Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
318 AM EDT Mon Jun 22 2020
Valid Jun 22/0000 UTC thru Jun 25/1200 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
00Z Model Evaluation Including Preferences and Forecast Confidence
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Closed low over Manitoba/Ontario
Shortwaves crossing the Plains
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Preference: Day 1: general model blend
Day 2: non-GFS
Day 3: ECMWF/UKMET
Confidence: Average
Large closed upper level low over Manitoba will settle over the
northern Great Lakes by the end of the period with several
shortwave troughs and convective complexes expected over the
Plains. The models show fairly good agreement with the large scale
upper level pattern but differ somewhat with the surface fronts
and associated low positions for day 2/3, where the GFS is to the
south and slower with its low position during day 2 and by day 3,
the UKMET/ECMWF becomes more favored as the NAM/GFS show higher
spread compared to the model consensus.
Troughs approaching British Columbia and Pacific Northwest
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Preference: General model blend
Confidence: Average
07Z update: The 00Z ECMWF trended much more favorably and toward
the GFS/UKMET solutions with a more ampoflied shortwave trough
moving through the region on day 3. Although it remains the faster
solution, the spread is significantly less and fits the expected
pattern better, so the model blend preference was updated to
include a general model blend of the available deterministic
guidance.
---previous discussion---
A pair of shortwave troughs will approach the Pacific Northwest
over the next couple of days, the first impacting mainly British
Columbia Monday. A second, stronger shortwave trough digs across
the Pacific Northwest mid-week where the are some model
differences. The 21.12Z ECMWF is faster and flatter with its upper
level wave across the northern Rockies in the 60-84 hour range,
which seems a bit of an outlier compared to the est of the
guidance and the ensemble means. The 21.00Z ECMWF showed more
similarity to the GFS/UKMET/CMC models, so it could be considered
more useful. The incoming 00Z guidance will show whether the 12Z
ECMWF is a true outlier or the beginning of a trend, but for now
will lean on a non-ECMWF blend.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Taylor