[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 27 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
1145 UTC.

...SPECIAL FEATURE...

HURRICANE IRENE IS CENTERED NEAR 35.5N 76.3W AT 27/1800 UTC OR
ABOUT 40 WNW OF CAPE HATTERAS NORTH CAROLINA...AND 80 NM S OF
NORFOLK VIRGINIA MOVING N-NE AT 13 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 950 MB. MAXIMUM SUSTAINED WIND SPEED IS 74 KT WITH
GUSTS TO 95 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. STRONG BANDS OF HEAVY SHOWERS AND
THUNDERSTORMS ARE MOSTLY INLAND AND OVER THE COASTAL WATERS OF
NORTH CAROLINA AND NORTHWARD. IRENE IS FORECAST TO GRADUALLY
WEAKEN AS IT MOVES ALONG THE EAST COAST OF THE UNITED STATES DUE
TO LAND INTERACTION...DRY AIR ENTRAINMENT...AND INCREASING
SOUTHWESTERLY SHEAR.

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

THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA. IT BARELY ENTERS
THE E TROPICAL ATLC THROUGH THE COAST OF GUINEA-BISSAU NEAR
12N16W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 3N-14N E
OF 23W. A 1011 MB LOW...REMNANTS OF T.D. TEN...IS CENTERED NEAR
18N35W. A SURFACE TROUGH EXTENDS ALONG THE LOW CENTER FROM
22N32W 18N35W 12N40W 10N47W WITH SCATTERED WEAK SHOWERS 70 NM W
OF THE LOW AND WITHIN 170 NM S OF THE TROUGH AXIS W OF 36W.
ANOTHER SURFACE TROUGH IS IN THE W TROPICAL ATLC ALONG 58W FROM
12N-16N MOVING TOWARD THE LESSER ANTILLES WITH SCATTERED
SHOWERS/THUNDERSTORMS W OF THE TROUGH TO OVER THE LESSER
ANTILLES.

...DISCUSSION...

GULF OF MEXICO...
DRY SUBSIDENT AIR IN THE MID AND UPPER LEVELS OF THE ATMOSPHERE
IS KEEPING MOST OF THE GULF UNDER FAIR WEATHER CONDITIONS THIS
AFTERNOON. EXCEPT FOR THE NE CORNER OF THE GULF...THE ENTIRE
GULF OF MEXICO HAS LIGHT AND VARIABLE WINDS. ONLY A FEW ISOLATED
SHOWERS ARE OBSERVED OVER THE FAR WRN BASIN OFF THE COAST OF
TAMPICO AND OVER THE BAY OF CAMPECHE NEAR THE COASTAL WATERS OF
VERACRUZ MEXICO. WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL
LONGWAVE/TROUGH EXTENDING ACROSS THE NRN GULF COAST STATES. THIS
SYSTEM SUPPORTS A SLOW MOVING COLD FRONT ACROSS THE S AND SE
CONUS. THIS FRONT IS EXPECTED TO DROP INTO THE FAR N GULF WATERS
LATER THIS AFTERNOON...THEN BECOME STATIONARY AND DISSIPATE
THROUGH LATE MON.

CARIBBEAN SEA...
AN UPPER TROUGH OVER THE CENTRAL ATLC EXTENDS ITS AXIS S OVER
THE E AND CENTRAL CARIBBEAN. DEEP LAYER MOISTURE REMAINS ACROSS
MOST OF THE CARIBBEAN BASIN E OF 77W. THESE CONDITIONS COMBINED
WITH THE UPPER TROUGH FLOW ALOFT ARE GENERATING CLUSTERS OF
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE CENTRAL
AND ERN CARIBBEAN BETWEEN 63W-77W. THE MONSOON TROUGH EXTENDS
FROM SOUTHERN NICARAGUA TO CENTRAL COLOMBIA GENERATING SIMILAR
CONVECTION NEAR THE COASTAL WATERS OF COSTA RICA...PANAMA AND
COLOMBIA. THE REMAINDER OF THE DISCUSSION AREA IS UNDER MOSTLY
CLEAR SKIES THIS AFTERNOON EXCEPT A FEW ISOLATED SHOWERS NEAR
THE COAST OF BELIZE. A WEAK PRESSURE PATTERN WILL PREVAIL
THROUGH SUNDAY...AS WEAK SURFACE TROUGH CURRENTLY OVER THE W
TROPICAL ATLC MOVES INTO THE E CARIBBEAN.

ATLANTIC OCEAN...
THE PRIMARY FOCUS THIS MORNING CONTINUES TO BE HURRICANE IRENE.
FOR MORE INFORMATION ON IRENE...SEE SPECIAL FEATURES ABOVE. THE
BROAD CYCLONIC WIND FIELD FROM IRENE IS DRAWING DEEP MOISTURE
FROM THE N CENTRAL CARIBBEAN WATERS SUPPORTING LINES OF
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS MOVING OVER THE
COASTAL WATERS OF CENTRAL BAHAMAS...AND NE OF THE ISLANDS N OF
26N BETWEEN 70W-74W. TO THE EAST OF THIS AREA OF CONVECTION...A
WELL DEFINED 1008 MB LOW IS CENTERED NEAR 28N64W SUPPORTED BY A
LARGE ELONGATED CYCLONIC CIRCULATION SE OF THE LOW CENTER.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE FROM 22N-32N
BETWEEN 60W-67W. THE SAME UPPER LEVEL FEATURE ALSO SUPPORTS A
SURFACE TROUGH THAT IS TO THE SE OF THE SURFACE LOW EXTENDING
FROM 25N56W TO 20N55W GENERATING SCATTERED WEAK ISOLATED SHOWERS
WITHIN 20 NM ON EITHER SIDE OF THE TROUGH AXIS. THE REMAINDER OF
THE ATLC BASIN IS DOMINATED BY A LARGE SURFACE RIDGE ANCHORED N
OF THE DISCUSSION AREA. CENTRAL ATLC SURFACE RIDGE WILL BUILD
WESTWARD IN THE WAKE OF IRENE MONDAY THROUGH WEDNESDAY.

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

$$

GARCIA



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