[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI SEP 22 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...
HELENE IS CENTERED NEAR 35.4N 53.0W OR ABOUT 710 MILES...1140
KM...EAST-NORTHEAST OF BERMUDA AT 22/2100 UTC MOVING NORTHEAST
AT 18 KT.  ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 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 HAS WEAKENED
SLIGHTLY OVER THE LAST SEVERAL HOURS DUE TO INCREASING VERTICAL
SHEAR...DECREASING SSTS...AND DRY MIDDLE TO UPPER-LEVEL AIR
WRAPPING AROUND THE SOUTHERN SIDE OF THE CYCLONE. HELENE IS ALSO
ENTERING THE EARLY STAGES OF EXTRATROPICAL TRANSITION. SCATTERED
MODERATE CONVECTION COVERS THE AREA FROM 35N-43N BETWEEN
50W-56W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 39W/40W S OF 19N WITH A 1010 MB LOW ALONG
THE WAVE NEAR 13N MOVING W 15 KT. THIS SYSTEM HAS NOT BECOME ANY
BETTER ORGANIZED THAN YESTERDAY...BUT STILL HAS POTENTIAL FOR
SLOW DEVELOPMENT OVER THE NEXT COUPLE OF DAYS.  SCATTERED
MODERATE CONVECTION IS FROM 12N-15N BETWEEN 36W-38W...AND FROM
10N-13N BETWEEN 40W-43W.  SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS FROM 15N-20N BETWEEN 35W-40W.

TROPICAL WAVE IS ALONG 54W S OF 17N WITH A 1012 MB LOW ALONG
THE WAVE NEAR 13N MOVING W NEAR 10 KT. SOME CYCLONIC ROTATION IS
EVIDENT ON SATELLITE IMAGERY.  SCATTERED SHOWERS REMAIN FROM
10N-18N BETWEEN 53W-56W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 8N25W 13N40W 10N45W 12N53W
9N60W. APART FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...WIDELY SCATTERED MODERATE CONVECTION IS FOUND FROM 5N-8N
BETWEEN 18W-26W...AND FROM 4N-10N BETWEEN 28W-34W.

...DISCUSSION...
GULF OF MEXICO...
THE GULF OF MEXICO HAS SLY RETURN FLOW DUE TO SURFACE RIDGING.
ISOLATED MODERATE CONVECTION IS OVER S FLORIDA FROM 24N-26N
BETWEEN 80W-82W.  SIMILAR CONVECTION IS OVER W CUBA FROM 22N-23N
BETWEEN 83W-85W.  FAIR WEATHER DOMINATES THE REMAINDER OF THE
GULF.  IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS CENTERED OVER
THE SE GULF OF MEXICO NEAR 23N87W WITH STRONG SUBSIDENCE EXCEPT
NEAR THE CONVECTION MENTIONED ABOVE.  EXPECT SIMILAR CONDITIONS
OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
MODERATE TRADEWINDS ARE NOTED OVER THE CARIBBEAN SEA.  SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS MOSTLY INLAND OVER
NICARAGUA AND HONDURAS FROM 12N-16N BETWEEN 84W-87W.  SIMILAR
CONVECTION IS INLAND OVER EL SALVADOR AND GUATEMALA FROM 13N-18N
BETWEEN 88W-93W.  SCATTERED MODERATE CONVECTION IS OVER INLAND
HISPANIOLA...AND W CUBA...BETWEEN 71W-80W.  PATCHES OF SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS MOSTLY INLAND OVER NW
VENEZUELA AND N COLOMBIA FROM 8N-11N BETWEEN 70W-76W.  IN THE
UPPER LEVELS... NELY TO ELY UPPER LEVEL FLOW COVERS THE ENTIRE
CARIBBEAN SEA WITH STRONG SUBSIDENCE EXCEPT NEAR THE CONVECTION
MENTIONED ABOVE. EXPECT MORE CONVECTION OVER THE W CARIBBEAN AND
CENTRAL AMERICA OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...
A DISSIPATING COLD FRONT IS OVER THE W ATLANTIC ALONG 31N60W
29N70W 30N77W.  NO CONVECTION IS ALONG THE FRONT.  A SURFACE
TROUGH IS S OF HURRICANE HELENE ALONG 30N56W 25N60W.  SCATTERED
SHOWERS ARE WITHIN 60 NM OF THE TROUGH.  A 1023 MB HIGH IS OVER
THE CENTRAL ATLANTIC NEAR 35N36W.  IN THE UPPER LEVELS...
RIDGING IS OVER THE W ATLANTIC N OF 23N BETWEEN 65W-80W.  AN
UPPER LEVEL LOW IS CENTERED NEAR 23N58W.  ANOTHER UPPER LEVEL
LOW IS CENTERED NEAR 25N41W.  A LARGE HIGH IS CENTERED OVER THE
CAPE VERDE ISLANDS NEAR 18N25W.

$$
FORMOSA






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