630
FXUS10 KWNH 260423
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1122 PM EST WED DEC 25 2019
VALID DEC 26/0000 UTC THRU DEC 29/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.
SYSTEM APPROACHING PACIFIC NORTHWEST SUNDAY MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/UKMET 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. THE 12Z
ECMWF WAS OUT OF TOLERANCE WITH THIS SYSTEM AS IT MOVED A SHARP
SHORTWAVE OUT IN ADVANCE OF IT WHICH WAS NOT SEEN IN ANY OF THE
OTHER GUIDANCE AND LIKELY LED TO TOO WEAK OF A LOOK WITH THE
SYSTEM NEAR 47N 130W SUNDAY MORNING (EVEN WHEN COMPARED TO ITS
ENSEMBLE MEAN). A COMPROMISE OF THE 00Z GFS/12Z 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: 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. 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 12Z ECMWF/12Z UKMET/12Z
CANADIAN WITH THE PLAINS/MIDWESTERN SYSTEM WITH 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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