11am Ivan-85 mph winds

[Brent]

Hurricane Ivan Advisory Number 12

Statement as of 11:00 am AST on September 05, 2004

...Ivan continues to strengthen while moving quickly westward...

Interests in the Lesser Antilles should monitor the progress of
Ivan.

At 11 am AST...1500z...the center of Hurricane Ivan was located near
latitude 9.9 north...longitude 46.0 west or about 1040
miles...1670 km...east of the Windward Islands.

Ivan is moving toward the west near 21 mph...33 km/hr...and a
gradual turn to the west-northwest is expected during the next 24
hours.

Maximum sustained winds have increased to near 85 mph...140
km/hr...with higher gusts. Continued strengthening is forecast
during the next 24 hours.

Hurricane force winds extend outward up to 25 miles... 35 km...
from the center...and tropical storm force winds extend outward up
to 125 miles...205 km.

Estimated minimum central pressure is 980 mb...28.94 inches.

Repeating the 11 am AST position... 9.9 N... 46.0 W. Movement
toward...west near 21 mph. Maximum sustained winds... 85 mph.
Minimum central pressure... 980 mb.

For storm information specific to your area...please monitor
products issued by your local weather office.

The next advisory will be issued by the National Hurricane Center at
5 PM AST.

Forecaster Pasch

Hurricane Ivan Discussion Number 12

Statement as of 11:00 am EDT on September 05, 2004

Ivan is strengthening rather rapidly at this time. The eye is
becoming better defined on the visible imagery and Dvorak intensity
estimates support at least 75 kt for the current intensity. This
makes Ivan the strongest tropical cyclone for such a low latitude
in the Atlantic Basin records. Cirrus outflow is well established
over all quadrants of the hurricane. All parameters seem to be in
place for Ivan to continue strengthening...and there is a high
likelihood that this will become the season's fourth major
hurricane. The official wind speed forecast is similar to the
SHIPS guidance...and it may be conservative.

The motion continues at about 280/18...and the short-term motion may
be even faster. The track forecast reasoning remains essentially
unchanged. Ivan is on the south side of a strong subtropical
ridge...a regime that is likely to continue for the next 3-4 days
and which would steer the hurricane west-northwestward over that
time span. In the 4-5 day time frame...there is of course more
uncertainty...and where Ivan winds up by the end of the period will
depend largely on the strength of the ridge to its north by that
time. The official forecast is in good agreement with the
dynamical model consensus...and in even better agreement with a
consensus that excludes the GFS...I.E. GUNS. The GFS has not been
showing a realistic solution since it weakens Ivan into a tropical
wave over the Caribbean. Given the current trend in Ivan's
intensity...such a scenario does not seem very likely at this time.
The wind radii have been adjusted a little based on a recent
Quikscat pass that covered the circulation of Ivan.

Forecaster Pasch

forecast positions and Max winds

initial 05/1500z 9.9n 46.0w 75 kt
12hr VT 06/0000z 10.6n 48.7w 80 kt
24hr VT 06/1200z 11.5n 52.3w 85 kt
36hr VT 07/0000z 12.4n 55.9w 90 kt
48hr VT 07/1200z 13.3n 59.4w 95 kt
72hr VT 08/1200z 15.0n 65.5w 105 kt
96hr VT 09/1200z 17.5n 71.0w 110 kt
120hr VT 10/1200z 20.5n 75.0w 70 kt...inland near Guantanmano Bay, Cuba

Track is farther west