11 PM JEANNE DISCUSSION...

[yoda]

Tropical Storm Jeanne Discussion Number 10


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



the initial motion estimate is 295/8. Jeanne has actually been
moving due west along the northwestern coast of Puerto Rico for the
past 4-5 hours...but a more representative 12-hour motion is 295
degrees. Once Jeanne clears the terrain effects of the western end
of Puerto Rico...it should begin moving back toward the
west-northwest. This motion...however...could bring Jeanne near the
northern coast of the Dominican Republic on Thursday. In the longer
term...the subtropical ridge to north of Jeanne is expected to
remain intact through at 72-96 hours. After that...the models
diverge widely on how and if the ridge erodes due to Ivan stalling
over the southeast U.S. The GFS has been verifying the best with
the upper-level flow pattern the past 48 hours...and it maintains
more ridging to the north of Jeanne at 120 hours. Whether Ivan
moves northeastward or turns back southwestward like most of the
global models are suggesting...some ridging should be maintained
between the two systems...especially since Jeanne is expected to
remain a small circulation. The official forecast track was shifted
a little to the left of the previous forecast track owing to the
more westward initial position...and the speed was decreased after
96 hours similar to the GFS model.

Jeanne has a well-defined inner-core circulation and a well-defined
eye has even appeared in satellite imagery. If Jeanne was not
interacting with the high terrain of Puerto Rico...it likely would
be a hurricane. Given the impressive structure in both radar and
satellite data...Jeanne is forecast to quickly become a hurricane
over the Mona Passage. In the medium range...possible interaction
with Hispaniola and moderate northerly vertical shear should
inhibit the intensification process. Afterwards...though...the
upper-level flow pattern is forecast to become quite favorable and
steady intensification is expected.

Forecaster Stewart

forecast positions and Max winds

initial 16/0300z 18.5n 67.3w 55 kt
12hr VT 16/1200z 19.0n 68.7w 65 kt
24hr VT 17/0000z 20.0n 70.4w 65 kt
36hr VT 17/1200z 20.9n 72.0w 65 kt
48hr VT 18/0000z 22.0n 73.6w 70 kt
72hr VT 19/0000z 23.6n 75.3w 75 kt
96hr VT 20/0000z 26.0n 77.0w 80 kt
120hr VT 21/0000z 28.5n 78.0w 90 kt