICO THROUGH THU.

ATLANTIC OCEAN...
A QUASI-STATIONARY FRONT ENTERS THE W ATLC NEAR 32N79W ACROSS
FLORIDA INTO THE GULF OF MEXICO NEAR DAYTONA BEACH GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM OF THE
FRONT MAINLY N OF 31N. SIMILAR SHOWERS/THUNDERSTORMS ARE OVER
THE N BAHAMA ISLANDS FROM 24N-27N BETWEEN 76W-79W. A SWATH OF
DRY STABLE AIR IS TO THE E WITHIN 120 NM OF LINE FROM THE S
BAHAMA ISLANDS NEAR 23N73W TO 33N77W. THE UPPER RIDGE ASSOCIATED
WITH HURRICANE KATIA COVERS AN AREA FROM 19N-32N BETWEEN
58W-72W. A WEAKENING UPPER LOW IS OVER THE W/CENTRAL ATLC
CENTERED NEAR 27N55W GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 17N-27N BETWEEN 49W-54W. THIS UPPER LOW
APPEARS TO BECOME CUT OFF FROM THE MUCH LARGER UPPER TROUGH THAT
COVERS THE REMAINDER OF THE CENTRAL AND INTO E ATLC AND EXTENDS
S INTO THE TROPICS BETWEEN 20W-40W N OF T.D. FOURTEEN. A WEAK
BROAD SURFACE RIDGE DOMINATES THE ATLC N OF 20N W OF 60W.
HURRICANE KATIA WILL MOVE N OF THE AREA EARLY THU. THE FRONT
OVER THE W ATLC WILL GRADUALLY DISSIPATE BY THU. SURFACE RIDGE
WILL BUILD ACROSS THE W ATLC IN THE WAKE OF KATIA THU THROUGH
SAT. T.D. FOURTEEN IS EXPECTED TO REACH THE W TROPICAL ATLC FRI
AS A TROPICAL STORM THEN MOVE NW TOWARD THE LEEWARD ISLAND OVER
THE WEEKEND.

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

$$
PAW





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