[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 042349
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI OCT 04 2013

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 STORM KAREN IS CENTERED 25.9N 90.3W AT 04/2100 UTC OR
ABOUT ABOUT 205 NM S-SW OF THE MOUTH OF THE MISSISSIPPI RIVER
AND ABOUT 235 NM S-SE OF MORGAN CITY LOUISIANA WITH THE PRESENT
MOVEMENT NEAR STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS
1002 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55
KT. PLEASE SEE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MAITCPAT2/WTNT32 KNHC AND THE NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 25N-27N
BETWEEN 87W-90W. CLUSTERS OF SCATTERED TO HEAVY SHOWERS WITH
EMBEDDED ISOLATED THUNDERSTORMS ARE OVER THE E GULF AND THE
YUCATAN CHANNEL FROM 21N-29N BETWEEN 84W-89W INCLUDING PORTIONS
OF W CUBA AND NW YUCATAN PENINSULA.

...TROPICAL WAVES...
A TROPICAL WAVE WAS ADDED TO THE 04/1800 UTC ANALYSIS FROM
15N18W TO 5N18W MOVING W 5-10 KT. BASED ON THE UPPER AIR
SOUNDING FROM BAMAKO MALI AND DAKAR SENEGAL THIS WAVE MOVED OFF
THE COAST OF AFRICA LAST NIGHT. WAVE IS WELL DEFINED AT LOW
LEVELS IN THE SATELLITE DERIVED WINDS AS WELL AS THE GLOBAL
MODELS AT THE MID AND UPPER LEVELS. WAVE IS EMBEDDED WITHIN A
NEW SURGE OF DEEP MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE
WATER IMAGERY. HOWEVER...THERE IS NO ASSOCIATED CONVECTION.

TROPICAL WAVE EXTENDS FROM 18N47W TO 11N49W MOVING W5-10 KT.
WAVE IS EMBEDDED WITHIN A SURGE OF DEEP MOISTURE AS DEPICTED ON
THE TOTAL PRECIPITABLE WATER IMAGERY. NO ASSOCIATED CONVECTION.

TROPICAL WAVE EXTENDS FROM 19N55W THROUGH A 1011 MB LOW NEAR
14N57W TO 12N57W MOVING W 5-10 KT. WAVE IS EMBEDDED WITHIN A
BROAD AREA OF DEEP MOISTURE THAT COVERS THE CARIBBEAN ACROSS THE
LESSER ANTILLES INTO THE W TROPICAL ATLC AS DEPICTED ON THE
TOTAL PRECIPITABLE WATER IMAGERY. A BROAD UPPER E/W RIDGE
ANCHORED NEAR 12N48W IS PROVIDING DIFFLUENCE ALOFT TO GENERATE
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 9N-17N
BETWEEN 52W-62W ENCOMPASSING THIS WAVE.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC
NEAR 11N14W ALONG 8N22W TO 7N29W WHERE THE ITCZ BEGINS AND
CONTINUES ALONG 5N34W 6N47W TO 9N56W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE ITCZ TO 10N
BETWEEN 40W-49W. SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS ARE INLAND AND WITHIN 60 NM ALONG THE COAST OF W
AFRICA FROM LIBERIA TO GUINEA BISSAU.

...DISCUSSION...

GULF OF MEXICO...
THE PRIMARY CONCERN THIS EVENING CONTINUES TO BE TROPICAL STORM
KAREN MOVING THROUGH THE CENTRAL GULF. SEE SPECIAL FEATURES
ABOVE. BROAD UPPER RIDGE ASSOCIATED WITH TROPICAL STORM KAREN
COVERS MOST OF THE GULF AND IS ANCHORED NEAR 21N91W. THE WEAK
SURFACE RIDGE IS GIVING WAY WITH THE APPROACH OF KAREN. THE
WATER VAPOR SATELLITE IMAGERY SHOWS THE NW GULF DOMINATED BY DRY
STABLE AIR ALOFT. HOWEVER...VISIBLE SATELLITE IMAGERY AND MOSAIC
RADAR SHOWS LOW LEVEL FEEDER BANDS OF KAREN PRODUCING ISOLATED
SHOWERS N OF 24N BETWEEN 89W-95W. TROPICAL STORM KAREN WILL BE
CLOSE TO THE MISSISSIPPI DELTA LATE SAT/EARLY SUN THEN WILL MOVE
INLAND OVER THE W FLORIDA PANHANDLE LATER SUN. A COLD FRONT WILL
MOVE OFF SE TEXAS COAST SUN REACHING FROM THE FLORIDA PANHANDLE
TO W BAY OF CAMPECHE LATE MON BEFORE BECOMING DIFFUSE TUE. HIGH
PRESSURE WILL FOLLOW BEHIND THE FRONT WED.

CARIBBEAN SEA...
TROPICAL STORM KAREN IS STILL PRODUCING SHOWERS/THUNDERSTORM
ACTIVITY OVER THE YUCATAN CHANNEL. SEE SPECIAL FEATURES ABOVE.
THE UPPER RIDGE ASSOCIATED WITH KAREN COVERS THE W CARIBBEAN W
OF 73W AND IS PROVIDING DIFFLUENCE ALOFT TO ENHANCE AFTERNOON
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND AND WITHIN 60/75
NM ALONG THE S COAST OF CUBA. AN UPPER TROUGH OVER THE W ATLC
DIPS S OVER THE N/CENTRAL CARIBBEAN N OF 16N BETWEEN THE VIRGIN
ISLANDS AND HAITI GENERATING SCATTERED TO HEAVY SHOWERS WITH
EMBEDDED THUNDERSTORMS N OF 17N BETWEEN PUERTO RICO AND HAITI
INCLUDING THE MONA PASSAGE. A BROAD E/W UPPER RIDGE OVER THE
TROPICAL ATLC COVERS THE REMAINDER OF THE E CARIBBEAN PROVIDING
DIFFLUENCE ALOFT TO GENERATE ISOLATED SHOWERS/THUNDERSTORMS S OF
16N BETWEEN 69W-78W AND S OF 17N E OF 69W TO OVER THE LESSER
ANTILLES. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N75W
TO ACROSS COSTA RICA NEAR 11N84W GENERATING SCATTERED SHOWERS
AND POSSIBLE ISOLATED THUNDERSTORMS S OF 11N W OF 80W. SURFACE
RIDGE OVER THE W ATLC WILL MAINTAIN MOSTLY GENTLE TO MODERATE
TRADE WINDS ACROSS ENTIRE BASIN THROUGH WED.

HISPANIOLA...
AN UPPER TROUGH OVER THE W ATLC DIPS S ACROSS HISPANIOLA
GENERATING SCATTERED TO HEAVY SHOWERS WITH EMBEDDED
THUNDERSTORMS OVER THE ISLAND INCLUDING THE MONA PASSAGE.  THIS
UPPER TROUGH WILL PERSIST THROUGH MID WEEK PROVIDING INSTABILITY
AND COUPLE WITH THE PERSISTENCE OF LOW LEVEL MOISTURE BROUGHT IN
BY THE EASTERLY TRADE WINDS THEN COUPLED WITH PEAK DAYTIME
HEATING COULD GENERATE DAILY AFTERNOON SCATTERED SHOWERS AND
THUNDERSTORMS.

ATLANTIC OCEAN...
THE UPPER RIDGE ASSOCIATED WITH TROPICAL STORM KAREN COVERS THE
W ATLC W OF 73W. A CUT-OFF UPPER LOW IS TO THE E CENTERED NEAR
26N66W COVERING THE AREA S OF 30N TO OVER THE N/CENTRAL
CARIBBEAN BETWEEN 60W-72W GENERATING SCATTERED TO HEAVY SHOWERS
WITH EMBEDDED THUNDERSTORMS S OF 20N BETWEEN 65-71W AND CLUSTERS
OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 20N-28N BETWEEN
62W-66W. A WEAK SURFACE RIDGE COVERS THE W ATLC TO OVER THE FAR
THE NE GULF OF MEXICO ANCHORED BY A PAIR 1021 MB HIGHS N OF THE
DISCUSSION AREA BETWEEN BERMUDA AND NORTH CAROLINA. A WEAK
SURFACE TROUGH IS NE OF THE LEEWARD ISLANDS EXTENDING FROM
25N49W THROUGH A WEAK 1015 MB LOW NEAR 21N52W TO 20N53W WITH
POSSIBLE ISOLATED SHOWERS WITHIN 30 NM OF LINE FROM 22N46W TO
23N51W. A SHORTWAVE UPPER TROUGH IS IN THE E/CENTRAL ATLC ALONG
40W SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 27N38W TO
21N41W GENERATING ISOLATED SHOWERS WITHIN 250 NM E OF THE
SURFACE TROUGH. A WEAK SURFACE RIDGE COVERS THE E ATLC ANCHORED
BY A 1020 MB HIGH NEAR 32N26W. W ATLC SURFACE RIDGE WILL PERSIST
THROUGH SAT. SOUTHERLY SURFACE FLOW OFF NE FLORIDA WILL INCREASE
SUN AND MON AS KAREN PASSES ACROSS THE SE CONUS AHEAD OF A COLD
FRONT THAT WILL WEAKEN AS IT MOVES OFF THE NE FLORIDA COAST WED.

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

$$
PAW


This weather bulletin was brought to you by:
www.nashvilleweather.net