[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181143
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0915 UTC.

...TROPICAL WAVES...                                     A
TROPICAL WAVE IS OVER THE EASTERN ATLC WITH AN AXIS EXTENDING
FROM 17N25W TO 09N26W...MOVING W AT AROUND 15 KT. A 1014 MB LOW
IS ALONG THE WAVE NEAR 14N25W. SSMI TPW SHOWS HIGH MOISTURE S OF
12N WITH DRIER AIR N OF 12N. ENHANCED METEOSAT IMAGERY INDICATES
SAHARAN DUST N OF 14N ALONG THE WAVE. SCATTERED MODERATE
CONVECTION IS FROM 06N TO 11N BETWEEN 24W AND 28W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AN AXIS EXTENDING
FROM 20N48W TO 10N49W...MOVING W AT AROUND 20 KT OVER THE PAST
24 HOURS. THIS WAVE IS AT THE LEADING EDGE OF A DEEP LAYER
MOISTURE SURGE WITH HIGH MOISTURE NOTED S OF 14N. ISOLATED
MODERATE CONVECTION IS FROM 10N TO 13N BETWEEN 46W AND 50W.

A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN SEA WITH AN AXIS
EXTENDING FROM 20N83W TO 09N83W...MOVING W AT AROUND 15 KT OVER
THE PAST 24 HOURS. THIS WAVE IS EMBEDDED IN AN ENVIRONMENT OF
MODERATE TO HIGH MOISTURE. SCATTERED MODERATE CONVECTION IS
WITHIN 75 NM OF THE WAVE AXIS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
07N35W. THE ITCZ BEGINS NEAR 09N45W AND CONTINUES TO THE COAST
OF S AMERICA NEAR 06N59W. IN ADDITION TO THE CONVECTION
ASSOCIATED WITH THE E ATLC TROPICAL WAVE...CLUSTERS OF MODERATE
TO STRONG CONVECTION ARE FROM 03N TO 11N BETWEEN 28W AND 35W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD MID TO UPPER LEVEL RIDGE REMAINS CENTERED OVER THE NW
GULF NEAR 29N93W WITH A SURFACE HIGH OF 1017 MB CENTERED NEAR
26N89W. A SURFACE TROUGH EXTENDS OVER THE NE GULF FROM N FL NEAR
30N83W TO 29N88W. SCATTERED THUNDERSTORMS ARE FROM 26N TO 20N
BETWEEN 83W AND 88W. ANOTHER SURFACE TROUGH IS OVER THE SW GULF
FROM 22N92W TO 17N93W. THE COMBINATION OF THIS SURFACE TROUGH
AND UPPER LEVEL DIFFLUENCE BETWEEN THE RIDGE OVER THE NW GULF
AND ANOTHER RIDGE OVER THE E PACIFIC SUPPORTS CLUSTERS OF
THUNDERSTORMS S OF 22N W OF 94W. E TO SE WINDS IF 10 TO 15 KT
COVER THE GULF SE OF THE SURFACE 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
TONIGHT.

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 20N BETWEEN 74W AND 81W. 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 NE TRADE WINDS OF 15 TO 20 KT DOMINATE THE
CARIBBEAN. CONVECTION WILL REMAIN POSSIBLE OVER THE NORTH-
CENTRAL AND NW CARIBBEAN UNDER A DIFFLUENT ENVIRONMENT ALOFT
THROUGH TONIGHT. SSMI TPW INDICATES DRY AIR SURGING WESTWARD
ACROSS THE CENTRAL CARIBBEAN. THIS WILL KEEP CONVECTION TO A
MINIMUM E OF 74W OVER THE NEXT 24 HOURS.

...HISPANIOLA...
DRY AIR IS SPREADING ACROSS THE ISLANDS FROM THE EAST THIS
MORNING WITH SAHARAN DUST BEING REPORTED IN SURFACE OBSERVATIONS
OVER THE DOMINICAN REPUBLIC. THIS DRY AIR WILL INHIBIT
CONVECTION ACROSS THE ISLAND TODAY AND POSSIBLY THROUGH SUNDAY.

ATLANTIC OCEAN...
A PLUME OF MODERATE TROPICAL MOISTURE OVER THE WESTERN ATLC
BETWEEN A 1021 MB HIGH CENTERED NEAR 28N65W AND A STATIONARY
FRONT N OF OUR AREA OF DISCUSSION SUPPORTS SCATTERED MODERATE
CONVECTION AND THUNDERSTORMS FROM 27N TO 31N BETWEEN 66W AND
75W. A SURFACE TROUGH EXTENDS FROM 28N53W TO 22N59W...AS A
REFLECTION OF AN UPPER LOW NEAR 25N57W. ISOLATED SHOWERS AND
THUNDERSTORMS ARE FROM 23N TO 29N BETWEEN 53W AND 64W. A 1023 MB
HIGH CENTERED NEAR 30N34W DOMINATES THE SUBTROPICAL ATLC E OF
50W. TWO TROPICAL WAVES ARE OVER THE TROPICAL NORTHERN ATLC.
PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. A 1012
MB LOW IS OVER THE CENTRAL TROPICAL ATLC NEAR 11N42W. SCATTERED
MODERATE CONVECTION IS FROM 03N TO 13N BETWEEN 38W AND 45W.
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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