[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 250558
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU AUG 25 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 FEATURE...
HURRICANE IRENE IS CENTERED NEAR 24.2N 76.0W AT 25/0600 UTC OR
ABOUT 91 NM ESE OF NASSAU AND ABOUT 660 NM S OF CAPE HATTERAS
NORTH CAROLINA MOVING NW AT 10 KT. MINIMUM CENTRAL PRESSURE
REPORTED BY THE AIR FORCE HURRICANE HUNTERS WAS 950 MB. MAXIMUM
SUSTAINED WIND SPEED IS 100 KT WITH GUSTS TO 120 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.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS A BROAD
AREA FROM 22N-27N BETWEEN 71W-77W. HURRICANE IRENE IS A LARGE
TROPICAL CYCLONE WITH HURRICANE FORCE WINDS EXTENDING OUTWARD UP
TO 60 NM FROM THE CENTER AND TROPICAL STORM FORCE WINDS
EXTENDING OUTWARD UP TO 225 NM. IRENE IS EXPECTED TO PRODUCE
RAINFALL ACCUMULATIONS OF 6 TO 12 INCHES OVER THE BAHAMAS DURING
THE NEXT 36 HOURS. RAINS WILL BE DIMINISHING ACROSS THE TURKS
AND CAICOS ISLANDS WITH ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3
INCHES POSSIBLE...BRINGING THE MAXIMUM STORM TOTAL TO 6 TO 12
INCHES.

A 1007 MB LOW IS CENTERED SW OF THE CAPE VERDE ISLANDS NEAR
12N28W WITH SCATTERED/NUMEROUS STRONG CONVECTION FROM 11N-14N
BETWEEN 29W-33W. THIS SYSTEM IS BECOMING BETTER ORGANIZED AND A
TROPICAL DEPRESSION COULD BE FORMING.  IF CURRENT TRENDS
CONTINUE ADVISORIES WILL LIKELY BE INITIATED LATER THIS MORNING.
THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD OR
WEST-NORTHWESTWARD AT 9-13 KT.

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

THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA ENTERING THE E
TROPICAL ATLC NEAR 17N16W THROUGH THE 1007 MB LOW IN THE SPECIAL
FEATURES TO NEAR 8N38W. THE ITCZ AXIS CONTINUES FROM 8N38W ALONG
7N50W TO INLAND OVER SOUTH AMERICA NEAR 7N59W. A SURFACE TROUGH
IS JUST N OF THE ITCZ EXTENDING ALONG 49W FROM 11N-15N. CLUSTERS
OF SCATTERED MODERATE CONVECTION ARE WITHIN 120 NM OF LINE FROM
15N52W TO 9N58W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE DOMINATES THE W GULF W OF 90W ANCHORED OVER W
TEXAS. UPPER DIFFLUENCE OVER THE FAR NW GULF IS GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND OVER LOUISIANA
AND E TEXAS AND ISOLATED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS WITHIN 60 NM ALONG THE N GULF COAST FROM THE
FLORIDA PANHANDLE TO E TEXAS. AN UPPER LOW IS OVER THE NE GULF
NEAR 27N86W WITH AN UPPER TROUGH EXTENDING S TO THE YUCATAN
CHANNEL GENERATING ISOLATED SHOWERS/THUNDERSTORMS FROM 22N-27N
BETWEEN 84W-88W. A WEAK SURFACE RIDGE REMAINS ACROSS THE FAR N
GULF ANCHORED INLAND OVER THE SE CONUS. THIS IS LEAVING MOST OF
THE GULF UNDER CLEAR SKIES TONIGHT. THE WEAK SURFACE RIDGE WILL
LINGER OVER THE N GULF THROUGH FRI. HURRICANE IRENE CURRENTLY
MOVING ACROSS THE BAHAMAS WILL REACH THE NW BAHAMAS ON THU WITH
TROPICAL STORM CONDITIONS EXPECTED TO REMAIN WELL E OF THE GULF
WATERS. HOWEVER...THE TIGHTENING PRESSURE GRADIENT WILL INCREASE
WINDS AND SEAS OVER THE E GULF THU THROUGH LATE FRI. A WEAK COLD
FRONT WILL REACH THE N GULF COAST EARLY SAT.

CARIBBEAN SEA...
HURRICANE IRENE CONTINUES TO GENERATE SCATTERED TO HEAVY SHOWERS
WITH ISOLATED THUNDERSTORMS OVER THE N/CENTRAL CARIBBEAN MAINLY
N OF 17N FROM THE VIRGIN ISLANDS TO CENTRAL CUBA. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE NW CARIBBEAN N OF
19N W OF 78W. A WEAK SURFACE TROUGH EXTENDS FROM THE COAST OF
CUBA NEAR 21N77W ACROSS W JAMAICA ALONG 16N80W TO OFF THE COAST
OF NICARAGUA NEAR 12N83W. BROAD OUTFLOW FROM HURRICANE IRENE
COVERS THE E AND CENTRAL CARIBBEAN. THIS IS DRAWING TROPICAL
MOISTURE N ACROSS THE S CARIBBEAN AND GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 13N TO INLAND OVER
COLOMBIA BETWEEN 72W-76W. THIS UPPER FLOW IS ALSO RESPONSIBLE
FOR THE HIGH DEBRIS CLOUDS COVERING THE AREA E OF 80W. HURRICANE
IRENE OVER THE BAHAMAS IS EXPECTED TO MOVE AWAY FROM CARIBBEAN
LATER TODAY.

ATLANTIC OCEAN...
THE PRIMARY CONCERN TONIGHT CONTINUES TO BE HURRICANE IRENE
MOVING THROUGH THE BAHAMA ISLANDS TONIGHT...SEE SPECIAL FEATURES
ABOVE. THE UPPER RIDGE ASSOCIATED WITH HURRICANE IRENE COVERS
THE W ATLC W OF 65W. A LARGE UPPER LOW JUST TO THE E IS CENTERED
NEAR 25N55W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS WITHIN 120 NM OF LINE FROM 27N50W TO 24N57W. A
WEAK 1015 MB SURFACE LOW IS CENTERED IN THE CENTRAL ATLC NEAR
23N45W GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION
FROM 24N-26N BETWEEN 44W-46W. THE REMAINDER OF THE ATLC BASIN N
OF 25N E OF 65W IS DOMINATED BY A LARGE SURFACE RIDGE ANCHORED
BY A 1026 MB HIGH N OF THE DISCUSSION AREA ABOUT 450 NM WSW OF
THE AZORES. HURRICANE IRENE IS FORECAST TO MOVE MORE N-NW ACROSS
CENTRAL BAHAMAS TONIGHT AND INTENSIFY AS IT REACHES THE N
BAHAMAS EARLY THU THEN N OF THE BAHAMAS ON ON FRI BEFORE MOVING
N OF AREA FRI EVENING.

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

$$
PAW





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