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AXNT20 KNHC 281749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 28 2015

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 1715 UTC.


...SPECIAL FEATURES... TROPICAL STORM ERIKA IS CENTERED NEAR 17.7N 70.2W AT 28/1800 UTC OR ABOUT 50 NM SW OF SANTO DOMINGO DOMINICAN REPUBLIC AND ABOUT 265 NM SE OF GREAT INAGUA ISLAND MOVING W AT 16 KT. ESTIMATED CENTRAL PRESSURE IS 1009 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. NUMEROUS MODERATE AND ISOLATED STRONG CONVECTION IS FROM 13N-19N BETWEEN 66W-70W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.


...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 12N37W TO 19N36W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH LOW-AMPLITUDE 700 MB TROUGHING ON THE SOUTHERN PERIPHERY OF A MID-LEVEL RIDGE CENTERED OVER THE EASTERN TROPICAL ATLC NEAR 24N34W. SCATTERED MODERATE CONVECTION IS FROM 11N-14N BETWEEN 36W-42W.

TROPICAL WAVE EXTENDS FROM 09N51W TO 18N50W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A BROAD AND RELATIVELY AMPLIFIED 700 MB TROUGH BETWEEN 45W-58W. NO SIGNIFICANT CONVECTION IS NOTED IN THE VICINITY OF THE WAVE AXIS AT THIS TIME.


...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO 13N27W TO 11N40W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 11N40W TO 10N49W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG 36W...SCATTERED MODERATE CONVECTION IS FROM 07N-13N BETWEEN 13W-21W...AND FROM 08N-12N BETWEEN 42W-45W.


...DISCUSSION...

GULF OF MEXICO... A BROAD AND ELONGATED MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE NORTH-CENTRAL GULF NEAR 29N88W THAT STRETCHES TROUGHING ALOFT FROM OVER THE SE CONUS SW TO A BROAD BASE OVER THE SW GULF NEAR 20N93W. WHILE NORTHERLY FLOW EMBEDDED IN DRY AIR ALOFT... AND STABLE CONDITIONS ARE NOTED OVER MUCH OF THE NW GULF WATERS...THE TROUGHING SUPPORTS A STATIONARY FRONT MEANDERING FROM THE FLORIDA PANHANDLE NEAR 30N84W SW TO 24N93W. LOW-LEVEL MOISTURE CONVERGENCE ALONG AND SOUTH OF THE WEAK FRONT...ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE TROUGH AXIS IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 18N-25N BETWEEN 88W- 95W...WITH ISOLATED SHOWERS AND TSTMS OCCURRING ELSEWHERE WITHIN 210 NM EAST OF THE FRONT ACROSS PORTIONS OF THE EASTERN GULF. THE FRONT IS EXPECTED TO DISSIPATE FULLY BY SATURDAY WITH GENERALLY GENTLE TO MODERATE E-SE BREEZE CONDITIONS PREVAILING. CERTAINLY WITH THE APPROACH OF TROPICAL STORM ERIKA BY SUNDAY... INTERESTS LOCATED IN THE EASTERN GULF WATERS AND FLORIDA STRAITS...KEYS...AND PENINSULA SHOULD MONITOR THE PROGRESS OF ERIKA.

CARIBBEAN SEA... ALL EYES ON TROPICAL STORM ERIKA THROUGH SUNDAY AS THE CURRENT TRACK TAKES THE CYCLONE ACROSS HISPANIOLA AND NW INTO THE FLORIDA STRAITS. MAIN IMPACT OUTSIDE OF TROPICAL STORM FORCE WINDS WILL BE LARGE AMOUNTS OF HEAVY PRECIPITATION ACROSS HISPANIOLA AND THE ADJACENT COASTAL WATERS RESULTING IN FLASH FLOODING AND DANGEROUS MUD SLIDES. OTHERWISE...THE REMAINDER OF THE BASIN REMAIN RELATIVELY QUIET WITH MOSTLY DRY AIR NOTED ON WATER VAPOR IMAGERY ALOFT DUE TO AN UPPER LEVEL RIDGE ANCHORED NEAR 13N73W THAT EXTENDS AN AXIS WEST-NORTHWESTWARD TO 17N84W. ACROSS PORTIONS OF THE CENTRAL CARIBBEAN AND THE WESTERN CARIBBEAN...MODERATE TO OCCASIONAL FRESH E-NE TRADES PREVAIL AND WITH THE PASSAGE OF ERIKA TO THE NORTH THROUGH THE WEEKEND...AS SURFACE RIDGING FOLLOWS IN ERIKA'S WAKE...TRADES ARE FORECAST TO INCREASE ACROSS THE CENTRAL CARIBBEAN INTO THE FRESH TO STRONG BREEZE RANGE AND PERSIST THROUGH SUNDAY...THEN DECREASE SLIGHTLY INTO MONDAY.


...HISPANIOLA... THE CENTER OF TROPICAL STORM ERIKA IS EXPECTED TO MOVE NEAR OR OVER HISPANIOLA DURING THE EVENING AND OVERNIGHT HOURS. MAIN IMPACT FROM ERIKA ASIDE FROM TROPICAL STORM FORCE WINDS IS THE THE LARGE AMOUNT OF RAINFALL EXPECTED WITH ERIKA RESULTING IN LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.

ATLANTIC OCEAN... MIDDLE TO UPPER-LEVEL DIFFLUENCE ACROSS THE SW NORTH ATLC IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE FLORIDA STRAITS AND NW BAHAMAS NW OF A LINE FROM 23N79W TO 32N73W THIS AFTERNOON. TO THE SOUTHEAST...ISOLATED SHOWERS IN ASSOCIATION WITH TROPICAL STORM ERIKA ARE BEGINNING TO MOVE INTO THE ATLC WATERS IN THE VICINITY OF PUERTO RICO...THE MONA PASSAGE...AND EASTERN HISPANIOLA. THE REMAINDER OF THE BASIN IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A PAIR OF 1021 MB HIGHS CENTERED NEAR 29N63W AND NEAR 27N30W.

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

$$ HUFFMAN

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