[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211043
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU SEP 21 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 HELENE IS CENTERED NEAR 28.4N 56.8W OR ABOUT 478 MILES
EAST-SOUTHEAST OF BERMUDA AT 21/0900 UTC MOVING NORTH AT 11 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 964 MB. MAXIMUM SUSTAINED
WIND SPEED IS 80 KT WITH GUSTS TO 100 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
COVERS THE AREA FROM 27N-30N BETWEEN 55W-58W. DENSE OVERCAST
CLOUDS COVERS A MUCH LARGER AREA FROM 26N-33N BETWEEN 53W-62W.

...TROPICAL WAVES...
TROPICAL WAVE IS W OF THE CAPE VERDE ISLANDS ALONG 33W S OF 19N
MOVING W 15-20 KT. BROAD MID LEVEL INVERTED-V CURVATURE WITH A
LARGE AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 13N-19N BETWEEN 26W-37W.

TROPICAL WAVE IS ALONG 48W/49W S OF 18N MOVING W 15 KT.
INVERTED-V SIGNATURE WITH SCATTERED MODERATE/ISOLATED STRONG
CONVECTION E OF THE WAVE AXIS WITHIN 60 NM OF LINE
13N42W-16N45W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N14W 11N23W 13N31W 12N40W 14N51W
11N62W ACROSS N PORTION OF SOUTH AMERICA AND PANAMA INTO THE E
PACIFIC REGION NEAR 9N83W. SCATTERED CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 6N-15N E OF 27W TO
THE COAST OF AFRICA AND FROM 8N-13N BETWEEN 33W-38W.

...DISCUSSION...
GULF OF MEXICO...
BROAD UPPER RIDGE ANCHORED ALONG THE W COAST OF MEXICO COVERS
ALL OF MEXICO WITH A RIDGE AXIS EXTENDING NE MOVING JUST E OF
THE MISSISSIPPI VALLEY AND A SECOND RIDGE AXIS EXTENDING E OVER
THE GULF ALONG 24N TO 86W. DEEP LAYER TROUGH OVER THE FAR E US
AND THE W ATLC EXTENDS S OVER THE E GULF N OF 24N E OF 85W WITH
THE ASSOCIATED STATIONARY FRONT ENTERING THE GULF OVER S FLORIDA
NEAR LAKE OKEECHOBEE TO 26N86W WHERE IT BEGINS TO DISSIPATE
ACROSS THE REMAINDER OF THE GULF. ISOLATED SHOWERS ARE WITHIN 90
NM OF THE FRONTAL BOUNDARY. DIFFLUENCE OVER THE BAY OF CAMPECHE
IS GENERATING SCATTERED SHOWERS/THUNDERSTORMS S OF 20N TO INLAND
OVER S MEXICO FROM 92W-95W.

CARIBBEAN SEA...
AN UPPER LOW IS IN THE W CARIBBEAN NEAR 18N83W WITH A TROUGH
EXTENDING TO CENTRAL CUBA NEAR NEAR 23N80W AND SW TO OVER
HONDURAS NEAR 15N86W. THIS IS GENERATING SCATTERED SHOWERS/
THUNDERSTORMS OFF THE COAST OF NICARAGUA FROM 13N-16N BETWEEN
77W-83W. UPPER HIGH COVERS THE REMAINDER OF THE CARIBBEAN
ANCHORED JUST S OF HAITI NEAR 17N74W THUS LEAVING THE CARIBBEAN
E OF 77W DRY THIS MORNING.

ATLANTIC OCEAN...
BROAD UPPER TROUGH OVER THE FAR E US AND THE GULF OF MEXICO
COVERS THE W ATLC N OF A LINE FROM FLORIDA NEAR 25N80W TO BEYOND
32N70W WITH THE ASSOCIATED COLD FRONT ENTERING THE AREA NEAR
32N69W SW TO THE BAHAMAS NEAR 27N78W WHERE IT PULLS UP
STATIONARY ACROSS FLORIDA INTO THE GULF OF MEXICO NEAR LAKE
OKEECHOBEE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN
90 NM E OF THE COLD FRONT N OF 28N. AN UPPER RIDGE IS ANCHORED E
THE BAHAMAS NEAR 24N70W EXTENDING A RIDGE AXIS NE TO BEYOND
32N67W. UPPER HIGH ASSOCIATED WITH HURRICANE HELENE COVERS AN
AREA FROM 23N-40N BETWEEN 50W-64W. NARROWING CUT-OFF UPPER LOW E
OF HELENE IS BEING COMPRESSED BY THE UPPER HIGH OFF THE COAST OF
AFRICA AND IS CENTERED NEAR 22N38W EXTENDING A TROUGH AXIS NE/SW
FROM 27N33W-19N42W. UPPER HIGH ANCHORED NE THE CAPE VERDE
ISLANDS NEAR 19N20W COVERS THE REMAINDER OF THE E ATLC. AT THE
SURFACE...A 1022 MB HIGH IS LOCATED NEAR 29N41W WITH A RIDGE
EXTENDING S TO 20N FROM 20W-50W. THIS AREA REMAINS VERY DRY THIS
MORNING.

$$
WALLACE






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