678
FXUS10 KWNH 170633
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
133 AM EST SUN NOV 17 2019
VALID NOV 17/0000 UTC THRU NOV 20/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 00Z GFS, NAM, ECMWF
CONFIDENCE: AVERAGE
---06Z UPDATE---
NO CHANGE TO THE PRELIMINARY PREFERENCE. THE 00Z ECMWF DID TREND
FASTER WITH THE TROUGH APPROACHING THE SOUTHWEST ON TUESDAY, AND
IS IN BETTER ALIGNMENT WITH THE GFS AND NAM NOW.
---PREVIOUS DISCUSSION---
MODELS SHOW REASONABLE SIMILARITY WITH THE OVERALL SYNOPTIC
PATTERN OVER THE NEXT FEW DAYS, ALTHOUGH BY MONDAY NIGHT AND
TUESDAY THERE IS A MODERATE AMOUNT OF SPREAD. NEVERTHELESS, THERE
IS STILL A FAIR AMOUNT OF MODEL AGREEMENT ON PLACEMENT OF
PRECIPITATION REGIONS DESPITE THE INCREASING SPREAD. THERE DOES
NOT APPEAR TO BE A SYSTEMIC BIAS THAT WOULD FAVOR ONE MODEL
CONSISTENTLY, AND THUS AN EQUALLY WEIGHTED MODEL BLEND IS THE
PREFERENCE.
THE 12Z CMC AND UKMET WERE EXCLUDED FROM THE PREFERENCE, HOWEVER,
DUE TO MORE SUBSTANTIAL DIFFERENCES WITH A DIGGING SHORTWAVE OVER
THE MIDWEST ON MONDAY NIGHT AND TUESDAY. THESE TWO MODELS SHOW A
MUCH STRONGER VORTICITY MAXIMUM AND A CORRESPONDING SWATH OF
HIGHER QPF. ADDITIONALLY, THE UKMET CONTINUES TO SHOW THE SURFACE
LOW TRACKING MUCH FURTHER WEST THAN ANY OTHER MODELS IN THE
VICINITY OF NEW ENGLAND IN THE DAY 2-3 TIME FRAME.
THEREFORE, THE PREFERENCE IS FOR A BLEND OF THE GFS, NAM AND
ECMWF. THE MOST SIGNIFICANT DIFFERENCE (WITH AN IMPACT ON QPF)
BETWEEN THESE REMAINING MODELS IS THE TIMING OF THE TROUGH
APPROACHING THE SOUTHWEST ON TUESDAY. THE ECMWF IS SLOWER, WHILE
THE GFS IS FASTER, AND THIS IS A COMMON BIAS FOR THESE MODELS. A
COMPROMISE BETWEEN THE TIMING IS PREFERRED.
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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