Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
145 PM EST Tue Jan 14 2020
Valid Jan 14/1200 UTC thru Jan 18/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation with Preferences and Forecast Confidence
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...Shortwave crossing the Great Lakes/Northeast through Wed...
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Preference: General model blend
Confidence: Above average
The low-amplitude shortwave impulse currently moving into the
Great Lakes region will cross the Northeast on Wednesday. The
guidance is in very good agreement with this system, so a general
model blend will be preferred.
...Shortwave currently over the Northwest...
...Crossing the Upper Midwest/Northeast through Wed/Thurs...
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Preference: Blend of the 12Z GFS/CMC/ECMWF
Confidence: Slightly above average
The shortwave trough moving across the Northwest around the base
of the deep upper low over southwest Canada will eject quickly
east across the northern Plains and Upper Midwest through
Wednesday, and then amplify into the Northeast on Thursday.
Surface low pressure associated with this system will cross the
Midwest and advance through New York and New England early
Thursday before deepening over the Gulf of Maine by midday
Thursday. The guidance is in good agreement until it arrives
across the Northeast where the 12Z NAM begins to edge a tad
stronger than the global models with the upper trough, and also
tends to tuck the surface low in a little closer to eastern Maine.
There is a little bit of latitudinal spread seen with the global
models as the 12Z non-NCEP guidance is a tad south of the NAM and
GFS solutions. The 12Z UKMET is overall the farthest south as the
low ejects through the Gulf of Maine. Accounting for the NAM and
UKMET solutions, the preference will be toward a blend of the GFS,
CMC and ECMWF at this time which is reasonably well supported by
the latest GEFS/ECENS means.
...Deep upper trough crossing into the West by Thurs...
...Ejecting out across the Plains/Midwest late Fri...
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Preference: Blend of the 12Z ECMWF/GEFS and 00Z ECENS
Confidence: Slightly above average
The guidance brings a strong deep layer trough into the West by
Thursday with the height falls and an area of leeside cyclogenesis
then ejecting out across the Plains and Midwest on Friday. The 12Z
GFS is on the faster side of the guidance by late Friday with the
12Z NAM the slowest. The NAM also is appearing to be a bit too
deep with the northern portion of the trough as it ejects across
the northern Plains. Generally, the 12Z non-NCEP models split the
difference. The 12Z ECMWF appears to best approximate the model
consensus, and has good support from the latest GEFS/ECENS suites.
A blend of the ECMWF and ensemble means will be preferred.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison