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AXNT20 KNHC 010004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE JUN 30 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 2315 UTC.


...SPECIAL FEATURES...


...GALE IN THE CARIBBEAN... A GALE WARNING WILL GO INTO EFFECT FOR THE SW CARIBBEAN FROM 11.5N-12N BETWEEN 74W-75W OVERNIGHT TONIGHT THROUGH EARLY WED MORNING. THESE GALE FORCE WINDS WILL PULSE AGAIN FRI NIGHT AND SAT NIGHT. THESE WINDS ARE GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN THE SURFACE RIDGE OVER THE W ATLC AND THE LOWER PRESSURE OVER SOUTH AMERICA. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS.


...TROPICAL WAVES...

TROPICAL WAVE IN THE E TROPICAL ATLC EXTENDS ALONG 25W FROM 6N- 13N MOVING W NEAR 15 KT OVER THE PAST 24 HOURS. THE UPPER LEVEL SATELLITE WINDS INDICATED THE MED TO UPPER SUPPORT IS AHEAD OF THE SURFACE WAVE AXIS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE SURFACE WAVE AXIS IS ALONG THE LEADING EDGE OF A SURGE OF DEEP MOISTURE. NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE IN THE E CARIBBEAN EXTENDS FROM 18N61W OVER THE LEEWARD ISLANDS TO THE COAST OF VENEZUELA NEAR 10N65W MOVING W- NW AT 20-25 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE ALONG THE LEADING EDGE OF A LOW AMPLITUDE SURGE OF DEEP MOISTURE. THIS SURGE IS BEING AMPLIFIED NORTHWARD BY THE UPPER LEVEL FEATURES. ACTIVITY OVER THE SE CARIBBEAN IS ASSOCIATED WITH THE UPPER LEVEL FEATURES AND IS BEING ENHANCED BY THE TROPICAL WAVE.

TROPICAL WAVE IN THE CENTRAL CARIBBEAN EXTENDS FROM HISPANIOLA NEAR 19N71W TO INLAND OVER COLOMBIA NEAR 11N73W MOVING W NEAR 25 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE REMAINS EMBEDDED WITHIN AN AREA OF DRY AIR. NO ASSOCIATED DEEP CONVECTION.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC NEAR 20N16W ALONG 12N19W TO E OF THE TROPICAL WAVE NEAR 9N24W. THE ITCZ BEGINS W OF THE WAVE NEAR 8N28W AND CONTINUES ALONG 5N43W TO SOUTH AMERICA NEAR 5N53W. SCATTERED MODERATE CONVECTION IS FROM 7N-10N BETWEEN 24W-27W AND IS BEING ENHANCED BY THE TROPICAL WAVE. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 60 NM OF THE ITCZ BETWEEN 36W-41W AND FROM 50W-53W.


...DISCUSSION...

GULF OF MEXICO... A BROAD UPPER TROUGH COVERS THE E CONUS WITH THE AXIS EXTENDING FROM THE GREAT LAKES OVER THE LOWER MISSISSIPPI VALLEY AND ENCOMPASSING THE UPPER LOW THAT HAS REMAINED OVER THE GULF NEAR 25N85W. THIS IS GENERATING LARGE CLUSTERS OF SCATTERED SHOWERS/ THUNDERSTORMS N OF 27N TO INLAND OVER THE N GULF COAST BETWEEN THE FLORIDA PENINSULAR AND NE TEXAS. AN UPPER RIDGE EXTENDS FROM THE E PACIFIC REGION ACROSS S MEXICO COVERING THE SW GULF AND PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS FROM 21N-27W W OF 94W TO INLAND OVER MEXICO. NOAA/NESDIS AEROSOL PRODUCT AND VISIBLE SATELLITE IMAGERY INDICATES THAT A PLUMB OF AEROSOLS OR SAHARAN DUST HAS MOVED FROM THE W CARIBBEAN OVER THE S GULF. THE DIURNAL SURFACE TROUGH IS ALONG THE W COAST OF THE YUCATAN PENINSULA. HOWEVER DUE TO THE INFLUX OF DRY AIR AND AEROSOLS...NO CONVECTION IS BEING GENERATED. SURFACE RIDGE EXTENDS FROM THE ATLC ACROSS S FLORIDA TO TEXAS WITH A 1020 MB HIGH NEAR 27N85W. THE SURFACE RIDGE WILL SHIFT N TO A POSITION FROM NEAR TAMPA BAY FLORIDA TO NE TEXAS THIS EVENING WHERE IT WILL REMAIN THROUGH THU THEN SHIFT FURTHER N TO CEDAR KEY FLORIDA TO THE MISSISSIPPI DELTA BY THE WEEKEND.

CARIBBEAN SEA... THE UPPER LEVEL FEATURES OVER THE W ATLC AND GULF OF MEXICO COVER THE N CARIBBEAN WITH NEAR ZONAL W FLOW ALOFT DOMINATING THE S CARIBBEAN. THE UPPER LOW N OF HISPANIOLA COMBINED WITH THE TROPICAL WAVE MOVING ACROSS THE ISLAND ARE GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 18N BETWEEN 66W-78W INCLUDING PUERTO RICO...HISPANIOLA...AND JAMAICA. THE UPPER TROUGH OVER THE GULF OF MEXICO DIPS S OVER THE NW CARIBBEAN AND IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER W CUBA W OF 82W. ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS COVER THE S CARIBBEAN S OF A LINE FROM THE COSTA RICA/NICARAGUA BORDER ALONG 12N75W THE GUADELOUPE IN THE LESSER ANTILLES. THIS IS LEAVING THE REMINDER OF THE CARIBBEAN WITH FAIR WEATHER THIS EVENING. NOAA/NESDIS AEROSOL PRODUCT AND VISIBLE SATELLITE IMAGERY INDICATES THAT A PLUMB OF AEROSOLS OR SAHARAN DUST COVES THE W CARIBBEAN LIMITING ANY DEEP CONVECTION. A PERSISTENT W ATLC SURFACE RIDGE WILL MAINTAIN STRONG TO NEAR GALE TRADE WINDS ACROSS THE S/CENTRAL CARIBBEAN THROUGH END OF THE WEEK WITH WINDS TO GALE FORCE OVERNIGHT PULSING AGAIN FRI NIGHT AND SAT NIGHT. TROPICAL WAVE IN THE CENTRAL CARIBBEAN WILL MOVE INTO THE W CARIBBEAN WED AND OVER CENTRAL AMERICA THU. THE E CARIBBEAN TROPICAL WAVE WILL MOVE INTO THE CENTRAL CARIBBEAN WED AND THE W CARIBBEAN BY THU NIGHT/EARLY FRI. A THIRD TROPICAL WAVE WILL MOVE INTO THE E CARIBBEAN WED THEN INTO THE CENTRAL CARIBBEAN BY THU AND THE W CARIBBEAN BY SAT.


...HISPANIOLA... SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE ISLAND ARE BEING GENERATED BY AN UPPER LOW CENTERED N OF THE ISLAND AND ENHANCED BY THE TROPICAL WAVE MOVING ACROSS THE ISLAND. AN UPPER TROUGH WILL PERSIST OVER THE ISLAND AS THE UPPER LOW SHIFTS N AWAY FROM THE ISLAND. LINGERING MOISTURE WILL BE RE-ENFORCED BY THE NEXT TROPICAL WAVE MOVING THROUGH THE E CARIBBEAN AND WILL BE OVER THE ISLAND WED AND WED NIGHT. THIS WILL CONTINUE TO GENERATE SHOWERS/ISOLATED THUNDERSTORMS EARLY THU WITH SOME CLEARING FRI.

ATLANTIC OCEAN... A NARROW UPPER RIDGE IS ANCHORED NEAR 31N74W COVERING THE W ATLC W OF 70W AND IS PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 28N W OF 79W TO OVER FLORIDA. THE UPPER LOW N OF HISPANIOLA IS CENTERED 21N69W AND IS GENERATING ISOLATED SHOWERS/THUNDERSTORMS S OF 25N BETWEEN 64W-73W. A NARROW UPPER TROUGH IS IN THE E ATLC SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N21W TO 29N29W THEN DISSIPATES ALONG 29N34W TO 28N39W WHERE IT BECOMES A DISSIPATING STATIONARY FRONT ALONG 28N47W 26N52W TO 27N57W. THE REMAINDER OF THE ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1029 MB HIGH N OF THE AREA NEAR 34N48W AND EXTENDING A RIDGE AXIS THROUGH 32N58W TO ACROSS S FLORIDA AND INTO THE GULF OF MEXICO. NOAA/NESDIS AEROSOL PRODUCT AND THE LAST VISIBLE SATELLITE IMAGERY INDICATES THAT A LARGE DENSE PLUMB OF AEROSOLS OR SAHARAN DUST COVERS THE TROPICS N OF THE ITCZ AND S OF LINE FROM THE CANARY ISLANDS ALONG 24N40W TO 22N60W. THE SURFACE RIDGE WILL PERSIST THROUGH THU THEN SHIFT N INTO THE WEEKEND.

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

$$ PAW

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