Prognostic Meteorological Discussion
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000
FXUS10 KWNH 231831
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 PM EDT MON OCT 23 2017

VALID OCT 23/1200 UTC THRU OCT 27/0000 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z MODEL PREFERENCES WITH CONFIDENCE INTERVALS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


FAST MOVING SYSTEM DIGGING INTO MN LATE THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/UKMET BLEND; CONFIDENCE AVERAGE

A STRONG CLOSED HIGH OFFSHORE THE PACIFIC NORTHWEST SHOULD LEAD TO
AN AMPLIFYING TROUGH MID-CONTINENT.  THIS ARGUES AGAINST THE MORE
OPEN/PROGRESSIVE 00Z CANADIAN, A MORE NORTHERLY 12Z NAM, AND THE
SLOWER/LESS DUG IN 12Z ECMWF.  A COMPROMISE OF THE 12Z GFS AND 12Z
UKMET IS CLOSE TO A COMPROMISE OF THE 12Z GEFS/00Z ECMWF ENSEMBLE
MEAN COMPROMISE, WHICH IS PREFERRED WITH AVERAGE CONFIDENCE AS
MODEL SPREAD HAS INCREASED WITH THIS SYSTEM.


MERGING SYSTEMS NEAR THE GREAT LAKES MONDAY NIGHT
EJECTING EASTERN TROUGH THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/12Z UKMET BLEND; CONFIDENCE BELOW AVE

THE GUIDANCE IS QUITE AGREEABLE UNTIL TUESDAY MORNING.  ON
WEDNESDAY, THE 12Z NAM/12Z CANADIAN/12Z ECMWF BECOME LOW/DEEP
ALOFT WITH THE MAIN SYSTEM, DECIDEDLY SLOWER THAN THE 00Z
ECMWF/12Z GEFS ENSEMBLE MEANS.  HOWEVER, THE 12Z GFS OUTPACES ITS
06Z ENSEMBLE MEAN BY THEN.  SINCE LARGE SPREAD REMAINS, WILL STAY
RELATIVELY CLOSE TO THE PREVIOUS PREFERENCE AND PREFER A 00Z
ECMWF/12Z UKMET COMPROMISE HERE.  CONSIDERING THE MODEL SPREAD AND
POSSIBLE SYSTEM ACCELERATION, CONFIDENCE IS BELOW AVERAGE HERE.


www.wpc.ncep.noaa.gov/html/model2.shtml
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

ROTH
$$




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