[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 300551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT SEP 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

...SPECIAL FEATURES...
THE CENTER OF TROPICAL STORM ISAAC AT 30/0300 UTC IS NEAR 30.1N
57.4W MOVING WEST-NORTHWEST 7 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 995 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 60 KT
WITH GUSTS TO 75 KT. PLEASE READ THE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE
PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS.
THE CLOUD PATTERN HAS BECOME A LITTLE BETTER ORGANIZED AND MORE
TYPICAL OF A TROPICAL STORM. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS ON THE NORTHERN SEMICIRCLE FROM 30N-32N BETWEEN
56W-59W. ACCORDING TO ALL INTENSITY MODELS...ISAAC COULD BECOME
THE FIFTH HURRICANE OF THE SEASON TODAY.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 30/31W SOUTH OF 20N MOVING WEST 10 KT. A
CYCLONIC TURNING IS SEEN AT LOW LEVELS. SCATTERED SHOWERS ARE ON
THE NORTHERN END OF THE WAVE AXIS AND WITHIN THE ITCZ.

TROPICAL WAVE IS ALONG 56W SOUTH OF 14N MOVING WEST 10 KT.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE AHEAD OF THE WAVE A
AXIS FROM 10N-14N BETWEEN 56W-61W.

A TROPICAL WAVE IS OVER THE U.S VIRGIN ISLANDS ALONG 65/66W
MOVING WEST AT 10 TO 15 KT. THIS WAVE WILL MOVE ACROSS PUERTO
RICO TONIGHT REACHING DOMINICAN REPUBLIC DURING THE MORNING
HOURS. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED TO
NUMEROUS SHOWERS WITH EMBEDDED TSTMS ACROSS THE U.S VIRGIN
ISLANDS...PUERTO RICO AND COASTAL WATERS. THE HEAVIEST SHOWERS
ARE OVER THE OCEAN. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE
WAVE AXIS. THE NORTHERN END OF THE WAVE IS INTERACTING WITH AN
UPPER LOW LOCATED NEAR 22N64W. SCATTERED MODERATE CONVECTION IS
FROM 24N-26W BETWEEN 62W-64W.

A TROPICAL WAVE IS INLAND OVER CENTRAL AMERICA ALONG 90W SOUTH
OF 18N MOVING WEST 10-15 KT. THIS WAVE EXTENDS ACROSS GUATEMALA
INTO THE E PACIFIC. A CLUSTER OF MODERATE/ ISOLATED STRONG
CONVECTION IS OVER THE GULF OF FONSECA AND THE EASTERN PORTION
OF EL SALVADOR. SIMILAR CONVECTION IS ALSO FOUND ALONG THE WAVE
AXIS FROM 13N-15N AND ACROSS SOUTHERN MEXICO.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 12N28W 12N35W 11N50W 10N60W.
OUTSIDE THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...
SCATTERED MODERATE CONVECTION IS ALONG THE COAST OF W AFRICA
FROM 6N-11N EAST OF 17W. WIDELY SCATTERED MODERATE CONVECTION IS
FROM 4N-10N BETWEEN 18W-28W.

...DISCUSSION...
THE GULF OF MEXICO...
AS OF 0300 UTC...A COLD FRONT ENTERS THE AREA NEAR 31N72W THEN
CONTINUES SOUTHWESTWARD ACROSS CENTRAL FLORIDA JUST NORTH OF
LAKE OKEECHOBEE. A DYING STATIONARY FRONT EXTENDS FROM CENTRAL
FLORIDA TO SE TEXAS ALONG 27N82W 27N90W 29N95W. A NARROW LINE OF
CLOUDS WITH ISOLATED SHOWERS IS ASSOCIATED WITH THE FRONT. A
PREFRONTAL TROUGH EXTENDS FROM 30N72W TO CENTRAL CUBA NEAR
22N78W. SCATTERED MODERATE CONVECTION IS WITHIN 80/100 NM SE OF
THE FRONT FROM 25N-30N. IN THE UPPER LEVELS...THE BASE OF A
LONGWAVE TROUGH IS OVER THE GULF OF MEXICO MOVING E. THE FRONTAL
BOUNDARY WILL CONTINUE TO DISSIPATE ACROSS THE GULF. A STRONG
HIGH PRESSURE WILL BUILD OVER THE AREA BEHIND THE FRONT WITH
INCREASING EASTERLY WINDS MON THROUGH WED.

THE CARIBBEAN SEA...
MODERATE TRADEWINDS ARE BLOWING ACROSS THE BASIN. WIDELY
SCATTERED MODERATE CONVECTION IS OVER THE NW CARIBBEAN WEST OF
80W. AN UPPER HIGH IS NEAR 10N86W. A RIDGE EXTENDS NE FROM THIS
ANTICYCLONE ACROSS THE NW CARIBBEAN...CUBA AND THE BAHAMAS TO
27N68W. THIS FEATURE ALSO COVERS CENTRAL AMERICA. AN UPPER LOW
IS CENTERED OVER HISPANIOLA NEAR 18N68W. A TROUGH RUNS FROM THE
LOW TO WESTERN VENEZUELA. THE COMBINATION OF THIS TROUGH AND THE
COLOMBIAN LOW IS GENERATING CLUSTERS OF SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION OVER WESTERN VENZUELA AND NORTHERN
COLOMBIA. THE TRADE WINDS WILL SLIGHTLY INCREASE ON SUNDAY
ACROSS THE CENTRAL CARIBBEAN...SOUTH OF 15N.

THE ATLANTIC OCEAN...
A COLD FRONT IS OVER THE W ATLANTIC AND EXTENDS SW TO CENTRAL
FLORIDA MOSTLY VOID OF ALL CONVECTION. A PREFRONTAL TROUGH
EXTENDS FROM 30N72W TO CENTRAL CUBA NEAR 22N78W. A 1017 MB HIGH
IS OVER THE CAROLINAS WHILE ANOTHER ONE IS OVER SE LOUISIANA. AN
UPPER TROUGH IS ENTERING THE NW CORNER OF THE AREA SUPPORTING
THE COLD FRONT MENTIONED ABOVE. A RIDGE IS JUST SE OF THIS
TROUGH AND EXTENDS FROM A HIGH LOCATED NEAR 10N86W ACROSS CUBA
AND THE BAHAMAS. A PAIR OF UPPER LOWS ARE SEEN IN THE
EAST-CENTRAL ATLC NEAR 19N42W AND 27N32W. THERE IS A REFLECTION
OF THE WRN MOST OF THESE UPPER LOWS AT THE SURFACE AS A TROUGH
ALONG 26N42W 20N44W. AN UPPER HIGH OVER WRN AFRICA IS DOMINATING
THE MID TO UPPER LEVELS OVER THE FAR ERN ATLC. CLOUDINESS AND
ISOLATED SHOWERS COVER AN AREA FROM 20N-30N SEAT OF 34W TO THE
CANARY ISLANDS.

$$
GR



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