[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170007
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...
HURRICANE GORDON IS CENTERED NEAR 31.7N 54.0W OR ABOUT 635
MILES...1020 KM...EAST OF BERMUDA AT 16/2100 UTC AND IS MOVING
NORTH-NORTHWEST AT 3 KT. 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 REMAINS IN A WEAK
STEERING ENVIRONMENT AND HAS CHANGED LITTLE TODAY. THE CYCLONE
IS FAIRLY SYMMETRIC WITH A RAGGED EYE ABOUT 15 NM IN DIAMETER.
GORDON HAS BEEN A COMPACT SYSTEM THROUGHOUT ITS LIFE WITH ITS
RAIN FIELD COVERING A SMALL AREA OF LESS THAN 300 NM ACROSS.
SCATTERED MODERATE CONVECTION IS FROM 30N-34N BETWEEN 52W-56W.

HURRICANE HELENE IS CENTERED NEAR 19.3N 46.3W OR ABOUT 1145
MILES...1845 KM...EAST OF THE NORTHERN LEEWARD ISLANDS AT
16/2100 MOVING NORTHWEST AT 11 KT. 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 MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HELENE
IN CONTRAST TO GORDON IS A LARGE SYSTEM WITH GOOD OUTFLOW IN ALL
QUADRANTS. NUMEROUS STRONG CONVECTION IS NEAR THE CENTER FROM
17N-20N BETWEEN 45W-48W.  SCATTERED MODERATE CONVECTION EXTENDS
FROM 16N-22N BETWEEN 41W-50W.

...TROPICAL WAVES AND TROPICAL LOWS...
A 1010 MB LOW IS IN THE E ATLANTIC CENTERED NEAR 16N21W...ABOUT
115 NM E OF THE CAPE VERDE ISLANDS MOVING W AT 10 KT.  NO
SIGNIFICANT CONVECTION IS NOTED.

TROPICAL WAVE IS ALONG 79W S OF 17N MOVING W AT 12 KT. SOME
LOW-MID LEVEL CYCLONIC TURNING IS NOTED ON SATELLITE IMAGERY.
A FAIRLY LARGE AREA OF DEEP CONVECTION IS IN THE SW CARIBBEAN
AHEAD OF THE ANALYZED AXIS FROM 10N-20N BETWEEN 80W-86W.

TROPICAL WAVE IS OVER CENTRAL AMERICA ALONG 87W S OF 16N MOVING
W AT 10 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.  PATCHES OF SCATTERED MODERATE
CONVECTION ARE FROM 9N-17N BETWEEN 86W-91W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N11W 9N30W 17N40W 15N48W 10N53W
9N60W. SCATTERED MODERATE SHOWERS ARE WITHIN 90 NM OF THE ITCZ.

...DISCUSSION...

GULF OF MEXICO...
A WEAK 1016 MB HIGH IS OVER THE NE GULF OF MEXICO NEAR 28N88W.
WINDS ARE 5-10 KT AROUND THE HIGH.  WIDELY SCATTERED MODERATE
CONVECTION IS OVER SOUTH FLORIDA FROM 25N-27N BETWEEN 80W-82W.
ISOLATED MODERATE CONVECTION IS ALONG THE COAST OF LOUISIANA
FROM 28N-32N BETWEEN 89W-94W.  IN THE UPPER LEVELS...A RIDGE IS
OVER MEXICO AND THE GULF OF MEXICO.  EXPECT LOW LEVEL RETURN
FLOW AND A NEW COLD FRONT OVER TEXAS TO PRODUCE CONVECTION OVER
TEXAS...AND THE W GULF OF MEXICO WITHIN 24 HOURS.

CARIBBEAN SEA...
TWO TROPICAL WAVES ARE TRAVERSING THE CARIBBEAN SEA PRODUCING
CONVECTION W OF 80W... SEE ABOVE.  FAIR WEATHER AND AFRICAN DUST
IS OVER THE E CARIBBEAN E OF 75W MOVING W.  ELSEWHERE...
SCATTERED MODERATE CONVECTION REMAINS OVER INLAND CUBA BETWEEN
75W-84W.  SIMILAR CONVECTION IS OVER THE YUCATAN PENINSULA FROM
19N-22N BETWEEN 88W-90W.  IN THE UPPER LEVELS... AN UPPER LEVEL
HIGH IS CENTERED S OF JAMAICA NEAR 15N78W.  DIFFLUENCE FROM THIS
HIGH IS ENHANCING THE CONVECTION OVER THE W CARIBBEAN AND
CENTRAL AMERICA.  EXPECT...THE TROPICAL WAVES TO MOVE W WITH
CONVECTION DURING THE NEXT 24 HOURS.  THE E CARIBBEAN SHOULD
CONTINUE TO HAVE FAIR WEATHER.

ATLANTIC OCEAN...
A SLOW MOVING COLD FRONT IS OVER THE W ATLANTIC ALONG 32N69W
26N80W.  ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE
FRONT.  A PREFRONTAL TROUGH IS ALONG 32N66W 26N73W 24N80W.
ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE TROUGH. A
1018 MB HIGH IS N OF THE LEEWARD ISLANDS NEAR 25N61W.  HURRICANE
GORDON IS FURTHER E OVER THE CENTRAL ATLANTIC...SEE ABOVE.  A
DOMINATE 1022 MB HIGH IS OVER THE E ATLANTIC NEAR 34N21W.  IN
THE UPPER LEVELS... A TROUGH IS OVER THE W ATLANTIC N OF 25N W
OF 70W.  AN UPPER LEVEL HIGH IS NE OF THE LEEWARD ISLANDS NEAR
21N63W.  GOOD UPPER LEVEL OUTFLOW IS OVER HURRICANE GORDON.  A
TROUGH IS OVER THE CENTRAL ATLANTIC N OF 20N BETWEEN 20W-40W.  A
RIDGE IS OVER W AFRICA N OF 20N AND E OF 20W.  HURRICANE HELENE
ALSO HAS GOOD UPPER LEVEL OUTFLOW.

$$
FORMOSA


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