[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201806
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED NOV 20 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...
TROPICAL STORM MELISSA IS CENTERED NEAR 35.6N 47.7W AT 20/1500
UTC OR ABOUT 1004 NM W OF THE AZORES. MELISSA IS MOVING E-NE AT
25 KT AND HAS AN ESTIMATED MINIMUM CENTRAL PRESSURE OF 988 MB.
MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT.
NUMEROUS MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 36N-39N
BETWEEN 47W-50W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM
34N-40N BETWEEN 46W-50W. PLEASE SEE LATEST PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT4/ WTNT34 KNHC AND THE FULL FORECAST
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE EAST TROPICAL
ATLC NEAR 07N13W AND CONTINUES TO 06N17W WHERE THE ITCZ BEGINS
AND CONTINUES ALONG 05N27W TO 04N40W. CLUSTERS OF
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 04N-08N E OF 20W.
SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 03N-11N E OF
20W...FROM 01N-09N BETWEEN 20W-30W AS WELL AS FROM 0N-09N
BETWEEN 30W-43W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER-LEVEL TROUGH OVER THE NW ATLC N OF THE DISCUSSION
AREA DRAPES A COLD FRONT FROM THE W ATLC SW TO THE EASTERN-
CENTRAL COAST OF FLORIDA NEAR 27N79W. FROM THERE THE FRONT
TRANSITIONS INTO A STATIONARY FRONT ALONG 26N82W TO THE CENTRAL
GULF NEAR 25N90W TO THE EASTERN-CENTRAL COAST OF TEXAS NEAR
27N96W. RADAR IMAGERY SHOW SHOWERS AND TSTMS ON THE NW GULF
WITHIN 100 NM N OF THE FRONTAL BOUNDARY BETWEEN 92W-97W. IN THE
EASTERN GULF...SCATTERED SHOWERS AND ISOLATED TSTMS ARE N OF 25N
E OF 86W. OVER THE SW GULF...A SURFACE TROUGH EXTENDS FROM
22N94W TO SOUTHERN MEXICO NEAR 15N92W ENHANCING ISOLATED SHOWERS
S OF 20N E OF 95W. OTHERWISE...E-SE WIND FLOW IN THE RANGE OF 10-
15 KT DOMINATES ACROSS THE BASIN WHILE A BROAD UPPER RIDGE
EXTENDING FROM OVER CENTRAL AMERICA INTO THE W ATLC PROVIDES
WESTERLY FLOW ALOFT. THE STATIONARY FRONTAL BOUNDARY IS EXPECTED
TO DISSIPATE WITHIN 24 HOURS WHILE A SURFACE RIDGE OVERTAKE THE
GULF WATERS ANCHORED BY A HIGH PRESSURE CENTER N OF THE
DISCUSSION AREA.

CARIBBEAN SEA...
A MIDDLE TO UPPER LEVEL RIDGE CENTERED NEAR JAMAICA COVERS THE
WESTERN CARIBBEAN WITH DRY AIR SUBSIDENCE TO SUPPORT FAIR
WEATHER. A WEAKNESS IN THE RIDGE NE PERIPHERY SUPPORTS A SURFACE
TROUGH ACROSS THE EASTERN DOMINICAN REPUBLIC SW TO 13N75W.
ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH
AXIS. ANOTHER SURFACE TROUGH EXTENDS FROM EASTERN HONDURAS TO
NORTHERN COSTA RICA GENERATING ISOLATED SHOWERS S OF 16N W OF
82W. A BROAD UPPER-LEVEL TROUGH EXTENDS OVER THE CENTRAL ATLC SW
TO THE EASTERN CARIBBEAN...HOWEVER EXCEPT FOR THE WINDWARD
ISLANDS...DRY AIR SUBSIDENCE IS INHIBITING CONVECTIVE ACTIVITY.
GENTLE TO MODERATE TRADE WINDS WILL PREVAIL ACROSS MOST OF THE
REGION THROUGH SAT.

...HISPANIOLA...
A WEAKNESS IN THE NE PERIPHERY OF AN UPPER-LEVEL RIDGE CENTERED
OVER THE WESTERN CARIBBEAN SUPPORTS A SURFACE TROUGH ACROSS THE
EASTERN DOMINICAN REPUBLIC SW TO 13N75W. ISOLATED SHOWERS ARE
WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS. NE TO E SURFACE
FLOW IS FORECAST TO BRING IN MILD TEMPERATURES AND LIGHT RAINS
TO THE ISLAND FOR THE NEXT FEW DAYS.

ATLANTIC OCEAN...
A BROAD UPPER-LEVEL TROUGH OVER THE NW ATLC N OF THE DISCUSSION
AREA DRAPES A COLD FRONT FROM THE W ATLC SW TO 30N61W TO THE
EASTERN-CENTRAL COAST OF FLORIDA NEAR 27N79W. A PRE-FRONTAL
TROUGH EXTENDS FROM THE NORTHERN BAHAMAS SW TO THE STRAITS OF
FLORIDA SUPPORTING SHOWERS IN THOSE REGIONS. SCATTERED SHOWERS
AND TSTMS ARE ALSO WITHIN 60 NM N OF THE COLD FRONT W OF 72W. A
1018 MB HIGH IS SE OF THE FRONT NEAR 26N63W...WHICH IS EXPECTED
TO DISSIPATE WITHIN THE NEXT 24 HOURS. AN UPPER-LEVEL TROUGH
COVERS THE CENTRAL ATLC INTO THE E CARIBBEAN. TROPICAL STORM
MELISSA IS BENEATH THIS UPPER TROUGH. AN UPPER RIDGE TO THE E
EXTENDS FROM THE TROPICS TO BEYOND 30N PROVIDING DIFFLUENCE ALOFT
TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 15N
BETWEEN 39W-45W. A SURFACE RIDGE DOMINATES THE E ATLC ANCHORED
BY A 1025 MB HIGH JUST S OF THE AZORES.

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

$$
NR


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