Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
254 AM EDT Wed Mar 28 2018

Valid Mar 28/0000 UTC thru Mar 31/1200 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

00Z model evaluation...including final preferences
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...Southern stream trough over the New Mexico advancing east...
...Surface low tracking from the lower Mississippi valley Thursday
morning to the Northeast Friday morning...
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Preference: Blend of the 00Z UKMET/ECMWF/GFS
Confidence: Slightly below average

The 00Z NAM is still on the faster side of the model spread with
the ejecting shortwave through the Ohio valley on Thursday. The
ECMWF trended slower with this feature and is nearer to the GFS
compared to yesterday, but the 00Z GFS remains a slower than the
00Z ECMWF and 00Z UKMET...with the ensembles (GEFS and ECENS)
reflecting their parent models. The ensemble scatter low surface
plots support a broad blend of the 00Z GFS, 00Z ECMWF and 00Z
UKMET with future wobbles expected. The 00Z CMC is similar but
toward the southern edge of the ensembles with the surface low as
it tracks into the northeast, and is therefore not included in the
blend.


...Shortwave digging across the north-central U.S. today...
...Surface low tracking through Ontario today with trailing cold
front across the Great Lakes...
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Preference: General model blend
Confidence: Above average

The models show similarly with this system.


...Shortwave moving over the Northwest by Friday...
...Surface low dropping down across Montana and nearing the upper
Mississippi Valley Saturday morning...
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Preference: 00Z NAM/UKMET/CMC blend
Confidence: Average

The models bring a shortwave in across the Northwest by Friday and
drop a surface low down across Montana. The 00Z UKMET sped up from
its previously slow solution somewhat but remains a tad slow with
the surface low as it reaches the High Plains Friday evening. The
00Z NAM/GFS/ECMWF/CMC are all faster than the 00Z UKMET. There has
been a flip in model timing however, where the slower models from
yesterday are now faster and vice versa. The ensemble spaghetti
height plots at 500 mb show modest spread in timing and a low
amplitude shortwave making the 12Z/00Z EMCWF a bit too deep...with
little change noted between the 00Z ECMWF and its 12Z run.
Ensemble scatter low plots split the difference between the
farther south 00Z GFS surface low track and the farther north
12Z/00Z ECMWF. A blend of the 00Z NAM/UKMET/CMC currently splits
this difference and lies in the middle of the deterministic and
ensemble spread.

Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

Otto