[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301727
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED SEP 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

JOAQUIN BECAME A HURRICANE THIS MORNING...CURRENTLY CENTERED
NEAR 24.7N 72.6W AS OF 30/1500 UTC OR ABOUT 185 NM ENE OF THE
CENTRAL BAHAMAS...MOVING WSW AT 5 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 988 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH
GUSTS UP TO 85 KT. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION
IS FROM 20N-27N BETWEEN 68W-77W. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS.

A LARGE AREA OF CLOUDINESS CONTINUES OVER THE CENTRAL ATLANTIC
ASSOCIATED WITH A 1009 MB SURFACE LOW...REMNANTS OF
IDA...CENTERED NEAR 25N57W AND ITS ASSOCIATED SURFACE TROUGH
EXTENDING FROM 26N62W TO 24N52W. THIS SYSTEM HAS BECOME A BETTER
ORGANIZED SINCE YESTERDAY AND ADDITIONAL DEVELOPMENT IS EXPECTED
DURING THE NEXT SEVERAL DAYS WHILE IT MOVES NW. SCATTERED
MODERATE CONVECTION IS OBSERVED FROM 24N-30N BETWEEN 50W-65W.
THE CHANCE OF FORMATION OVER THE NEXT 48 HOURS IS MEDIUM.

...TROPICAL WAVES...

A TROPICAL WAVE IS NEAR THE CAPE VERDE ISLANDS WITH AN AXIS
EXTENDING FROM 19N22W TO 12N24W...MOVING W AT 5-10 KT. AN
INVERTED V PATTERN IS NOTICED IN VISIBLE IMAGERY. TPW IMAGERY
SHOWS THE WAVE EMBEDDED IN A MODERATE TO HIGH MOIST ENVIRONMENT
THAT ALONG WITH MID TO UPPER-LEVEL DIFFLUENCE IN THE WAVE REGION
SUPPORTS SCATTERED MODERATE CONVECTION FROM 06N-18N AND E OF 31W.

A TROPICAL WAVE IS IN THE CENTRAL ATLANTIC WITH AN AXIS
EXTENDING FROM 18N36W TO 11N40W...MOVING W AT 5 KT. THE INVERTED
V PATTERN IS ALSO NOTICED WITH THIS WAVE IN VISIBLE IMAGERY. TPW
IMAGERY SHOWS THE WAVE EMBEDDED IN A MODERATE MOIST ENVIRONMENT.
HOWEVER...DRY AIR INTRUSION IS ALSO DEPICTED IN THE WAVE
ENVIRONMENT LIMITING THE CONVECTION TO THE SOUTHERN PORTION OF
THE WAVE CLOSE TO THE MONSOON TROUGH S OF 12N.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF AFRICA NEAR 14N17W
TO 10N47W. FOR CONVECTION INFORMATION...PLEASE SEE THE TROPICAL
WAVES SECTION.

...DISCUSSION...

GULF OF MEXICO...

UPPER-LEVEL SW FLOW CONTINUES TO DOMINATE THE GULF WATERS
BETWEEN AN UPPER-LEVEL TROUGH EXTENDING FROM OVER THE MID-
MISSISSIPPI RIVER VALLEY SW TO A BASE OVER NE MEXICO AND AN
ELONGATED UPPER-LEVEL RIDGE ANCHORED OVER THE YUCATAN CHANNEL.
AT THE SURFACE...A 1008 MB SURFACE LOW IS LOCATED NEAR 26N93W. A
SURFACE TROUGH EXTENDS FROM THE LOW TO 31N85W. ISOLATED
CONVECTION IS OBSERVED IN THE VICINITY OF THE TROUGH. A WEAK
1011 MB SURFACE HIGH IS NEAR 22N92W. UPPER-LEVEL DIFFLUENCE IS
SUPPORTING CLUSTERS OF MODERATE CONVECTION OVER THE SE GULF FROM
23N-25N BETWEEN 82W-86W. LOOKING AHEAD...A COLD FRONT IS
FORECAST TO MOVE ACROSS THE GULF BY THURSDAY/FRIDAY INTRODUCING
MODERATE TO FRESH N-NE WINDS ACROSS THE NORTHERN PORTION OF THE
BASIN.

CARIBBEAN SEA...

UPPER-LEVEL NE FLOW PREVAILS OVER MUCH OF THE CENTRAL AND
WESTERN CARIBBEAN PROVIDING OVERALL STABLE CONDITIONS AND FAIR
WEATHER ACROSS MOST OF THE BASIN. THE ONLY AREA WITH ISOLATED
CONVECTION IS THE S-CENTRAL PORTION...WHERE THE PROXIMITY OF THE
MONSOON TROUGH IS ENHANCING THIS CONVECTION MAINLY S OF 10N
BETWEEN 77W-82W. CLOUDINESS AND SCATTERED CONVECTION PREVAILS
OVER HISPANIOLA SUPPORTED BY THE OUTER RAIN BANDS OF HURRICANE
JOAQUIN CURRENTLY IN THE SW ATLANTIC. SCATTEROMETER DATA DEPICTS
MODERATE TO FRESH TRADES ACROSS THE BASIN WITH THE STRONGEST
WINDS NOTED ACROSS S-CENTRAL PORTION.

...HISPANIOLA...

THE OUTER RAINBANDS OF HURRICANE JOAQUIN SUPPORT CLOUDINESS
ACROSS THE ISLAND WITH POSSIBLE ISOLATED CONVECTION EXPECTED
ACROSS THE NORTHERN HALF OF THE ISLAND. SIMILAR ACTIVITY IS
EXPECTED TO CONTINUE THROUGH THE NEXT 24 HOURS AS JOAQUIN MOVES
WSW TOWARDS THE BAHAMAS BEFORE TAKING A NORTHWARD TURN ON FRIDAY.

ATLANTIC OCEAN...

THE MAIN FEATURE OVER THE ATLANTIC IS HURRICANE JOAQUIN...PLEASE
SEE SPECIAL FEATURES SECTION ABOVE FOR DETAILS. TO THE E OF
JOAQUIN...A 1009 MB LOW...REMNANTS OF IDA...IS TRYING TO BECOME
ORGANIZED ACROSS THE NW ATLANTIC. PLEASE REFER TO THE SPECIAL
FEATURES SECTION FOR MORE DETAILS. A STATIONARY FRONT PREVAILS
ACROSS THE CENTRAL AND E ATLANTIC EXTENDING FROM 25N48W TO
23N43W TO 28N31W...THEN BECOMING A COLD FRONT TO 31N21W.
ISOLATED MODERATE CONVECTION IS OBSERVED ALONG THESE FRONTAL
BOUNDARIES. A SURFACE RIDGE IS ACROSS THE E ATLANTIC ANCHORED BY
A 1017 SURFACE HIGH LOCATED NEAR 31N13W.

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

$$

ERA
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