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AXNT20 KNHC 071754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE JUL 07 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 1700 UTC.


...TROPICAL WAVES...

A TROPICAL WAVE CAME OFF THE WEST AFRICAN COAST EARLY THIS MORNING AND IS NOW LOCATED ALONG 19W FROM 07N TO 17N...MOVING W AT AN ESTIMATED 20 KT OVER THE PAST 12 HOURS. SSMI TOTAL PRECIPITABLE WATER TPW IMAGERY SHOWS A SURGE OF MODERATE TO HIGH MOISTURE S OF 16N ALONG THE WAVE AXIS. METEOSAT ENHANCED IMAGERY SHOWS SAHARAN AIR WITH DUST N OF 16N. SCATTERED MODERATE CONVECTION IS FROM 06N TO 10N BETWEEN 17W AND 21W. THIS CONVECTION MAY ALSO BE ASSOCIATED WITH THE MONSOON TROUGH.

A TROPICAL WAVE CROSSED THE LESSER ANTILLES THIS MORNING AND IS NOW OVER THE EASTERN CARIBBEAN ALONG 62W/63W FROM 09N TO 17N...MOVING W AT NEAR 25 KT OVER THE PAST 24 HOURS. SSMI TPW IMAGERY SHOWS MODERATE MOISTURE S OF 13N WITH LOW MOISTURE N OF 13N. IN ADDITION...STRONG SHEAR IS KEEPING ANY CONVECTION ASSOCIATED WITH THE SOUTHERN PORTION OF THE WAVE TO THE EAST OF THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS FROM 08N TO 17N BETWEEN 53W TO 63W. SOME OF THE COLDER CLOUD TOPS ASSOCIATED WITH THE NORTHERN CONVECTION MAY BE PRODUCING LITTLE IF ANY PRECIPITATION DUE TO THE DRY UNDERLYING AIR MASS.

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ALONG 72W FROM 11N TO 18N...MOVING W AT 20 TO 25 KT OVER THE PAST 24 HOURS. LOW TO MODERATE MOISTURE IS S OF 15N IN THE ENVIRONMENT OF THE WAVE. STRONG DEEP LAYER SHEAR IS INHIBITING CONVECTION ALONG THE WAVE. ISOLATED THUNDERSTORMS ARE S OF 13N BETWEEN 68W AND 74W.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16 TO 09N25W TO 08N37W...WHERE THE ITCZ BEGINS AND CONTINUES THROUGH 07N45W TO THE COAST OF S AMERICA NEAR 07N58W. OTHER THAN CONVECTION ASSOCIATED WITH THE EASTERN ATLC TROPICAL WAVE... ISOLATED MODERATE CONVECTION IS WITHIN 50 NM OF THE MONSOON TROUGH E OF 34W...AND WITHIN 50 NM OF THE ITCZ AXIS BETWEEN 47W AND 55W.


...DISCUSSION...

GULF OF MEXICO...

THE GULF BASIN CONTINUES UNDER THE INFLUENCE OF A BROAD UPPER LEVEL LOW CENTERED NEAR 25N87W. THE COMBINATION OF LIFT ASSOCIATED WITH THE UPPER LOW AND MODERATE MOISTURE OVER THE EASTERN GULF SUPPORTS SCATTERED THUNDERSTORMS FROM 24N TO 27N BETWEEN 81W AND 89W. AT THE SURFACE...A 1021 MB HIGH CENTERED NEAR 29N86W IS PART OF A LARGER SURFACE RIDGE OVER THE WESTERN ATLC WITH AN AXIS THAT EXTENDS ACROSS N FL TO THE TX COAST. VARIABLE SURFACE WINDS OF 5 TO 10 KT COVER THE GULF E OF 87W. 10 TO 15 KT SE WINDS ARE OVER THE REMAINDER OF THE GULF BASIN. OVER THE NEXT 24 HOURS...THE RIDGE AXIS WILL CONTINUE TO PRODUCE SIMILAR WINDS ACROSS THE GULF OF MEXICO. THE ONGOING INTERACTION OF THE UPPER LOW WITH MOISTURE OVER THE EASTERN GULF WILL SUPPORT SCATTERED THUNDERSTORMS THROUGH WEDNESDAY.

CARIBBEAN SEA...

THE UPPER LOW OVER THE CENTRAL GULF OF MEXICO COMBINED WITH MARGINAL MOISTURE OVER THE NW PORTION OF THE BASIN IS SUPPORTING SCATTERED THUNDERSTORMS FROM 16N TO 19N BETWEEN 80W AND 88W. THE REMAINDER OF THE BASIN N OF 13N IS COVERED IN DRY AIR AND IS CONVECTION FREE. SCATTERED MODERATE CONVECTION OVER THE SW CARIBBEAN S OF 13N BETWEEN 78W AND 84W IS ASSOCIATED WITH DEEP MOISTURE INTERACTING WITH THE NEARBY PACIFIC MONSOON TROUGH. WINDS OF E TO NE TRADE WINDS OF 25 TO 30 KT COVER THE S CENTRAL CARIBBEAN FROM 11N TO 13.5N BETWEEN 74W AND 77.5W. SEAS OF 8 TO 13 FEET ARE OCCURRING IN THE AREA. MAINLY 15 TO 25 KT TRADE WINDS COVER THE REMAINDER OF THE CARIBBEAN BASIN. TWO TROPICAL WAVES ARE OVER THE CENTRAL AND EASTERN CARIBBEAN. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. EXPECT CONVECTION TO CONTINUE OVER THE SW CARIBBEAN OVER THE NEXT 24 HOURS...WITH LITTLE CONVECTION ALONG THE TROPICAL WAVES AS THEY MOVE ACROSS THE CENTRAL CARIBBEAN.


...HISPANIOLA...

DRIER AIR HAS MOVED OVER THE ISLAND TODAY WHICH IS INHIBITING CONVECTION. SAHARAN AIR WITH DUST IS ALSO BEING REPORTED OVER THE ISLAND THIS AFTERNOON. EXPECT SIMILAR CONDITIONS THROUGH WEDNESDAY...WITH JUST AN ISOLATED CHANCE FOR THUNDERSTORMS MAINLY OVER THE HIGHER TERRAIN DURING THE AFTERNOON AND EVENING.

ATLANTIC OCEAN...

A SURFACE TROUGH EXTENDS FROM THE NORTHERN BAHAMAS NEAR 26N79W TO 31N79W AND NORTHWARD OFFSHORE THE MID ATLC COAST. SCATTERED THUNDERSTORMS ARE WITHIN 100 NM OF THE TROUGH AXIS S OF 31N.. INCLUDING OVER THE NORTHERN BAHAMAS AND S FL. AN UPPER LOW CENTERED NEAR 25N72W IS SUPPORTING SCATTERED THUNDERSTORMS FROM 22N TO 28N BETWEEN 69W AND 73W. SURFACE RIDGING COVERS THE REMAINDER OF THE SUBTROPICAL CENTRAL AND EASTERN ATLC WITH A 1025 MB HIGH CENTERED NEAR 30N64W AND ANOTHER 1025 MB HIGH CENTERED NEAR 34N36W. A TROPICAL WAVE IS OVER THE FAR EASTERN TROPICAL ATLC. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS THE UPPER LOW WILL CONTINUE TO GENERATE SCATTERED THUNDERSTORMS OVER THE WESTERN ATLC. MODELS ARE FORECASTING FOR THE SURFACE TROUGH NEAR THE E COAST AND N BAHAMAS TO DISSIPATE TONIGHT.

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

$$ LATTO

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