Prognostic Meteorological Discussion
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000
FXUS10 KWNH 221843
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 PM EDT SAT JUL 22 2017

VALID JUL 22/1200 UTC THRU JUL 26/0000 UTC

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

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


SYSTEM APPROACHING THE PACIFIC NORTHWEST LATE TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CANADIAN; CONFIDENCE SLIGHTLY ABOVE AVE

THE 12Z CANADIAN IS OFF TO THE RACES WITH THIS SYSTEM, BRINGING
THE TROUGH INTO WESTERN CANADA/NORTHWEST WA TUESDAY AFTERNOON,
THOUGH IT SHOWS LOWER AMPLITUDE THAN ITS 00Z RUN.  THE REMAINDER
OF THE GUIDANCE IS QUITE A BIT SLOWER, MORE SUPPORTIVE OF THE 00Z
ECMWF/06Z GEFS MEAN SOLUTIONS.  BOTH RIDGING BUILDING OVER THE TOP
OF THIS SYSTEM IN SOUTHERN AK AND A TRAILING SYSTEM A BIT TO ITS
SOUTHWEST SUPPORT A SLOWER FORWARD PROGRESSION.  A COMPROMISE OF
THE 12Z NAM, 12Z GFS, 12Z UKMET, AND 12Z ECMWF WILL DEAL WITH THIS
MAIN ISSUE ALONG WITH HOW MUCH LEADING SHORTWAVE ENERGY MOVES
AHEAD OF IT INTO SOUTHWEST CANADA EFFECTIVELY.


SYSTEM MOVING THROUGH SOUTH-CENTRAL CANADA MONDAY/TUESDAY
UPPER LOW NEAR CALIFORNIA SUNDAY-TUESDAY
SHORTWAVE MOVING ACROSS THE GREAT LAKES SUN/NORTHEAST MON
SHORTWAVE MOVING THROUGH THE NORTHERN MID-ATL TODAY/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS REASONABLE AGREEMENT WITH THIS SYSTEM.  A BLEND
OF THE 12Z ECMWF, 12Z UKMET, 12Z CANADIAN, 12Z GFS, AND 12Z NAM
WILL DEAL WITH ANY LINGERING ISSUES EFFECTIVELY.  CONFIDENCE IS
ABOVE AVERAGE IN THIS CHOICE.  FOR RAINFALL FORECAST PREFERENCES,
SEE OUR QPF DISCUSSION (QPFPFD).


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

ROTH
$$




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