[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271204
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 27 2012

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 1015 UTC.

...SPECIAL FEATURES...

HURRICANE SANDY WAS DOWNGRADED TO TROPICAL STORM SANDY AT
27/0900 UTC AND HAS NOW BEEN UPGRADED BACK TO A HURRICANE AS OF
27/1200 UTC DUE TO DATA FROM AIR FORCE AIRCRAFT THAT FOUND
HURRICANE-FORCE WINDS. THE CENTER OF HURRICANE SANDY AT 27/1200
UTC IS NEAR 28.8N 76.8W. SANDY IS ABOUT 145 NM TO THE NORTH OF
GREAT ABACO ISLAND IN THE NORTHERN BAHAMAS...AND ABOUT 290 NM TO
THE SOUTHEAST OF CHARLESTON SOUTH CAROLINA. SANDY IS MOVING
NORTH-NORTHEAST 9 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS
960 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 65 KNOTS WITH
GUSTS TO 80 KNOTS. PLEASE READ THE FORECAST/ADVISORY UNDER THE
AWIPS/WMO HEADERS MIATCMAT3/ WTNT23 KNHC...AND THE PUBLIC
ADVISORY UNDER MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS.
CONVECTIVE PRECIPITATION...SCATTERED STRONG FROM 28N TO 30N
BETWEEN 76W AND 80W...SCATTERED MODERATE TO STRONG TO THE NORTH
OF 20N BETWEEN 60W AND 70W IN THE ATLANTIC OCEAN...SCATTERED
MODERATE AROUND HISPANIOLA. THE SURFACE PRESSURE PATTERN OF LOW
PRESSURE COVERS THE CARIBBEAN SEA FROM 14N TO 35N IN THE
ATLANTIC OCEAN BETWEEN 65W IN THE ATLANTIC OCEAN AND 85W IN THE
EASTERN GULF OF MEXICO AND IN THE NORTHWESTERN CARIBBEAN
SEA...IN A CLOSED 1008 MB ISOBAR. A DEVELOPING WARM FRONT IS
ALONG 29N71W 27N63W 26N54W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 47W TO THE SOUTH OF
17N. THE WAVE HAS BEEN MOVING WESTWARD 10 KNOTS DURING THE
LAST 24 HOURS. CONVECTIVE PRECIPITATION...SCATTERED MODERATE
TO ISOLATED STRONG FROM 8N TO 14N BETWEEN 36W AND 47W.
AN UPPER LEVEL TROUGH PASSES THROUGH 32N42W TO 22N38W TO 16N44W.
AN INVERTED MIDDLE LEVEL TO UPPER LEVEL TROUGH IS ALONG 15N47W
12N55W BEYOND SOUTHEASTERN VENEZUELA. WIDELY SCATTERED MODERATE
TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS WITHIN 240 NM
ON EITHER SIDE OF 16N39W 10N43W 6N46W 4N51W. THE TROUGHS ARE
IN THE AREA OF THIS TROPICAL WAVE.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 52W TO THE SOUTH OF
16N. THE WAVE HAS BEEN MOVING WESTWARD 10 KNOTS DURING THE
LAST 24 HOURS. CONVECTIVE PRECIPITATION...NO SIGNIFICANT DEEP
PRECIPITATION.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL GUINEA NEAR 11N15W
TO 9N18W. THE ITCZ CONTINUES FROM 9N18W TO 7N30W. THE ITCZ
IS BROKEN UP BY THE WIND FLOW THAT IS AROUND THE TROPICAL WAVES.
THE ITCZ CONTINUES FROM 6N43W TO 5N50W. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG TO THE
SOUTH OF 10N BETWEEN 30W AND 40W...ISOLATED MODERATE TO LOCALLY
STRONG TO THE SOUTH OF 10N TO THE EAST OF 30W. A SURFACE TROUGH
IS ALONG 30W/31W TO THE SOUTH OF 10N...AS NOTED IN THE LATEST
SCATTEROMETER WIND DATA.

...DISCUSSION...

THE GULF OF MEXICO...

A DEEP LAYER TROUGH THAT IS MOVING THROUGH THE CENTRAL U.S.A.
IS SUPPORTING A COLD FRONT THAT PASSES THROUGH THE WESTERN
FLORIDA PANHANDLE...THROUGH SOUTHEASTERN LOUISIANA...INTO THE
NORTHWESTERN GULF OF MEXICO...TO 23N98W IN NORTHERN COASTAL
MEXICO. A STATIONARY FRONT CONTINUES FROM 23N98W...TO JUST
TO THE SOUTH OF THE TEXAS BIG BEND...BEYOND 32N108W. ISOLATED
MODERATE CONVECTIVE PRECIPITATION IS TO THE NORTHWEST OF THE
LINE THAT PASSES THROUGH 30N88W 26N93W 19N92W. DEEP LAYER
NORTHWESTERLY WIND FLOW COVERS THE AREA.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT4...FOR DETAILS ABOUT 20 TO 25 KNOT
WINDS AND 8 TO 12 FOOT SEA HEIGHTS STARTING OUT TO THE EAST OF
85W...AND CHANGING TO BE TO THE NORTHEAST OF THE LINE FROM 30N89W
23N80W. A COLD FRONT STARTS NEAR 30N88W 23N98W...NEAR 28N83W
TO 18N94W AT 24 HOURS...AND TO 26N81W 20N88W AT 48 HOURS. EXPECT
20 TO 30 KNOT WIND SPEEDS AND 8 TO 10 FOOT SEA HEIGHTS AROUND
THE FRONT.

THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL SHORT WAVE TROUGH PASSES THROUGH
THE SOUTHERN BAHAMAS TO JAMAICA...INTO THE SOUTHWESTERN CORNER
OF THE AREA. COMPARATIVELY DRIER AIR IN SUBSIDENCE SURROUNDS THE
TROUGH AND IS TO THE WEST OF THE LINE THAT PASSES THROUGH THE
WINDWARD PASSAGE TO COASTAL COSTA RICA ALONG 10N. THIS TROUGH
IS PART OF THE FEATURE THAT WAS A 22N82W CYCLONIC CIRCULATION
CENTER ON 25N/1200 UTC.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR DETAILS ABOUT 20 TO 30 KNOT
WINDS AND 8 TO 10 FOOT SEA HEIGHTS TO THE NORTH OF 18N BETWEEN
72W AND 77W FOR THE NEXT 24 HOURS OR SO.

THE ATLANTIC OCEAN...

AN UPPER LEVEL TROUGH PASSES THROUGH 32N42W TO 22N38W TO 16N44W.
THE TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH 32N40W TO
27N44W AND 26N54W. THIS PART OF THE COLD FRONT CONNECTS TO THE
EASTERN END OF THE DEVELOPING WARM FRONT THAT IS NEAR THE
NORTHEASTERN QUADRANT OF HURRICANE SANDY. BROKEN TO OVERCAST
MULTILAYERED CLOUDS AND OTHER POSSIBLE PRECIPITATION IS TO THE
NORTH OF 20N BETWEEN 25W AND 60W.

A COLD FRONT EXTENDS FROM A 1008 MB LOW PRESSURE CENTER
THAT IS NEAR 32N23W...TO 25N30W AND 21N40W. CONVECTIVE
PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM 21N
TO 23N BETWEEN 37W AND 40W AND FROM 29N TO 32N BETWEEN
29W AND 32W...SCATTERED MODERATE TO ISOLATED STRONG
TO THE NORTH OF 29N BETWEEN 36W AND 41W.

A SURFACE RIDGE EXTENDS FROM THE CANARY ISLANDS TO A 1014 MB
HIGH PRESSURE CENTER IS NEAR 21N28W TO 19N40W AND 20N62W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR DETAILS
ABOUT TROPICAL STORM SANDY. A SECOND AREA OF INTEREST RELATES
TO A COLD FRONT THAT IS ALONG 31N41W 27N45W 25N54W...AND THEN
TO 31N40W 27N50W 29N60W AT 24 HOURS. A NEW COLD FRONT FORMS
AT 48 HOURS ALONG 31N35W 23N47W. EXPECT 20 TO 30 KNOT WINDS
AND 8 TO 13 FOOT SEA HEIGHTS AROUND THE COLD FRONT.

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

$$
MT





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