[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU SEP 08 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...SPECIAL FEATURES...

HURRICANE KATIA IS CENTERED NEAR 34.2N 70.0W AT 08/1800 UTC OR
ABOUT 330 MI...535 KM WNW OF BERMUDA MOVING N AT 14 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 973 MB. MAXIMUM SUSTAINED
WIND SPEED IS 70 KT WITH GUSTS TO 85 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 SHOWERS AND THUNDERSTORMS COVER THE AREA FROM 32N-37N
BETWEEN 66W-72W. 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. GLOBAL MODELS
INDICATE THAT KATIA WILL REMAIN A POWERFUL CYCLONE OVER THE NEXT
DAY OR SO. THE FORECAST TAKES THE REMNANTS OF KATIA NORTH OF THE
BRITISH ISLES IN ABOUT FOUR DAYS.

TROPICAL STORM NATE IS CENTERED NEAR 19.9N 92.4W AT 08/1800 UTC
OR ABOUT 125 MI...200 KM W OF CAMPECHE AND ABOUT 175 MI...285 KM
NE OF COATZACOALCOS MEXICO MOVING SE AT 1 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1000 MB. THE MAXIMUM SUSTAINED WIND SPEED IS
50 KT WITH GUSTS TO 60 KT. PLEASE SEE THE LATEST INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT5/WTNT35 KNHC AND
THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT5/
WTNT25 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION REMAINS SW OF THE CENTER OVER THE W BAY OF
CAMPECHE TO INLAND OVER MEXICO S OF 21N BETWEEN 91W-96W. THE
OUTER CONVECTION FROM NATE ALSO COVERS IMMEDIATE COASTAL WATERS
OF THE EASTERN COAST OF THE YUCATAN PENINSULA AND IN THE GULF OF
HONDURAS. NATE IS CURRENTLY LOCATED IN AN ENVIRONMENT OF LIGHT
TO MODERATE NORTHEASTERLY SHEAR. NATE IS EXPECTED TO PRODUCE
TOTAL RAIN ACCUMULATIONS OF 2 TO 4 INCHES WITH ISOLATED MAXIMUM
AMOUNTS OF 8 INCHES OVER THE MEXICAN STATES OF CAMPECHE...
TABASCO...AND SOUTHERN VERACRUZ. A STORM SURGE WILL RAISE WATER
LEVELS BY AS MUCH AS 1 TO 3 FEET ABOVE NORMAL TIDE LEVELS ALONG
THE IMMEDIATE COAST IN THE WARNING AREA. THE SHEAR IS FORECAST
TO LESSEN DURING THE NEXT DAY OR SO...WHICH SHOULD ALLOW FOR
GRADUAL STRENGTHENING.

TROPICAL STORM MARIA IS CENTERED NEAR 13.0N 52.0W AT 08/1800 UTC
OR ABOUT 605 MI...975 KM E OF THE WINDWARD ISLANDS MOVING W AT
19 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 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. MARIA
HAS A RATHER DISORGANIZED APPEARANCE ON SATELLITE IMAGERY.
CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE
FROM 12N-17N BETWEEN 45W-55W. MARIA IS SOUTH OF A PERSISTENT AND
LARGE SUBTROPICAL RIDGE THAT EXTENDS WESTWARD ACROSS THE ATLC.
THIS STEERING PATTERN CALLS FOR A WEST TO WEST-NORTHWEST TRACK
OVER THE NEXT TWO TO THREE DAYS. AFTER THAT...A WEAKER RIDGE
NORTH OF THE CYCLONE IS EXPECTED TO ALLOW A MORE NORTHWESTWARD
TRACK AT A SOMEWHAT SLOWER FORWARD SPEED. GUIDANCE IS IN VERY
GOOD AGREEMENT...AND MOST OF THE MODELS ARE CLUSTERED HAVING
MARIA OVER OR JUST TO THE NORTH OF THE CENTRAL BAHAMAS IN FIVE
DAYS.

...TROPICAL WAVES...

TROPICAL WAVE IS WSW OF CAPE VERDE ISLANDS ANALYZED FROM 17N27W
TO 9N28W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN AN AREA OF
DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER
IMAGERY AND IS WELL DEFINED IN THE LOW LEVEL CLOUD FIELD ON
VISIBLE SATELLITE IMAGERY. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE WITHIN 120 NM ON EITHER SIDE OF THE WAVE AXIS.

TROPICAL WAVE IS JUST EAST OF DOMINICAN REPUBLIC IS ANALYZED
FROM 23N68W TO 15N68W MOVING WNW 15-20 KT. WAVE IS EMBEDDED
WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS AND THUNDERSTORMS
ARE AFFECTING THE NORTH CENTRAL CARIBBEAN N OF 15N BETWEEN
67W-81W...AND THE ATLC WATERS N OF PUERTO RICO FROM 19N-25N
BETWEEN 60W-68W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH IS ANALYZED OVER AFRICA INTO THE E TROPICAL
ATLC ACROSS THE NORTHERN COAST OF MAURITANIA NEAR 20N16W TO
17N20W. THE MONSOON TROUGH AND ITCZ AXIS HAS BEEN DISRUPTED BY
THE LACK OF CONFLUENCE IN THE TRADE WINDS AND THE PRESENCE OF
TROPICAL STORM MARIA. CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE WITHIN 170 NM OF COAST OF LIBERIA...SIERRA LEONE...AND
GUINEA. SIMILAR ACTIVITY OF FROM 1N-8N BETWEEN 30W-37W.

...DISCUSSION...

GULF OF MEXICO...
THE PRIMARY CONCERN THIS AFTERNOON IS TROPICAL STORM NATE...SEE
SPECIAL FEATURES SECTION ABOVE. A SHARP UPPER TROUGH MOVES
ACROSS THE FAR EAST CONUS SUPPORTING A NEARLY STATIONARY FRONTAL
BOUNDARY EXTENDS ACROSS CENTRAL FLORIDA INTO THE GULF WATERS
ALONG TAMPA BAY TO NEAR 25N86W. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE WITHIN 70 NM EITHER SIDE OF THE FRONT. VERY
DRY AIR AND SUBSIDENCE ALOFT COVERS THE NW AND N CENTRAL BASINS
...GIVING THIS REGION REMARKABLE CLEAR SKIES AND FAIR WEATHER
CONDITIONS NW OF A LINE FROM THE COAST OF FLORIDA NEAR 30N83W
THE COAST OF MEXICO NEAR TAMPICO. NATE WILL MOVE SLOWLY NORTH
THROUGH FRI MORNING...THEN WILL TURN NW EARLY SAT MORNING AND
BECOME STRONGER BEFORE IT TURNS WEST TOWARD MEXICO. STATIONARY
FRONT WILL WEAKEN INTO A TROUGH OVER THE E GULF LATER TODAY.

CARIBBEAN SEA...
THE OUTER CONVECTION FROM TROPICAL STORM NATE IS GENERATING
SHOWERS AND ISOLATED THUNDERSTORMS OVER THE EASTERN COAST OF
THE YUCATAN PENINSULA AND IN THE GULF OF HONDURAS...SEE SPECIAL
FEATURES SECTION ABOVE. THE MONSOON TROUGH EXTENDS ACROSS THE SW
CARIBBEAN FROM COSTA RICA TO NORTHERN COLOMBIA GENERATING
SCATTERED SHOWERS AND THUNDERSTORMS S OF 12N W OF 75W. SIMILAR
CONVECTION IS MOVING INTO THE NORTH CENTRAL BASIN N OF 15N
BETWEEN 67W-81W ASSOCIATED TO A TROPICAL WAVE JUST E OF
DOMINICAN REPUBLIC. DRY STABLE AIR ALOFT DOMINATES ELSEWHERE
ACROSS THE DISCUSSION AREA WITH A FEW ISOLATED LOW TOP SHOWERS
EMBEDDED IN THE EASTERLY TRADE WIND FLOW. MARIA IS FORECAST TO
APPROACH THE LEEWARD/VIRGIN ISLANDS EARLY SATURDAY. THE TROPICAL
WAVE OVER THE NE CARIBBEAN WILL MOVE ACROSS THE N CARIBBEAN
TODAY BEFORE LIFTING N OVER THE BAHAMAS ON FRIDAY.

ATLANTIC OCEAN...
A NEARLY STATIONARY FRONT ENTERS THE DISCUSSION AREA OVER THE
WEST ATLC NEAR 32N76W EXTENDING SW INTO CENTRAL FLORIDA ALONG
CAPE CANAVERAL GENERATING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS WITHIN 70 NM EITHER SIDE OF THE FRONT. A TROPICAL
WAVE IS ANALYZED JUST EAST OF DOMINICAN REPUBLIC GENERATING
SIMILAR CONVECTION N OF PUERTO RICO FROM 19N-25N BETWEEN
60W-68W. AN UPPER TROUGH MOVES ACROSS THE N CENTRAL ATLC
SUPPORTING A WEAK SURFACE EXTENDING FROM 32N32W ALONG 27N37W TO
25N423W GENERATING ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS
WITHIN 35 NM ON EITHER SIDE OF THE AXIS. A WEAKENING BROAD
SURFACE RIDGE DOMINATES ELSEWHERE ACROSS THE ATLC N OF 20N E OF
60W. HURRICANE KATIA IS N OF THE DISCUSSION AREA WITH TROPICAL
STORM CONDITIONS CONTINUING N OF 29N FOR TODAY. SURFACE RIDGING
WILL BUILD ACROSS THE AREA IN THE WAKE OF KATIA TODAY THROUGH
SAT. TROPICAL STORM MARIA WILL MOVE NEAR THE NRN LESSER ANTILLES
BETWEEN SATURDAY AND SUNDAY BEFORE MOVING E OF THE BAHAMAS
DURING THE FIRST OF THE WEEK.

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

$$

GARCIA



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