Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1218 AM EDT Tue Jun 11 2019

Valid Jun 11/0000 UTC thru Jun 14/1200 UTC

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

00Z Model Evaluation...with Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 00Z GFS and 12Z ECMWF
Confidence: Above average

A northern stream trough will quickly advance east in a negatively
tilted fashion across the Northeast on Tuesday as a cold front
sweeps offshore the East Coast. However, a portion of the front
will still be crossing New England through midday, and the
guidance shows good agreement in developing a wave of low pressure
near southern New England that then advances northeast across the
Gulf of ME and offshore Nova Scotia by Tuesday night. On Tuesday,
additional northern stream shortwave impulses will be digging down
across the Midwest in response to strong upstream ridging building
along the West Coast and into the Great Basin. However, the
guidance all shows the downstream shortwave energy amplifying into
a strong trough with possible closed low development on Wednesday
over the Midwest. On Thursday, the trough axis takes on a bit of a
negative tilt as it moves into the Great Lakes region. On Friday,
a closed low will advance near the lower Great Lakes as the
broader trough moves across the upper OH Valley, northern
Mid-Atlantic and Northeast. The guidance is in good agreement
generally until Friday, when the 12Z CMC suggests a weaker
trough/closed evolution compared to the remaining guidance. The
00Z GFS also tends to be the strongest solution with its height
falls by the end of the period.

At the surface, low pressure developing over the Midwest on
Tuesday will shift east toward the Great Lakes region by later
Wednesday and Thursday before encroaching on the Northeast by
Friday. The 00Z GFS is a tad more progressive than the remaining
guidance, with the 12Z CMC generally the slowest. Although the
overall model spread is rather modest. Meanwhile, the guidance all
supports a separate low center riding northeast up across the
Southeast coastal plain and into the Mid-Atlantic region Wednesday
through Thursday along a frontal zone. This wave will then lift
north across southern New England Thursday night and early Friday
while gradually becoming absorbed by the deeper layer low center
near the Great Lakes. Model spread is modest with this feature.

Elsewhere, the larger scale ridging that builds along the West
Coast and the Great Basin over the next couple of days is expected
to break down as low-amplitude Pacific shortwave energy arrives
late Wednesday and Thursday. The 12Z CMC is somewhat on the
stronger side of the guidance, with the 12Z UKMET the weakest, but
all of the models do show reasonably good timing agreement as the
energy advances across the Intermountain West by Friday.

Based on all of this, the models generally with the best overall
clustering and ensemble support are the 00Z GFS and 12Z ECMWF, and
so a blend of these solutions will be preferred for the time being
across the CONUS.


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

Orrison