PREDICT Ensemble Discussion
Posted by JAC on 9/4/2010, 8:45 am
PREDICT Ensemble Discussion

Date(UTC): 2010/09/04 11:50
Author: Ryan Torn
Submitted at(UTC): 2010/09/04 12:15
Current Conditions/Review of Yesterday's Forecast:

****** IMPORTANT NOTE: Due to computer problems at NCAR on
Friday night, there will not be any ensemble forecasts for 4
September.  Hopefully, the issues will be rectified by the time
the 0000 UTC 5 September forecasts are started.  The following
discussion uses the 1200 UTC forecast from yesterday.

The remnants of Gaston (PGI38L) continue to drift westward.  The
ensemble has done a fairly good job with developing the system
fairly slow, rather then being aggressive making a TS out of
this system.  In addition, it has also done a good job with the
slow movement of this system.  The ensemble appears to be
initializing the system in the correct location.  INVEST99
(PGI39L) has also been handled well by the ensemble and is being
initialized in the correct position.  PGI40L is right on the
edge of the domain, thus I am hesitant to put too much faith in
forecast of this system.
DAY 1 (Next 24 hours) Outlook:

For most ensemble members, the circulation and thickness
anomalies do not change much over the first 24 hours of the
forecast.  Most of the position variance is oriented a little N
of E-W.  The stronger members tend to be moving faster.
INVEST99 also shows little change in intensity, with all members
below genesis criteria.  The position variance is oriented SW-NE
and the stronger members are to the SW.  PGI40L shows very small
circulation and OW values throughout this period.
DAY 2 (24 - 48 hours) Outlook:

Gaston shows a very small increase in circulation and thickness
during this period, with some of the extreme ensemble members
now approaching genesis criteria.  Interestingly, the minimum
SLP is falling in all members, which could suggest that genesis
is happening.  The position variance is still oriented E-W,
though there is no pattern in intensity.  INVEST99's circulation
and thickness anomaly values are decreasing steadily during this
period.  The position variance is scattered uniformly about the
ensemble-mean position north of the Cape Verde Islands.  PGI40L
is difficult to track in nearly all ensemble members.
Extended Outlook:

Gaston is still slowing intensifying in MSLP, circulation and
thickness anomaly.  It is still mostly the extreme members that
are indicating genesis has happened, though the ensemble mean is
creeping toward the criteria values.  The position variance is
stretched in the E-W direction.  It appears that INVEST99 is
weakening to the point where it is getting difficult to track
the system.  PGI40L is also difficult to track in nearly all
ensemble members.
97
In this thread:
Gaston gathering tonight - Jake, 9/3/2010, 11:39 pm
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