[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161039
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 16 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 31.3N 53.7W AT 16/0900 UTC AND
IS NEAR STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987
MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT.
SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. GORDON HAS REMAINS NEAR
STATIONARY AND THE EYE HAS BECOME RAGGED WITH WARMER CLOUD TOP
TEMPERATURES. GORDON IS EXPECTED TO CONTINUE WEAKENING OVER THE
NEXT DAY OR SO. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 60 NM OF THE CENTER IN THE N QUADRANT. SCATTERED MODERATE
CONVECTION IS WITHIN 120 NM FROM THE CENTER IN THE REMAINING
QUADRANTS.

TROPICAL STORM HELENE IS CENTERED NEAR 17.9N 44.7W AT 16/0900
MOVING WEST-NORTHWEST AT 13 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 992 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH
GUSTS TO 75 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
CONVECTION ASSOCIATED WITH HELENE SEEMS TO PULSATE IN DIFFERENT
QUADRANTS AS THE SYSTEM CONTINUES TO INTENSIFY AND COULD BE COME
A HURRICANE LATER TODAY. SCATTERED MODERATE/STRONG CONVECTION IS
WITHIN 30/45 NM RADIUS OF 19N45W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION COVERS THE REMAINDER OF THE AREA WITHIN 140 NM
OF LINE 21N41W-16N47W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 21W/22W S OF 20N WITH A 1011 MB LOW ALONG
THE WAVE NEAR 15N MOVING W NEAR 10 KT. WELL-DEFINED LOW/MID
LEVEL CYCLONIC CIRCULATION WITH SCATTERED MODERATE/STRONG
CONVECTION FROM 15N-19N BETWEEN 19W-24W INCLUDING SOME THE CAPE
VERDE ISLANDS.

TROPICAL WAVE IS ALONG 77W S OF 17N MOVING W 15 KT. BROAD
WELL-DEFINED LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS
OBSERVED OVER THE CENTRAL CARIBBEAN AS THE WAVE PASSES BENEATH
AN UPPER RIDGE WHICH IS ENHANCING SCATTERED MODERATE/STRONG
CONVECTION WITHIN 9N-13N BETWEEN 76W-80W.

TROPICAL WAVE IS ALONG 85W S OF 16N MOVING W 10-15 KT.
WELL-DEFINED LOW/MID LEVEL INVERTED-V SATELLITE SIGNATURE IS
OBSERVED IN THE E PACIFIC REGION AS THE N PORTION IS INLAND OVER
CENTRAL AMERICA. WAVE IS BENEATH THE WESTERN EDGE OF AN UPPER
RIDGE WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
13N-16N BETWEEN 82W-84W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N10W 6N16W 14N37W 9N56W ACROSS THE
N PORTION OF SOUTH AMERICA AND THE S CARIBBEAN ALONG 11N72W INTO
THE E PACIFIC REGION NEAR 9N82W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 13N-18N BETWEEN 37W-43W.

...DISCUSSION...

GULF OF MEXICO...
BROAD DEEP LAYERED TROUGH COVERS THE E US AND THE W ATLC
ANCHORED BY AN UPPER LOW ALONG THE NE COAST COVERING THE NE
GULF N OF 25N E OF 90W WITH ASSOCIATED FRONTAL BOUNDARY IN THE W
ATLC. BROAD UPPER RIDGE EXTENDS ACROSS THE W GULF ANCHORED BY AN
UPPER HIGH ASSOCIATED WITH A HURRICANE OFF THE W COAST OF MEXICO
COVERING THE GULF W OF 90W. AN UPPER TROUGH IN THE W CARIBBEAN
IS PRODUCING ISOLATED SHOWERS ACROSS THE STRAITS OF FLORIDA S OF
24N E OF 84W. OTHERWISE THE GULF GULF REMAINS RATHER CLEAR THIS
MORNING.

CARIBBEAN SEA...
NARROW UPPER TROUGH EXTENDS FROM AN UPPER LOW JUST N OF E CUBA
ALONG 20N77W SW TO THE GULF OF HONDURAS AND CENTRAL AMERICA.
ISOLATED SHOWERS ARE FROM 20N-22N W OF 81W TO THE YUCATAN
PENINSULA. AN UPPER HIGH IS LOCATED OFF THE COAST OF COLOMBIA
NEAR 13N75W WITH A RIDGE EXTENDING W TO NEAR 16N84W ENHANCING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM OF LINE
FROM HAITI ACROSS JAMAICA TO NE HONDURAS. AN UPPER RIDGE
ANCHORED IN THE CENTRAL ATLC IS ADVECTING DRY AIR OVER THE E
CARIBBEAN E OF 70W.

ATLANTIC OCEAN...
BROAD DEEP LAYERED TROUGH THAT COVERS THE E US AND THE NE GULF
EXTENDS INTO THE W ATLC N OF 25N W OF 75W AND IS ANCHORED BY AN
UPPER LOW ALONG THE NE US COAST WITH THE ASSOCIATED FRONTAL
BOUNDARY EXTENDING INTO THE W ATLC FROM A 1010 MB LOW N OF THE
REGION THROUGH 32N72W TO THE UPPER FLORIDA KEYS.SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 22N-28N BETWEEN 77W-80W
AND WITHIN 60 NM E OF THE FRONT FROM 27N-30N. NARROW UPPER
TROUGH EXTENDS FROM 28N66W TO AN UPPER LOW BETWEEN THE BAHAMAS
AND E CUBA NEAR 22N75W CONTINUING INTO THE W CARIBBEAN. SURFACE
TROUGH EXTENDS FROM 31N66W TO THE CENTRAL BAHAMAS NEAR 25N76W
GENERATING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 90 NM OF
THE SURFACE TROUGH. BROAD UPPER RIDGE COVERS THE W/CENTRAL ATLC
ANCHORED NEAR 22N58W COVERING THE AREA S OF 26N FROM 50W-71W.
TROPICAL MOISTURE IS BEING DRAWN N OF HAITI TO GENERATE AN AREA
OF SCATTERED SHOWERS S OF 23N TO OVER HAITI FROM 72W-74W. GORDON
REMAINS N OF THIS UPPER RIDGE. AN UPPER TROUGH IS TO THE E OF
GORDON N OF 24N FROM 28W-43W BUT IS A RATHER BENIGN FEATURE AND
NOT PRODUCING ANY SHOWER ACTIVITY. AN UPPER HIGH ASSOCIATED WITH
TROPICAL STORM HELENE COVERS THE SE TROPICAL ATLC WITH AN UPPER
LOW TO THE E CENTERED N OF THE CAPE VERDE ISLANDS NEAR 20N24W
COVERING THE AREA FROM 15N-24N BETWEEN 19W-28W. THE SUBTROPICAL
RIDGE IS ONCE AGAIN SPREADING W OVER THE ATLC IN SPITE OF THE
PRESENCE OF HURRICANE GORDON. AN AREA OF AFRICAN DUST COVERS THE
W TROPICAL ATLC AND E CARIBBEAN S OF 23N FROM 50W-72W.

$$
WALLACE





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