463
FXUS10 KWNH 251618
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1117 AM EST WED DEC 25 2019
VALID DEC 25/1200 UTC THRU DEC 29/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH PREFERENCE AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/00Z UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THERE IS GOOD MODEL AGREEMENT IN THE SHORT TERM (THROUGH ABOUT
27/12Z), WITH THE 12Z NAM/GFS CLOSE TO THE CONSENSUS BRINGING THE
CLOSED MID LEVEL LOW FROM THE CA COAST INTO AZ. AFTER THAT TIME,
THERE IS AN INCREASING MODEL SPREAD CONCERNING HOW THE MID LEVEL
SYSTEM AS IT CROSSES THE SOUTHERN ROCKIES ON ITS WAY TO THE
CENTRAL PLAINS AND UPPER MS VALLEY.
BOTH THE 12Z NAM/GFS ARE STRONGER AND FASTER WITH A NORTHERN
STREAM SHORT WAVE THAT TRACKS FROM 49N 149W THIS AFTERNOON INTO
THE NORTHERN ROCKIES BY 28/00Z. THE STRONGER NORTHERN STREAM SPINS
UP SURFACE LOW PRESSURE OVER EASTERN CO MORE QUICKLY THAT THE
NON-NCEP GUIDANCE, RESULTING IN AN EASTWARD DISPLACEMENT IN THE
AXIS OF HEAVIEST QPF. BY CONTRAST, THE NON-NCEP GUIDANCE IS SLOWER
WITH THE SHORT WAVE ENERGY IN THE NORTHERN STREAM, ALLOWING IT TO
DROP INTO THE DEVELOPING LONG WAVE TROUGH. THIS RESULTS IN A
WESTWARD DISPLACEMENT WITH THE TRACK OF THE SURFACE LOW, AND
WESTWARD PLACEMENT OF THE AXIS OF HEAVIEST QPF.
THE ECMWF/UKMET HAS BEEN MORE CONSISTENT POINTING TO THE SLOWER
SOLUTION, WHILE THE NCEP GUIDANCE HAS BEEN CONSISTENTLY FASTER. AT
THIS POINT, DROPPING THE SHORT WAVE ENERGY INTO THE LONG WAVE
TROUGH APPEARS TO MAKE MORE SYNOPTIC SENSE, SO THE SLOWER/MORE
WESTWARD SOLUTION IS PREFERRED. HOWEVER, GIVEN THE AMOUNT OF
SPREAD IN THE GUIDANCE WITH THIS FEATURE, FORECAST CONFIDENCE IS
SLIGHTLY BELOW AVERAGE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAYES
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