Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1259 PM EDT Sat Mar 14 2020
Valid Mar 14/1200 UTC thru Mar 18/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z Final Model Evaluation with Final Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...Overview of systems affecting the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Slightly above average
The upper pattern across the lower 48 will be quasi-amplified in
the short range with highly meridional flow along the west coast
of North America and zonal flow over the eastern 2/3 of the
nation...at least early on. By Monday, a longwave trough will
begin to sweep across the north-central U.S./Great Lakes region
into the middle of the week.
There were some minor differences with a strong closed low
dropping south along the West Coast with the 12Z NAM/GFS stronger
with the 850-500 mb low compared to the 00Z ECMWF/UKMET/CMC. The
ensemble means split the difference in strength. By Monday
evening, minor timing differences arise with the 12Z NAM fastest
with a lobe of energy into the Southwest, bringing the closed low
to the east faster than a strong majority of guidance. However by
Tuesday evening, the differences in timing are reduced and so a
general model blend appears reasonable for this system with
perhaps less 12Z NAM influence Monday into Tuesday.
Up north, the 12Z GFS continues to be slightly faster with a
longwave trough and associated cold front through the northern
U.S. The 00Z ECMWF/UKMET catch up with the 12Z GFS by later Monday
though with perhaps the 12Z NAM and 00Z CMC looking a bit slow.
The differences in timing are more of an impact to Ontario and
Quebec with resulting impacts across the U.S. relatively minor.
Other systems affecting the lower 48, including a weakening
shortwave across the Mississippi River Valley today and a frontal
boundary across the southern U.S. show rather good agreement with
model mass fields, supporting a general model blend.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Otto