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AXNT20 KNHC 012355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUL 01 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-12.5N BETWEEN 74W-77W OVERNIGHT THU NIGHT INTO EARLY FRI THEN PULSING AGAIN FRI NIGHT INTO EARLY SAT. THESE WINDS ARE GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN THE STRONG SURFACE RIDGE OVER THE 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 30W/31W FROM 5N-12N WITH A WEAK 1013 MB LOW ALONG THE WAVE NEAR 9N. THE WAVE/LOW ARE MOVING W NEAR 15 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS EMBEDDED WITHIN AN SURGE OF DEEP MOISTURE. NO ASSOCIATED DEEP CONVECTION.

A WEAK TROPICAL WAVE WAS INTRODUCED IN THE CENTRAL/W TROPICAL ATLC ALONG 45W FROM 5N-11N MOVING 10-15 KT OVER THE PAST 12 HOURS. THIS WAVE POSITION IS BASED ON THE 700 MB SIGNATURE AND THE TOTAL PRECIPITABLE WATER IMAGERY IN ADDITION TO ANALYSIS GUIDANCE. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS EMBEDDED WITHIN LOW AMPLITUDE SURGE OF DEEP MOISTURE. WAVE IS INTERACTING WITH AN UPPER LOW DEEPENING THE WAVE AXIS AND ALSO INTERACTING WITH THE ITCZ TO GENERATE SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF THE ITCZ BETWEEN 40W- 44W.

TROPICAL WAVE IN THE CENTRAL CARIBBEAN EXTENDS ALONG 73W/74W FROM HAITI TO INLAND OVER COLOMBIA MOVING W AT 20-25 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS EMBEDDED WITHIN A SURGE OF MODERATE MOISTURE. THIS WAVE IS INTERACTING WITH AN UPPER TROUGH THAT COVERS HISPANIOLA. SEE CARIBBEAN SECTION BELOW.

TROPICAL WAVE IN THE W CARIBBEAN EXTENDS ALONG 83W S OF 18N TO INLAND OVER COSTA RICA MOVING W NEAR 25 KT OVER THE PAST 24 HOURS. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS ALONG THE LEADING EDGE OF THE SURGE OF MODERATE MOISTURE THAT ENCOMPASSES THE PREVIOUS TROPICAL WAVE. THIS WAVE HAS SPLIT WITH A SURFACE TROUGH TO THE N WHILE THE TROPICAL WAVE REMAINS S OF 18N. SEE CARIBBEAN SECTION BELOW. NO ASSOCIATED DEEP CONVECTION.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC NEAR 20N16W ALONG 13N21W TO E OF THE TROPICAL WAVE NEAR 9N27. THE ITCZ BEGINS W OF THE WAVE NEAR 8N33W ALONG 10N38W TO E OF THE NEXT TROPICAL WAVE NEAR 8N44W THEN RESUMES W OF THIS WAVE NEAR 7N47W INTO SOUTH AMERICA NEAR 5N53W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION IS FROM 7N-13N E OF 18W TO INLAND OVER W AFRICA.


...DISCUSSION...

GULF OF MEXICO... A BROAD UPPER TROUGH COVERS THE NE CONUS WITH A NARROW UPPER TROUGH AXIS EXTENDING FROM SE GEORGIA ACROSS FLORIDA NEAR PANAMA CITY TO INLAND OVER TEXAS NEAR CORPUS CHRISTI. THIS IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND AND WITHIN 60 NM ALONG THE NW GULF COAST BETWEEN MOBILE ALABAMA TO CORPUS CHRISTI TEXAS. THE UPPER LOW CENTERED OVER W CUBA NEAR HAVANA AND EXTENDING AN UPPER TROUGH OVER THE SE GULF IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 25N TO FORT MYERS E OF 83W TO INLAND OVER THE S FLORIDA PENINSULA. CLUSTERS OF SIMILAR ACTIVITY ARE OVER CUBA AND IN THE YUCATAN CHANNEL. AN UPPER RIDGE IS OVER THE SW GULF EXTENDING FROM THE W BAY OF CAMPECHE TO 25N96W WITH DENSE CLOUDS AND POSSIBLE SCATTERED SHOWERS FROM 20N-25N W OF 93W TO OVER MEXICO. THE DIURNAL SURFACE TROUGH IS OFF THE W COAST OF THE YUCATAN PENINSULA. HOWEVER DUE TO THE INFLUX OF DRY AIR...NO CONVECTION IS BEING GENERATED. SURFACE RIDGE EXTENDS FROM THE ATLC ACROSS CENTRAL FLORIDA TO NE TEXAS WITH A 1021 MB HIGH NEAR 28N87W. THE SURFACE RIDGE WILL PERSIST THROUGH THU THEN SHIFT N TO A POSITION FROM NEAR CEDAR KEY FLORIDA TO THE MISSISSIPPI DELTA THROUGH THE WEEKEND.

CARIBBEAN SEA... AN UPPER LOW IS CENTERED OVER W CUBA NEAR HAVANA AND EXTENDS AN UPPER TROUGH N INTO THE GULF OF MEXICO AND S TO 16N81W. THIS IS GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 20N W OF 81W TO OVER CUBA...THE YUCATAN...AND THROUGH THE YUCATAN CHANNEL. THE N PORTION OF THE W CARIBBEAN TROPICAL WAVE IS NOW A SURFACE TROUGH THAT IS INTERACTING WITH THE UPPER TROUGH. A HIGHLY AMPLIFIED UPPER RIDGE IS OVER THE E CARIBBEAN/W TROPICAL ATLC DRAWING TROPICAL MOISTURE OVER THE E CARIBBEAN. AN UPPER LOW IS CENTERED N OF HISPANIOLA EXTENDING AN UPPER TROUGH OVER HISPANIOLA TO JAMAICA AND IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER E CUBA E OF 79W AND HISPANIOLA. THIS ACTIVITY OVER HISPANIOLA IS FURTHER ENHANCED BY THE CENTRAL CARIBBEAN TROPICAL WAVE. THIS IS LEAVING THE REMAINDER 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 STRONG 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 THU NIGHT AND FRI NIGHT. TROPICAL WAVE IN THE W CARIBBEAN WILL MOVE OVER CENTRAL AMERICA THIS EVENING. THE CENTRAL CARIBBEAN TROPICAL WAVE WILL MOVE INTO THE W CARIBBEAN THU THROUGH FRI NIGHT. A THIRD TROPICAL WAVE WILL MOVE INTO THE E CARIBBEAN FRI NIGHT WITH A FOURTH TROPICAL WAVE ENTERING THE E CARIBBEAN ON SUN.


...HISPANIOLA... SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ACROSS THE ISLAND AND 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 INTO THE WEEKEND. LINGERING MOISTURE WILL CONTINUED THROUGH THU AFTERNOON THEN RETURN ON SAT MORNING WHEN THE NEXT TROPICAL WAVE APPROACHES THE ISLAND. THIS MOISTURE WILL CONTINUE TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS THROUGH THU AND RETURNING SAT.

ATLANTIC OCEAN... AN UPPER TROUGH EXTENDS ALONG SOUTH CAROLINA AND NE GEORGIA COAST WHERE IT CROSSES SW INTO THE GULF OF MEXICO. AN UPPER RIDGE IS ANCHORED NEAR 29N75W COVERING THE W ATLC W OF 73W AND IS PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 26N BETWEEN 71W- 77W. THE UPPER LOW N OF HISPANIOLA IS CENTERED 24N70W AND IS GENERATING THE ACTIVITY OVER HISPANIOLA WITH ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 26N BETWEEN 61W-71W. A REMNANT DISSIPATING COLD FRONT ENTERS THE E ATLC NEAR 32N13W TO 28N19W THEN BECOMES A DISSIPATING STATIONARY FRONT MEANDERING ALONG 25N25W 26N47W TO 29N55W. THE FRONT ABOVE IS WEAKENING AS THE STRONG SURFACE RIDGE BUILDS IN DOMINATING THE REMAINDER OF THE ATLC ANCHORED BY A 1029 MB HIGH N OF THE AREA NEAR 34N51W AND EXTENDING A RIDGE AXIS THROUGH 32N61W TO ACROSS CENTRAL 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 TO 24N/25N INTO THE CARIBBEAN. THE SURFACE RIDGE WILL PERSIST THROUGH THE WEEKEND.

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

$$ PAW

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