[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120001
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU SEP 11 2014

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
2345 UTC.

...SPECIAL FEATURES...

AS OF 2100 UTC...THE CENTER OF TROPICAL DEPRESSION SIX IS
LOCATED AT 17N38W. MAXIMUM SUSTAINED WINDS ARE NEAR 30 KT...WITH
HIGHER GUSTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB
AND IT IS MOVING NW AT AROUND 13 KT. THIS SYSTEM IS SLOWLY
BECOMING ORGANIZED...WITH INCREASING CONVECTION BANDING IN THE
NORTHWESTERN SEMICIRCLE. SCATTERED TO NUMEROUS MODERATE
CONVECTION IS NW OF THE CENTER FROM 17N-20N BETWEEN 38W-41W.
OUTER BANDS WITH ISOLATED MODERATE CONVECTION IS OCCURRING
BETWEEN 150NM AND 300NM OF THE CENTER OF THE DEPRESSION. MORE
STRENGTHENING IS EXPECTED DURING THE NEXT 48 HOURS...THEREFORE
THE SYSTEM COULD BECOME A TROPICAL STORM LATER TONIGHT. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 FOR MORE DETAILS.

...TROPICAL WAVES...

A NEW TROPICAL WAVE HAS COME OUT OF AFRICA. ITS AXIS EXTENDS
FROM 14N20W TO 05N20W. SCATTERED MODERATE CONVECTION IS FROM 08N-
13N BETWEEN 21W-24W. SSMI TPW IMAGERY SHOWS A HIGH AMOUNT OF
MOISTURE IN THE ENVIRONMENT OF THIS WAVE.

A TROPICAL WAVE IS MOVING ACROSS THE LESSER ANTILLES WITH AXIS
EXTENDING FROM 20N62W TO 10N63W...MOVING W AT 15 KT. DESPITE THE
FACT THAT NO SIGNIFICANT CONVECTION IS RELATED TO THIS WAVE DUE
TO A HIGH CONCENTRATION OF DUST AND A DRY SAHARAN AIRMASS IN THE
AREA...SURFACE OBSERVATIONS ACROSS THE ANTILLES ARE CLEARLY
SHOWING THE WIND SIGNATURE THAT CHARACTERIZES A TROPICAL WAVE.
THE DRY AIRMASS EXTENDS FROM 14N-20N. S OF 14N...ISOLATED
CONVECTION IS PRESENT FROM 58W-63W AFFECTING THE WINDWARD
ISLANDS.

A TROPICAL WAVE IS MOVING ACROSS THE BAY OF CAMPECHE...WITH AXIS
EXTENDING FROM 24N94W TO 14N94W. THIS WAVE IS MOVING AT 10-15
KT. SCATTERED THUNDERSTORMS ARE FROM 18N-25N BETWEEN 90W-97W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 14N17W TO 10N24W TO 12N29W. THE
ITCZ AXIS EXTENDS FROM 11N41W TO THE COAST OF VENEZUELA NEAR
09N61W. OTHER THAN CONVECTION MENTIONED IN THE TROPICAL WAVES
SECTION ABOVE...SCATTERED MODERATE CONVECTION IS ALONG THE
AFRICAN COAST BETWEEN 12N-14N.

...DISCUSSION...

GULF OF MEXICO...

SCATTERED MODERATE CONVECTION PREVAILS ACROSS THE SW GULF WATERS
AS A TROPICAL WAVE REMAINS OVER THE BAY OF CAMPECHE (SEE
TROPICAL WAVES SECTION FOR MORE INFORMATION). THE PROXIMITY OF A
SURFACE LOW OVER THE BAHAMAS IS ENHANCING THE CONVECTION ACROSS
THE FLORIDA PENINSULA AND HENCE...THE EAST GULF WATERS FROM 24N-
28N BETWEEN 82W-84W. AT UPPER LEVELS...AN UPPER-LEVEL LOW
REMAINS OVER THE WESTERN GULF WITH CENTER NEAR 21N96W. AN UPPER
LEVEL HIGH IS LOCATED OVER MISSISSIPPI WITH CENTER NEAR 32N90W.
THESE SYSTEMS ARE INTERACTING WITH AN UPPER-LEVEL LOW ACROSS THE
ATLANTIC TO KEEP A DIFFLUENT FLOW ACROSS THE EASTERN GULF WATERS
ENHANCING CONVECTION. FOR THE NEXT 24 HOURS...THE UPPER LEVEL
HIGH IS EXPECTED TO MOVE ACROSS THE NORTHERN GULF COAST. A LARGE
AREA OF MID TO UPPER LEVEL DRY AIR EXPECTED TO LIMIT CONVECTION
ACROSS THE NORTHERN HALF OF THE GULF ON FRIDAY. UPPER LEVEL
DIFFLUENCE TO THE SOUTH OF THIS HIGH COMBINED WITH DEEP LAYER
MOISTURE WILL HELP SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE S GULF THROUGH FRIDAY. THE SURFACE LOW OVER THE
BAHAMAS IS EXPECTED TO MOVE W ACROSS THE FLORIDA PENINSULA
FRIDAY AND MAY BRING ADDITIONAL MOISTURE/CONVECTION TO THE E
GULF OVER THE WEEKEND.

CARIBBEAN SEA...

A LARGE DRY SAHARAN AIRMASS IS ENTERING THE CARIBBEAN
ACCOMPANIED BY A TROPICAL WAVE (REFER TO THE TROPICAL WAVES
SECTION FOR MORE INFORMATION). UPPER LEVEL WESTERLIES COVER MUCH
OF THE CARIBBEAN ON THE SOUTH SIDE OF A BROAD AREA OF UPPER
LEVEL LOW PRESSURE CENTERED NEAR 22N64W. A WEAK AREA OF UPPER
LEVEL DIFFLUENCE OVER THE YUCATAN PENINSULA AND CENTRAL AMERICA
COMBINED WITH DEEP MOISTURE IS SUPPORTING SCATTERED MODERATE
CONVECTION OVER THIS AREA WHICH COULD MOVE TO THE WESTERN
CARIBBEAN LATER TONIGHT. DIURNAL CONVECTION IS PRESENT ACROSS
CUBA AND HISPANIOLA AND IS MOVING SW TO THE NORTHERN CARIBBEAN
WATERS WHILE WEAKENING QUICKLY. OVER THE NEXT 24 HOURS...THE
AREA OF DIFFLUENCE OVER THE YUCATAN WILL WEAKEN AND SHIFT W.
WITH THIS...CONVECTION ACROSS THE NW CARIBBEAN WILL BE LIMITED
IN COVERAGE AND INTENSITY. THE TROPICAL WAVE THAT IS ENTERING
THE E CARIBBEAN COULD BRING SOME ISOLATED CONVECTION TO THIS
PORTION OF THE BASIN...WHICH WILL BE LIMITED BY THE DRY SAHARAN
AIRMASS.

...HISPANIOLA...

DIURNAL CONVECTION CONTINUES ACROSS THE ISLAND AND WEAKENING
QUICKLY THROUGH THE EVENING. AT UPPER LEVELS...AN UPPER-LEVEL
LOW CENTERED OVER THE ATLANTIC IS KEEPING A NORTHERLY FLOW
ACROSS THE ISLAND. OVER THE NEXT 24 HOURS...A TROPICAL WAVE WILL
APPROACH THE ISLAND AND WITH THE ONGOING INFLUENCE FROM THE
UPPER LOW...SCATTERED CONVECTION COULD BE EXPECTED.

ATLANTIC OCEAN...

ASIDE FROM THE CONVECTION GENERATED AROUND THE TROPICAL WAVE SW
OF THE CAPE VERDE ISLANDS AND THE TROPICAL DEPRESSION SIX...AN
UPPER-LEVEL LOW IS SUPPORTING SCATTERED MODERATE CONVECTION FROM
23N-32N BETWEEN 57W-67W. A 1014 MB SURFACE LOW IS LOCATED NEAR
27N78W AND DRIFTING SW. A SURFACE TROUGH EXTENDS FROM 30N77W TO
25N79W THROUGH THE CENTER OF THE LOW. SCATTERED MODERATE
CONVECTION IS FROM 25N-28N BETWEEN 74W AND THE FL E COAST NEAR
80W. THIS LOW IS EXPECTED TO CONTINUE SLOWLY WESTWARD ACROSS
SOUTHERN FL OVER THE NEXT 48 HOURS. FOR MORE INFORMATION ABOUT
TROPICAL DEPRESSION SIX...PLEASE REFER TO THE SPECIAL FEATURES
SECTION.


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

$$
RIVERA


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