Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
254 AM EDT Fri Jun 07 2019

Valid Jun 07/0000 UTC thru Jun 10/1200 UTC

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

00Z Model Evaluation...with Confidence and Preference
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...Overall Pattern Across the CONUS...
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Preference: General model blend...through 48 hours
            00Z GFS/ECMWF blend...after 48 hours
Confidence: Slightly above average

The models continue to support an amplified northern stream
pattern with the southern stream flow taking on a
slow-moving/blocky pattern over the next couple of days. This will
be characterized by a rather deep northern stream trough crossing
the Pacific Northwest through Friday before then lifting northeast
toward central Canada this weekend, due to the enhanced ridging
from the southern stream that is expected to be focused downstream
over portions of southeast Canada, the lower Great Lakes region
and Northeast. The southern stream trough/closed low over the
southern High Plains will continue to advance slowly east and will
reinforce the downstream ridge just off the East Coast and to the
north of it. By Sunday and Monday, there will be additional
intrusion of northern stream shortwave energy across the northern
Plains and Midwest which will begin to break down the ridging over
the Great Lakes and Northeast, and this will help to shun the
southern stream troughing/closed low down across the Southeast U.S.

After about 48 hours, the 00Z NAM begins to outrun the remaining
guidance a bit with the timing of the northern stream trough
across the northern Plains and upper Midwest although at the
surface with respect to the cold front, the difference are very
minor. The 00Z GFS is a bit slower by comparison, but the non-NCEP
guidance has trended a bit slower collectively compared to their
previous run, and do lag the NAM/GFS camp in general. The latest
ensemble means are split with the GEFS mean more progressive and
the ECENS/CMCE suites a little slower. Will favor a compromise
between camps at this point with a blend of the GFS and ECMWF
suggested after 48 hours with the northern stream energy.

Regarding the southern stream energy evolution, the models show
good agreement at least until about 48 hours and then begin to
show some differences primarily with respect to the placement of
the frontal zone setting up over the coastal plain of the
Southeast and Mid-Atlantic region. Also, there are differences
with the degree of low pressure attempting to form along this
front just east of the NC Outer Banks and up near the mouth of the
Chesapeake Bay Saturday night and early Sunday. The 00Z NAM is the
most aggressive solution with this wave of low pressure and
supporting shortwave energy focused near the East Coast in between
the upstream closed low/trough and deep layer ridge just off the
East Coast and nosing northwest across the northern Mid-Atlantic
region. The 00Z CMC did trend a bit weaker with its low center
solution compared to its previous run and is close to the flatter
00Z GFS/UKMET/ECMWF solutions. The NAM and CMC though both are a
bit quicker to lift a warm front northward up across the coastal
plain of the Southeast and Mid-Atlantic. There is a bit more
support overall for a solution that involves a front tending to be
a tad more suppressed by comparison which the GFS, UKMET and ECMWF
favor. More ensemble support resides with this solution too which
also gives respect to the degree of surface ridging that will be
in place across the Northeast and down across the interior of the
Mid-Atlantic through the weekend. Therefore, will be preferring a
blend of the GFS and ECMWF overall beyond about the 48 hour time
frame, with a general model blend prior to this.


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

Orrison