091
FXUS10 KWNH 031646
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1246 PM EDT SUN MAY 03 2020
VALID MAY 03/1200 UTC THRU MAY 07/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING INITIAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SHORTWAVE AND SURFACE LOW TRACKING FROM GREAT LAKES TO THE
NORTHEAST THROUGH MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: HIGH
ONLY MINOR TIMING DIFFERENCES EXIST WITH THIS SYSTEM, AND ALTHOUGH
THE ECMWF IS MORE AMPLIFIED AND THE CMC A LITTLE WEAKER ONCE
EMERGING OFFSHORE, THE DIFFERENCES ARE SMALL ENOUGH THAT A GENERAL
MODEL BLEND CAN BE USED FOR THIS SYSTEM FROM THE GREAT LAKES,
NORTHEAST AND CENTRAL/SOUTHERN APPALACHIANS.
MID-LEVEL SHORTWAVE OVER THE NORTHWEST THIS MORNING, EVENTUALLY
REACHING THE UPPER MIDWEST ON TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS, 00Z ECMWF, 00Z UKMET BLEND
CONFIDENCE: MODERATE
A COMPLEX EVOLUTION WILL TAKE PLACE AS A SHORTWAVE TROUGH OVER
INTERIOR PORTIONS OF THE NORTHWEST TRACKS EASTWARD AS A CLOSED LOW
CROSSES SOUTHERN ALBERTA/SASKATCHEWAN ON MONDAY. MEANWHILE, A
WEAKER MID-LEVEL SHORTWAVE IS EXPECTED TO TRACK EASTWARD FROM NEAR
THE OREGON/CALIFORNIA BORDER SUNDAY EVENING, REACHING NEAR IOWA BY
TUESDAY MORNING. AT THE SURFACE, LOW PRESSURE IS EXPECTED TO
DEVELOP OVER THE OZARKS BY MONDAY NIGHT ALONG A FRONTAL BOUNDARY,
AND THEN REACH THE EAST COAST LATE TUESDAY. THE GFS TRENDED A
LITTLE MORE AMPLIFIED ACROSS THE OHIO VALLEY AND THE MID-SOUTH
COMPARED TO ITS 6Z RUN, AND THE CMC IS A LITTLE WEAKER THAN THE
MODEL CONSENSUS AND SLIGHTLY SUPPRESSED WITH ITS SURFACE LOW
TRACK.
PAIR OF SHORTWAVE TROUGHS AFFECTING THE PACIFIC NORTHWEST THROUGH
TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/ECENS/12Z GFS BLEND
CONFIDENCE: LOW-MODERATE
THE FIRST OF TWO SHORTWAVE TROUGHS TO PIVOT AROUND THE BROAD UPPER
LEVEL GYRE OVER THE GULF OF ALASKA WILL CLIP THE PACIFIC NORTHWEST
MONDAY NIGHT, WITH THE 00Z UKMET STANDING OUT WITH A STRONGER
SHORTWAVE COMPARED TO THE OTHER MODELS. THE SECOND AND STRONGER
SHORTWAVE THAT FOLLOWS WILL APPROACH THE PACIFIC NORTHWEST ON
TUESDAY/TUESDAY NIGHT WITH AN ACCOMPANYING COLD FRONT AT THE
SURFACE. IN TERMS OF THE LATEST MODEL GUIDANCE, THE CMC IS MORE
PROGRESSIVE WITH THE TROUGH DURING THE DAY 3 PERIOD, AND THE 12Z
GFS TRENDED A LITTLE FASTER COMPARED TO ITS 6Z RUN, ALBEIT NOT TO
THE SAME DEGREE AS THE CMC. THE 12Z NAM IS ON THE STRONGER SIDE
OF THE MODEL GUIDANCE. ENSEMBLE TRENDS HAVE SHOWED CONVERGENCE
SINCE YESTERDAY WITH THE TIMING OF THE TROUGH WEDNESDAY MORNING,
BUT HAVE NOT WAVERED SIGNIFICANTLY ON TIMING. FOR NOW, A BLEND OF
THE 00Z ECMWF/ECENS/12Z GFS IS CLOSEST TO THE MIDDLE OF THE
ENSEMBLE GUIDANCE AND CLOSEST TO THEIR MEANS.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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