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Atlantic Tropical Weather Discussion (Text)



000
AXNT20 KNHC 280004
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL 
205 PM EDT THU AUG 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...SPECIAL FEATURES... 

TROPICAL STORM ERIKA IS CENTERED NEAR 16.6N 64.0W AT 27/2100 UTC 
OR ABOUT 151 NM W OF GUADELOUPE...MOVING W-NW AT 13 KT. 
ESTIMATED CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WINDS 
ARE 40 KT WITH GUSTS TO 50 KT. NUMEROUS MODERATE TO ISOLATED 
STRONG CONVECTION IS FROM 14N TO 18N BETWEEN 61W AND 65W. 
SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 11N TO 19N 
BETWEEN 60W AND 65W. PLEASE SEE THE LATEST FORECAST/ADVISORY 
UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. 

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS APPROXIMATELY 
ALONG 27W...MOVING W AT ABOUT 20 KT OVER THE PAST 24 HRS. 
MODERATE MOISTURE IS ASSOCIATED WITH THIS WAVE FROM THE SURFACE 
TO 850 MB AS INDICATED BY CIRA LAYER PRECIPITABLE WATER IMAGERY. 
HOWEVER...THE PRESENCE OF SAHARAN DRY AIR AND DUST IN THE WAVE 
ENVIRONMENT SUPPRESS THE DEVELOPMENT OF CONVECTION. AHEAD OF THE 
TROPICAL WAVE...A 1012 MB LOW IS EMBEDDED IN THE MONSOON TROUGH 
NEAR 10N32W. MODERATE TO HIGH MOISTURE FROM THE SURFACE TO NEAR 
700 MB AND MIDDLE LEVEL DIFFLUENCE SUPPORT SCATTERED MODERATE 
CONVECTION FROM 07N TO 13N BETWEEN 34W AND 38W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS NEAR 46W
...MOVING W AT 15-20 KT DURING THE PAST 24 HOURS. MODERATE 
MOISTURE FROM THE SURFACE TO NEARLY 700 MB IS ASSOCIATED WITH 
THIS WAVE AS INDICATED BY CIRA LAYER PRECIPITABLE WATER IMAGERY. 
HOWEVER...THE PRESENCE OF SAHARAN DRY AIR AND DUST IN THE WAVE 
ENVIRONMENT SUPPRESS THE DEVELOPMENT OF CONVECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS INTO THE TROPICAL ATLANTIC NEAR 
14N17W TO 13N28W TO A 1012 MB LOW NEAR 10N32W TO 07N36W. THE 
ITCZ BEGINS NEAR 07N36W AND CONTINUES TO 08N45W. A 1012 MB LOW 
IS EMBEDDED IN THE MONSOON TROUGH NEAR 10N32W. MODERATE TO HIGH 
MOISTURE FROM THE SURFACE TO NEAR 700 MB AND MIDDLE LEVEL 
DIFFLUENCE SUPPORT SCATTERED MODERATE CONVECTION FROM 07N TO 13N 
BETWEEN 34W AND 38W. 

...DISCUSSION...

GULF OF MEXICO... 

A BROAD MIDDLE TO UPPER-LEVEL TROUGH EXTENDS FROM THE OHIO 
VALLEY S-SW ACROSS THE GULF TO A BASE OVER THE GULF OF CAMPECHE. 
THIS TROUGH SUPPORTS A STATIONARY FRONT THAT EXTENDS FROM 
NORTHERN FLORIDA TO A 1012 MB LOW NEAR 28N85W TO 23N88W TO 
24N95W. THE UPPER TROUGH ALSO SUPPORT A SURFACE TROUGH S OF THE 
FRONT TAIL FROM 23N96W TO 19N94W. MOISTURE ADVECTION FROM THE 
CARIBBEAN IS CONVERGING WITH MOISTURE ASSOCIATED WITH THE FRONT 
GENERATING INSTABILITY THAT ALONG WITH A DIVERGENT ENVIRONMENT 
ALOFT SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS OVER THE 
SW GULF S OF 24N. SIMILAR CONVECTION IS OVER THE SE GULF WATERS 
AHEAD OF THE FRONT...S OF 27N E OF 87W. DRY AIR SUBSIDENCE AND 
ADVECTION FROM SOUTHERN U.S. SUPPORT FAIR WEATHER N AND W OF THE 
FRONT. NORTHERLY WIND FLOW OF OF LESS THAN 15 KT COVERS THE 
BASIN. THE LOW PRESSURE CENTER IS FORECAST TO DISSIPATE BY 
FRIDAY MORNING...THE STATIONARY FRONT EXPECTED TO DISSIPATE BY 
SATURDAY MORNING LEAVING A TROUGH OF LOW PRESSURE IN THE NE GULF.

CARIBBEAN SEA... 

THE MAIN FEATURE OF INTEREST IN THE BASIN IS TROPICAL STORM 
ERIKA OVER THE EASTERN CARIBBEAN. PLEASE REFER TO THE SPECIAL 
FEATURES SECTION FOR MORE DETAILS. A COMBINATION OF UPPER 
DIFFLUENCE GENERATED BY THE TROUGH IN THE GULF AND AN UPPER HIGH 
S OF CUBA AND AN UPPER LOW FARTHER E OVER CENTRAL CUBA IS 
CAUSING AN UNSTABLE ENVIRONMENT THAT ALONG WITH MODERATE LOW 
LEVEL MOISTURE IN THE NW CARIBBEAN SUPPORT HEAVY SHOWERS AND 
TSTMS ACROSS CUBA. ISOLATED SHOWERS AND TSTMS ARE OVER THE NW 
BASIN W OF JAMAICA. THE CENTER OF ERIKA WILL MOVE NEAR THE 
VIRGIN ISLANDS THIS EVENING...MORE NEAR OR OVER PUERTO RICO 
TONIGHT...AND NEAR OR OVER THE DOMINICAN REPUBLIC ON FRIDAY. 
ERIKA IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 4 
TO 8 INCHES WITH MAXIMUM AMOUNTS OF 12 INCHES POSSIBLE ACROSS 
PORTIONS OF THE LEEWARD ISLANDS...VIRGIN ISLANDS...PUERTO RICO 
TONIGHT...THE DOMINICAN REPUBLIC...TURKS AND CAICOS ISLANDS AND 
SOUTHERN BAHAMAS THROUGH SATURDAY. RAINS COULD CAUSE LIFE-
THREATENING FLASH FLOODS AND MUD SLIDES. TROPICAL STORM FORCE 
WINDS WITHIN 90 NM E SEMICIRCLE AND 0 NM W SEMICIRCLE OF ERIKA. 
SEAS 12 FT OR GREATER WITHIN 180 NM NE QUADRANT WITH SEAS TO 16 
FT. ELSEWHERE WITHIN 270 NM NE SEMICIRCLE WINDS 20 TO 33 KT. 
SEAS 8 TO 12 FT. EASTERLIES OF 10-15 KT DOMINATE ELSEWHERE 
ACROSS THE BASIN.

...HISPANIOLA...                                               

CURRENTLY CLOUDY SKIES WITH POSSIBLE ISOLATED SHOWERS OVER 
EASTERN HISPANIOLA AS TROPICAL STORM ERIKA CONTINUE TO MOVE W-NW 
OVER EASTERN CARIBBEAN WATERS. THE CENTER OF ERIKA WILL MOVE 
NEAR OR OVER THE DOMINICAN REPUBLIC ON FRIDAY. ERIKA IS EXPECTED 
TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 4 TO 8 INCHES WITH 
MAXIMUM AMOUNTS OF 12 INCHES POSSIBLE ACROSS PORTIONS OF THE 
ISLAND THROUGH SATURDAY. RAINS COULD CAUSE LIFE-THREATENING 
FLASH FLOODS AND MUD SLIDES. 

ATLANTIC OCEAN... 

UPPER LEVEL DIVERGENCE AHEAD OF A STATIONARY FRONT EXTENDING 
ACROSS NORTHERN FLORIDA INTO THE GULF OF MEXICO ALONG WITH LOW 
LEVEL MOISTURE CONVERGENCE OVER THE FAR SW N ATLC SUPPORT 
SCATTERED HEAVY SHOWERS AND TSTMS N OF 22N W OF 70W. SCATTERED 
MODERATE CONVECTION ASSOCIATED WITH ERIKA...DISCUSSED IN THE 
SPECIAL FEATURES...IS S OF 19N BETWEEN 60W AND 65W. THERE ARE 
TWO TROPICAL WAVES...ONE OVER THE CENTRAL BASIN AND OTHER W OF THE 
CAPE VERDE ISLANDS NONE GENERATING CONVECTION AT THE TIME. SEE 
THE TROPICAL WAVES SECTION. A LOW PRESSURE CENTER IS BETWEEN THE 
WAVES GENERATING SCATTERED MODERATE CONVECTION FROM 07N TO 13N 
BETWEEN 34W AND 38W. OTHERWISE...SURFACE RIDGING AND FAIR 
WEATHER DOMINATE ELSEWHERE.

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

$$
NR

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Page last modified: Friday, 28-Aug-2015 00:04:57 UTC