Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1256 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/12Z 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 and 12Z UKMET begin to outrun
the remaining guidance 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 12Z CMC appears to be a tad too weak with the
height falls, with the 00Z GFS and 12Z ECMWF in decent agreement
with their timing and with the depth of the trough. Generally, a
blend of the GFS and ECMWF is 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 and
12Z CMC in general are more aggressive 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 NAM and CMC 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 weaker surface wave, and
with the front tending to be a tad more suppressed by comparison
which the 00Z GFS and 12Z ECMWF support along with a good number
of the ensemble members. This also would tend to respect 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