257
FXUS10 KWNH 221851
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 PM EDT MON JUN 22 2020
VALID JUN 22/1200 UTC THRU JUN 26/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER ONTARIO/QUEBEC
SHORTWAVES OVER THE LOWER MS/OH VALLEYS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THE LARGE CLOSED UPPER LEVEL LOW OVER WESTERN ONTARIO WILL ADVANCE
GRADUALLY EAST OVER THE NEXT COUPLE OF DAYS INTO QUEBEC AS A
LARGER SCALE TROUGH EXTENDING SOUTH FROM THIS CROSSES THE MIDWEST,
GREAT LAKES AND OH VALLEY. MEANWHILE, SEPARATE CONVECTIVE ENHANCED
VORTS/SHORTWAVES WILL EJECT ACROSS THE LOWER MS VALLEY AND THE OH
VALLEY GENERALLY AHEAD OF THE LARGER SCALE HEIGHT FALLS. MODEL
MASS FIELD SPREAD IS LARGELY MINIMAL WITH THESE SHORTWAVES AS THEY
LIFT NORTHEAST OVER THE NEXT 24 HOURS AND BEGIN TO DAMPEN OUT.
REGARDING THE DEEPER LAYER TROUGH AND CLOSED LOW, THE MODELS SHOW
RELATIVELY GOOD AGREEMENT WITH SOME MODEST SPATIAL AND DEPTH
SPREAD WITH THE HEIGHT FALLS AND THE SURFACE LOW REFLECTION. A
GENERAL MODEL BLEND WILL BE PREFERRED AS A RESULT AT THIS POINT.
TROUGHS APPROACHING BRITISH COLUMBIA AND PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM/CMC/UKMET
CONFIDENCE: AVERAGE
A PAIR OF SHORTWAVE TROUGHS WILL APPROACH THE PACIFIC NORTHWEST
OVER THE NEXT COUPLE OF DAYS, THE FIRST IMPACTING MAINLY BRITISH
COLUMBIA THROUGH TONIGHT. A SECOND, STRONGER SHORTWAVE TROUGH DIGS
ACROSS THE PACIFIC NORTHWEST MID-WEEK AND EDGES INTO THE
INTERMOUNTAIN REGION BY THURSDAY. MODEL SPREAD IS MINIMAL WITH THE
FIRST IMPULSE. HOWEVER, THE 12Z ECMWF BECOMES A RELATIVELY WEAKER
AND MORE PROGRESSIVE OUTLIER WITH THE SECOND SHORTWAVE TROUGH. THE
12Z GFS IS ALSO A TAD DEEPER THAN THE REMAINING GUIDANCE WITH THE
SECOND IMPULSE. THE BETTER MODEL CLUSTERING AND ENSEMBLE SUPPORT
RESIDES WITH THE 12Z NAM/UKMET/CMC GUIDANCE AT THIS POINT AND SO A
BLEND OF THESE SOLUTIONS WILL BE PREFERRED.
MID-LEVEL ENERGY LINGERING OVER THE LOWER MS VALLEY/TEXAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS SUGGEST SOME OF THE CONVECTIVELY DRIVEN SHORTWAVE
ENERGY LINGERING OVER THE LOWER MS VALLEY OVER THE NEXT COUPLE OF
DAYS WHICH WILL TEND TO SEPARATE OUT FROM THE WESTERLIES AND MAY
ACTUALLY TEND TO RETROGRADE WESTWARD. THE 12Z NAM APPEARS OVERALL
TO BE A BIT TOO STRONG WITH THE MID-LEVEL ENERGY. THE BETTER MODEL
CLUSTERING TENDS TO BE WITH THE 12Z GFS AND 12Z ECMWF WITH THIS
ENERGY, AND SO A BLEND OF THESE SOLUTIONS WILL BE PREFERRED.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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