432
FXUS10 KWNH 190439
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1139 PM EST WED DEC 18 2019
VALID DEC 19/0000 UTC THRU DEC 22/1200 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: 12Z ECMWF, 12Z ECMWF ENSEMBLE MEAN, 12Z CMC
CONFIDENCE: AVERAGE
A SOMEWHAT AMPLIFIED PATTERN ACROSS THE CONUS WILL BECOME
INCREASINGLY AMPLIFIED OVER THE NEXT FEW DAYS. A STRONG CLOSED LOW
WILL DEVELOP ALOFT ALONG THE GULF COAST, WITH A LARGE, POSITIVELY
TILTED TROUGH APPROACHING THE WEST COAST. IN SITUATIONS LIKE THIS,
THE PREFERENCE IS TO GENERALLY LEAN AWAY FROM THE FASTER WAVE
PROGRESSION BIAS OF THE GFS AND NAM AS AN AMPLIFYING PATTERN TENDS
TO SUPPORT SLOWER PROGRESSION OF SYNOPTIC SCALE SYSTEMS.
WITH THE GULF COAST CLOSED LOW, THE TREND OVER THE PAST SEVERAL
MODEL CYCLES WITH THE GFS HAS BEEN TO SLOW IT DOWN DESPITE THE GFS
AND GEFS MEMBERS STILL BEING FASTER THAN JUST ABOUT ALL REMAINING
ENSEMBLE MEMBERS. GIVEN THE SLOWER TREND AND LACK OF SUPPORT FROM
OTHER MODELS, THE PREFERENCE IS TO LEAN AWAY FROM THE GFS (AND
NAM, WHICH IS SIMILARLY FAST).
THE 12Z UKMET IS SHOWING THE OPPOSITE -- IT IS GENERALLY ON THE
SLOWER END OF MODEL GUIDANCE, PARTICULARLY WITH THE GULF COAST
LOW. AS WITH THE GFS AND NAM, IT CAN'T BE COMPLETELY DISCOUNTED AS
A POSSIBILITY, BUT THE PREFERENCE IS TO LEAN TOWARD THE ECMWF,
ECMWF ENSEMBLE MEAN, AND CMC WHICH OFFER AN APPROXIMATE MEDIAN
SCENARIO AND GOOD CONSISTENCY BETWEEN THEIR FORECAST DEPICTIONS.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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