469
FXUS10 KWNH 211646
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 PM EDT SUN JUN 21 2020
VALID JUN 21/1200 UTC THRU JUN 25/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
MCV OVER THE RED RIVER VALLEY APPROACHING THE ARKLATEX
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z ARW/ARW2/NMMB/HRRR
CONFIDENCE: AVERAGE
A WELL-DEFINED MCV OVER THE RED RIVER VALLEY OF THE SOUTH WILL BE
MOVING SLOWLY OFF TO THE EAST THIS AFTERNOON AND WILL CROSS THE
ARKLATEX AND ADJACENT AREAS OF THE LOWER MS VALLEY GOING THROUGH
TONIGHT. THE GLOBAL MODELS HAVE A VERY POOR HANDLE ON THE STRENGTH
OF THIS ENERGY, ESPECIALLY WITH THEIR RESULTING QPF SIGNAL. THE
HIRES CAM GUIDANCE IS GOING MUCH BETTER WITH STRONG EXCEPTION TO
THE 12Z NAM-CONEST WHICH APPEARS TO BE DAMPENING OUT ITS ENERGY
TOO QUICKLY THIS AFTERNOON AND EVENING. WILL PREFER A BLEND OF THE
HIRES GUIDANCE WITH THIS ENERGY LED BY THE 12Z ARW/ARW2/NMMB/HRRR
SOLUTIONS.
MCV/TROUGH OVER THE OH VALLEY APPROACHING THE MID-ATLANTIC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A LARGER MCV/TROUGH THAT IS TRAVERSING THE LOWER OH VALLEY WILL
LIFT NORTHEAST AND CROSS AREAS OF THE CENTRAL APPALACHIANS AND THE
NORTHERN MID-ATLANTIC REGION GOING THROUGH MONDAY. THE GLOBAL
MODELS AND HIRES CAM GUIDANCE SHOW A RATHER SHARP LEESIDE TROUGH
DEVELOPING OVER SOUTH-CENTRAL PENNSYLVANIA, WESTERN MARYLAND,
EASTERN WEST VIRGINIA AND WESTERN VIRGINIA BY MIDDAY WHICH THEN
SHIFTS SLOWLY EASTWARD BY EVENING TO NEAR OR JUST EAST OF THE BLUE
RIDGE. THE 12Z GFS/NAM/NAM-CONEST SOLUTIONS ARE A TAD STRONGER
WITH THE LEESIDE TROUGH THAN THE 00Z NON-NCEP MODELS ALONG WITH
THE REMAINING 12Z HIRES CAM SUITE OF GUIDANCE, BUT THERE IS VERY
GOOD AGREEMENT ON THE PLACEMENT OF IT. A GENERAL MODEL BLEND WILL
BE PREFERRED FOR THE TIME BEING.
CLOSED LOW OVER MANITOBA/ONTARIO
SHORTWAVES CROSSING THE GREAT PLAINS AND MIDWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/ARW/ARW2 AND 00Z UKMET BLEND...PLAINS ENERGY
NON-NAM BLEND...BROADER CLOSED LOW/TROUGH
CONFIDENCE: AVERAGE
THE LARGE CLOSED LOW CURRENTLY OVER MANITOBA WILL REMAIN THE
DOMINANT WEATHER DRIVER OVER THE PLAINS AND MIDWEST AS MULTIPLE
SHORTWAVE TROUGHS ROUND THE BASE OF IT AND INTERACT WITH EXISTING
FRONTS ACROSS THE REGION. THE MODELS IN PARTICULAR DRIVE ONE
SHORTWAVE TROUGH DOWN ACROSS THE CENTRAL PLAINS TONIGHT AND EARLY
MONDAY WHICH WILL LIKELY LEAD TO A SIGNIFICANT CONVECTIVE OUTBREAK
AND THREAT OF EXCESSIVE RAINFALL. THE 12Z NAM APPEARS TO BE A TAD
TOO STRONG WITH THIS ENERGY, WITH THE GLOBAL MODELS REASONABLY
WELL CLUSTERED. THE 00Z ECMWF THOUGH APPEARS TO BE ONE EXCEPTION
AS IT LOOKS TOO WEAK. OF THE HIRES CAM GUIDANCE, THE 12Z NMMB
APPEARS TO BE TOO WEAK AS WELL. BASED ON THE LATEST MODEL
CLUSTERING, A BLEND OF THE 12Z GFS, 00Z UKMET, 12Z ARW AND 12Z
ARW2 WILL BE PREFERRED WITH THIS SHORTWAVE.
REGARDING THE UPPER LOW, THE GLOBAL MODELS ARE RELATIVELY WELL
CLUSTERED WITH TIMING AND DEPTH THROUGH THE PERIOD AS IT MOVES
EAST. TOWARD THE END OF THE PERIOD, THE 12Z NAM PLACES ITS UPPER
LOW A TAD NORTH OF THE MULTI-MODEL CONSENSUS, AND ALSO HAS
STRONGER SHORTWAVE ENERGY ROUNDING THE BASE OF IT INVOLVING THE
GREAT LAKES AND THE OH VALLEY. A NON-NAM BLEND WILL BE PREFERRED
THE BROADER CLOSED LOW AND TROUGHING EVOLUTION AS A RESULT.
TROUGHS APPROACHING BRITISH COLUMBIA AND PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A PAIR OF SHORTWAVE TROUGHS WILL IMPACT THE PACIFIC NORTHWEST AND
ADJACENT AREAS OF BRITISH COLUMBIA GOING THROUGH THE MIDDLE OF THE
WEEK AS ENERGY ROUNDS THE BASE OF THE DEEP GULF OF ALASKA CLOSED
LOW. THE FIRST SHORTWAVE WILL ARRIVE MAINLY ACROSS BRITISH
COLUMBIA BY LATE MONDAY. THE 12Z GFS IS A SLOWER AND STRONGER
OUTLIER SOLUTION WITH THIS ENERGY VERSUS THE REMAINING WELL
CLUSTERED GUIDANCE WHICH AGREES ON A RELATIVELY FLATTER AND MORE
PROGRESSIVE EVOLUTION. A SECOND SHORTWAVE WILL BE ARRIVING AND
TENDING TO AMPLIFY A BIT OVER THE PACIFIC NORTHWEST ON WEDNESDAY.
THE 12Z GFS IS ALSO SEEN AS BEING A TAD DEEPER WITH THIS ENERGY
COMPARED TO THE REMAINING MODELS. THE LATEST ENSEMBLE GUIDANCE
YIELDS POOR SUPPORT FOR THE GFS, AND THEREFORE A NON-GFS BLEND
WILL BE PREFERRED GIVEN THIS AND THE CLUSTERING OF SOLUTIONS AWAY
FROM IT.
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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