[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201810
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED SEP 20 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 20/1500 UTC WAS NEAR 26.0N
56.3W. HELENE IS MOVING NORTHWEST 10 KT. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 958 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 90 KT WITH GUSTS TO 110 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 AND THE
COLDEST CLOUD TOP TEMPERATURES NEAR -76C FROM 25N TO 26N
BETWEEN 56W AND 58W. OTHER POSSIBLE SHOWERS AND THUNDERSTORMS
ARE ELSEWHERE FROM 23N TO 31N BETWEEN 54W AND 60W.

THE CENTER OF TROPICAL STORM GORDON AT 20/1800 UTC WAS NEAR
37.8N 20.9W. GORDON IS MOVING ESTE 29 KT. IT IS EXPECTED TO
BECOME EXTRATROPICAL LATER TODAY.
THE MAXIMUM SUSTAINED WIND SPEEDS ARE 50 KT WITH GUSTS TO 60 KT.
 THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 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 27W/28W SOUTH
OF 17N MOVING WEST 10 TO 15 KT. STRONG SHOWERS AND THUNDERSTORMS
ARE TO THE WEST OF THE WAVE FROM 12N TO 14N BETWEEN 30W AND 32W.
ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND THUNDERSTORMS
ARE FROM 9N TO 14N BETWEEN 19W AND 28W.\

AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 44W/45W SOUTH
OF 19N MOVING WEST 10 TO 15 KT. SCATTERED MODERATE SHOWERS TO
ISOLATED STRONG THUNDERSTORMS FROM 12N TO 15N BETWEEN 43W AND
46W.

...THE ITCZ...
7N12W 8N23W 7N30W 10N37W 13N40W 11N47W 9N56W 9N63W. 10N36W 8N41W
7N48W 11N56W 11N61W. ISOLATED MODERATE TO LOCALLY STRONG SHOWERS
AND THUNDERSTORMS FROM 5N TO 10N BETWEEN 18W AND 36W. ISOLATED
MODERATE SHOWERS AND THUNDERSTORMS FROM 7N TO 14N BETWEEN 50W
AND 58W.

...DISCUSSION...

THE GULF OF MEXICO AND THE WESTERN ATLANTIC OCEAN WITH
THE U.S.A. EAST COAST TROUGH...
A DEEP LAYER TROUGH HAS MOVED OFF THE U.S.A. EAST COAST.
THIS TROUGH PASSES THROUGH 32N77W TO NORTH CENTRAL FLORIDA
NEAR 28N82W...INTO THE NORTH CENTRAL GULF OF MEXICO NEAR
27N90W...TO THE LOWER TEXAS COAST. A RIDGE IS EAST OF THE
TROUGH THROUGH 32N72W TO 30N75W 27N80W. A SURFACE COLD FRONT
PASSES THROUGH 32N76W TO NORTH CENTRAL FLORIDA NEAR 29N82W
TO THE NORTH CENTRAL GULF OF MEXICO NEAR 27N90W TO 25N96W
IN THE WESTERN GULF OF MEXICO...TO THE MEXICO COASTAL PLAINS
NEAR 22N97.5W. THE SKY NORTH OF 29N82W 28N90W 27N97W IS CLEAR.
ISOLATED MODERATE SHOWERS AND LOCALLY STRONG THUNDERSTORMS ARE
ALONG THE COLD FRONT FROM 24N TO 28N BETWEEN TEXAS/MEXICO AND
FLORIDA. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND
THUNDERSTORMS ARE SOUTH OF THE LINE 24N97W 22N93W 20N92W.
UPPER LEVEL ANTICYCLONIC FLOW IS IN THE SOUTHWESTERN CORNER
OF THE AREA. THE SOUTHERN END OF THE COLD FRONT IS UP AGAINST
THE COAST NEAR 22N. A MIDDLE LEVEL LOW PRESSURE CENTER IS ABOUT
75 NM TO THE WEST-NORTHWEST OF THE NORTHWESTERN YUCATAN
PENINSULA.

THE CARIBBEAN SEA...
THE DEEP LAYER TROUGH FROM THE LAST FEW DAYS HAS MOVED EASTWARD
NOW FROM 26N68W IN THE ATLANTIC OCEAN...ACROSS THE BAHAMAS AND
CUBA TO A MIDDLE TO UPPER LEVEL LOW PRESSURE CENTER NEAR 19N81W.
THE TROUGH ENDS NEAR 14N87W IN SOUTHWESTERN HONDURAS. AN UPPER
LEVEL HIGH PRESSURE CENTER IS NEAR 14N75W. ANOTHER MIDDLE
TO UPPER LEVEL INVERTED TROUGH IS ALONG 68W FROM VENEZUELA
NORTHWARD TO 15N. THE CYCLONIC FLOW AROUND THIS 68W TROUGH
IS SOUTH OF 15N BETWEEN 63W AND 73W. ISOLATED MODERATE SHOWERS
TO LOCALLY STRONG THUNDERSTORMS ARE BEING ENHANCED MIXTURE
OF THE HONDURAS TROUGH...THE 14N75W HIGH PRESSURE CENTER...
AND THE WESTWARD MOVEMENT OF THE INVERTED TROUGH...SOUTH
OF 16N WEST OF 72W. 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 MIDDLE TO UPPER LEVEL TROUGH IS IN
THE VICINITY OF THE 44W/45W TROPICAL WAVE...GOING FROM 29N31W
TO A LOW PRESSURE CENTER NEAR 23N37W TO 16N42W. AN INVERTED
MIDDLE TO UPPER LEVEL TROUGH IS ALONG 10N43W 5N46W 3N47W.
BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE REST OF THE
ATLANTIC OCEAN WATERS NORTH OF 20N EAST OF THE 29N31W 16N42W
TROUGH.

$$
MT


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