047
FXUS10 KWNH 200649
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
149 AM EST FRI DEC 20 2019
VALID DEC 20/0000 UTC THRU DEC 23/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCE AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS, 00Z ECMWF, 12Z ECMWF ENSEMBLE MEAN
CONFIDENCE: AVERAGE
---06Z UPDATE---
NO CHANGE TO THE PRELIMINARY PREFERENCE. A BLEND OF THE ECMWF AND
GFS STILL OFFERS A RELATIVELY CONSISTENT FORECAST. THE 00Z CMC
CONTINUES TO PUSH THE SURFACE LOW ALONG THE GULF COAST FURTHER
NORTH AND FASTER THAN MOST OTHER MODELS OTHER THAN THE NAM, AND
THIS REMAINS A SCENARIO THAT SEEMS LESS LIKELY (FEWER ENSEMBLE
MEMBERS IN AGREEMENT).
---PREVIOUS DISCUSSION---
THE 00Z GFS HAS SHOWN SOME IMPORTANT TRENDS TOWARD A SLOWER
PROGRESSION OF THE LARGE SCALE WAVES ACROSS THE CONUS OVER THE
NEXT FEW DAYS. IT NOW SHOWS VERY CLOSE ALIGNMENT TO THE 12Z ECMWF
WITH THE STRONG CLOSED LOW ALONG THE GULF COAST. ALTHOUGH IT STILL
PUSHES HEIGHT FALLS EASTWARD THROUGH THE INTERMOUNTAIN WEST AND
ROCKIES FASTER IN ADVANCE OF THE WEST COAST TROUGH, THE STRUCTURE
OF THE TROUGH AND POSITION OF EMBEDDED WAVES IS NOW VERY CLOSE TO
THE ECMWF. THIS STILL DOES YIELD SLIGHTLY FASTER FRONTAL TIMING ON
THE WEST COAST IN THE GFS, AND FOR DETAILS LIKE THIS THE
PREFERENCE WOULD BE A SLIGHT LEAN TOWARD THE ECMWF AND ECMWF
ENSEMBLE MEAN.
GLOBAL MODELS SHOW RELATIVELY GOOD CONSISTENCY WITH THE QPF
PATTERNS IN THE WEST DESPITE SOME SMALL DIFFERENCES IN THE TIMING
AND AMPLITUDE OF THE APPROACHING TROUGH. THEREFORE, THE 12Z CMC
AND 12Z UKMET SEEM TO OFFER REASONABLE FORECASTS IN ADDITION TO
THE ECMWF AND GFS IN THIS REGION.
THE 00Z NAM IS NOW SLOWER THAN THE CONSENSUS WITH THE GULF COAST
SYSTEM, AND PROGRESSES THE SURFACE LOW FURTHER INLAND ACROSS
GEORGIA. THE 12Z CMC AND UKMET ALSO PROGRESS THE SURFACE LOW
FURTHER INLAND THAN THE GFS AND ECMWF, AND THIS AFFECTS THE QPF
DISTRIBUTION IN THOSE MODELS. THIS HAS SOME ENSEMBLE SUPPORT, BUT
FAR LESS THAN THE GFS AND ECMWF.
CONSIDERING ALL THESE FACTORS, THE MODEL PREFERENCE IS FOR A BLEND
OF THE GFS, ECMWF AND ECMWF ENSEMBLE MEAN, WHICH WILL PROVIDE GOOD
CONSISTENCY WITH THE PREVIOUS PREFERENCE FOR MOST AREAS OF THE
CONUS, AND HAS THE GREATEST ENSEMBLE SUPPORT AT THE MOMENT.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
LAMERS
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