TROPICAL WEATHER DISCUSSION

[AussieMark]

000
AXNT20 KNHC 190600
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI 19 SEP 2003

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...AND ATLANTIC OCEAN
TO THE AFRICAN COAST FROM THE EQUATOR TO 32N INCLUDING NORTHERN
SECTIONS OF SOUTH AMERICA. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY... WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

SPECIAL FEATURE...
HURRICANE ISABEL WAS DOWNGRADED TO TROPICAL STORM AT 19/0300 UTC
AND IS CENTERED NEAR 37.7N 78.0W AT 19/0300 UTC MOVING NNW AT 20
KT. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 972 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. ISABEL IS RAPIDLY WEAKENING AND SHOULD BECOME
EXTRATROPICAL IN THE NEXT COUPLE OF DAYS. ALL ASSOCIATED DEEP
CONVECTION IS INLAND OVER THE NE UNITED STATES WITH BANDS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM OF 69W
FROM 33N TO 38N.

TROPICAL WAVES/ITCZ...
TROPICAL WAVE IS ALONG 23W S OF 20N WITH A 1011 MB LOW ALONG THE
WAVE NEAR 14N MOVING W 10 KT. SCATTERED MODERATE/STRONG
CONVECTION IS WITHIN A 60 NM RADIUS OF 16N20.5W. CLUSTERS OF
SIMILAR CONVECTION ARE WITHIN 45/60 NM OF A LINE FROM 18N20W TO
14N29W.

TROPICAL WAVE IS ALONG 49W S OF 20N WITH A 1010 MB LOW ALONG THE
WAVE NEAR 13N MOVING W 5-10 KT. LARGE CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 10N TO 18N BETWEEN
41W AND 58W.

TROPICAL WAVE IS ALONG 73W/74W S OF 20N MOVING W 10 KT. WAVE IS
OBSCURED BY HIGH CLOUDS WITH NO ASSOCIATED DEEP CONVECTION.

AXIS OF ITCZ-RELATED CLOUDS/CONVECTION IS CENTERED ALONG 6N10W
8N20W 6N30W 9N43W 9N61W. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 120 NM OF THE AXIS FROM 41W TO 46W.
CLUSTERS OF SCATTERED MODERATE TO SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE WITHIN 90 NM OF THE AXIS E OF 17W TO
INLAND OVER AFRICA AND FROM 22W TO 30W.

MIDDLE/UPPER LEVEL SYNOPTIC FEATURES...
BROAD ANTICYCLONIC FLOW COVERS THE W GULF OF MEXICO S OF 32N W
OF 87W WITH A RIDGE AXIS EXTENDING ACROSS MEXICO NEAR 22N100W TO
31N87W. THIS IS BRINGING PACIFIC MOISTURE ACROSS MEXICO INTO THE
W GULF.

SHORTWAVE TROUGH NOW EXTENDS FROM OVER THE W ATLANTIC NEAR
32N80W S ALONG 23N82W TO OVER THE NW CARIBBEAN TO NEAR 15N88W.
CYCLONIC FLOW IS WITHIN 200 NM OF THE AXIS. STRONG SUBSIDENCE IS
FROM 29N TO JUST S OF OF THE OUTFLOW FROM ISABEL NEAR 34N
BETWEEN 75W AND 83W. WEAK/MODERATE SUBSIDENCE IS WITHIN 220 NM
OF A LINE FROM 29N81W TO 16N88W INCLUDING THE FLORIDA AND
YUCATAN PENINSULAS.

RIDGE AXIS EXTENDS FROM 23N71W TO BEYOND 32N69W WITH
ANTICYCLONIC FLOW FROM 66W TO 75W.

ANTICYCLONIC FLOW COVERS THE S CARIBBEAN S OF 15N W OF 66W TO
OVER CENTRAL AMERICA.

TROUGH AXIS IN THE CENTRAL/WESTERN ATLANTIC EXTENDS FROM A
WEAKENING CYCLONIC CIRCULATION NEAR 34N44W SW ALONG 30N53W TO A
SECOND STRONGER CYCLONIC CIRCULATION CENTERED NEAR 23N59W TO
12N61W IN THE W TROPICAL ATLANTIC. CYCLONIC FLOW IS WITHIN
250/300 NM OF THE AXIS. MODERATE SUBSIDENCE IS FROM 27N TO 31N
BETWEEN 58W AND 66W.

RIDGE AXIS EXTENDS ALONG 18N E OF 45W TO INLAND OVER AFRICA WITH
ANTICYCLONIC FLOW S OF 26N. STRONG SUBSIDENCE IS FROM 10N TO 23N
BETWEEN 26W AND 40W. MODERATE/STRONG SUBSIDENCE IS FROM 19N TO
23N E OF 26W TO INLAND OVER AFRICA.

TROUGH IS OVER THE NE ATLANTIC N OF 27N FROM 15W TO 34W.

SURFACE SYNOPTIC FEATURES...
SURFACE TROUGH EXTENDS INTO THE REGION IN THE W ATLANTIC NEAR
32N77W S TO 29N78W THEN SW ACROSS CENTRAL FLORIDA NEAR 27N81W TO
23N90W IN THE CENTRAL GULF OF MEXICO.

HIGH PRESSURE COVERS THE CENTRAL/WESTERN ATLANTIC N OF 20N E OF
70W WITH A RIDGE AXIS EXTENDING THROUGH 32N47W ESE ALONG 27N36W
THEN E TO 29N15W.

SIGNIFICANT CLOUDS/CONVECTION...
GULF OF MEXICO...
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 24N TO 27N
W OF 93W TO INLAND OVER MEXICO AND FAR S TEXAS. BROKEN/OVERCAST
MID/HIGH CLOUDS COVERS THE NW GULF N OF 23N W OF 90W.

CARIBBEAN SEA...
SCATTERED MODERATE/STRONG CONVECTION IS INLAND OVER VENEZUELA
AND LAKE MARACAIBO. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS S OF 13N TO INLAND OVER COLOMBIA FROM 70W TO 74W
INCLUDING THE GULF OF VENEZUELA. CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE FROM 18N TO INLAND OVER CUBA FROM 73W
TO 79W INCLUDING THE S PENINSULA OF HAITI. ISOLATED SHOWERS ARE
N OF 16N TO OVER THE DOMINICAN REPUBLIC FROM 67W TO 72W.
BROKEN/OVERCAST MID/HIGH CLOUDS WITH SCATTERED SHOWERS COVERS
THE S CARIBBEAN S OF 14N W OF 73W.

TROPICAL ATLANTIC...
SEE TROPICAL WAVES ABOVE. SCATTERED MODERATE CONVECTION IS
WITHIN 90 NM OF A LINE FROM 17N57W TO 22N55W.

SUBTROPICAL ATLANTIC...
ISOLATED SHOWERS ARE FROM 20N TO 27N BETWEEN 47W AND 67W.

$$
WALLACE