798
FXUS10 KWNH 030652
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 AM EDT SUN MAY 03 2020
VALID MAY 03/0000 UTC THRU MAY 06/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SHORTWAVE AND SURFACE LOW TRACKING FROM GREAT LAKES TO THE
NORTHEAST THROUGH MONDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
..07Z UPDATE
THERE ARE NO SIGNIFICANT CHANGES TO NOTE FROM THE 00Z
ECMWF/UKMET/CMC.
..PREVIOUS DISCUSSION FOLLOWS
ONLY MINOR TIMING DIFFERENCES EXIST WITH THIS SYSTEM AND WHILE THE
00Z GFS REMAINS SLIGHTLY FASTER THAN THE REMAINING MODEL
CONSENSUS, THE DIFFERENCES ARE SMALL ENOUGH SUCH 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: 00Z GFS, 00Z ECMWF, 00Z UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
..07Z UPDATE
THE 00Z ECMWF SHOWS A LITTLE MORE SEPARATION BETWEEN MID-LEVEL
VORTICITY MOVING THROUGH THE INTERMOUNTAIN WEST AND THE MID-LEVEL
SHORTWAVE ACROSS ALBERTA AND SASKATCHEWAN. THE 00Z ECMWF TIMING IS
SLIGHTLY FASTER BUT NOT SIGNIFICANT ENOUGH TO EXCLUDE IT FROM THE
PREFERENCE. THE 00Z UKMET ON THE OTHER HAND DID ADJUST
SIGNIFICANTLY FASTER ALOFT AND LOOKS REASONABLE WHEN USED AS PART
OF A BLEND. THE LEADING SHORTWAVE TROUGH FROM 00Z CMC IS A BIT
FASTER THAN THE CONSENSUS AND VORTICITY PATTERNS DO NOT MATCH THE
REMAINING GUIDANCE. THE FINAL PREFERENCE HAS BEEN ADJUSTED TO
REFLECT THESE CHANGES.
..PREVIOUS DISCUSSION FOLLOWS
A COMPLEX EVOLUTION AS A SHORTWAVE TROUGH OVER INTERIOR PORTIONS
OF THE NORTHWEST TRACKS EASTWARD AS A CLOSED LOW ACROSS SOUTHERN
ALBERTA/SASKATCHEWAN ON MONDAY. MEANWHILE, A WEAKER MID-LEVEL
SHORTWAVE IS EXPECTED TO TRACK EASTWARD FROM NEAR THE OR/CA BORDER
SUNDAY EVENING, REACHING NEAR IA TUESDAY MORNING. AT THE SURFACE,
LOW PRESSURE WILL ORGANIZE OVER THE OZARKS MONDAY NIGHT ALONG A
FRONTAL BOUNDARY AND REACH THE EAST COAST LATE TUESDAY.
THE ENSEMBLE MEANS PAINT A SIMILAR PICTURE WITH STRENGTH AND
TIMING BUT NO SINGLE MODEL MATCHES THE MEANS. A ROUGH BLEND OF THE
00Z NAM (SLOWER) WITH THE 00Z GFS (WEAKER) AND 12Z ECMWF (FASTER)
IS THE CLOSEST OF THE DETERMINISTIC GUIDANCE. THE 12Z UKMET IS
SIGNIFICANTLY SLOWER WITH THIS SYSTEM WHILE THE 12Z CMC IS MUCH
FASTER.
...MID-LEVEL SHORTWAVE CLIPPING THE PACIFIC NORTHWEST MONDAY
NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
..07Z UPDATE
THERE ARE NO SIGNIFICANT CHANGES TO NOTE FROM THE 00Z
ECMWF/UKMET/CMC.
..PREVIOUS DISCUSSION FOLLOWS
THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.
...NEXT MID-LEVEL SHORTWAVE/ASSOCIATED COLD FRONT REACHING THE
PACIFIC NORTHWEST TUESDAY NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/00Z UKMET/12Z CMC BLEND
CONFIDENCE: BELOW AVERAGE
..07Z UPDATE
THE 00Z CMC ADJUSTED FASTER, TOO MUCH SO TO INCLUDE IT IN THE
PREFERENCE. BOTH THE 00Z ECMWF/UKMET ADJUSTED A LITTLE SLOWER
COMPARED TO THEIR 12Z CYCLES, BUT OVERALL, THEY...WHEN COMBINED
WITH THE 12Z CMC...CONTINUE TO REPRESENT A FAVORED MIDDLE GROUND
NEAR THE ENSEMBLE MEANS.
..PREVIOUS DISCUSSION FOLLOWS
YET ANOTHER SHORTWAVE WILL NEAR THE PACIFIC NORTHWEST ON TUESDAY
WITH AN ACCOMPANYING COLD FRONT AT THE SURFACE. THE 00Z NAM IS
STRONGEST WITH A COMPACT VORTICITY MAXIMUM WITHIN THE TROUGH AXIS
WHICH REACH WASHINGTON WEDNESDAY MORNING. THE 00Z GFS IS SLOWER
WITH A MORE ELONGATED VORTICITY MAXIMUM OFFSHORE OF OREGON AT THE
SAME TIME. WHILE THE SEMI-AGREEABLE ENSEMBLE MEANS SHOW A MORE
FOCUSED VORTICITY MAX WITHIN THE APPROACHING TROUGH, THERE IS NOT
ENOUGH AGREEMENT TO GO WITH A STRONGER NAM SOLUTION OR SLOWER GFS
SOLUTION AT THIS TIME.
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 12Z
ECMWF/UKMET/CMC 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
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