[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED AUG 19 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
0545 UTC.

...SPECIAL FEATURES...

TROPICAL STORM DANNY IS LOCATED NEAR 11.2N 38.8W AT 0300
UTC...MOVING W-NW AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
IS 1000 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO
55 KT. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 04N TO
13N BETWEEN 34W AND 47W. SOME ADDITIONAL STRENGTHENING IS
FORECAST DURING THE NEXT 48 HOURS AND DANNY IS EXPECTED TO
BECOME A HURRICANE BY THURSDAY. PLEASE SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS TCMAT4/WTNT24 KNHC FOR
MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS EAST OF THE CAPE VERDE ISLANDS WITH AXIS NEAR
20W...MOVING W AT 5-10 KT OVER THE PAST 18 HOURS. CIRA LAYER
PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS WITHIN A MODERATE
MOIST ENVIRONMENT EXTENDING FROM THE SURFACE TO 700 MB.
HOWEVER...METEOSAT ENHANCED IMAGERY SHOW SAHARAN DRY AIR AND
DUST IN THE WAVE ENVIRONMENT...WHICH IS KEEPING A WAVE DEVOID OF
CONVECTION.

A TROPICAL WAVE IS WITHIN 370 NM E-SE OF THE LESSER ANTILLES
WITH AXIS NEAR 55W...MOVING W AT 10-15 KT OVER THE PAST 24
HOURS. CIRA LAYER PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS
WITHIN A MODERATE MOIST ENVIRONMENT EXTENDING FROM THE SURFACE
TO 850 MB THAT ENHANCES SCATTERED MODERATE CONVECTION AND
ISOLATED TSTMS FROM 08N TO 12N BETWEEN 53W AND 58W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 20N16W TO E OF THE TROPICAL WAVE NEAR 17N18W THEN
RESUMES W OF THE TROPICAL WAVE NEAR 13N21W TO E OF T.S. DANNY
NEAR 12N33W. THE ITCZ BEGINS W OF T.S. DANNY NEAR 10N43W TO E OF
THE WESTERNMOST TROPICAL WAVE NEAR 08N54W. ASIDE THE CONVECTION
ASSOCIATED WITH DANNY AND THE TROPICAL WAVES...SCATTERED MODERATE
CONVECTION IS FROM 07N TO 14N BETWEEN 23W AND 33W.

...DISCUSSION...

GULF OF MEXICO...

A BROAD MIDDLE TO UPPER LEVEL RIDGE CONTINUE OVER THE GULF
ANCHORED NEAR 26N87W...WHICH IS SUPPORTING AN OVERALL STABLE
ENVIRONMENT ACROSS THE BASIN. BROAD SURFACE HIGH PRESSURE ACROSS
THE ATLC EXTENDS A RIDGE AXIS W-SW ACROSS THE FLORIDA PENINSULA
TO THE SW GULF...THUS PROVIDING SE WIND FLOW OF LESS THAN 15 KT
BASIN-WIDE. SURFACE RIDGING OVER THE GULF IS BEING ANCHORED BY A
1017 MB HIGH NEAR 29N83W. A WEAKNESS IN THE RIDGE IS BEING
ANALYZED AS A SURFACE TROUGH FROM JACKSONVILLE COASTAL WATERS SW
ACROSS SOUTHERN FLORIDA TO THE KEYS...WHICH ALONG WITH MOISTURE
INFLOW ACROSS THE BASIN FROM THE CARIBBEAN SEA SUPPORT ISOLATED
SHOWERS AND TSTMS S OF 28N E OF 83W. SURFACE RIDGE WILL EXTEND
ACROSS THE N GULF THROUGH THU.

CARIBBEAN SEA...

AN UPPER LOW COVERS THE CARIBBEAN W OF 74W GENERATING A
DIFFLUENT ENVIRONMENT OVER THE FAR NW BASIN...WHICH ALONG WITH
SHALLOW MOISTURE SUPPORT SHOWERS AND THUNDERSTORMS N OF 21N
BETWEEN 81W AND 83W...INCLUDING WESTERN CUBA. SIMILAR CONVECTION
IS OBSERVED WITHIN 60 NM OFF THE COASTS OF COSTA RICA AND
NORTHERN PANAMA. DRY AIR AND STRONG DEEP LAYER WIND SHEAR HINDER
CONVECTION ELSEWHERE ACROSS THE CARIBBEAN. 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...

EXCEPT FOR HAITI AND THE WINDWARD PASSAGE WHERE MODERATE SHALLOW
MOISTURE IS OBSERVED IN CIRA LAYER PRECIPITABLE WATER
IMAGERY...DEEP LAYER DRY AIR IS OVER THE ISLAND SUPPORTING FAIR
WEATHER. CLOUDINESS AND POSSIBLE ISOLATED SHOWERS ARE MAINLY
OFF THE WESTERN COAST OF HAITI. THERE WILL BE A MOISTURE
INCREASE THU NIGHT AS A TROPICAL WAVE MOVES ACROSS THE ISLAND
WITH SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS.

ATLANTIC OCEAN...

THE MAIN FEATURE IN THE BASIN IS TROPICAL STORM DANNY WHICH IS
FORECAST TO STRENGTHEN INTO A HURRICANE DURING THE NEXT COUPLE
OF DAYS. SEE SPECIAL FEATURES FOR MORE DETAILS. THE SECOND
FEATURE OF INTEREST ARE TWO TROPICAL WAVES DISCUSSED IN THE WAVES
SECTION. OTHERWISE...THE ATLC IS DOMINATED BY A SURFACE RIDGE
ANCHORED BY A 1025 MB HIGH OVER THE AZORES AND A WEAK 1021 MB
HIGH NEAR 29N48W. 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

$$
NR
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