[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 191805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE SEP 19 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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 HELENE AT 19/1500 UTC WAS NEAR
24.6N 52.9W. HELENE IS MOVING WEST-NORTHWEST 8 KT. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 960 MB. THE MAXIMUM SUSTAINED WIND
SPEEDS ARE 100 KT WITH GUSTS TO 120 KT. PLEASE READ THE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23
KNHC OR THE PUBLIC ADVISORY UNDER MIATCPAT3/WTNT33 KNHC FOR MORE
DETAILS. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 23N TO
25N BETWEEN 52W AND 55W...AND FROM 25N TO 27N BETWEEN 55W.

THE CENTER OF HURRICANE GORDON AT 19/1800 UTC WAS NEAR 37.8N
34.0W. THIS POSITION ALSO IS ABOUT 330 NM/610 KM WEST OF THE
ISLAND OF TERCEIRA IN THE AZORES. GORDON IS MOVING EAST 27 KT/
50 KM/HR. THIS GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE
NEXT 24 HOURS. THIS TRACK WOULD BRING GORDON ACROSS THE AZORES
TONIGHT. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 75 KT WITH GUSTS
TO 90 KT. FASTER WINDS...ESPECIALLY IN GUSTS...ARE LIKELY OVER
ELEVATED TERRAIN. GORDON IS A CATEGORY ONE HURRICANE ON THE
SAFFIR-SIMPSON SCALE. GORDON IS EXPECTED TO BE A HURRICANE AS
IT PASSES NEAR OR ACROSS THE AZORES ISLANDS. HURRICANE FORCE
WINDS EXTEND OUTWARD UP TO 35 NM/65 KM FROM THE CENTER...AND
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 150 NM/
280 KM. LARGE AND DANGEROUS BATTERING WAVES ALONG WITH STORM
SURGES OF 1 TO 3 FT ARE POSSIBLE IN AREAS OF ONSHORE WINDS IN
THE AZORES. GORDON IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 2 TO 4 INCHES OVER THE AZORES... WITH ISOLATED
MAXIMUM AMOUNTS OF 6 INCHES OVER THE HIGHER TERRAIN.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 979 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 75 KT WITH GUSTS TO 90 KT. PLEASE
READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC OR THE PUBLIC ADVISORY UNDER
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. NUMEROUS STRONG SHOWERS
AND THUNDERSTORMS FROM 38N TO 39N BETWEEN 35W AND 36W. OTHER
SHOWERS ARE POSSIBLE FROM 37N TO 40N BETWEEN 33W AND 36W.

...TROPICAL WAVES...
AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 39W/40W AS
SEEN IN THE LOW CLOUD MOVEMENTS ON VISIBLE SATELLITE IMAGERY.
IT IS POSSIBLE THAT THE SHOWERS AND THUNDERSTORMS ALONG THE
NORTHERN EDGE OF THE ITCZ FROM 9N TO 14N BETWEEN 37W AND 41W
ARE BEING AFFECTED OR ENHANCED BY THIS WAVE. A MIDDLE TO UPPER
LEVEL TROUGH CONTINUES TO BE IN THE VICINITY OF THIS WAVE...
GOING FROM 27N31W TO 24N34W TO 18N36W AND 13N42W. THE UPPER
LEVEL WIND FLOW IS SHEARING THE HIGHER CLOUDS OF THE OTHER
SHOWERS AND THUNDERSTORMS THAT ALSO ARE ALONG THE NORTHERN
EDGE OF THE ITCZ...FROM 10N TO 15N BETWEEN 30W AND 35W.

...THE ITCZ...
11N12W 8N21W 10N36W 8N41W 7N48W 11N56W 11N61W. ISOLATED TO
WIDELY SCATTERED MODERATE SHOWERS AND THUNDERSTORMS FROM 5N
TO 10N BETWEEN 13W AT THE AFRICA COAST AND 33W...AND WITHIN
60 NM ON EITHER SIDE OF 8N40W 7N44W 6N48W 9N50W. ISOLATED
MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS WITHIN 60 TO
75 NM ON EITHER SIDE OF 17N47W 14N48W 10N50W. BROKEN
MULTILAYERED CLOUDS AND POSSIBLE SHOWERS ELSEWHERE FROM
THE COAST OF SOUTH AMERICA TO 12N BETWEEN 50W AND 60W.

...DISCUSSION...

THE GULF OF MEXICO AND THE WESTERN ATLANTIC OCEAN
NORTHWEST OF THE LINE FROM 32N63W TO THE SOUTHERN BAHAMAS...
AND IN THE NORTHWESTERN CARIBBEAN SEA...
A DEEP LAYER TROUGH IS MOVING THROUGH EAST CENTRAL ALABAMA TO
THE SOUTHEASTERN TIP OF LOUISIANA TO THE LOWER TEXAS COAST.
A SEPARATE MIDDLE TO UPPER LEVEL LOW PRESSURE CENTER IS IN THE
WESTERN GULF OF MEXICO NEAR 23N94W. UPPER LEVEL ANTICYCLONIC
FLOW COVERS THE SOUTHWESTERN CORNER OF THE AREA...ON THE
SOUTHERN SIDE OF THE 23N94W LOW PRESSURE CENTER. NUMEROUS
STRONG SHOWERS AND THUNDERSTORMS FROM 4 TO 5 HOURS AGO IN THE
SOUTHWESTERN CORNER HAVE WEAKENED. ISOLATED MODERATE SHOWERS
TO LOCALLY STRONG THUNDERSTORMS ARE WITHIN 150 NM TO THE
NORTHWEST OF 30N82W 27N87W 24N95W...AND FROM 20N TO 25N BETWEEN
91W AND THE MEXICO COAST. A SURFACE COLD FRONT PASSES THROUGH
THE EXTREME WESTERN TIP OF THE FLORIDA PANHANDLE TO THE
SOUTHEASTERN TIP OF LOUISIANA TO A 1012 MB GULF OF MEXICO LOW
PRESSURE CENTER NEAR 26N96W...TO NORTHEASTERN MEXICO TO 25N99W
AND 26N101W. THE FRONT BECOMES STATIONARY FROM 26N101W TO THE
EASTERN SECTION OF THE TEXAS BIG BEND. AN UPPER LEVEL RIDGE RUNS
FROM CENTRAL GEORGIA TO 27N86W IN THE NORTHEASTERN GULF OF
MEXICO TO 25N90W IN THE CENTRAL GULF WATERS. A DEEP LAYER TROUGH
GOES FROM A WESTERN ATLANTIC OCEAN LOW PRESSURE CENTER NEAR
33N69W TO 26N75W TO 23N79W IN BETWEEN CUBA AND ANDROS ISLAND TO
17N87W JUST EAST OF BELIZE IN THE NORTHWESTERN CARIBBEAN SEA.

THE CARIBBEAN SEA...
A DEEP LAYER TROUGH RUNS FROM A WESTERN ATLANTIC OCEAN LOW
PRESSURE CENTER NEAR 33N69W TO 17N87W JUST EAST OF BELIZE.
BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS SOUTHERN MEXICO IN
THE AREA OF THE ISTHMUS OF TEHUANTEPEC AND EASTWARD TO
GUATEMALA. AN INVERTED MIDDLE TO UPPER LEVEL TROUGH AND ITS
ASSOCIATED CYCLONIC FLOW STILL COVER THE SOUTHWESTERN CORNER
OF THE AREA. THE REMAINING SHOWERS AND THUNDERSTORMS IN THE
WATERS OFF THE NORTHERN COAST OF COLOMBIA ARE IN AN AREA OF
UPPER LEVEL DIFFLUENT FLOW...AS SOME OF THE FLOW VEERS AWAY
FROM THE INVERTED TROUGH TOWARD THE CENTRAL CARIBBEAN SEA.
SHOWERS AND THUNDERSTORMS ALSO ARE IN THE CARIBBEAN SEA WATERS
AND REACHING NICARAGUA AND HONDURAS SOUTH OF 16N BETWEEN 80W
AND 85W. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS
IN THE AREA OF THE NETHERLANDS ANTILLES HAVE DEVELOPED IN THE
SURFACE EASTERLY WIND FLOW AND IN AN AREA OF ENOUGH UPPER LEVEL
DIFFLUENT WIND FLOW. BROAD UPPER LEVEL ANTICYCLONIC FLOW AND
DRY AIR ARE EAST OF 70W.

THE ATLANTIC OCEAN...
BROAD UPPER LEVEL ANTICYCLONIC FLOW AND DRY AIR COVER THE
ATLANTIC OCEAN AND THE CARIBBEAN SEA FROM 10N TO 30N BETWEEN
55W AND 70W...RIGHT UP TO THE FLOW AROUND HURRICANE HELENE.
AN EASTERN ATLANTIC OCEAN TROUGH IS IN THE VICINITY OF THE
39W/40W TROPICAL WAVE...GOING FROM 27N31W TO 24N34W TO 18N36W
AND 13N42W. THE UPPER LEVEL WIND FLOW IS SHEARING THE HIGHER
CLOUDS OF THE OTHER SHOWERS AND THUNDERSTORMS THAT ALSO ARE
ALONG THE NORTHERN EDGE OF THE ITCZ...FROM 10N TO 15N BETWEEN
30W AND 35W.  BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE
REST OF THE ATLANTIC OCEAN WATERS EAST OF THE TROUGH.

$$
MT


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