588
FXUS10 KWNH 280440
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1139 PM EST FRI DEC 27 2019
VALID DEC 28/0000 UTC THRU DEC 31/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES/CONFIDENCE INTERVALS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CENTRAL CONUS LARGE CLOSED LOW/SURFACE CYCLONE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
WITH THE CLOSED LOW NOW PUSHING OUT OF THE SOUTHWEST U.S. AND INTO
THE SOUTHERN PLAINS, THE LATEST MODEL GUIDANCE IS TRENDING TOWARD
BETTER AGREEMENT WITH THE EVOLUTION THROUGH THE NEXT FEW DAYS.
ALOFT, THE INCOMING 00Z AND PREVIOUS CYCLE GUIDANCE SHOWS LESS
SPREAD OVERALL. THE 12Z ECMWF/ECENS ARE NEARLY IDENTICAL AND HAVE
SHOWN THE BEST CONSISTENCY OVER THE LAST SEVERAL CYCLES. THE 00Z
GFS IS SLIGHTLY STRONGER WITH ITS MID/UPPER LEVEL FORCING AND ITS
LOW TRACK IS A BIT TO THE SOUTH COMPARED TO THE ECMWF/CMC/UKMET
AND THE 18Z GEFS MEAN POSITION. MEANWHILE, THE 00Z NAM IS ON THE
NORTHERN PERIPHERY OF THE MODEL SPREAD, PARTICULARLY WITH ITS 500
MB LOW POSITION. THE GFS (AND THE NAM TO SOME DEGREE) ARE MUCH
FURTHER NORTH WITH ITS 250 MB JET MAX (REACHING WISCONSIN;
COMPARED TO MO/IA IN THE NON-NCEP GUIDANCE) AND GIVEN THE TRENDS,
THIS IS LESS FAVORED. SO WHILE THE LARGE SCALE SOLUTIONS ARE ALL
FAIRLY SIMILAR, THE SMALLER SCALE DIFFERENCES LEND TOWARD A
PREFERENCE FOR A NON-NAM BLEND (AND LESSER WEIGHT OF THE GFS) WITH
A PRIMARY BLEND OF THE ECMWF/UKMET/CMC.
..PACIFIC SHORTWAVE DIVING ALONG THE WEST COAST SUN-TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
AN ANOMALOUSLY DEEP BUT NARROW SHORTWAVE TROUGH APPROACHES THE
WESTERN U.S. LATE IN THE WEEKEND AND EARLY NEXT WEEK, REACHING THE
PACIFIC NORTHWEST COAST INITIALLY THEN CLOSING OFF AS THE SYSTEM
DROPS THROUGH THE CALIFORNIA COAST EARLY NEXT WEEK. MODEL
CONSISTENCY OVER THE LAST SEVERAL CYCLES HAS BEEN ABOVE AVERAGE
RUN TO RUN AND BETWEEN MODELS AND OVERALL THE LARGE SCALE SETUP
SHOWS GOOD SIMILARITIES IN TIMING AND STRENGTH IN THE DAY 2/3
PERIOD. THE ENSEMBLE LOW TRACKS ARE REASONABLY CLUSTERED AS WELL
WITH LITTLE SPREAD SEEN THROUGH THE NEXT 3 DAYS. OVERALL, WITH THE
ABOVE AVERAGE FORECAST CONFIDENCE AND MODEL AGREEMENT, A GENERAL
MODEL BLEND CAN APPLIED TO THIS REGION FOR THE PERIOD.
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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