464
FXUS10 KWNH 031659
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EST FRI JAN 03 2020
VALID JAN 03/1200 UTC THRU JAN 07/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..AMPLIFYING LONGWAVE TROUGH ACROSS THE CENTRAL U.S.
...SURFACE LOW TRACKING FROM THE OHIO VALLEY TO OFFSHORE NEW
ENGLAND...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM AND 00Z ECMWF BLEND
CONFIDENCE: AVERAGE
MODEL SPREAD CONCERNING THE INTERACTION BETWEEN TWO PIECES OF
ENERGY WITHIN A LONGWAVE TROUGH SHIFTING EASTWARD HAS DIMINISHED
CONSIDERABLY COMPARED TO PREVIOUS DAYS. HOWEVER, SOME MINOR TIMING
DIFFERENCES REMAIN WITH THE 500 MB TROUGH AXIS WHICH RESULTS IN
DIFFERING PLACEMENTS OF THE CORRESPONDING SURFACE LOW TO TRACK
EAST-NORTHEASTWARD JUST SOUTH OF NEW ENGLAND ON SATURDAY. THE 12Z
GFS APPEARS A BIT FAST COMPARED TO THE LATEST
DETERMINISTIC/ENSEMBLE SPREAD. THE GEFS/EC ENSEMBLE MEANS ALSO
SUPPORT A SLOWER TRACK THAN THE 12Z GFS WITH THE 12Z NAM AND 00Z
ECMWF CLOSEST TO WHAT IS CONSIDERED BEST FOR THIS SYSTEM.
..SHORTWAVE TROUGH/LOW IMPACTING THE PACIFIC NORTHWEST
..ENERGY EJECTING OUT ACROSS THE PLAINS/MIDWEST BY SAT/SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z CMC BLEND
CONFIDENCE: AVERAGE
THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE SHORTWAVE
TRACKING FROM THE PACIFIC NORTHWEST FRIDAY NIGHT TOWARD THE GREAT
LAKES REGION SUNDAY NIGHT. THE 12Z NAM/GFS ARE ORIENTED FARTHER
NORTH WITH THE NEGATIVELY TILTED TROUGH AXIS EXTENDING FROM THE
UPPER MISSISSIPPI VALLEY TO THE UPPER OHIO VALLEY SUNDAY EVENING
COMPARED TO THE 00Z ECMWF/UKMET/CMC. THE 00Z CMC IS SLOWEST AND
FARTHEST SOUTH, SO IT WILL BE DISCOUNTED GIVEN BETTER AGREEMENT
FOR A BLEND BETWEEN THE NAM/GFS AND ECMWF/UKMET FORECASTS.
..SPLIT FLOW TROUGH NEAR THE PACIFIC NORTHWEST BY SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z CMC BLEND
CONFIDENCE: AVERAGE
SIMILAR TO THE ABOVE SYSTEM, MODEL SPREAD IS SMALL WITH THE
MID-LEVEL TROUGH AXIS REACHING THE PACIFIC NORTHWEST ON SUNDAY.
HOWEVER, THE 00Z CMC STANDS OUT AS SLOW COMPARED TO THE REMAINING
AVAILABLE GUIDANCE BY LATE MONDAY. THEREFORE, WHILE DIFFERENCES
ARE RELATIVELY MINOR, A NON 00Z CMC BLEND WILL BE PREFERRED FOR
THIS SYSTEM.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
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