074
FXUS10 KWNH 250452
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 AM EDT THU JUN 25 2020
VALID JUN 25/0000 UTC THRU JUN 28/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS EVALUATION INCLUDING PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER ONTARIO/QUEBEC
TROUGH CROSSING THE EASTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS WITH THE MID LEVEL
CLOSED LOW AS IT TRACKS FROM EASTERN ONTARIO INTO WESTERN QUEBEC,
BEFORE SLOWING DOWN AND SPINNING OVER CENTRAL QUEBEC THROUGH
28/12Z. HOWEVER, THE 00Z NAM APPEAR TO BE TOO FAST WITH ITS
SURFACE LOW CROSSING NORTHERN ME, WHILE THE 00Z GFS/12Z ECMWF SHOW
BETTER CLUSTERING WITH THE 12Z ECMWF ENSEMBLE MEAN (AND THE FRONT
THAT MOVES ACROSS THE EAST COAST LATE IN THE PERIOD). GIVEN THE
GENERALLY GOOD CLUSTERING WITH THE MID LEVEL AND SURFACE SYSTEMS
(OUTSIDE OF THE 00Z NAM), FORECAST CONFIDENCE IS SLIGHTLY ABOVE
AVERAGE. HOWEVER, DUE TO ITS FASTER SURFACE SOLUTION, THE 00Z NAM
IS NOT INCLUDED IN THE PREFERRED BLEND.
SHORT WAVE CROSSING THE PACIFIC NORTHWEST AND PLAINS/MIDWEST
LONG WAVE TROUGH DIGGING INTO THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND FOR THE NORTHERN STREAM SHORT WAVE
NON 12Z CMC FOR THE LONG WAVE IN THE SOUTHWEST
CONFIDENCE: ABOVE AVERAGE
FOR THE SHORT WAVE ENERGY TRACKING FROM THE PACIFIC NORTHWEST INTO
THE NORTHERN PLAINS, THE 00Z NAM/GFS ARE CLOSE TO THE CONSENSUS
TAKING IT ACROSS SD INTO IA/IL, AS WELL AS THE SURFACE LOW MOVING
ACROSS ONTARIO. THESE SOLUTIONS ARE CLOSE TO THEIR ENSEMBLE MEANS,
AS WELL AS THE 12Z ECMWF ENSEMBLE MEAN. GIVEN THE TIGHT
CLUSTERING, A GENERAL MODEL BLEND IS PREFERRED.
FOR THE POSITIVELY TILTED LONG WAVE TROUGH CROSSING CA AFTER
26/00Z, THE 12Z CMC IS TOO FAST FROM THE ONSET AS IT REACHES THE
SOUTHWEST STATES BY 28/12Z. OTHERWISE, THERE IS GOOD MODEL
CLUSTERING WITH THIS FEATURE AS WELL, SO A NON 12Z CMC BLEND IS
PREFERRED WITH ABOVE AVERAGE CONFIDENCE.
STRONG SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST THIS WEEKEND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING SHORT WAVE
ENERGY FROM THE GULF OF AK ACROSS THE BRITISH COLUMBIA COAST AFTER
27/00Z. ADDITIONAL MID LEVEL ENERGY DROPPING INTO THE SHORT WAVE
POSITION OVER BRITISH COLUMBIA/ALBERTA CAUSES THE SYSTEM TO CLOSED
OFF OVER THE PACIFIC NORTHWEST TOWARD THE END OF THE PERIOD. BY
THAT TIME, THE 00Z NAM/GFS ARE A BIT FASTER THAN THE CONSENSUS,
BUT THERE IS MORE SPREAD IN GENERAL THROUGHOUT THE MODEL
SOLUTIONS. HOWEVER, THIS CLUSTER IS NOT FAR FROM THE 12Z ECMWF
ENSEMBLE MEAN/GEFS MEAN, SO THE SLIGHTLY FASTER SOLUTIONS ARE NOT
TOO FAST NOT TO INCLUDE IN A GENERAL MODEL BLEND. GIVEN THE
SPREAD, THOUGH, FORECAST CONFIDENCE IS AVERAGE.
LOWER MS VALLEY AND GULF COAST STATES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THOUGH THE 00Z GFS IS A BIT STRONGER WITH THE SHORT WAVE ENERGY IN
THE MID LEVEL FLOW ACROSS THE REGION, IT DOES HAVE SOME SUPPORT
FROM THE 12Z UKMET. OVERALL, THERE IS FAIRLY GOOD CLUSTERING IN
THE MID LEVEL FLOW (OUTSIDE OF WEAK IMPULSES IN THE MID LEVEL FLOW
THAT REGIONAL/GLOBAL MODELS CANNOT YET RESOLVE) AS HEIGHTS FALL
ACROSS THE LOWER MS VALLEY AND GULF COAST STATES. BASED ON THIS, A
GENERAL MODEL BLEND IS PREFERRED, WITH SLIGHTLY ABOVE AVERAGE
CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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