[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION FOUR WAS UPGRADED TO TROPICAL STORM AT
18/2100 UTC. TROPICAL STORM DANNY IS CENTERED NEAR 10.9N37.5W AT
18/2100 UTC OR ABOUT ABOUT 1386 NM E OF THE WINDWARD ISLANDS
MOVING W AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008
MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 9N-13N
BETWEEN 36W-41W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WITHIN 60/75 NM OF LINE FROM 9N37W TO 6N40W. PLEASE SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS TCMAT4/
WTNT24 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE IN THE FAR E TROPICAL ATLC EXTENDS ALONG 19W FROM
11N-9N MOVING W 10-15 KT OVER THE PAST 12 HOURS. THE SURFACE LOW
IS NO LONGER DISCERNIBLE. THE TOTAL PRECIPITABLE WATER IMAGERY
SHOWS THE WAVE IS EMBEDDED WITHIN A SURGE OF DEEP MOISTURE.
HOWEVER THE LAST VISIBLE SATELLITE IMAGERY SHOWS AN INTRUSION
OF DRY AIR N OF 15N. NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE IN THE W TROPICAL ATLC EXTENDS ALONG 54W/55W S OF
13N TO INLAND OVER SOUTH AMERICA MOVING W-SW 10-15 KT. THE TOTAL
PRECIPITABLE WATER IMAGERY SHOWS THE WAVE IS EMBEDDED WITHIN A
LOW AMPLITUDE SURGE OF MODERATE DEEP MOISTURE. CLUSTERS
OF ISOLATED MODERATE CONVECTION ARE FROM 7N-11N BETWEEN 53W-57W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 14N17W TO E OF THE TROPICAL WAVE NEAR 14N18W THEN
RESUMES W OF THE TROPICAL WAVE NEAR 13N20W TO 14N31W. THE ITCZ
BEGINS W OF T.S. DANNY NEAR 12N40W TO THE NEXT TROPICAL WAVE
NEAR 9N53W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN A
60/75 NM RADIUS OF 12.5N30W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 10N-13N BETWEEN 27W-30W. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 10N-13N
BETWEEN 23W-27W AND FROM 8N-10N BETWEEN 41W-49W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE DOMINATES THE GULF THIS EVENING EXTENDING FROM
THE E BAY OF CAMPECHE TO OVER THE SE CONUS NEAR MOBILE ALABAMA.
THIS IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED TO
NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE N GULF N
OF 28N BETWEEN 87W-96W AND ALONG THE IMMEDIATE COASTAL WATERS
FROM S FLORIDA TO THE FLORIDA/ALABAMA LINE. A WEAK SURFACE
TROUGH IS IN THE W GULF EXTENDING ALONG 95W FROM 20N-24N MOVING
RAPIDLY NORTHWARD AND GENERATING SCATTERED TO NUMEROUS SHOWERS
WITH POSSIBLE ISOLATED THUNDERSTORMS FROM 23N-27N BETWEEN 92W-
96W. A WEAK SURFACE RIDGE EXTENDS FROM THE W ATLC ACROSS
CENTRAL FLORIDA TO NE TEXAS. THIS IS LEAVING THE REMAINDER OF
THE GULF UNDER CLEAR SKIES THIS EVENING. SURFACE RIDGE WILL
EXTEND ACROSS THE N GULF THROUGH THU.

CARIBBEAN SEA...
AN UPPER LOW COVERS THE W CARIBBEAN W OF 75W AND CENTERED NEAR
18N78W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
INLAND AND WITHIN 75 NM ALONG THE S AND W COAST OF CUBA...
INLAND AND WITHIN 60 NM ALONG THE N COAST OF JAMAICA...AND S OF
11N E OF 80W TO INLAND OVER PANAMA AND COSTA RICA. WATER VAPOR
SATELLITE IMAGERY SHOWS THE CARIBBEAN E OF 68W UNDER DRY STABLE
AIR ALOFT. HOWEVER THE TRADE WINDS ARE USHERING IN SOME ISOLATED
LOW LEVEL SHOWERS N OF 12N BETWEEN 65W-71W INCLUDING THE MONA
PASSAGE. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN WITH
MOSTLY CLEAR SKIES THIS EVENING. FRESH TO STRONG TRADES WILL
CONTINUE OVER THE S/CENTRAL CARIBBEAN INCREASING TO NEAR GALE
FORCE OFF THE NW COAST OF COLOMBIA ON WED NIGHT. TROPICAL WAVE
WILL ENTER THE E CARIBBEAN WED THEN INTO THE CENTRAL CARIBBEAN
THU.

...HISPANIOLA...
THE TRADE WINDS ARE GENERATING ISOLATED SHOWERS DOTTING THE
ISLAND THIS EVENING. THESE ISOLATED SHOWERS WILL PERSIST THROUGH
THU. THU NIGHT MOISTURE WILL INCREASE AS A TROPICAL WAVE MOVES
ACROSS THE ISLAND. THIS WILL INCREASE THE CHANCE OF SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS.

ATLANTIC OCEAN...
THE UPPER RIDGE OVER THE GULF OF MEXICO EXTENDS ACROSS CENTRAL
FLORIDA TO OVER THE W ATLC W OF 70W. AN UPPER LOW IS OVER THE NW
ATLC N OF THE DISCUSSION AREA. THE DIFFLUENT AREA BETWEEN THESE
UPPER FEATURES IS GENERATING SCATTERED TO NUMEROUS SHOWERS WITH
ISOLATED THUNDERSTORMS N OF 28N BETWEEN 60W-78W. THE ATLC IS
DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH OVER THE
AZORES AND A WEAK 122 MB HIGH NEAR 30N46W AND A SURFACE RIDGE
EXTENDS W THROUGH A 1019 MB HIGH NEAR 29N75W THEN ACROSS CENTRAL
FLORIDA INTO THE GULF OF MEXICO. THE SURFACE RIDGE ACROSS THE W
ATLC WILL SHIFT S AS A WEAK TROUGH PASSES E ACROSS N PORTION OF
THE W ATLC S OF BERMUDA ON WED WITH LOW DEVELOPING NEAR S OF
BERMUDA ON THU NIGHT.

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

$$
PAW
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