Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
320 AM EDT Sat Sep 14 2019

Valid Sep 14/0000 UTC thru Sep 17/1200 UTC

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

00Z Model Evaluation with Preferences and Forecast Confidence
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...CONUS...
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Preference: General Model Blend
Exceptions: Non-UKMET in Pacific Northwest
Confidence: Above average

07Z Update: The 00Z UKMET still is too progressive with the
shortwave over the Pacific Northwest though the spread is less
compared to the previous cycle. For now, will continue to prefer a
non-UKMET blend over the Pacific Northwest. Otherwise across the
rest of the CONUS, a general model blend still is sufficient.

---previous discussion---
Most of the energy across the CONUS will track along the northern
tier of the US and southern Canada with the stronger closed low
opening up as it continues lifting north of the Great Lakes. A
compact shortwave trough will skirt the northern Upper Midwest
today and here model agreement remains well above average such
that a general model blend should be more than sufficient.

An anomalously deep closed upper level low then approaches the
Pacific Northwest late Saturday into Sunday. While model agreement
has increased in the last 2-3 cycles, the 12Z UKMET still remains
the faster outlier compared to the rest of the deterministic
models. The preference for this cycle is to exclude the UKMET but
the rest of the models appear in good agreement to include at this
time.

Elsewhere across the CONUS, latest guidance in good agreement
showing a subtle shortwave trough over the southwest US lifting
northward through Day 2/3 and getting absorbed into the large
scale developing trough over the Rockies. Here, the 12Z CMC offers
a good compromise and lies near the consensus of the models, where
the GFS is faster (east) compared to the slower (west) ECMWF.

...Tropical Storm Humberto...
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Preference: Official NHC Forecast
Best Proxy: 12Z ECMWF/00Z NAM through 24-36 hours; then consensus
of available guidance
Confidence: Slightly below average

The latest trends in the forecast guidance shift the track of now
Tropical Storm Humberto east, generally away from the FL and
southeast US coastline. Based on the initial 00Z guidance
(GFS/NAM) and 12Z non-NCEP guidance, the latest (03Z) official NHC
track lies near the consensus of the available guidance. The GFS
tracks generally to the left (west) while the ECMWF/UKMET lie to
the right (east). The NAM and to some degree the 12Z ECMWF are a
fairly good proxy to the official track, though no model agrees
with the official track throughout the next 84 hours. The spread
increases considerably beyond 48 hours such that the forecast
confidence is below average to slightly below average.


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

Taylor