[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231153
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE AUG 23 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
1115 UTC.

...SPECIAL FEATURE...
HURRICANE IRENE IS CENTERED NEAR 20.6N 70.7W AT 23/1200 UTC OR
ABOUT 70 MI...110 KM SSE OF GRAND TURK ISLAND...OR ABOUT 55
MI...90 KM N OF PUERTO PLATA DOMINICAN REPUBLIC MOVING WNW AT 10
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB. MAXIMUM
SUSTAINED WIND SPEED IS 85 KT WITH GUSTS TO 105 KT MAKING IRENE
A CATEGORY TWO HURRICANE. 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/NUMEROUS
STRONG CONVECTION PERSISTS FROM THE NORTH COAST OF HISPANIOLA TO
21N BETWEEN 69W-72W. A BAND OF STRONG CONVECTION IS ALSO NOTED
FROM 17N TO THE SOUTHERN COAST OF DOMINICAN REPUBLIC 68W AND
70W. BANDS OF SHOWERS CONTINUE TO PUSH N AGAINST THE CENTRAL
HIGHLANDS IN PUERTO RICO AS WELL AS ACROSS THE US AND BRITISH
VIRGIN ISLANDS. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 40 NM
FROM THE CENTER AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP
TO 160 NM TO THE NE OF THE CENTER.

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

THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA ENTERING THE E
TROPICAL ATLC NEAR A 1006 MB LOW NEAR DAKAR SENEGAL ALONG 13N18W
TO 12N24W TO 14N30W. NO MONSOON TROF OR ITCZ ARE NOTED IN A
LIGHT WINDS PATTERN EVIDENT BETWEEN 30W AND 40W...S OF A LOW
PRES AREA NEAR 21N35W. AN ITCZ IS NOTED FROM 12N41W TO 15N60W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE CONTINUES TO DOMINATE THE GULF ANCHORED OVER
CENTRAL TEXAS. A LIGHT PRES PATTERN REMAINS IN PLACE OVER THE
ENTIRE GULF THIS MORNING...WITH SURFACE WINDS GENERALLY 5 TO 10
KT IN E TO SE FLOW OVER THE WESTERN GULF AND NE TO E WINDS OVER
THE EASTERN GULF. SEAS REMAIN 1 TO 3 FT. THE EXCEPTION REMAINS
OVER THE STRAITS OF FLORIDA WHERE WINDS ARE 15 TO 20 KT IN E
FLOW...ENHANCED IN PART BY THE APPROACH OF HURRICANE IRENE INTO
THE SOUTHERN BAHAMAS. A FEW SHOWERS AND TSTMS ARE NOTED OVER THE
SE GULF...W OF THE FLORIDA KEYS AND N OF WESTERN CUBA...THE
RESULT OF THE ENHANCED SURFACE FLOW AND WEAK DIVERGENCE ALOFT AT
THE BASE OF AN UPPER TROUGH DIGGING THROUGH THE EASTERN UNITED
STATES. HURRICANE IRENE CURRENTLY N OF MONA PASSAGE/E DOMINICAN
REPUBLIC IS FORECAST TO TRACK NW JUST N OF HISPANIOLA TONIGHT
THEN ACROSS BAHAMAS TUE AND WED WITH TROPICAL STORM CONDITIONS
NOT CURRENTLY EXPECTED IN THE GULF WATERS.

CARIBBEAN SEA...
PRIMARY CONCERN THIS EVENING CONTINUES TO BE HURRICANE IRENE
CENTERED N OF HISPANIOLA. THE PROXIMITY OF IRENE IS KEEPING
MODERATE TO FRESH WINDS IN PLACE ALONG SCATTERED TO NUMEROUS
SHOWERS AND TSTMS IN PLACE OVER THE NE CARIBBEAN WATERS...N OF
15N E OF 75W. NE WINDS ARE INCREASING TO 20 KT THROUGH THE
WINDWARD PASSAGE AS WELL. LIGHT TO MODERATE NE WINDS COVER THE
REMAINDER OF THE WESTERN CARIBBEAN. SCATTERED SHOWERS AND
ISOLATED TSTMS ARE NOTED OVER THE FAR NW CARIBBEAN NEAR THE
YUCATAN CHANNEL IN RESPONSE TO DIVERGENCE ASSOCIATED WITH AN
INVERTED UPPER TROUGH EXTENDING FROM WESTERN CUBA THROUGH
HONDURAS. CONVECTION IS LIMITED ELSEWHERE IN THE CARIBBEAN DUE
TO SUBSIDENCE ON THE PERIPHERY OF IRENE. HURRICANE IRENE IS
FORECAST TO MOVE JUST N OF HISPANIOLA TONIGHT THROUGH THIS
EVENING.

ATLANTIC OCEAN...
THE PRIMARY CONCERN THIS EVENING CONTINUES TO HURRICANE IRENE
CENTERED N OF HISPANIOLA. A SURFACE RIDGE EXTENDS FROM ROUGHLY
31N50W TO CENTRAL FLORIDA. ASCAT DATA SHOW WINDS OF 20 TO 30 KT
FROM N OF THE LEEWARD ISLAND NEAR 19N TO 25N BETWEEN 60W AND
70W...BETWEEN IRENE THE RIDGING TO THE NORTH. SCATTERED SHOWERS
AND TSTMS ARE NOTED IN THE CAY SAL AREA OF THE BAHAMAS...DUE TO
ENHANCED MODERATE TO FRESH SURFACE LOW AND DIVERGENCE ALOFT AT
THE BASE OF AN UPPER TROUGH DIGGING THROUGH THE SE UNITED
STATES. FURTHER E...BROAD LOW LEVEL TROUGHING IS NOTED ON GOES
HIGH DENSITY WIND OUTPUT...TO THE SE OF AN UPPER TROUGH NEAR
18N50W. SUBSIDENT DRY AIR TO THE W OF THE UPPER LOW IS
INHIBITING CONVECTION FROM THE LEEWARD ISLANDS TO 50W. A 1012 MB
SURFACE LOW IS NOTED NEAR 21N35W. DESPITE THIS BEING A FAIRLY
WEAK LOW...THE GRADIENT REMAINS TIGHT AGAINST HIGH PRES OVER THE
N CENTRAL ATLC...ALLOWING FRESH E WINDS TO THE N OF THE
LOW...ALONG WITH SCATTERED MODERATE CONVECTION WITHIN 120 NM NE
QUADRANT OF THE LOW. FURTHER E...AN ACTIVE LOW PRES AREA REMAINS
OFF THE COAST OF SENEGAL NEAR 14N21W...WITH SCATTERED MODERATE
TO ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM N SEMICIRCLE.

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

$$
CHRISTENSEN





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