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AXNT20 KNHC 181052
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU SEP 18 2014

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 1030 UTC.


...SPECIAL FEATURES...

AS OF 18/0900 UTC...HURRICANE EDOUARD IS CENTERED NEAR 39.6N 45.3W OR ABOUT 775 NM W OF FAYAL ISLAND IN THE WESTERN AZORES MOVING E-NE AT 24 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 965 MB. MAXIMUM SUSTAINED WINDS ARE 75 KT WITH GUSTS TO 90 KT. EDOUARD IS EXPECTED TO WEAKEN BELOW HURRICANE STRENGTH LATER TODAY OR TONIGHT AND BECOME A POST-TROPICAL CYCLONE BY FRIDAY NIGHT. SCATTERED MODERATE CONVECTION IS FROM 37N-43N BETWEEN 41W- 46W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.


...TROPICAL WAVES...

TROPICAL WAVE IS RIGHT OFF THE WESTERN COAST OF AFRICA WITH AXIS EXTENDING FROM 18N17W TO A 1011 MB LOW NEAR 10N17W. METEOSAT RGB AND SAL IMAGERY SHOW BOTH DUST AND DRY AIR ENGULFING THE N-NW WAVE ENVIRONMENT...WHICH REMAINS DEVOID OF CONVECTION. MAINLY THICK HIGH CLOUDS ARE TO THE S-SW OF THE WAVE WHERE SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE OBSERVED FROM 5N-13N EAST OF 28W.

TROPICAL WAVE IS OVER THE CENTRAL TROPICAL ATLANTIC WITH AXIS EXTENDING FROM 19N40W TO 10N43W...MOVING WEST AT 15-20 KT. THE GOES-R SEVIRI DUST PRODUCT SHOW DUST ON THE CENTRAL AND WESTERN WAVE ENVIRONMENT AND LOW TO HIGH CLOUDS ON THE NORTHERN WAVE REGION WHERE SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE NOTED FROM 15N-20N BETWEEN 34W-42W. THE REST OF THE WAVE ENVIRONMENT IS DEVOID OF CONVECTION.

TROPICAL WAVE IS OVER THE LESSER ANTILLES WITH AXIS EXTENDING FROM 26N59W TO 11N61W...MOVING WEST AT 15 KT. SCATTERED MODERATE CONVECTION AND TSTMS INCREASED THIS MORNING IN THE NORTHERN WAVE ENVIRONMENT AND EXTENDED FURTHER SOUTH TO 14N. GOES-R SEVIRI DUST PRODUCT SHOW LOW TO HIGH CLOUDS IN THIS REGION OF CONVECTION. STRONG DEEP LAYER ENVIRONMENTAL SHEAR IS HINDERING CONVECTION ELSEWHERE.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO A 1011 MB LOW NEAR 10N17W TO 12N36W. THE ITCZ AXIS BEGINS WEST OF A TROPICAL WAVE NEAR 10N45W AND CONTINUES TO 8N58W. OTHER THAN THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES ALREADY DISCUSSED...SCATTERED MODERATE CONVECTION IS FROM 6N-11N BETWEEN 44W-48W.


...DISCUSSION...

GULF OF MEXICO...

A BROAD MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE EASTERN U.S. TO THE WEST ATLC NEAR 60W WITH ITS BASE EXTENDING ACROSS FLORIDA AND THE SW N ATLC. SOUTHWEST OF THE TROUGH ALOFT...THE EASTERN PERIPHERY OF A MIDDLE TO UPPER LEVEL RIDGE DOMINATES ELSEWHERE. MODERATE DEEP LAYER MOISTURE IS ACROSS THE NW...SW AND SE GULF...WHICH IS ENHANCING ISOLATED SHOWERS AND TSTMS. TROUGHINESS ALOFT ALSO SUPPORTS A SURFACE TROUGH ALONG 26N80W TO 25N84W...WHICH IS SUPPORTING THE CONVECTION IN THE SE BASIN. DRY AIR AND STRONG DEEP LAYER ENVIRONMENTAL SHEAR SUPPRESS CONVECTION ELSEWHERE. A COLD FRONT STARTED MOVING ACROSS NORTHERN FLORIDA THIS MORNING AND IS EXPECTED TO CONTINUE MOVING ACROSS THE REMAINDER PENINSULA TODAY WHILE THE PORTION OF THE FRONT OVER GULF WATERS IS FORECAST TO STALL ACROSS THE NORTHERN TO CENTRAL GULF. THE FRONTAL SYSTEM WILL TRANSITION COMPLETELY TO A STATIONARY FRONT ACROSS THE CENTRAL AND SE GULF ON FRIDAY.

CARIBBEAN SEA...

AN OVERALL UNSTABLE ENVIRONMENT CONTINUES MAINLY ACROSS THE CENTRAL AND NE BASIN BEING SUPPORTED BY ABUNDANT DEEP LAYER MOISTURE AND A DIFFLUENT ENVIRONMENT ALOFT BEING GENERATED BY A MIDDLE TO UPPER LEVEL INVERTED TROUGH ON THE NW BASIN AND A RIDGE DOMINATING ELSEWHERE. THIS SYNOPTIC PATTERN IS ENHANCING ISOLATED SHOWERS S OF 19N BETWEEN 70W-83W. A TROPICAL WAVE IS MOVING ACROSS THE LESSER ANTILLES AND IS SUPPORTING CONVECTION ON THE NE BASIN. SEE THE TROPICAL WAVES SECTION ABOVE. STRONG DEEP LAYER ENVIRONMENTAL SHEAR INHIBITS CONVECTION ELSEWHERE. OTHERWISE...A RELAXED PRESSURE GRADIENT CONTINUE TO SUPPORT TRADES OF 10-15 KT ACROSS THE BASIN. THE TROPICAL WAVE IS FORECAST TO MOVE ACROSS HISPANIOLA FRIDAY AND ACROSS CUBA SATURDAY.


...HISPANIOLA...

FORMER CONVECTION ON PORTIONS OF THE ISLANDS HAS DISSIPATED. RAINSHOWERS ACTIVITY IS FORECAST TO RESUME THIS AFTERNOON AND WILL GRADUALLY INCREASE BY FRIDAY DUE TO THE PASSAGE OF A TROPICAL WAVE.

ATLANTIC OCEAN...

A BROAD MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE EASTERN U.S. TO THE WEST ATLC NEAR 60W WITH ITS BASE EXTENDING ACROSS FLORIDA AND THE SW N ATLC. SOUTH-SOUTHEAST OF THE TROUGH...A BROAD MIDDLE TO UPPER LEVEL RIDGE EXTENDS NORTHWARD FROM THE CARIBBEAN. THIS SYNOPTIC PATTERN ALOFT IS GENERATING A DIFFLUENT ENVIRONMENT IN THE SW N ATLC WHICH ALONG ABUNDANT DEEP LAYER MOISTURE SUPPORT SCATTERED MODERATE/ISOLATED STRONG CONVECTION AND TSTMS N OF 26N BETWEEN 68W-79W. SCATTERED TSTMS ARE ALSO FROM 25N-28N BETWEEN 64W-67W. OTHERWISE...BESIDES THE TWO TROPICAL WAVES DISCUSSED IN THE WAVES SECTION...SURFACE RIDGING AND FAIR WEATHER DOMINATE ELSEWHERE.

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

$$ NR

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