11 P.M. DISC. -- NICK TRACK ADJUSTED TO LEFT........

[dixiebreeze]

Tropical Storm Nicholas Discussion Number 14


Statement as of 11:00 PM EDT on October 16, 2003



although the center is impossible to locate on IR or night-vis
imagery...there is evidence that the Nicholas has been moving to
the left of the previous forecast track. Analysis of the 21z
Quikscat ambiguities strongly indicates that the center is not
underneath the deep convection...but rather is near or beyond its
southwest edge. A microwave pass...also at 21z...is consistent
with this location. If this analysis is correct...then the
southwesterly shear is re-asserting itself and Nicholas is not as
well organized as it was earlier. The initial motion is estimated
to be 300/8 and the initial intensity is held at 55 kt.
The global models...particularly the GFS...suggest that
southwesterly shear is going to be an issue for Nicholas over the
next several days...and how the cyclone responds to the shear will
determine both the intensity and the track. The shear should be
lowest over the next 48 hours...and so the official forecast still
shows Nicholas reaching hurricane strength. However... towards the
end of the forecast period stronger westerlies are likely to either
take a stronger system on a more northerly track...or leave a
sheared system behind on a more westerly path. The former option
is represented by the GFDL...while the latter by the shallow and
medium BAM and the GFS. It is quite possible that Nicholas will
oscillate between a west-northwest and north-northwest track with
short-term variations in the shear and deep convection. The
official forecast has been adjusted a little to the left of the
previous track by virtue of the shift in the initial position...but
is otherwise similar. Confidence in this forecast... especially by
days 4 and 5...is not real high.

Forecaster Franklin