[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211204
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU NOV 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURE...

THE CENTER OF TROPICAL STORM MELISSA AT 21/0900 UTC IS NEAR
39.1N 38.5W...ABOUT 1005 KM/545 NM...TO THE WEST OF THE AZORES.
MELISSA IS MOVING EAST-NORTHEASTWARD 28 KNOTS. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 984 MB. THE MAXIMUM SUSTAINED WIND
SPEEDS ARE 45 KNOTS WITH GUSTS TO 55 KNOTS. PUBLIC ADVISORIES ON
TROPICAL STORM MELISSA ARE ISSUED UNDER WMO HEADER WTNT34 KNHC
AND UNDER AWIPS HEADER MIATCPAT4. FORECAST/ADVISORIES ON
TROPICAL STORM MELISSA ARE ISSUED UNDER WMO HEADER WTNT24 KNHC
AND UNDER AWIPS HEADER MIATCMAT4. GALE-FORCE WINDS ARE EXPECTED
TO AFFECT THE WESTERN AND CENTRAL AZORES BEGINNING LATE TODAY OR
TONIGHT. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO
ISOLATED STRONG FROM 37N TO 43N BETWEEN 35W AND 43W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT1/FZNT01 KWBC...FOR
MORE DETAILS ABOUT THE WINDS AND SEA HEIGHTS THAT ACCOMPANY
TROPICAL STORM MELISSA.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH CONTINUES IN THE CENTRAL
ATLANTIC OCEAN TO THE SOUTH AND SOUTHWEST OF THE AREA OF
TROPICAL STORM MELISSA. A SURFACE TROUGH IS ALONG 32N46W 27N46W
22N48W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE
RAINSHOWERS ARE WITHIN 180 NM ON EITHER SIDE OF THE LINE THAT
PASSES THROUGH 32N33W 25N40W 18N48W.

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

THE MONSOON TROUGH PASSES ACROSS COASTAL GUINEA NEAR 8N13W TO
7N16W 6N21W. THE ITCZ CONTINUES FROM 6N21W TO 5N27W 5N32W 3N42W
AND 3N49W. A SURFACE TROUGH IS ALONG 5N44W 10N48W. CONVECTIVE
PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM 2N TO 7N
BETWEEN 22W AND 47W. SCATTERED MODERATE TO ISOLATED STRONG FROM
4N TO 6N BETWEEN 9W AND 16W...FROM 9N TO 10N BETWEEN AND 17W...
FROM 6N TO 10N BETWEEN 47W AND 53W.

...DISCUSSION...

THE GULF OF MEXICO...

MIDDLE LEVEL TO UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS THE
GULF OF MEXICO.

A MIDDLE LEVEL TO UPPER LEVEL CENTRAL ATLANTIC/EAST CENTRAL
ATLANTIC OCEAN TROUGH SUPPORTS A COLD FRONT THAT CUTS THROUGH
THE CENTRAL ATLANTIC OCEAN...THROUGH 32N52W TO 29N60W AND
28N65W. THE FRONT BECOMES STATIONARY FROM 28N65W ACROSS THE
NORTHERN BAHAMAS...TO FLORIDA JUST TO THE SOUTH OF LAKE
OKEECHOBEE...TO 25N87W IN THE SOUTHEASTERN GULF OF MEXICO.
CONVECTIVE PRECIPITATION...BROKEN TO OVERCAST MULTILAYERED
CLOUDS AND ISOLATED MODERATE ARE IN THE ATLANTIC OCEAN TO THE
NORTH OF 32N44W 26N60W 25N70W 25N80W...AND IN THE GULF OF MEXICO
TO THE NORTH OF 24N...AND IN THE SOUTHWESTERN CORNER OF THE AREA
WITHIN A 30 NM RADIUS OF 19N93.5W.

A SURFACE RIDGE PASSES THROUGH LOUISIANA INTO CENTRAL TEXAS.

LOW CLOUD CEILINGS AND MIDDLE LEVEL CLOUD CEILINGS COVER THE
TEXAS GULF COASTAL PLAINS...SOUTHERN COASTAL LOUISIANA. LOW
CLOUD CEILINGS AND VISIBILITIES OF 3 MILES OR LESS WITH FOG
AROUND LAKE PONTCHARTRAIN IN SOUTHEASTERN LOUISIANA. LOW CLOUD
CEILINGS AND VISIBILITIES OF 3 MILES OR LESS ARE IN SOUTH
CENTRAL COASTAL LOUISIANA. LOW CLOUD CEILINGS COVER THE FLORIDA
PANHANDLE FROM CROSS CITY WESTWARD. MULTILAYERED CLOUD CEILINGS
ARE OBSERVED IN THE TAMPA METROPOLITAN AREA...TO SARASOTA.

...HISPANIOLA...

A WEAK MIDDLE LEVEL TO UPPER LEVEL TROUGH CUTS ACROSS CENTRAL
SECTIONS OF HISPANIOLA. COMPARATIVELY DRIER AIR IN
SUBSIDENCE...AS SEEN IN WATER VAPOR IMAGERY...COVERS THE AREA.

THE GFS FORECAST FOR 250 MB SHOWS THAT NORTHWESTERLY WIND FLOW
WILL PASS ON TOP OF HISPANIOLA DURING THE NEXT 48 HOURS...BEING
ON THE NORTHEASTERN SIDE OF A RIDGE. THE GFS FORECAST FOR 500 MB
SHOWS THAT NORTHERLY WIND FLOW WILL PASS ON TOP OF HISPANIOLA
FOR THE NEXT 48 HOURS...WITH A WEST-TO-EAST ORIENTED RIDGE. THE
GFS FORECAST FOR 700 MB SHOWS THAT HISPANIOLA WILL START WITH
WEAK ANTICYCLONIC WIND FLOW FOR THE FIRST 12 HOURS OR SO...AND
THEN CONTINUE FOR THE REST OF THE 48 HOUR FORECAST PERIOD WITH
NORTHEASTERLY WINDS ACROSS THE AREA...IN A NORTHWEST-TO-
SOUTHEAST ORIENTED RIDGE.

THE REST OF THE CARIBBEAN SEA...

A SURFACE TROUGH IS ALONG 79W/80W FROM 11N TO 18N MOVING
WESTWARD ABOUT 10 KNOTS. CONVECTIVE PRECIPITATION...ISOLATED
MODERATE FROM 11N TO 20N BETWEEN 76W AND 81W.

CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO STRONG AROUND
THE ISLANDS OF THE NORTHEASTERN CARIBBEAN SEA FROM 17N TO 19N
BETWEEN 63W AND 66W. RAINSHOWERS ARE POSSIBLE ELSEWHERE FROM 12N
TO 20N BETWEEN 61W AND 75W. ISOLATED MODERATE ALSO TO THE NORTH
OF 16N TO THE WEST OF 80W IN THE NORTHWESTERN CORNER OF THE
CARIBBEAN SEA.

MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND FLOW COVERS THE
CARIBBEAN SEA TO THE EAST OF 74W. MIDDLE LEVEL EASTERLY WIND
FLOW IS MOVING ACROSS THE TOP OF THE SAME AREA. MIDDLE LEVEL TO
UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE AREA THAT IS TO
THE WEST OF 74W.

THE MONSOON TROUGH PASSES THROUGH 9N75W IN COLOMBIA...TO 9N80W
IN PANAMA...BEYOND 8N84W IN SOUTHERN COSTA RICA...INTO THE
EASTERN PACIFIC OCEAN. RAINSHOWERS ARE POSSIBLE TO THE SOUTH OF
11N TO THE WEST OF 76W.

THE REST OF THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 15N23W JUST TO THE EAST OF THE CAPE VERDE ISLANDS. CYCLONIC
WIND FLOW COVERS THE AREA FROM 3N TO 24N BETWEEN AFRICA AND 40W.
COMPARATIVELY DRIER AIR IN SUBSIDENCE...AS SEEN IN WATER VAPOR
IMAGERY...COVERS THE AREA FROM 6N TO 15N BETWEEN 20W AND 33W.

A SURFACE RIDGE EXTENDS FROM A 1022 MB HIGH PRESSURE CENTER THAT
IS NEAR 33N17W...TO A SECOND 1022 MB HIGH PRESSURE CENTER THAT
IS NEAR 30N26W...TO 28N35W AND 18N38W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT1/FZNT01 KWBC...FOR
MORE DETAILS ABOUT THE WINDS AND SEA HEIGHTS THAT ACCOMPANY
TROPICAL STORM MELISSA. ONE AREA OF INTEREST CONSISTS OF SOUTH
TO SOUTHWEST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS 8 TO 11 FEET
TO THE NORTH OF 30N BETWEEN 36W AND 40W. A SECOND AREA OF
INTEREST CONSISTS OF WINDS 20 KNOTS OR LESS AND SEA HEIGHTS 8 TO
12 FEET ELSEWHERE TO THE NORTH OF A LINE FROM 31N35W TO 24N46W
TO 31N52W. A THIRD AREA OF INTEREST CONSISTS OF A COLD FRONT
FROM 31N43W TO 28N65W THEN STATIONARY TO 26N80W. EXPECT
NORTHEAST TO EAST WINDS 20 TO 25 KNOTS AND SEA HEIGHTS 8 TO 10
FEET TO THE NORTH THE FRONT TO THE WEST OF 60W. A FOURTH AREA OF
INTEREST CONSISTS WINDS 20 KNOTS OR LESS AND SEA HEIGHTS 8 TO 9
FEET FROM 08N TO 17N TO THE EAST OF 46W.

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

$$
MT


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