[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071150
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...

HURRICANE KATIA IS CENTERED NEAR 28.7N 67.9W AT 07/0900 UTC OR
ABOUT 270 NM SW OF BERMUDA MOVING NW AT 9 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 973 MB. MAXIMUM SUSTAINED WIND SPEED IS 80
KT WITH GUSTS TO 100 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 IS WITHIN 120/150 NM OF LINE FROM 24N65W TO 32N67W.
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 12.0N 39.9W AT
07/0900 UTC OR ABOUT 955 NM W-SW OF THE CAPE VERDE ISLANDS AND
ABOUT 1265 NM E OF THE LESSER ANTILLES MOVING W AT 17 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 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 200 NM
OF THE CENTER IN THE NW QUADRANT. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE FROM 10N-15N BETWEEN 37W-40W AND FROM 10N-16N
BETWEEN 40W-46W.

THE 1007 MB SURFACE LOW IS CENTERED IN THE S GULF OF MEXICO NEAR
21N93W AT 07/0900 UTC AND REMAINS AT THE TAIL END OF A
QUASI-STATIONARY FRONTAL BOUNDARY. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE S OF 22N TO INLAND OVER
S MEXICO BETWEEN 92W-96W. THIS SYSTEM IS SHOWING SOME SIGNS OF
ORGANIZATION. ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR
DEVELOPMENT. IT IS POSSIBLE THAT THIS FEATURE MAY BECOME
A TROPICAL DEPRESSION DURING THE NEXT 48 HOURS. IT IS FORECAST
TO MOVE LITTLE DURING THE NEXT 48 HOURS. AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THE LOW
THIS AFTERNOON IF NECESSARY.

...TROPICAL WAVES...
TROPICAL WAVE IN THE E TROPICAL ATLC IS ALONG 21W/22W S OF 12N
MOVING W NEAR 15 KT. WAVE IS EMBEDDED WITHIN AN AREA OF DEEP
LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER
IMAGERY. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN
300/350 NM W OF THE WAVE AXIS.

TROPICAL WAVE IN THE W TROPICAL ATLC IS ALONG 57W S OF 20N
MOVING W NEAR 15 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF DEEP
LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER
IMAGERY. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
ARE FROM 15N-20N BETWEEN 55W-60W.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 19N16W TO 16N18W. A WEAK ITCZ AXIS EXTENDS FROM 5N46W
TO GUYANA SOUTH AMERICA NEAR 6N57W. CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE WITHIN 90 NM OF LINE FROM 3N20W TO W
AFRICA NEAR THE LIBERIA/SIERRA LEONE BORDER.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH IS MOVING ACROSS THE E CONUS COVERING THE
GULF W OF A LINE FROM FLORIDA NEAR CEDAR KEY TO VERACRUZ MEXICO
SUPPORTING A QUASI-STATIONARY FRONTAL BOUNDARY THAT AT 07/0900
UTC ENTERS THE GULF WATERS JUST S OF TAMPA FLORIDA ALONG 25N87W
SW TO THE 1007 MB LOW NEAR 21N93W THAT IS DISCUSSED IN THE
SPECIAL FEATURES SECTION ABOVE. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE WITHIN 90 NM EITHER SIDE OF THE FRONT. AN
UPPER RIDGE IS TO THE SE OF THE FRONT FROM NE YUCATAN TO ACROSS
S FLORIDA ENHANCING SCATTERED SHOWERS/THUNDERSTORMS IN THE
YUCATAN CHANNEL S OF 23N BETWEEN 84W-87W. DRY AIR ALOFT AND
REMARKABLE CLEAR SKIES DOMINATE THE GULF WATERS NW OF A LINE
FROM APALACHICOLA BAY FLORIDA ALONG 25N90W TO TUXPAN MEXICO.
STATIONARY FRONT WILL DISSIPATE THU 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 22N AND IN THE GULF OF HONDURAS S OF 19N W
OF 87W TO INLAND OVER CENTRAL AMERICA. 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 S OF A LINE FROM CENTRAL
NICARAGUA NEAR 13N84W TO COLOMBIA NEAR 10N75W. DRY STABLE AIR
ALOFT DOMINATES THE CENTRAL CARIBBEAN BETWEEN 65W-80W. THIS IS
LEAVING THE REMAINDER OF THE CARIBBEAN UNDER REMARKABLY CLEAR
SKIES AGAIN THIS MORNING WITH THE EXCEPTION OF SOME ISOLATED
SHOWERS OVER THE FAR E CARIBBEAN AND THE LESSER ANTILLES DUE TO
THE APPROACHING TROPICAL WAVE. HIGH DEBRIS CLOUDS FROM HURRICANE
KATIA COVER THE E CARIBBEAN ISLANDS FROM THE UPPER MOST WINDWARD
ISLANDS TO HISPANIOLA. 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 30N. SIMILAR SHOWERS/THUNDERSTORMS ARE FROM
28N-31N BETWEEN 77W-78W. A SWATH OF DRY STABLE AIR IS TO THE E
WITHIN 90 NM OF LINE FROM THE S BAHAMA ISLANDS NEAR 23N73W TO
32N77W. THE UPPER RIDGE ASSOCIATED WITH HURRICANE KATIA COVERS
AN AREA FROM 18N-33N BETWEEN 60W-72W. A CUTOFF UPPER LOW IS TO
THE E OF KATIA CENTERED NEAR 26N56W GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-27N BETWEEN 52W-58W. A
LARGE UPPER TROUGH COVERS THE REMAINDER OF THE CENTRAL AND INTO
E ATLC AND S INTO THE TROPICS BETWEEN 20W-45W N OF T.D. FOURTEEN
SUPPORTING A SURFACE TROUGH THAT ENTERS THE E/CENTRAL ATLC NEAR
32N35W EXTENDING ALONG 30N37W TO 2942W GENERATING CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 26N TO BEYOND 32N
BETWEEN 32W-47W. A WEAKENING BROAD SURFACE RIDGE DOMINATES THE
ATLC N OF 20N E OF 60W WITH A WEAKNESS IN THE VICINITY OF THE
ABOVE SURFACE TROUGH. 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 FORECAST 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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