Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
232 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
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...Overview of systems affecting the CONUS...
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Preference: General model blend
Confidence: Slightly above average
...19Z update...
Only minor changes were noted with the 12Z ECMWF/UKMET/CMC
compared to their previous 00Z cycles. The 12Z ECMWF/UKMET/CMC
adjusted slightly stronger and in some cases a nudge faster with
the closed low dropping down the West Coast. The 12Z NAM continues
to appear fastest on Monday and should be given less weight for
that time period while a general model blend appears reasonable
across the remainder of the country.
...previous discussion follows...
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