Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1154 PM EST Thu Feb 27 2020
Valid Feb 28/0000 UTC thru Mar 02/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00z NAM/GFS Evaluation w/Model Preferences & Forecast Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS initialization errors do not seem to degrade their short
range forecasts.
System slowly pulling away from the Northeast through Sunday
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The guidance shows good agreement here, so prefer a compromise of
the 12z Canadian, 12z UKMET, 12z ECMWF, 00z NAM, and 00z GFS with
above average confidence.
System moving through southern Canada & its trailing front
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Closest to the 12z Canadian
Confidence: Slightly above average
The guidance shows spread with this system's progression, with the
12z ECMWF the sharpest/slowest aloft while the 00z GFS is the
quickest/broadest aloft. This system is moving through an
increasingly zonal flow pattern aloft, which argues against the
amplified ECMWF. The GFS can be speedy with systems in the
Westerlies, but that can't be ruled out in an increasingly zonal
flow pattern. The 12z Canadian makes for a nice compromise
solution here and is preferred with slightly above average
confidence.
System dropping down the West Coast Sunday & Monday
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Closest to the 12z UKMET
Confidence: Average
By Sunday, the 12z Canadian ends up more westward with this system
than the other guidance, a bias it sometimes displays with
amplified systems aloft. The general flow pattern doesn't rule
this out, as a northern stream ridge builds in the wake of the
system moving just north of the US/Canadian border which would
lead to a southward moving system near the West Coast. For now,
prefer a compromise of the available guidance, which wouldn't be
as far west as the Canadian and closest to the 12z UKMET, with
average confidence.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Roth