Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
152 AM EST Wed Feb 13 2019

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

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

00Z Model Evaluation...with Final Preferences and Confidences
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 00Z GFS, GEFS; 12Z ECMWF, EC ENS
Confidence: Average

---06Z UPDATE---
No change to the preliminary preference. The 00Z ECMWF remained
relatively consistent with its previous run. Greater weight was
still given to the ECMWF along the West Coast, with a more even
blend of the GFS and ECMWF elsewhere.

---PREVIOUS DISCUSSION---
The general model preference is for a blend of the GFS, ECMWF, and
the ensemble means of each over the next few days. There are some
important differences, and thus certain model systems are favored
in specific areas of the country. However, for the overall
synoptic mass fields, a blend of the GFS and ECMWF seems
reasonable (and offers continuity with the previous model
diagnostic).

The greatest variability exists with the approach of a potent
trough to the West Coast on Thursday. This is associated with an
upper level low currently closing off around 135W. The 00Z GFS
continues to be considerably slower than other models with the
eastward ejection, and thus has a slower and stronger secondary
surface low approaching the coast. This secondary surface low
position already considerably lags the most recent (13.00Z)
surface analysis, and thus the preference is to lean toward a
faster scenario represented well by the 12Z ECMWF and its ensemble
mean from Wednesday Night to Thursday Night along the West Coast.
Despite these timing differences, longer-term (24-36hr) QPF is not
substantially different, and the primary affects would likely be
to timing details and specific placement of enhanced precipitation
at lower elevations. The GFS also pushes another upper level low
further south on Friday along the West Coast, and the preference
is once again to give stronger weight to the ECMWF mass fields.

East of the Continental Divide, more of an even compromise between
the GFS and ECMWF is preferred. The greatest differences exist
with a weak low projected to develop over the Mid South later
Friday. The ECMWF is further north with the trajectory of the low,
while the GFS is further south. The primary impact to model
differences with that system are with placement (particularly in a
latitudinal direction). Opting for placement between the two
models seems prudent, and closely aligns with the ECMWF ensemble
mean (which is in between). The 12Z ECMWF also seems far too light
with the QPF in the Great Lakes Region on Thursday and Thursday
Night. Other models (CMC, UKMET and NAM) are similar enough to the
GFS and ECMWF over the East that they could also be incorporated
into model blends.


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

Lamers