646
FXUS10 KWNH 171840
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 PM EDT FRI JUL 17 2020
VALID JUL 17/1200 UTC THRU JUL 21/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SHORT WAVE TROUGH CROSSING THE NORTHERN PLAINS TONIGHT TO LAKE
SUPERIOR WITH AN ACCOMPANYING SURFACE COLD FRONT CROSSING THE
NORTHERN PLAINS ACROSS THE UPPER MS VALLEY AND GREAT LAKES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF UKMET/ECMWF/CANADIAN
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS ARE FORECASTING A 850-700 MB SHORTWAVE AND LOW LEVEL
COLD FRONT TO CROSS THE NORTHERN PLAINS TONIGHT AND UPPER MS
VALLEY SAT, FOLLOWED BY THE UPPER GREAT LAKES AND ADJACENT CANADA
SAT NIGHT-SUNDAY.
THE MODELS/ENSEMBLE MEAN ARE IN GOOD OVERALL AGREEMENT. THE 12Z
NAM SHOW CONVECTIVE/GRID SCALE FEEDBACK TONIGHT IN EASTERN ND AND
NORTHWEST MN, LOWERING SFC PRESSURES AS A RESULT.
WITH GOOD CLUSTERING OF THE 00Z ECMWF/UKMET/CANADIAN, A BLEND OF
THESE MODELS IS PREFERRED.
...LONG WAVE TROUGH CROSSING THE PACIFIC NORTHWEST TODAY, MOVING
INTO SOUTH CENTRAL CANADA BY SAT, THEN CLIPPING THE NORTHERN
PLAINS INTO UPPER GREAT LAKES BY SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
A MID LEVEL SHORTWAVE CROSSING THE NORTHERN ROCKIES TONIGHT THEN
PROGRESSES ACROSS THE NORTHERN PLAINS SAT AND UPPER MS VALLEY SAT
NIGHT, AND UPPER GREAT LAKES SUN. THE NAM/ECMWF/UKMET CLUSTER
WELL, SO A BLEND OF THESE SOLUTIONS SHOULD WORK WELL.
THE NEXT POTENTIAL WAVE COMES OUT OF THE NORTHERN ROCKIES AND
NORTHERN PLAINS AT THE END OF THE WEEKEND INTO EARLY NEXT WEEK.
THE 12Z NAM/GFS/00Z-12 UKMET CLUSTER WELL WITH THE DEVELOPING WAVE
WHILE THE 00Z-12Z ECMWF HAVE A LOWER AMPLITUDE SOLUTION. GIVEN
THIS IS THE MEAN MULTI-DAY POSITION OF THE TROUGH, I RECOMMEND
GIVING LESS WEIGHTING TO THE OPERATIONAL ECMWF, AND MORE TO THE
12Z UKMET/12Z NAM/12Z GFS ON MONDAY. THE 12Z CANADIAN HAS JOINED
TO PREFERRED GROUP WITH A HIGHER AMPLITUDE 700 MB WAVE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
THIS PRODUCT WILL TERMINATE AUGUST 15, 2020:
WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN20-58PMDHMD_TERMINATION.
PETERSEN
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