533
FXUS10 KWNH 120725
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
325 AM EDT TUE MAY 12 2020
VALID MAY 12/0000 UTC THRU MAY 15/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...MID-LEVEL TROUGH AMPLIFYING ACROSS THE NORTHEAST WITH
ACCOMPANYING SURFACE LOW THROUGH TUESDAY MORNING...
...SHORTWAVE MOVING ACROSS THE GREAT LAKES AND NORTHEAST TUESDAY
AND WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
MODELS SHOW OVERALL GOOD AGREEMENT WITH THE LEAD UPPER LEVEL
SHORTWAVE AND ASSOCIATED SURFACE LOW LIFTING ALONG THE NORTHERN
NEW ENGLAND COAST INTO THE CANADIAN MARITIMES TUESDAY MORNING.
THROUGH LATE TUESDAY, THERE IS ALSO GENERALLY GOOD AGREEMENT WITH
A SECOND SHORTWAVE FORECAST TO MOVE FROM THE GREAT LAKES INTO THE
NORTHEAST TUESDAY AND WEDNESDAY. BY EARLY WEDNESDAY AS THE SYSTEM
BEGINS TO MOVE EAST THROUGH THE GULF OF MAINE, MODELS BEGIN TO
SHOW MINOR TIMING DIFFERENCES - WITH THE NAM AND UKMET SLOWER THAN
THE GFS, ECMWF AND THEIR ENSEMBLE MEANS.
...UPPER TROUGH/CLOSED LOW ALONG THE NORTHWEST COAST THROUGH
WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE MEAN CLOSED
MID-LEVEL LOW POSITION AS IT MEANDERS ALONG THE PACIFIC NORTHWEST
COAST THROUGH EARLY THURSDAY, AND THEN AS THE LOW WEAKENS AND
MOVES INLAND, UNDERCUTTING THE RIDGE CENTERED OVER BRITISH
COLUMBIA THURSDAY INTO EARLY FRIDAY.
...UPPER LOW CLOSING OFF OVER WESTERN CANADA ON TUESDAY BEFORE
MOVING EAST THROUGH THE CANADIAN PRAIRIE WEDNESDAY-THURSDAY...
...SURFACE CYCLONE MOVING TROUGH THE NORTH-CENTRAL U.S. WEDNESDAY
NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF, UKMET, NAM AND 12Z EC ENSEMBLE MEAN
CONFIDENCE: BELOW AVERAGE
A COMBINATION OF SHORTWAVES WILL IMPACT THE NORTH-CENTRAL U.S.
FROM WEDNESDAY INTO THURSDAY. THE FIRST WILL BE RELATIVELY WEAK,
EMANATING FROM ID/MT/WY TUESDAY NIGHT AND REACHING EASTERN MONTANA
AND THE DAKOTAS ON WEDNESDAY. OVERALL, MODELS ARE FAIRLY GOOD
AGREEMENT WITH THIS FEATURE.
THIS LEADING WAVE IS FORECAST TO LIFT OUT AHEAD OF AN UPPER THAT
IS FORECAST TO DEVELOP AND DROP SOUTH ALONG THE EASTERN FRONT OF
THE CANADIAN ROCKIES TUESDAY INTO WEDNESDAY. OVERALL, MODELS ARE
IN GOOD AGREEMENT THROUGH EARLY WEDNESDAY AS THE SYSTEM DROPS INTO
SOUTHERN ALBERTA AND SASKATCHEWAN. HOWEVER, SIGNIFICANT TIMING
DIFFERENCES EMERGE AS THE UPPER SYSTEM BEGINS TO MOVE EAST THROUGH
THE CANADIAN PRAIRIE WEDNESDAY NIGHT AND THURSDAY. THE NAM,
UKMET, ECMWF AND EC ENSEMBLE MEAN ALL CLUSTER FAIRLY WELL - WITH
SOLUTIONS THAT ARE FASTER THAN THE GFS, GEFS MEAN AND THE
CANADIAN. OF THE SLOWER SOLUTIONS, THE CANADIAN IS THE MOST
NOTABLE OUTLIER, ESPECIALLY BY 00Z FRIDAY. WHILE THE GFS MAY BE
TOO SLOW AS WELL, (ESPECIALLY FROM EARLY THURSDAY ACROSS THE
NORTHERN PLAINS TO THE GREAT LAKES), THE GENERAL TREND IN THE
GUIDANCE, INCLUDING THE ECMWF HAS BEEN TOWARD A SLOWER SOLUTION,
MAKING IT DIFFICULT TO COMPLETELY RULE OUT THE GFS AT THIS POINT.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
PEREIRA
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