Prognostic Meteorological Discussion
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000
FXUS10 KWNH 231829
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 PM EDT SUN JUL 23 2017

VALID JUL 23/1200 UTC THRU JUL 27/0000 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
SYSTEM MOVING THROUGH SOUTH-CENTRAL CANADA MONDAY/TUESDAY
UPPER LOW NEAR CALIFORNIA SUNDAY-TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS REASONABLY GOOD AGREEMENT WITH THIS SYSTEMS.  A
COMPROMISE OF THE 12Z GFS, 12Z NAM, 12Z ECMWF, 12Z CANADIAN, AND
12Z UKMET IS PREFERRED TO DEAL WITH LINGERING DETAIL ISSUES WITH
ABOVE AVERAGE CONFIDENCE.  FOR QPF DETAILS, SEE OUR QPF DISCUSSION
(QPFPFD).



SHORTWAVE MOVING ACROSS THE GREAT LAKES SUN/NORTHEAST MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM COMPROMISE; CONFIDENCE SLIGHTLY ABOVE AVE

THE 12Z NAM LAGS THE OTHER GUIDANCE NOTICEABLY AT THE 500 HPA AND
700 HPA LEVELS ON TUESDAY AND WEDNESDAY -- ITS USUAL BIAS.  WITH A
KICKER SHORTWAVE MOVING INTO ONTARIO TUESDAY/WEDNESDAY MORNING,
PREFER THE FASTER 12Z CANADIAN, 12Z UKMET, 12Z ECMWF, AND 12Z GFS
GUIDANCE WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.  FOR QPF DETAILS,
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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