Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
303 AM EDT Fri Mar 22 2019
Valid Mar 22/0000 UTC thru Mar 25/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z Model Evaluation Including Preferences and Confidence
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...Trough and Coastal Low in the East...
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Preference: General model blend (weighted toward GFS and ECMWF)
Confidence: Slightly above average
07z update: The rest of the 00z guidance shows fairly good
consistency from previous runs and overall, the preference for a
general model blend remains the same.
---previous discussion---
The shortwave trough over the Mid-Atlantic will begin to phase
with another shortwave trough dropping through the Great Lakes
region through Friday night, forming a large trough over the
Mid-Atlantic and Northeast US. At the surface, deepening low
pressure will track up the coast toward Maine then lift
north/northeast through southeastern Canada. Overall, through the
next 48-60 hours, the general suite of models show very good
agreement and consistency though the GFS/NAM are perhaps a touch
fast at the surface compared to the ECMWF/UKMET/CMC solutions. But
overall, the general model blend is preferred for this region and
should yield a reasonable solution for the mass fields.
Beyond 60 hours through 25.00z, troughing will be confined mainly
to the northern Great Lakes and northern New England regions while
a weak mid-level shortwave trough skirts through the MS/OH
Valleys. The NAM is strongest with the feature while the UKMET is
slowest. The latest GFS/ECMWF are in pretty good agreement, so
will lean the general model blend in favor of those two solutions
for now.
...Remainder of the CONUS...
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Preference: 00z NAM/ECMWF/CMC blend for central US
General model blend western US
Confidence: Average
07z update: The rest of the model guidance from the 00z cycle
shows pretty good agreement to the earlier guidance such that the
model preference remains the same. The GFS remains a faster
outlier solution for the surface low moving across the Plains and
OH Valley late in the forecast period while the rest of the
guidance is clustered together fairly well.
--previous discussion---
Closed mid/upper low over the Southwest US will weaken as it
advances into the mean ridge over the Plains region by Saturday
night. Meanwhile, across the eastern Pacific and west coast, a
series of shortwaves will push onshore ahead of a large closed low
that will eventually approach the coast by 25.12z.
The biggest model differences lie across the Plains and OH Valley
as the remnants of the southwest US wave eject out into the Plains
Saturday into Saturday night. The GFS is considerably faster with
the surface low tracking east, with its position across KY/OH by
25.12z, whereas the ECMWF is further west over southern IL. The
NAM/CMC are closer to the ECMWF solution as well. With that in
mind, will prefer a ECMWF/NAM/CMC solution for the central US. Out
west, there is fairly good model agreement such that a general
model blend is preferred.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Taylor