920
FXUS10 KWNH 260626
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
126 AM EST THU DEC 26 2019
VALID DEC 26/0000 UTC THRU DEC 29/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES/CONFIDENCE INTERVALS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.
SYSTEM APPROACHING PACIFIC NORTHWEST SUNDAY MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE
THERE ARE COMPETING FACTORS CLOUDING THE FORECAST PICTURE ACROSS
THE PACIFIC NORTHWEST AND PLAINS/MIDWEST BY SUNDAY. A SYSTEM
APPROACHING THE PACIFIC NORTHWEST AT THAT TIME HAS A BUILDING
RIDGE SEEN IN ALL THE GUIDANCE IN ITS WAKE, WHICH SHOULD YIELD A
STRENGTHENING SYSTEM ALOFT MOVING TOWARDS THE REGION, WHICH THE
00Z GUIDANCE IS TRENDING TOWARD. THE 00Z NAM HAS A STRONG LEADING
SHORTWAVE MOVING BY WESTERN WA SATURDAY NIGHT THAT LOOKS A BIT
WEAKER IN THE OTHER GUIDANCE (WEAKER IS A BETTER FIT TO THE
SYNOPTIC PATTERN IN WHICH IT IS EMBEDDED). A COMPROMISE OF THE
00Z GFS/00Z UKMET/00Z ECMWF/00Z UKMET LOOKS IDEAL WITH THE
NORTHWEST SYSTEM WITH ABOVE AVERAGE CONFIDENCE.
SYSTEM MOVING FROM THE WEST INTO THE MIDWEST FRI-SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/UKMET/CANADIAN COMPROMISE
CONFIDENCE: SLIGHT ABOVE AVERAGE
DOWNSTREAM, THE GUIDANCE IS PLAGUED WITH STREAM INTERACTION AS THE
SYSTEM MOVING FROM THE WEST INTO THE PLAINS STARTS OUT UNPHASED
BUT BECOMES PHASED WITH TIME AS A SHARPLY AMPLIFIED RIDGE BUILDING
INTO WESTERN CANADA. THE QUICKEST SOLUTIONS WITH THE
PLAINS/MIDWEST SYSTEM ARE THE 00Z GFS AND 00Z NAM -- THE OTHER
GUIDANCE IS A BIT SLOWER. SINCE THE FLOW OVERALL IS BECOMING MORE
AMPLIFIED, A SLOWER SOLUTION IN THE PLAINS/MIDWEST IS PREFERRED BY
SUNDAY MORNING SINCE THE KICKING INFLUENCE OF THE SYSTEM
APPROACHING THE PACIFIC NORTHWEST SHOULDN'T BE FELT QUITE YET
(OVER 15 DEGREES LATITUDE/900 MILES AWAY). PREFER A COMPROMISE OF
THE 00Z ECMWF/00Z UKMET/00Z CANADIAN WITH THE PLAINS/MIDWESTERN
SYSTEM WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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