700
FXUS10 KWNH 060645
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 AM EDT THU AUG 6 2020
VALID AUG 6/0000 UTC THRU AUG 9/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
OVERALL WEATHER PATTERN ACROSS THE CONTINENTAL U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 00Z SATURDAY, THEN 00Z
ECMWF/CMC/GFS BLEND
CONFIDENCE: AVERAGE
A MODERATELY AMPLIFIED UPPER LEVEL PATTERN EXISTS ACROSS THE
CONTINENTAL U.S. WITH A WESTERN U.S. TROUGH, BROAD RIDGE AXIS
ACROSS THE PLAINS, AND ANOTHER LONGWAVE TROUGH ACROSS THE GREAT
LAKES AND OHIO VALLEY THURSDAY MORNING. OVER THE NEXT FEW DAYS,
THE UPPER RIDGE IS EXPECTED TO BUILD FURTHER ACROSS THE SOUTHERN
PLAINS, AND THE RIDGE NORTH OF BERMUDA ALSO HOLDS STRONG THROUGH
THE END OF THE WEEK. ALTHOUGH THE CLOSED LOW INITIALLY OVER
QUEBEC WILL LIFT NORTHEAST ACROSS NEWFOUNDLAND, A BROAD TROUGH
AXIS WILL CONTINUE ACROSS THE APPALACHIANS WITH SLOW EASTWARD
PROGRESS. ACROSS THE PACIFIC NORTHWEST, A SHORTWAVE PIVOTING
AROUND THE TROUGH IS EXPECTED TO BECOME NEGATIVELY TILTED ACROSS
SOUTHWEST CANADA AND THEN EVOLVE INTO A CLOSED LOW BY FRIDAY
EVENING, AND A BROAD POSITIVELY TILTED TROUGH AXIS ACROSS
CALIFORNIA AND NEVADA.
THE MODELS ARE GENERALLY IN VERY GOOD AGREEMENT THROUGH FRIDAY
EVENING ACROSS THE CONTINENTAL U.S. AND ADJACENT AREAS, SO A
GENERAL MODEL BLEND CAN BE PREFERRED THROUGH THAT TIME. BY
SATURDAY MORNING, BOTH THE 00Z AND 12Z UKMET APPEARS TOO FAST IN
PIVOTING THE DEVELOPING UPPER LOW ACROSS SOUTH-CENTRAL CANADA, AND
THE NAM FLATTER WITH THE DOWNSTREAM RIDGE ACROSS MANITOBA AND
ONTARIO, AND SLOWER WITH THE TROUGH CROSSING THE APPALACHIANS
THROUGH SUNDAY MORNING. BY THE END OF THE FORECAST PERIOD SUNDAY
MORNING, THE GFS REMAINS A LITTLE STRONGER WITH THE TROUGH ACROSS
THE PACIFIC NORTHWEST AND THE NORTHERN ROCKIES, AND THE ECMWF AND
CMC ON THE WEAKER SIDE OF THE GUIDANCE. TAKING THESE FACTORS INTO
ACCOUNT, A BLEND OF THE ECMWF/CMC/GFS SHOULD RESOLVE SOME OF THESE
DIFFERENCES AND REPRESENT A DECENT STARTING POINT IN THE FORECAST
PROCESS. THE MODELS ARE SIMILAR WITH THE MAGNITUDE OF THE
BUILDING UPPER RIDGE ACROSS THE SOUTH-CENTRAL U.S.
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.
HAMRICK
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