[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED OCT 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...SPECIAL FEATURES...

THE CENTER OF HURRICANE RAFAEL AT 17/1500 UTC IS NEAR
37.5N 59.1W...ABOUT 475 NM TO THE SOUTH-SOUTHEAST OF
NOVA SCOTIA. RAFAEL IS MOVING NORTH-NORTHEAST 30 KNOTS.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 975 MB.
THE MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT.
PLEASE READ THE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT2/WTNT32 KNHC AND THE FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
THE DEEPEST CONVECTIVE PRECIPITATION IS SHIFTING TO THE
NORTHWESTERN SEMICIRCLE. COOLER AND DRIER AIR IS BEGINNING
TO WRAP AROUND THE SOUTHERN PART OF THE CIRCULATION. RAFAEL
IS UNDERGOING AN EXTRATROPICAL TRANSITION. SCATTERED MODERATE
TO ISOLATED STRONG CONVECTIVE PRECIPITATION IN THE ATLANTIC
OCEAN IS WITHIN 30 TO 60 NM ON EITHER SIDE OF THE LINE THAT
PASSES THROUGH 32N54W 24N60W 22N63W 21N67W. THIS PRECIPITATION
IS FROM LINES OF CONFLUENT SURFACE WIND FLOW AS PART OF THE
LARGER-SCALE CYCLONIC WIND FLOW THAT HAS BEEN MOVING AROUND
THE HURRICANE. THE SWELLS THAT ARE BEING GENERATED BY RAFAEL
ARE EXPECTED TO AFFECT BERMUDA...EASTERN CANADA...AND PARTS
OF THE UNITED STATES EAST COAST DURING THE NEXT DAY OR SO.
IT IS LIKELY THAT THESE SWELLS WILL CAUSE LIFE-THREATENING
SURF AND RIP CURRENTS. PLEASE CONSULT BULLETINS FROM YOUR
LOCAL WEATHER OFFICE.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 16N36W 14N38W 11N38W.
THE WAVE HAS BEEN RE-POSITIONED IN ORDER TO AGREE WITH THE MOST
CURRENT SCATTEROMETER WIND DATA AND VISIBLE SATELLITE IMAGERY.
CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG
FROM 15N TO 19N BETWEEN 35W AND 37W. THE UPPER LEVEL TROUGH FROM
THE LAST FEW DAYS IS NOW NEARLY 400 NM TO THE NORTHWEST OF THE
AREA OF THE TROPICAL WAVE. OTHER SCATTERED MODERATE TO ISOLATED
STRONG CONVECTIVE PRECIPITATION IS FROM 14N TO 20N BETWEEN 30W
AND 34W. THIS PRECIPITATION MOST PROBABLY IS NOT RELATED TO
THE TROPICAL WAVE.

A SURFACE TROUGH IS ALONG 58W/59W FROM 10N TO 16N. THIS FEATURE
IS ABLE TO BE FOLLOWED CURRENTLY IN VISIBLE AND INFRARED
SATELLITE IMAGERY. RAINSHOWERS ARE POSSIBLE FROM 9N TO 12N
BETWEEN 56W AND 58W. THE CONVECTIVE CLOUDS IN THIS AREA ARE
BEING SHEARED BY THE UPPER LEVEL NORTHERLY WIND FLOW.

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

THE MONSOON TROUGH PASSES THROUGH COASTAL GUINEA-BISSAU NEAR
12N17W TO 10N20W AND 9N34W. THE ITCZ IS NON-EXISTENT TO THE
WEST OF 9N34W BECAUSE OF THE TRADEWIND FLOW. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG IN THE
ATLANTIC OCEAN WITHIN 120 NM ON EITHER SIDE OF 6N11W 7N20W
13N28W.

...DISCUSSION...

THE GULF OF MEXICO...

UPPER LEVEL NORTHWESTERLY WIND FLOW COVERS THE AREA. THIS
NORTHWESTERLY WIND FLOW IS ON THE WESTERN SIDE OF THE DEEP
LAYER TROUGH THAT IS STEERING THE CURRENT ATLANTIC OCEAN-
TO-GULF OF MEXICO FRONTAL BOUNDARY. THE FRONT ACTUALLY PASSED
THROUGH THE GULF OF MEXICO AT LEAST 24 HOURS AGO. BROKEN TO
OVERCAST MULTILAYERED CLOUDS ARE WITHIN 250 NM ON EITHER SIDE
OF THE LINE THAT PASSES THROUGH 32N76W IN THE ATLANTIC OCEAN...
TO 28N80W...AND WITHIN 90 TO 150 NM ON EITHER SIDE OF THE LINE
THAT RUNS FROM 28N80W TO 24N86W IN THE EASTERN GULF OF MEXICO...
BEYOND 26N97W ALONG THE TEXAS COAST. COMPARATIVELY DRIER AIR
IN SUBSIDENCE IS TO THE NORTH AND NORTHWEST OF THE CLOUDS.
A DISSIPATING STATIONARY FRONT PASSES THROUGH 31N72W IN THE
ATLANTIC OCEAN...ACROSS LAKE OKEECHOBEE IN FLORIDA...TO 26N85W
IN THE EAST CENTRAL GULF OF MEXICO...INTO SOUTHWESTERN LOUISIANA.

FROM THE WESTERN ATLANTIC OCEAN...ACROSS THE BAHAMAS AND CUBA...
INTO THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...

AN UPPER LEVEL TROUGH PASSES THROUGH 32N75W...THROUGH THE
WINDWARD PASSAGE...ACROSS JAMAICA...INTO SOUTHEASTERN NICARAGUA.
THE PART OF THE FRONT THAT IS IN THE ATLANTIC OCEAN IS THE PART
THAT IS STEERING THE COLD FRONT/STATIONARY FRONT THAT JUST
TO THE WEST OF HURRICANE RAFAEL.

THE REST OF THE CARIBBEAN SEA...

UPPER LEVEL NORTHEASTERLY WIND FLOW IS MOVING INTO THE
SOUTHEASTERN CORNER OF THE AREA AS A RESULT OF THE DIFFLUENT
FLOW PATTERN THAT IS MOVING AWAY FROM THE ATLANTIC OCEAN 25N40W
19N47W 5N52W UPPER LEVEL TROUGH. THE NORTHEASTERLY WIND FLOW
TRANSITIONS TO EASTERLY AND SOUTHEASTERLY GRADUALLY...FROM EAST
TO WEST BETWEEN 60W AND 70W. THE UPPER LEVEL WIND FLOW
EVENTUALLY BECOMES SOUTHERLY AND SOUTHWESTERLY WIND FLOW IN THE
REST OF THE AREA THAT IS BETWEEN 70W AND THE LINE THAT RUNS FROM
THE WINDWARD PASSAGE AND SOUTHEASTERN NICARAGUA.

THE MONSOON TROUGH IS ALONG 11N/12N...BETWEEN 74W IN THE
CARIBBEAN SEA JUST OFF THE COLOMBIA COAST...BEYOND NORTHWESTERN
NICARAGUA. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE
PRECIPITATION IS TO THE SOUTH OF 15N BETWEEN 70W AND 82W.

THE REST OF THE ATLANTIC OCEAN...

A SURFACE RIDGE IS ALONG 40W...FROM 20N TO A 1030 MB HIGH
PRESSURE CENTER THAT IS NEAR 39N40W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT 20 KNOT WINDS AND 8 TO 12 FOOT SEA HEIGHTS
TO THE NORTH OF 27N BETWEEN 49W AND 64W...AND  FROM 13N TO 23N
BETWEEN 38W AND 51W...ELSEWHERE BETWEEN LINE FROM 31N51W TO
24N59W AND ANOTHER LINE FROM 31N73W TO 24N66W WINDS 20 KT OR
LESS. SEAS 8 TO 10 FT IN MIXED NE AND SE SWELL...HIGHEST NE.
A SECOND AREA OF INTEREST IS FOR 20 KNOT WINDS AND 9 FOOT SEA
HEIGHTS FROM 13N TO 27N BETWEEN 35W AND 52W.

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

$$
MT




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