Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
249 AM EDT Fri May 24 2019

Valid May 24/0000 UTC thru May 27/1200 UTC

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

00Z Model Evaluation Including Preferences and Forecast
Confidence...
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...Overall CONUS Overview...
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Preference: General model blend
Confidence: Slightly above average

07z update: The most significant model difference noted with the
rest of the 00z guidance was toward the end of the forecast period
(Sunday night into Monday morning) as another shortwave trough
lifts through the central/northern Plains. While all of the
various model guidance has this feature, there are some large
spatial differences noted. The NAM is furthest north, with the
main shortwave over SD/MN by 12z Monday, while the CMC and ECMWF
are on the southern end of the model spread (over KS). The GFS and
UKMET lie in between. As expected this leads to fairly wide
solutions with the QPF maximums. For now, a general model blend
would put the surface low track through the lee side of the CO
Rockies through central Nebraska, with convection across OK/KS/NE
and stratiform precipitation north into SD/ND/MN. This seems like
a reasonable approach at this time.

Otherwise, the rest of the CONUS is fairly well agreed upon and a
general model blend is sufficient.

---previous discussion---
The synoptic scale pattern over the CONUS through the next 3 days
remains fairly consistent and locked with a persistent trough in
the western spitting out shortwaves in the central US while
ridging aloft remains anchored over the southeast US.

One shortwave trough over the northeast US will push offshore
later today. The next shortwave is currently working through the
Rockies and into the central Plains. This feature will close off
and lift rapidly into the northern Plains by later this evening.

Finally, toward the end of the period, the flow flattens out over
the Great Lakes / Northeast while a very anomalous closed low
drops through the western US coast.

An early look at the 00z guidance (and prior 12z guidance) shows
fairly good consistency in the large scale mass fields, especially
in the mid/upper levels. Looking at the GEFS and ECENS ensemble
means, the deterministic runs are fairly aligned with most of the
features, especially the large closed low for day 3 on the west US
coast. There are some slight timing/speed issues (NAM being fast
along with the GFS) but overall there is fairly good agreement.

For now, a general model blend for the mass fields can be applied.
Mesoscale boundary differences especially across the central US
will lead to varying QPF distributions in the model fields
however.


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

Taylor