[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180600
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT JUL 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE EASTERN ATLC WITH AN AXIS EXTENDING
FROM 18N23W TO 09N23W...MOVING W AT AROUND 15 KT. A 1014 MB LOW
IS ALONG THE WAVE NEAR 16N23W. SSMI TPW SHOWS HIGH MOISTURE S OF
13N WITH DRIER AIR N OF 13N. ENHANCED METEOSAT IMAGERY INDICATES
SAHARAN DUST N OF 14N ALONG THE WAVE. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 07N TO 11N BETWEEN 21W AND 27W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AN AXIS EXTENDING
FROM 20N46W TO 10N47W...MOVING W AT AROUND 15 KT. THIS WAVE IS
AT THE LEADING EDGE OF A DEEP LAYER MOISTURE SURGE WITH HIGH
MOISTURE NOTED S OF 14N. SCATTERED MODERATE CONVECTION IS FROM
10N TO 14N BETWEEN 43W AND 48W.

A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN SEA WITH AN AXIS
EXTENDING FROM 20N82W TO 09N82W...MOVING W AT AROUND 20 KT OVER
THE PAST 24 HOURS. THIS WAVE IS EMBEDDED IN AN ENVIRONMENT OF
MODERATE TO HIGH MOISTURE. CLUSTERS OF MODERATE CONVECTION ARE
FROM 17N TO 21N BETWEEN 78W AND 83W...INCLUDING THE CAYMAN
ISLANDS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
08N32W. THE ITCZ BEGINS NEAR 09N46W AND CONTINUES TO THE COAST
OF S AMERICA NEAR 06N58W. IN ADDITION TO THE CONVECTION
ASSOCIATED WITH THE E ATLC TROPICAL WAVE...SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 05N TO 10N BETWEEN 27W AND 34W.

...DISCUSSION...

GULF OF MEXICO...

A BROAD MID TO UPPER LEVEL RIDGE IS CENTERED OVER THE NW GULF
NEAR 29N93W WITH A SURFACE HIGH OF 1017 MB CENTERED NEAR 26N89W.
WEAKENING ISOLATED MODERATE CONVECTION...ASSOCIATED WITH THE
REMNANTS OF A SURFACE TROUGH OVER THE NE GULF COMBINED WITH DEEP
TROPICAL MOISTURE...EXTENDS FROM 27N TO 30N BETWEEN 82W AND 90W.
E TO SE WINDS IF 10 TO 15 KT COVER THE GULF SE OF THE HIGH. W TO
SW WINDS OF AROUND 10 KT ARE NE OF THE HIGH. WEAK TROUGHING IS
FORECAST TO PERSIST ACROSS THE NE GULF WHICH WILL CONTINUE TO
COMBINE WITH DEEP MOISTURE TO SUPPORT CONVECTION ACROSS THE
EASTERN GULF THROUGH SATURDAY.

CARIBBEAN SEA...

A MID TO UPPER LEVEL TROUGH EXTENDS FROM THE WESTERN
ATLC...ACROSS HISPANIOLA...AND TO THE COAST OF CENTRAL AMERICA
NEAR THE NICARAGUA/HONDURAS BORDER. UPPER LEVEL DIFFLUENCE
ASSOCIATED WITH THE TROUGH AXIS SUPPORTS SCATTERED MODERATE
CONVECTION FROM 17N TO 21N BETWEEN 73W AND 76W. OTHER CONVECTION
OVER THE NW CARIBBEAN IS PARTIALLY ASSOCIATED WITH A WESTWARD
MOVING TROPICAL WAVE. PLEASE SEE THE TROPICAL WAVES SECTION FOR
MORE DETAILS. E TO NW TRADE WINDS OF 15 TO 20 KT DOMINATE THE
CARIBBEAN. CONVECTION OVER THE W CARIBBEAN WILL GRADUALLY SHIFT
INLAND OVER MEXICO AND CENTRAL AMERICA THROUGH SATURDAY AS THE
TROPICAL WAVE CONTINUES WESTWARD. ADDITIONAL CONVECTION WILL
REMAIN POSSIBLE OVER THE GREATER ANTILLES AND SURROUNDING
OFFSHORE WATERS UNDER A DIFFLUENT ENVIRONMENT. SSMI TPW
INDICATES DRY AIR SURGING WESTWARD ACROSS THE CENTRAL CARIBBEAN.
THIS WILL KEEP CONVECTION TO A MINIMUM E OF 72W OVER THE NEXT 24
HOURS.

...HISPANIOLA...

DRY AIR IS SPREADING ACROSS THE ISLANDS FROM THE EAST TONIGHT
WITH SOME SAHARAN DUST BEING REPORTED IN SURFACE OBSERVATIONS
OVER THE DOMINICAN REPUBLIC. THE BACK EDGE OF DEEP MOISTURE OVER
W HAITI SUPPORTS MODERATE CONVECTION W OF 73W OVER HAITI...WHICH
SHOULD END OVER THAT PORTION OF THE ISLAND THROUGH THE EARLY
MORNING. THE DRY AIR WILL THEN INHIBIT CONVECTION ACROSS THE
ISLAND THROUGH SUNDAY.

ATLANTIC OCEAN...

A PLUME OF MODERATE TROPICAL MOISTURE OVER THE WESTERN ATLC
BETWEEN A 1022 MB HIGH CENTERED NEAR 28N65W AND A STATIONARY
FRONT N OF OUR AREA OF DISCUSSION SUPPORTS ISOLATED MODERATE
CONVECTION AND THUNDERSTORMS FROM 27N TO 31N BETWEEN 64W AND
80W. A SURFACE TROUGH EXTENDS FROM 27N55W TO 22N59W...AS A
REFLECTION OF AN UPPER LOW NEAR 23N63W. ISOLATED SHOWERS AND
THUNDERSTORMS ARE FROM 23N TO 29N BETWEEN 50W AND 63W. A 1025 MB
HIGH CENTERED NEAR 33N28W DOMINATES THE SUBTROPICAL ATLC E OF
48W. TWO TROPICAL WAVES ARE OVER THE TROPICAL NORTHERN ATLC.
PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. A 1011
MB LOW IS OVER THE CENTRAL TROPICAL ATLC NEAR 11N41W. SCATTERED
MODERATE CONVECTION IS FROM 04N TO 13N BETWEEN 38W AND 44W.
CONVECTION WILL CONTINUE S OF THE STATIONARY FRONT OVER
THE WESTERN ATLC THROUGH SUNDAY.

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

$$
LATTO
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