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AXNT20 KNHC 041757
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 04 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 DEPRESSION FRED CENTERED NEAR 22.3N 38.3W AT 04/1500 UTC OR ABOUT 1110 NM SW OF THE AZORES...MOVING WNW AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 35 KT. ISOLATED MODERATE CONVECTION IS WITHIN 200 NM OF THE CENTER IN THE EASTERN SEMI- CIRCLE OF THE SYSTEM. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

A TROPICAL WAVE IS BETWEEN THE AFRICAN COAST AND THE CAPE VERDE ISLANDS WITH AN AXIS EXTENDING FROM 18N20W...THROUGH A 1010 MB LOW NEAR 11N20W TO 08N20W. SCATTERED MODERATE CONVECTION IS FROM 07N TO 13N BETWEEN 17W AND 25W. THIS SYSTEM SHOWS SIGNS OF ORGANIZATION AND HAS A MEDIUM CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE OVER THE NEXT 48 HOURS AS IT MOVES W AT 15 TO 20 KT.


...TROPICAL WAVES...

A TROPICAL WAVE BETWEEN THE AFRICAN COAST AND CAPE VERDE ISLANDS INCLUDES THE SPECIAL FEATURE LOW. PLEASE REFER TO THE SPECIAL FEATURES SECTION ABOVE FOR MORE DETAILS.

A TROPICAL WAVE OVER THE EASTERN ATLC HAS AN AXIS THAT EXTENDS FROM 18N28W...THROUGH A 1012 MB LOW NEAR 12N28W...TO 11N28W...MOVING W AT AROUND 15 KT OVER THE PAST 24 HOURS. SSMI TPW SHOWS THE WAVE EMBEDDED IN HIGH MOISTURE S OF 14N. AN INVERTED 700 MB TROUGH IS INDICATED IN MODEL FIELDS BETWEEN 26W AND 33W. SCATTERED MODERATE CONVECTION IS FROM 10N TO 14N BETWEEN 27W AND 31W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AN AXIS EXTENDING FROM 16N52W TO 09N55W...MOVING W AT 15 TO 20 KT OVER THE PAST 24 HOURS. MODERATE MOISTURE IS NOTED S OF 10N WITH DRY AIR N OF 10N IN THE ENVIRONMENT OF THIS WAVE. NO DEEP CONVECTION IS OCCURRING AT THIS TIME.

A TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN WITH AN AXIS EXTENDING FROM 19N63W TO 11N64W...MOVING W AT AROUND 15 KT. THIS WAVE IS DEPICTED BY 700 MB MODEL FIELDS WITH A TROUGH NOTED BETWEEN 60W AND 65W. ONLY SHALLOW MOISTURE IS NOTED WITH THIS TROPICAL WAVE. NO DEEP CONVECTION IS OCCURRING AT THIS TIME.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM OVER AFRICA INTO THE E TROPICAL ATLC NEAR 13N17W...THROUGH THE 1010 MB LOW/TROPICAL WAVE NEAR 11N20W...THROUGH THE 1012 MB LOW/TROPICAL WAVE NEAR 12N28W...TO 11N37W...WHERE THE ITCZ BEGINS AND CONTINUES TO 10N53W. OTHER THAN CONVECTION ASSOCIATED WITH THE TWO LOWS...ISOLATED MODERATE CONVECTION IS FROM 07N TO 14N BETWEEN 31W AND 48W.


...DISCUSSION...

GULF OF MEXICO... AN UPPER RIDGE CENTERED OVER MEXICO HAS AN AXIS THAT EXTENDS EASTWARD OVER THE MAJORITY OF THE GULF BASIN. AN UPPER TROUGH JUST E OF THE SE US ATLC COAST HAS AN AXIS THAT EXTENDS OVER THE NE GULF. THIS UPPER TROUGH SUPPORTS A SURFACE TROUGH THAT EXTENDS ACROSS N FL TO THE NE GULF COAST NEAR CEDAR KEY...SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM 28N TO 29N E OF 85W. UPPER LEVEL DIFFLUENCE BETWEEN THE RIDGE AXIS AND UPPER TROUGH SUPPORTS ISOLATED MODERATE CONVECTION FROM 25N TO 30N BETWEEN 85W AND 89W. ELSEWHERE...A DIURNAL SURFACE TROUGH OVER THE SW GULF SUPPORTS ISOLATED THUNDERSTORMS FROM 18N TO 23N BETWEEN 93W AND 97W. A SURFACE HIGH CENTER OF 1016 MB NEAR 27N87W SUPPORTS E TO SE WINDS OF 10 TO 15 KT OVER THE S AND W GULF. N TO NW WINDS OF 5 TO 10 KT ARE E OF 85W. GENTLE VARIABLE WINDS ARE NEAR THE HIGH CENTER. OVER THE NEXT 24 HOURS THE SURFACE TROUGH OVER FL WILL EXPAND W OVER THE NORTHERN GULF WITH CONVECTION.

CARIBBEAN SEA... A PAIR OF UPPER LOWS ARE OVER THE CARIBBEAN WITH CENTERS LOCATED NEAR 16N88W AND PUERTO RICO. UPPER LEVEL RIDGING RESIDES BETWEEN THESE TWO LOWS OVER THE S CENTRAL CARIBBEAN. THE WESTERNMOST UPPER LOW SUPPORTS ISOLATED THUNDERSTORMS FROM 15N TO 19N W OF 84W. UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE UPPER RIDGE SUPPORTS SCATTERED MODERATE CONVECTION S OF 13N W OF 78W. DRY AIR AND STRONG SHEAR OVER THE EASTERN CARIBBEAN IS INHIBITING CONVECTION ASSOCIATED WITH THE EASTERNMOST UPPER LOW. A TROPICAL WAVE IS OVER THE E CARIBBEAN. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE NEAR THE UPPER LOW OVER THE NW CARIBBEAN AND OVER THE SW CARIBBEAN.


...HISPANIOLA... SHALLOW MOISTURE AND DAYTIME HEATING WILL SUPPORT ISOLATED SHOWERS AND THUNDERSTORMS OVER THE ISLAND THIS AFTERNOON AND EVENING. FAIR WEATHER IS EXPECTED TONIGHT. A SIMILAR PATTERN IS FORECAST ONCE AGAIN FOR SATURDAY AND SATURDAY NIGHT.

ATLANTIC OCEAN... AN UPPER LEVEL TROUGH JUST E OF THE SE US COAST SUPPORTS A 1012 MB SURFACE LOW NEAR 30N77W WITH A SURFACE TROUGH EXTENDING FROM 31N76W THROUGH THE SURFACE LOW TO N FL NEAR 29N83W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION ARE FROM 27N TO 31N BETWEEN 72W AND 77W...AND WITHIN 140 NM S OF THE SURFACE TROUGH AXIS W OF 77W...INCLUDING THE N BAHAMAS. ANOTHER UPPER TROUGH ALONG 65W SUPPORTS A SURFACE TROUGH FROM 31N64W TO 27N67W. THESE TWO FEATURES SUPPORT SCATTERED MODERATE CONVECTION FROM 27N TO 31N BETWEEN 55W AND 65W. FARTHER EAST...A WEAK 1016 MB LOW IS CENTERED NEAR 31N49W WITH A SURFACE TROUGH EXTENDING SW FROM THE SURFACE LOW TO 26N53W. A SHORTWAVE TROUGH IS ALONG 48W...COMBINING WITH THESE SURFACE FEATURES TO SUPPORT CLUSTERS OF MODERATE CONVECTION FROM 28N TO 31N BETWEEN 43W AND 48W. TROPICAL DEPRESSION FRED AND A SPECIAL FEATURE LOW WITH ASSOCIATED TROPICAL WAVE ARE OVER THE CENTRAL AND EASTERN ATLC...RESPECTIVELY. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. TWO OTHER TROPICAL WAVES ARE OVER THE TROPICAL ATLC. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS EXPECT CONVECTION TO BE LIKELY N OF 25N W OF 55W WITH THE TWO WESTERN ATLC SURFACE TROUGHS AND THE W ATLC SURFACE LOW.

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

$$ LATTO

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