[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 200604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...

THE CENTER OF SUBTROPICAL STORM MELISSA AT 20/0300 UTC IS NEAR
33.6N 52.4W...ABOUT 1165 KM/630 NM...TO THE EAST OF BERMUDA.
MELISSA IS MOVING NORTHEASTWARD 15 KNOTS. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 988 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 45 KNOTS WITH GUSTS TO 55 KNOTS. PUBLIC ADVISORIES ON
SUBTROPICAL STORM MELISSA ARE ISSUED UNDER WMO HEADER WTNT34
KNHC AND UNDER AWIPS HEADER MIATCPAT4. FORECAST/ADVISORIES ON
SUBTROPICAL STORM MELISSA ARE ISSUED UNDER WMO HEADER WTNT24
KNHC AND UNDER AWIPS HEADER MIATCMAT4. LARGE SWELLS WILL
CONTINUE TO AFFECT BERMUDA...SECTIONS OF THE NORTHERN LEEWARD
ISLANDS...PUERTO RICO...HISPANIOLA...AND THE SOUTHEASTERN
BAHAMAS DURING THE NEXT COUPLE OF DAYS...CAUSING LIFE-
THREATENING SURF AND RIP CURRENTS. PLEASE REFER TO STATEMENTS
FROM YOUR LOCAL WEATHER SERVICE OFFICE FOR MORE DETAILS.
CONVECTIVE PRECIPITATION...SCATTERED STRONG FROM 34N TO 35N
BETWEEN 51W AND 52W. WIDELY SCATTERED MODERATE TO ISOLATED
STRONG FROM 31N TO 34N BETWEEN 51W AND 55W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC...FOR
MORE DETAILS ABOUT THE WINDS AND SEA HEIGHTS THAT ACCOMPANY
SUBTROPICAL STORM MELISSA.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS IN THE ATLANTIC OCEAN
THROUGH 34N52W TO 26N54W AND 20N58W...INTO THE SOUTHEASTERN
CORNER OF THE CARIBBEAN SEA NEAR 13N64W...BEYOND 9N69W IN
VENEZUELA. CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE
WEST OF 32N43W 17N50W 9N60W. UPPER LEVEL SOUTHWESTERLY WIND FLOW
IS STREAMING FROM CENTRAL VENEZUELA...BEYOND 18N54W IN THE
ATLANTIC OCEAN. AN UPPER LEVEL RIDGE IS ALONG 4N51W 16N45W
25N41W BEYOND 32N38W. A SURFACE TROUGH IS ALONG 28N51W 23N54W
19N56W 15N56W. CONVECTIVE PRECIPITATION...SCATTERED STRONG FROM
12N TO 20N BETWEEN 45W AND 50W. SCATTERED MODERATE TO ISOLATED
STRONG ELSEWHERE WITHIN 150 NM ON EITHER SIDE OF THE LINE THAT
PASSES THROUGH 32N43W TO 24N46W TO 8N50W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH PASSES ACROSS COASTAL GUINEA NEAR 8N13W TO
7N15W. THE ITCZ CONTINUES FROM 7N15W TO 5N20W 5N28W 3N34W AND
3N40W. CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS STRONG
WITHIN 60 TO 120 NM ON EITHER SIDE OF 5N10W 5N16W 5N23W 4N30W
6N36W 8N39W. RAINSHOWERS ARE POSSIBLE ELSEWHERE TO THE SOUTH OF
10N TO THE EAST OF 60W.

...DISCUSSION...

THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL RIDGE EXTENDS FROM EL SALVADOR...
THROUGH THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...ACROSS
WESTERN CUBA...SOUTHEASTERN FLORIDA...BEYOND 32N77W IN THE
ATLANTIC OCEAN. MIDDLE LEVEL TO UPPER LEVEL SOUTHWESTERLY TO
WESTERLY WIND FLOW COVERS THE GULF OF MEXICO.

THE BASE OF A MIDDLE LEVEL TO UPPER LEVEL TROUGH REACHES 34N58W
IN THE ATLANTIC OCEAN. THE TROUGH SUPPORTS A COLD FRONT THAT
PASSES THROUGH 32N66W IN THE ATLANTIC OCEAN JUST TO THE WEST OF
BERMUDA...TO 30N70W...TO THE FLORIDA EAST COAST NEAR 28N80W. A
STATIONARY FRONT CONTINUES FROM 28N80W TO 26N86W IN THE EASTERN
GULF OF MEXICO...TO 26N94W AND 26N102W IN MEXICO. BROAD SURFACE
LOW PRESSURE WITH A NORTHWEST-TO-SOUTHEAST ORIENTED TROUGH
COVERS THE AREA FROM THE SOUTHWESTERN CORNER OF THE GULF OF
MEXICO TO THE WEST CENTRAL GULF ALONG THE MEXICO GULF COAST.
MULTILAYERED CLOUDS AND ISOLATED MODERATE CONVECTIVE
PRECIPITATION ARE TO THE NORTH OF 22N98W 23N90W 26N82W. A
SURFACE TROUGH IS ALONG 28N76W 26N79W 24N81W...FROM THE ATLANTIC
OCEAN...ACROSS THE NORTHERN BAHAMAS...TO THE FLORIDA KEYS/
FLORIDA STRAITS.

A SURFACE RIDGE PASSES THROUGH NORTHERN LOUISIANA INTO EAST
TEXAS...THROUGH THE DEEP SOUTH OF TEXAS...BRIDGING THE
STATIONARY FRONT...AND TO 20N97W IN THE COASTAL PLAINS OF
MEXICO.

FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE TO THE NORTH OF 27N
TO THE WEST OF 88W...

LOW CLOUD CEILINGS ARE OBSERVED AT THE FOLLOWING ICAO
STATIONS...KMZG...KBBF...KBQX...KVAF...KEMK...KGUL...KHQI...AND
KGBK. MIDDLE LEVEL CEILINGS ARE BEING OBSERVED AT THE FOLLOWING
ICAO STATIONS KGUL...KEHC...AND KGBK.

LOW CLOUD CEILINGS COVER TEXAS FROM BAY CITY SOUTHWARD TO THE
DEEP SOUTH OF TEXAS. MIDDLE LEVEL CLOUD CEILINGS COVER THE
FLORIDA PANHANDLE IN MARY ESTHER...IN PARTS OF THE PANAMA CITY
AREA...AND IN APALACHICOLA. HIGH LEVEL CLOUD CEILINGS ARE AT THE
NAVAL AIR STATION IN PENSACOLA FLORIDA. LOW CLOUD CEILINGS AND
HIGH CLOUD CEILINGS COVER THE TAMPA METROPOLITAN AREA. LOW CLOUD
CEILINGS ARE IN SARASOTA...PUNTA GORDA...AND CLEARING SOUTHWARD
TO NAPLES AND MARATHON KEY.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC...AND
THE OFFSHORE FORECAST...MIAOFFNT4/FZNT24 KNHC...FOR MORE DETAILS
ABOUT THE STATIONARY FRONT FROM 27N83W TO 27N90W TO 26N97W.
EXPECT NORTHEAST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS LOWER THAN
8 FEET TO THE NORTH OF THE FRONT TO THE WEST OF 90W.

...HISPANIOLA...

LARGE SWELLS FROM SUBTROPICAL STORM MELISSA WILL CONTINUE TO
AFFECT HISPANIOLA...PUERTO RICO...SECTIONS OF THE NORTHERN
LEEWARD ISLANDS...AND THE SOUTHEASTERN BAHAMAS DURING THE NEXT
COUPLE OF DAYS...CAUSING LIFE-THREATENING SURF AND RIP CURRENTS.
PLEASE REFER TO STATEMENTS FROM YOUR LOCAL WEATHER SERVICE
OFFICE FOR MORE DETAILS.

A SURFACE TROUGH IS ALONG 19N73W IN THE WESTERN SECTIONS OF
HAITI...ACROSS SOUTHWESTERN HAITI...TO 17N75W AND TO 15N76W.
CONVECTIVE PRECIPITATION...ISOLATED MODERATE FROM 14N TO 18N
BETWEEN 72W AND 76W.


MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY WIND FLOW IS MOVING
ACROSS HISPANIOLA. THIS WIND FLOW IS RELATED TO THE CYCLONIC
WIND FLOW THAT IS MOVING AROUND THE TROUGH THAT IS PART OF
SUBTROPICAL STORM MELISSA. COMPARATIVELY DRIER AIR...APPARENT IN
WATER VAPOR SATELLITE IMAGERY...ALSO COVERS HISPANIOLA.
SCATTERED TO BROKEN LOW LEVEL AND MIDDLE LEVEL CLOUDS AND
POSSIBLE RAINSHOWERS COVER HISPANIOLA.

CONVECTIVE PRECIPITATION...BROKEN LOW LEVEL TO MIDDLE LEVEL
CLOUDS AND ISOLATED MODERATE TO LOCALLY STRONG FROM 12N TO 18N
BETWEEN 71W AND 80W.

THE GFS FORECAST FOR 250 MB SHOWS THAT NORTHWESTERLY WIND FLOW
WILL PASS ON TOP OF HISPANIOLA DURING THE NEXT 48 HOURS. A
TROUGH WILL CUT ACROSS THE NORTHEASTERN CORNER OF THE CARIBBEAN
SEA TOWARD THE NETHERLANDS ANTILLES FOR THE ENTIRE TIME. THE GFS
FORECAST FOR 500 MB SHOWS THAT NORTHERLY WIND FLOW WILL PASS ON
TOP OF HISPANIOLA FOR THE NEXT 48 HOURS. AN ANTICYCLONIC
CIRCULATION CENTER WILL BE IN THE NORTHWESTERN CORNER OF THE
CARIBBEAN SEA FOR THE ENTIRE TIME. THE GFS FORECAST FOR 700 MB
SHOWS THAT HISPANIOLA WILL START WITH WEAK TO SLIGHTLY
ANTICYCLONIC WIND FLOW FOR THE FIRST 12 TO 18 HOURS. CYCLONIC
WIND FLOW WITH AN INVERTED TROUGH WILL COVER THE AREA FOR MOST
OF THE REST OF THE FORECAST PERIOD...UNTIL THE LAST 6 HOURS OR
SO WHEN ANTICYCLONIC WIND FLOW RETURNS.

THE REST OF THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL RIDGE EXTENDS FROM EL SALVADOR...
THROUGH THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...ACROSS
WESTERN CUBA...SOUTHEASTERN FLORIDA...BEYOND 32N77W IN THE
ATLANTIC OCEAN.

A SURFACE TROUGH IS ALONG 11N77W 12N80W 15N83W NEAR THE
NORTHEASTERN COAST OF NICARAGUA. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE TO ISOLATED STRONG TO THE NORTH OF 16N TO THE
WEST OF 83W.

MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND FLOW COVERS THE AREA
THAT IS TO THE EAST OF 75W. THE CYCLONIC WIND FLOW IS ASSOCIATED
WITH THE WIND FLOW THAT IS MOVING AROUND SUBTROPICAL STORM
MELISSA IN THE ATLANTIC OCEAN. MIDDLE LEVEL TO UPPER LEVEL
ANTICYCLONIC WIND FLOW COVERS THE CARIBBEAN SEA THAT IS TO THE
WEST OF 75W.

THE REST OF THE ATLANTIC OCEAN...

A SURFACE RIDGE PASSES THROUGH A 1028 MB HIGH PRESSURE CENTER
THAT IS NEAR 33N26W...TO 28N34W 23N39W 17N45W AND 10N49W. THIS
RIDGE IS TO THE EAST OF SUBTROPICAL STORM MELISSA.

SURFACE ANTICYCLONIC WIND FLOW MOVES AROUND A 1014 MB HIGH
PRESSURE CENTER THAT IS NEAR 26N70W...BETWEEN THE 28N51W 23N54W
19N56W 15N56W SURFACE TROUGH AND THE 28N76W 26N79W 24N81W
SURFACE TROUGH.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC...FOR
MORE DETAILS ABOUT THE WINDS AND SEA HEIGHTS THAT ACCOMPANY
SUBTROPICAL STORM MELISSA. A SECOND AREA OF INTEREST CONSISTS OF
A COLD FRONT FROM 31N69W TO 28N81W. EXPECT NORTH TO NORTHEAST
WINDS 20 TO 25 KNOTS AND SEA HEIGHTS TO 9 FEET TO THE NORTHWEST
OF THE FRONT.

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

$$
MT


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