5pm Discussion

[ericinmia]

Frances has continued to strengthen while maintaining a 20 nmi
diameter eye. The initial intensity is set at 115 kt based on a
Dvorak intensity estimate of t6.0...or 115 kt...from both TAFB and
SAB...a 3-hr average ODT of t5.9...or 113 kt...a 2.5-hr average ODT
of t6.0...and a subsequent increase in the Dvorak data T-number to
t6.5...or 127 kt...since the 18z satellite estimates were made.
Based on this information...Frances is now a category 4 hurricane
on the Saffir-Simpson hurricane scale.

The initial motion is 305/08. Frances remains on track and appears
to be making a turn back toward the west-northwest. Otherwise...
there is no change to the previous track forecasts or reasonings.
Most of the NHC model guidance agrees on gradually building the
subtropical ridge westward to the north of Frances throughout the
forecast period. The NHC running track errors through 28/18z are
44...71...and 104 nmi at 24-...48-...and 72-hr...respectively.
These errors are half our average errors...and are better than all
of the computer models...including the consensus models. Therefore
...We have a fair degree of confidence in our forecast track...which
remains between the GFS model to the south and the UKMET model to
the north. The NOGAPS model has been by far the worse performing
model with its strong right of track bias...so it was ignored for
this package. While our current forecast errors are quite good...
there is still enough uncertainty in the longer time periods to make
it too early to try and determine if...when...and where Frances
will make landfall. However...now would be a good time for everyone
in the southeastern U.S...the Bahamas...and the Turks and Caicos
Islands to check their hurricane preparedness plans and supplies.

Frances is embedded in a low-shear environment with excellent
outflow in all quadrants...including an outflow channel to the
north. The SSTs between 62-68w longitude are near 29c...so at least
some additional slow intensification should occur. It is possible
that Frances could even reach near-category 5 intensity at any time
during the forecast period...but a better opportunity would be
after 84 hours when the hurricane will be moving over near-30c SSTs
when a 50-60 kt northerly wind speed maximum is forecast by the GFS
...UKMET...GFDL...and NOGAPS models to dig southward along the east
side of Frances...enhancing the outflow in the eastern semicircle.

Forecaster Stewart

forecast positions and Max winds

initial 28/2100z 17.9n 52.6w 115 kt
12hr VT 29/0600z 18.7n 53.9w 120 kt
24hr VT 29/1800z 19.4n 55.8w 125 kt
36hr VT 30/0600z 20.0n 58.0w 125 kt
48hr VT 30/1800z 20.5n 60.5w 125 kt
72hr VT 31/1800z 21.3n 65.4w 125 kt
96hr VT 01/1800z 22.5n 70.5w 125 kt
120hr VT 02/1800z 24.0n 75.5w 125 kt

[wx247]

Wow. That is basically all I can say!

[Pebbles]

WOW that was an extremely interesting discussion! Prep time for those of you listed.....

[James]

Hurricane Frances Advisory Number 16


Statement as of 5:00 PM AST on August 28, 2004


...Frances strengthens into the second category four hurricane of
the 2004 Atlantic season...

a tropical storm watch may be required for portions of the northern
Leeward Islands on Sunday.

Interests in the northern Lesser Antilles and the northeastern
Caribbean Sea should closely monitor the progress of Frances over
the next several days.

At 5 PM AST...2100z...the center of Hurricane Frances was located
near latitude 17.9 north...longitude 52.6 west or about 690
miles...1110 km...east of the northern Leeward Islands.

Frances is moving toward the northwest near 9 mph...15 km/hr. A
gradual turn back to the west-northwest is expected by tonight or
Sunday.
Maximum sustained winds are near 135 mph...215 km/hr...with higher
gusts. Conditions appear favorable for some additional strengthening
to occur during the next 24 hours...and Frances could reach near
category five intensity on Sunday.

Hurricane force winds extend outward up to 35 miles... 55 km...
from the center...and tropical storm force winds extend outward up
to 115 miles...185 km.

The estimated minimum central pressure is 948 mb...27.99 inches.

Repeating the 5 PM AST position...17.9 N... 52.6 W. Movement
toward...northwest near 9 mph. Maximum sustained
winds...135 mph. Minimum central pressure... 948 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 11 PM AST.

Forecaster Stewart


$$

[chris_fit]

Crazy

[MW98GT]

I got chills when I read the statement for everyone to be sure to have their hurricane preperations ready. It looks like they are almost definite on expecting a landfall with this beast.