Tropical Weather Discussion
Issued by NWS

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000
AXNT20 KNHC 221149
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 22 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
1015 UTC.

...SPECIAL FEATURES...
HURRICANE DANNY IS CENTERED NEAR 15.2N 50.8W AT 22/0900 UTC OR
ABOUT 640 NM E OF THE LEEWARD ISLANDS MOVING WNW AT 9 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB. MAXIMUM SUSTAINED
WIND SPEED IS 85 KT WITH GUSTS TO 105 KT. SCATTERED MODERATE
CONVECTION IS OCCURRING FROM 14N-18N BETWEEN 48W-51W. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24
KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 09N24W TO 18N26W MOVING W AT 10-15
KT. THE WAVE COINCIDES WITH A RELATIVELY BROAD LOW-LEVEL
MONSOONAL GYRE FOCUSED ON A 1009 MB LOW CENTERED ALONG THE
MONSOON TROUGH AND WAVE AXIS NEAR 12N25W. THE GYRE AND
ASSOCIATED WAVE ENERGY IS EXPECTED TO DRIFT WESTWARD THROUGH
SUNDAY. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 13N-17N
BETWEEN 22W-27W...WITH WIDELY SCATTERED MODERATE CONVECTION
ELSEWHERE FROM 05N-13N BETWEEN 18W-30W.

TROPICAL WAVE EXTENDS FROM 10N33W TO 20N40W MOVING W AT 10-15
KT. THIS WAVE IS EMBEDDED WITHIN SAHARAN DUST AND DRY AIR
RESULTING IN MOSTLY STABLE CONDITIONS. THE OVERALL STABILITY
SURROUNDING THE WAVE AXIS IS INHIBITING ANY SIGNIFICANT DEEP
CONVECTION AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 09N80W TO 18N81W MOVING W AT 15-20
KT. THE WAVE IS ENCOUNTERING DRY AND STABLE AIR ALOFT OVER THE
NORTHERN PORTION OF THE AXIS WITH SCATTERED MODERATE CONVECTION
OCCURRING S OF 12N BETWEEN 79W-86W ACROSS THE SOUTHERN EXTENT OF
THE WAVE AXIS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
17N16W INTO A 1009 MB LOW CENTERED NEAR 12N25W TO 08N30W TO
06N41W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVE
ALONG 25W...ISOLATED MODERATE CONVECTION IS FROM 05N-11N BETWEEN
07W-16W...AND FROM 05N-08N BETWEEN 39W-42W.

...DISCUSSION...

GULF OF MEXICO...
GENERALLY EAST-SOUTHEASTERLY FLOW ALOFT INFLUENCES MUCH OF THE
GULF BASIN BETWEEN AN UPPER LEVEL RIDGE ANCHORED OVER NORTHERN
FLORIDA AND THE SW NORTH ATLC NEAR 29N79W AND AN UPPER LEVEL LOW
CENTERED OVER THE SW GULF NEAR 20N92W. ISOLATED SHOWERS AND
TSTMS ARE OCCURRING AROUND THE PERIPHERY OF BOTH UPPER LEVEL
FEATURES WITH NO SIGNIFICANTLY ORGANIZED CONVECTION. LIGHT AND
VARIABLE ANTICYCLONIC WINDS AND 1-3 FT SEAS WILL PERSIST ACROSS
THE NE HALF OF THE GULF...WITH MODERATE TO LOCALLY FRESH SE
RETURN FLOW AND 3-6 FT SEAS ACROSS THE SW HALF OF THE GULF. THE
STRONGEST WINDS ARE EXPECTED NW OF THE YUCATAN PENINSULA DURING
THE EVENING AND OVERNIGHT HOURS AS DIURNAL TROUGHING DEVELOPS
ACROSS THE PENINSULA EACH AFTERNOON. THE TROUGHING WILL THEN
MOVE TO THE WESTERN OFFSHORE WATERS AND INTO THE SW GULF WHERE
IT WILL DISSIPATE BY SUNRISE EACH DAY. THESE CONDITIONS ARE
FORECAST TO PERSIST THROUGH THE NEXT 48 HOURS.

CARIBBEAN SEA...
AN UPPER LEVEL CYCLONE IS CENTERED OVER THE SW GULF OF MEXICO
NEAR 20N92W WHILE AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER
THE SW CARIBBEAN NEAR 13N81W. W OF 74W...ONLY ISOLATED SHOWERS
AND TSTMS ARE OCCURRING AROUND THE PERIPHERY OF BOTH OF THESE
FEATURES WITH THE MOST ACTIVE AREA...SCATTERED SHOWERS AND
TSTMS...NOTED S OF 13N W OF 78W IN ASSOCIATION WITH A TROPICAL
WAVE ALONG 81W. THE CONVECTION INCLUDES INLAND PORTIONS OF COSTA
RICA AND SOUTHERN NICARAGUA. E OF 74W...AN UPPER LEVEL TROUGH
AXIS EXTENDS FROM 19N59W TO 16N71W AND REMAINS EMBEDDED WITHIN
VERY DRY AND STABLE AIR ALOFT. MAINLY MODERATE TO LOCALLY FRESH
TRADES AND 3-6 FT SEAS WILL PREVAIL ACROSS THE BASIN THROUGH THE
WEEKEND...EXCEPT IN THE S CENTRAL CARIBBEAN WHERE THE PRESSURE
GRADIENT WILL BE STRONG ENOUGH TO SUPPORT OCCASIONAL WINDS TO 20-
25 KT WHICH WILL BUILD SEAS TO 7-9 FT.

...HISPANIOLA...
CURRENTLY...SKIES HAVE CLEARED SOMEWHAT FROM LINGERING EARLIER
EVENING AND OVERNIGHT ISOLATED SHOWERS AND TSTMS. MOSTLY CLEAR
SKIES LIE TO THE EAST...HOWEVER SIMILAR DEVELOPMENT OF LATE
AFTERNOON AND EARLY EVENING ISOLATED SHOWERS AND TSTMS IS
POSSIBLE THROUGH THE WEEKEND WITH LITTLE CHANGE IN OVERALL
SYNOPTIC CONDITIONS ANTICIPATED.

ATLANTIC OCEAN...
AN UPPER LEVEL ANTICYCLONE IS CENTERED EAST OF NORTHERN FLORIDA
NEAR 29N79W. AN UPPER LEVEL CYCLONE IS JUST N OF THE DISCUSSION
AREA NEAR 32N66W WITH A TRAILING UPPER LEVEL TROUGH EXTENDING S
TO 25N66W. THE UPPER LEVEL CYCLONE AND TROUGH ARE SUPPORTING A
1011 MB LOW NEAR 27N66W WITH A SURFACE TROUGH EXTENDING FROM
32N64W INTO THE LOW THEN TO 25N70W TO 27N74W. SCATTERED SHOWERS
AND TSTMS ARE OCCURRING N OF 28N BETWEEN 56W-63W TO THE EAST OF
THE BOUNDARY AND FROM 23N-27N BETWEEN 61W-69W SE OF THE
BOUNDARY. LIGHT AND VARIABLE WINDS WILL PERSIST ACROSS THE
ENTIRE SW NORTH ATLC OFFSHORE WATERS BASIN THROUGH THE NEXT 48
HOURS. SEAS OF 3 FT OR LESS ARE EXPECTED W OF 70W...WITH 3-5 FT
SEAS E OF 70W. ANOTHER UPPER LEVEL LOW IS CENTERED NEAR 32N49W
THAT SUPPORTS A SURFACE TROUGH FROM 32N46W TO 30N46W TO 27N49W.
SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 29N-34N BETWEEN
43W-47W.

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

$$
HUFFMAN



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