Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1210 AM EST Wed Jan 08 2020
Valid Jan 08/0000 UTC thru Jan 11/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z Model Evaluation with Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...Northern stream trough crossing the Northeast on Wed...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Above average
The models advance a northern stream upper trough and attendant
cold front across the Northeast on Wednesday. Very good model
agreement continues, and so a general model blend will again be
preferred.
...Initial shortwave crossing the Pacific Northwest...
...Energy advancing east across the northern Plains/Midwest...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend...through 36 hours
Non-NAM blend...after 36 hours
Confidence: Above average
The models are in good agreement with the current shortwave that
is moving across the Pacific Northwest. This energy rapidly ejects
out across the Plains and Upper Midwest going through Thursday.
The 00Z NAM though eventually appears to be a tad too far north
with its downstream low track near the Upper Midwest, Upper Great
Lakes and portions of Ontario. A general model blend will be
preferred through about 36 hours, but thereafter, a non-NAM blend
will be preferred.
...Shortwave amplifying across the Four Corners/High Plains...
...Deepening surface low over the Lower MS Valley Fri/Sat...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of the 12Z UKMET/CMC/ECMWF
Confidence: Average
A second shortwave trough crossing the Pacific Northwest early
Thursday is expected to dive southeast and become detached from
the westerlies as it crosses the Four Corners region. This energy
then will amplify sharply out across the southern Plains on
Friday, before then beginning to lift northeastward through the
lower/mid MS Valley by Saturday. A very strong frontal zone will
be setting up across this region for the weekend, and low pressure
will be developing along it and riding northeastward. The 00Z
NAM/GFS solutions are more progressive than the 12Z non-NCEP
models as the energy ejects across the southern Plains and
lower/mid MS Valley. The NAM also ends up being a bit stronger
with its height falls compared to the global model suite. The
latest GEFS and ECENS suites support a somewhat slower trough
evolution like the collective non-NCEP camp, and as a result, the
more progressive NAM/GFS solutions will, not be preferred at this
time. Another consideration is the anomalously strong downstream
ridge developing over the southwest Atlantic which should tend to
foster at least a less progressive southern stream flow pattern.
So, for now, a blend of the 12Z UKMET/CMC/ECMWF solutions will be
preferred.
...Next upper trough over the Northwest by Sat...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Non-NAM blend
Confidence: Above average
Yet another shortwave trough will cross into the Northwest by
Saturday. The 00Z NAM appears to be a tad too deep and slow with
this system. The global models are rather well clustered though,
and thus a non-NAM blend will be preferred with this system.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison