Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
240 PM EST Sun Nov 10 2019
Valid Nov 10/1200 UTC thru Nov 14/0000 UTC
..See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
...12Z Model Evaluation with Preferences and Confidence...
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...Amplifying mid-level trough axis into the north-central U.S.
for Monday...
...Surface low in the vicinity of New England Tuesday morning...
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Preference: non 12Z UKMET blend
Confidence: Average
19Z update: The 12Z UKMET trended faster with its trough axis
moving through New England, ahead of the rest of the guidance. The
12Z ECMWF/CMC are in good agreement with the GFS/NAM at 500 mb. At
the surface, overall spread has lessened, and the non-UKMET blend
preference remains.
---previous discussion---
In the last 24 hours, model agreement has improved with the
shortwave trough axis swinging through the Great Lakes and
Northeast U.S. through Tuesday and with the surface low
development and track across New England. The consensus is for low
pressure to develop across the central Appalachians and then
toward southern New England by 12Z Tuesday and then enter the Gulf
of Maine toward 00Z Wednesday. Spread between the deterministic
models is low and overall a general model blend can be used for
the mass fields with this system.
...Cold front nearing the Pacific Northwest on Tuesday...
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Preference: GFS/ECMWF blend
Confidence: Slightly above average
19Z Update: The 12Z deterministic EC run improved with
timing/strength compared to its earlier run, and now agrees well
with the rest of the guidance, so some of the its solution can be
incorporated into the blend.
---
Ridging currently anchored over the western U.S. at the start of
the forecast period will break down as a shortwave trough and
associated cold front enter the Pacific Northwest Tuesday. Through
48 hours (12.12Z), there is above average agreement with the
latest deterministic guidance. Beyond that, the 00Z ECMWF
continues to be a bit deeper/amplified with its trough. The 00Z
ECENS mean would be a good compromise to the more amplified ECMWF
and also agrees well with the latest GFS. The NAM/CMC offer some
utility as well while the UKMET seems to be too slow compared to
the rest of the guidance. The preference for now will be a
non-UKMET blend, with heavier weights toward the ECENS/GFS.
...Closed low over northwestern Mexico...
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Preference: non 12Z UKMET blend
Confidence: Average
19Z update: The UKMET is not as big of an outlier as the earlier
run suggested, but by the end of the forecast period, it continues
to be a little ahead of the rest of the guidance. So, for now will
continue the non-UKMET blend preference.
---previous discussion---
The 00Z UKMET continues to be the faster outlier regarding the 500
mb low track across Mexico during the next few days. The 12Z
GFS/NAM offer similar solutions to the 00Z ECMWF/CMC, so with this
in mind, a non-00Z UKMET blend is preferred.
...Shortwave trough approaching California mid-week...
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Preference: General model blend
Confidence: Average
A shortwave trough will approach the western U.S. coast by mid to
late week. All of the deterministic guidance has this feature but
with some considerable spread in the timing. The usual biases are
noted, with the GFS/NAM way out ahead compared to the non-NCEP
guidance. The ECMWF is the slowest, while the UKMET/CMC offer a
solution near consensus. Relative strength/position looks similar,
so a general model blend would likely yield a good approach at
this time.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Taylor