11 PM IVAN DISCUSSION...

[yoda]

Hurricane Ivan Discussion Number 55


Statement as of 11:00 PM EDT on September 15, 2004


The eye remains well-defined on satellite images...but on the mobile
WSR-88D radar...there has been an erosion of the southwest
eyewall. Also...the NOAA plane reported that the eyewall was open
to the southwest. GPS dropsonde data at 200 mb from this evening's
NOAA G-IV jet mission do not suggest much vertical shear in the
environment of Ivan...although there is some westerly flow into the
hurricane at 250 and 300 mb. No large changes in strength are
likely until the center reaches the coast...and Ivan is expected to
make landfall as a major hurricane.
Over the last few hours the motion has been slightly east of
north...about 010/010. Because of this slight eastward shift in
heading...the track has been adjusted slightly to the right. This
remains close to the consensus of the track models as well as the
latest FSU superensemble run.
Since Ivan is so large and intense...it is expected to bring
hurricane force winds well inland...up to about 150 miles along its
track. Note that the inland gust factor is quite large because
high momentum air...aloft...can be brought to the surface in the
convective cells. Later in the period...the dynamical models show
the forward progress of Ivan being blocked. Therefore the official
forecast shows Ivan stalling near the southern Appalachians and
slowly dissipating in that area. Obviously this could be a major
flood event over portions of the southeastern U.S. In the coming
days.

Forecaster Pasch

forecast positions and Max winds

initial 16/0300z 29.3n 88.1w 115 kt
12hr VT 16/1200z 31.0n 87.9w 110 kt...inland
24hr VT 17/0000z 33.0n 87.2w 60 kt...inland
36hr VT 17/1200z 34.5n 86.5w 30 kt...inland
48hr VT 18/0000z 35.5n 85.5w 25 kt...inland
72hr VT 19/0000z 36.0n 84.0w 20 kt...inland
96hr VT 20/0000z 36.0n 84.0w 20 kt...dissipating
120hr VT 21/0000z...dissipated

[Windy]

Interesting... no mention of the dry air entrainment.

Looks like a hellish scenario for the Appalacians, though. Mountains + 12 inches of rain is pretty horrible. Flash floods out there are going to be INCREDIBLE.

[Anonymous]

The area over which Ivan stalls will receive 20 to 30 inches of rain, especially if it's over mountainous terrain. There could be locally higher rainfall accumulations.

Ivan is already spawning numerous tornadoes. I hope Ivan is not going to generate a ton of 'naders like Frances did.

[Stormsfury]

The area over which Ivan stalls will receive 20 to 30 inches of rain, especially if it's over mountainous terrain. There could be locally higher rainfall accumulations.

Ivan is already spawning numerous tornadoes. I hope Ivan is not going to generate a ton of 'naders like Frances did.

Unfortunately, the grounds are still overly saturated from Frances a week and a half ago in the Appalachains, and a stalling Ivan could produce a BIBLICAL type flood should 20"-30" of rain falls ...

The potential is there ... strong upglide and upslope on SE winds, training bands which will remain nearly stationary with a complete stall of Ivan, and shear parameters are progged to keep a very pronounced and prolonged threat of tornadoes ... and could rival or even surpass what we saw in Frances ... already 45 tornado warnings have been issued just today, mostly in Florida ...

SF