Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
238 AM EDT Sat Apr 13 2019

Valid Apr 13/0000 UTC thru Apr 16/1200 UTC

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

00Z Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: General model blend, less weight on 00Z GFS
Confidence: Average

The main forecast problem for this period is the development and
track of the surface low moving from TX on Day 1 into Newfoundland
by the end of Day 3. Almost from the start, the 00Z GFS is faster
moving the surface low and frontal boundary, most noticeably in
New England after 15/00Z. This occurs despite the fact that the
mid level heights from the 00Z GFS are similar to the consensus
throughout the forecast period. The 00Z UKMET has sped up its
solution to become closer to the pack with the surface low,
especially after 15/00z, and was included in the preference.

While the 00Z ECMWF is closer to the consensus with the track of
the surface low, it is still a few  millibars deeper than the rest
of the guidance, especially after 15Z/00. Even though the 12Z
ECMWF is deeper with the surface low, it was included in the
preference because of its consistency with the placement of the
low.

The next area of concern is across southern Canada, where once
again the 00Z GFS appears to be too fast with the short wave
energy tracking from the Pacific Northwest going into Day 2.
Otherwise, there is good model agreement with the timing and
strength of the low amplitude trough moving into southwest Ontario
by 16/12Z.

The last area of concern is the Pacific Northwest, where there are
still some timing issues with short wave energy originating over
the western Aleutians at the start of Day 1. The 00Z GFS and 00Z
UKMET are a bit faster bringing the trough across the Pacific
Northwest after 16/00Z. However, the differences are not
significant enough to rule out any solution here for Day 3.

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

Hayes