[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151042
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI SEP 15 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
HURRICANE GORDON IS CENTERED NEAR 30.9N 53.4W AT 15/0900 UTC
MOVING EAST-NORTHEAST AT 8 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 965 MB. MAXIMUM SUSTAINED WIND SPEED IS 95 KT WITH
GUSTS TO 115 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. GORDON
HAS BEGUN TO WEAKEN WITH THE EYE BECOMING SMALLER AND LESS
DISTINCT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 90 NM FROM THE CENTER IN THE E SEMICIRCLE. SCATTERED
MODERATE CONVECTION COVERS THE REMAINDER OF THE AREA FROM
29N-33N BETWEEN 50W-54W.

TROPICAL STORM HELENE IS CENTERED NEAR 15.0N 40.3W AT 15/0900
MOVING WEST-NORTHWEST AT 13 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH
GUSTS TO 50 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
HELENE CONTINUES TO MAINTAIN DEEP CONVECTION BUT IS NOW MOSTLY
SW OF THE LOW LEVEL CENTER. SCATTERED MODERATE TO SCATTERED
STRONG CONVECTION IS FROM 12N-16N BETWEEN 39W-43W. OUTER
RAINBAND CONSISTING OF CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 45 NM OF LINE 18N38W-16N42W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 60W S OF 15N MOVING W 10-15 KT. WEAK WAVE
SIGNATURE IS OBSERVED AS THE WAVE APPROACHES THE LESSER
ANTILLES. WAVE IS BENEATH THE W EDGE OF AN UPPER RIDGE AND A
LARGE AREA OF VERY DRY AIR...THUS NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE IS ALONG 72W/73W S OF 19N MOVING W 15 KT. BROAD
WELL-DEFINED LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS
OBSERVED OVER THE CENTRAL CARIBBEAN. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE N OF 16N TO THE COAST OF HISPANIOLA BETWEEN
69W-73W.

TROPICAL WAVE IS ALONG 82W S OF 17N MOVING W 15 KT. WEAK LOW
LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED OVER THE W
CARIBBEAN. WAVE IS EMBEDDED WITHIN DRY AIR THUS ONLY ISOLATED
SHOWERS ARE WITHIN 45 NM OF LINE FROM 20N76W-17N81W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N16W 13N26W 15N35W THEN ALONG
9N42W 7N51W INTO THE CARIBBEAN ALONG 11N66W ACROSS THE N PORTION
OF SOUTH AMERICA AND PANAMA INTO THE E PACIFIC REGION NEAR
10N82W. SCATTERED STRONG CONVECTION IS WITHIN 150 NM N OF THE
AXIS E OF 18W TO INLAND OVER AFRICA. SCATTERED MODERATE/STRONG
CONVECTION IS WITHIN 120/150 NM OF THE AXIS FROM 18W-23W AND
WITHIN 120 NM OF THE AXIS FROM 32W-36W.

...DISCUSSION...

GULF OF MEXICO...
BROAD DEEP LAYERED TROUGH COVERS THE E US...THE W ATLC AND THE N
GULF COAST ANCHORED BY AN UPPER LOW MOVING ACROSS NEW ENGLAND.
ASSOCIATED FRONTAL BOUNDARY EXTENDS INTO THE GULF FROM THE W
ATLC ACROSS THE FLORIDA PENINSULA NEAR FT. MYERS WHERE IT
BECOMING A SURFACE TROUGH ACROSS THE GULF TO OFF THE CENTRAL
TEXAS COAST. ISOLATED SHOWERS ARE OVER THE N GULF FROM 24N-28N
BETWEEN 86W-95W. UPPER RIDGE EXTENDS ACROSS THE REMAINDER OF THE
GULF ANCHORED BY AN UPPER HIGH ASSOCIATED WITH A TROPICAL STORM
OFF THE W COAST OF MEXICO ENTERING THE GULF NEAR TAMPICO MEXICO
INTO THE W ATLC OVER THE FLORIDA KEYS/STRAITS OF FLORIDA.
ISOLATED SHOWERS ARE FROM 23N-25N E OF 83W TO THROUGH THE
STRAITS OF FLORIDA AND S OF 24N W OF 95W TO INLAND OVER MEXICO.

CARIBBEAN SEA...
W CARIBBEAN IS DOMINATED BY NE UPPER FLOW FROM THE UPPER RIDGE
THAT EXTENDS ACROSS THE GULF OF MEXICO INTO THE W ATLC. THIS IS
PROVIDING DRY AIR ACROSS THE AREA INCLUDING THE TROPICAL WAVE
ALONG 81W. NARROWING UPPER TROUGH EXTENDS ACROSS FROM HAITI/E
CUBA SW TO CENTRAL NICARAGUA. AN UPPER HIGH IS LOCATED OVER
SOUTH AMERICA WITH A RIDGE EXTENDING N INTO THE CENTRAL
CARIBBEAN S OF 16N FROM 68W-80W. REMAINDER OF THE CARIBBEAN IS
DOMINATED BY S UPPER FLOW FROM AN UPPER RIDGE ANCHORED IN THE
TROPICAL/CENTRAL ATLC GENERATING SCATTERED MODERATE/ISOLATED
STRONG CONVECTION WITHIN 90 NM OF LINE 11N62W-15N67W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 10-14N BETWEEN
76W-83W IN ASSOCIATION WITH THE ITCZ ACROSS THE AREA.

ATLANTIC OCEAN...
BROAD DEEP LAYERED TROUGH THAT COVERS THE E US AND THE N GULF
EXTENDS INTO THE W ATLC IS ANCHORED BY AN UPPER LOW MOVING
ACROSS NEW ENGLAND. THE ASSOCIATED FRONTAL BOUNDARY EXTENDS INTO
THE W ATLC FROM A 1010 MB LOW OFF NORTH CAROLINA COAST THROUGH
32N76W INTO THE GULF NEAR WEST PALM BEACH GIVING THE AREA
SCATTERED MODERATE/ISOLATED STRONG CONVECTION E OF THE FRONT
WITHIN 75 NM OF LINE FROM 28N77W TO BEYOND 32N74W. SURFACE
TROUGH IS TO THE E OF THE FRONT EXTENDING THROUGH 32N69W TO THE
CENTRAL BAHAMAS NEAR 23N74W GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM E OF OF SURFACE
TROUGH. UPPER RIDGE AXIS EXTENDS
FROM THE GULF OF MEXICO INTO THE W ATLC ACROSS THE FLORIDA
KEYS/STRAITS OF FLORIDA NE TO NEAR 30N70W. NARROW UPPER TROUGH
EXTENDS ACROSS HAITI/E CUBA INTO THE W ATLC TO NEAR 25N69W.
BROAD UPPER RIDGE COVERS THE W/CENTRAL AND TROPICAL ATLC
ANCHORED NEAR 21N57W COVERING THE AREA S OF 28N FROM 50W-68W.
TROPICAL MOISTURE IS BEING DRAWN N OF THE E CARIBBEAN AND WITH
SUFFICIENT DIFFLUENCE TO GENERATE AN AREA OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS FROM 18N-24N BETWEEN 61W-68W.
GORDON IS N OF THIS UPPER RIDGE. AN UPPER RIDGE COVERS THE
REMAINDER OF THE E ATLC E OF 30W ANCHORED NEAR 30N24W EXTENDING
E TO OVER THE CANARY ISLANDS. AN UPPER HIGH ASSOCIATED WITH
TROPICAL STORM HELENE COVERS THE SE TROPICAL ATLC WITH A SMALL
UPPER LOW JUST TO THE E CENTERED N OF THE CAPE VERDE ISLANDS
NEAR 20N25W. THE SUBTROPICAL RIDGE IS ONCE AGAIN SPREADING W
OVER THE ATLC IN SPITE OF THE PRESENCE OF HURRICANE GORDON WITH
A 1026 MB HIGH OVER THE S MOST ISLANDS OF THE AZORES. THE FIRST
VISIBLE SATELLITE IMAGES THIS MORNING SHOWS A LARGE AREA OF
AFRICA DUST FROM THE ITCZ TO 27N BETWEEN 44W-64W INCLUDING THE
FAR E CARIBBEAN WITH HELENE JUST TO THE E OF THE DUST AND YET
ANOTHER AREA OF AFRICAN DUST MOVING OFF AFRICA FROM 13N-22N FROM
OVER THE CAPE VERDE ISLANDS TO THE COAST OF AFRICA.

$$
WALLACE





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