Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1224 PM EDT Wed Oct 30 2019

Valid Oct 30/1200 UTC thru Nov 03/0000 UTC

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

12Z Initial Model Evaluation with Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Central to Eastern U.S. storm through Friday
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend through Thursday evening, then
GFS/ECMWF/UKMET
Confidence: Slightly above average

An impressive and deep upper level trough over the Plains on
Wednesday, with a well-defined southern stream component, will
continue the active weather pattern through Halloween for the
central and eastern part of the nation.  This feature should then
close off and acquire negative tilt as it rapidly lifts northeast
across the lower Great Lakes and Northeast Thursday night and into
Friday morning.  Multiple waves of low pressure developing along
an attendant cold front will initially evolve over portions of the
TN/OH Valleys by late Wednesday, but these lows will consolidate
into one dominant wave of low pressure, which will deepen over the
upper Ohio Valley on Thursday before lifting up through the lower
Great Lakes and Northeast.  A strong cold front trailing south
from the surface low will cross the eastern U.S. and reach the
East Coast by later Thursday night.

The models are indicating good overall synoptic scale agreement
through about 36 hours, after which the NAM becomes stronger with
the upper low across the Great Lakes and northern New England. 
The GFS becomes slightly more amplified at the 500-700mb level
across the Ohio Valley and Great Lakes.  All of the models agree
on the cold front timing across the East Coast Thursday night.


Next upper trough/front over the Plains/Midwest by this weekend
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend through Friday morning, then
non-NAM consensus
Confidence: Above average

After a brief period of upper level ridging across the
north-central U.S. on Thursday, the next upper level trough
settles southward from western Canada and encompasses much of the
central and eastern Plains by Friday.  Broad cyclonic flow from
the Deep South to the Great Lakes will be in place by Saturday,
and an upper level ridge builds across the West Coast in response.
 The NAM is more amplified and slower than the model consensus at
all levels, with good overall agreement among the remaining
guidance.


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

Hamrick