396
FXUS10 KWNH 200733
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 AM EST THU FEB 20 2020
VALID FEB 20/0000 UTC THRU FEB 23/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...POSITIVELY TILTED MID-LEVEL TROUGH AXIS APPROACHING THE EAST
COAST THURSDAY NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
AS A SHORTWAVE TROUGH AXIS TRACKS EAST DURING THE DAY ON THURSDAY
INTO THURSDAY NIGHT, A SURFACE LOW WILL ORGANIZE OFF OF THE
SOUTHEAST COAST. THE 00Z NAM IS A TAD STRONGER AND FARTHER NORTH
WITH THE LOW COMPARED TO THE REMAINING DETERMINISTIC AND ENSEMBLE
GUIDANCE. THE 12Z CMC STANDS OUT AS WELL WITH A MORE NORTHWARD AND
SLIGHTLY QUICKER TROUGH PROGRESSION OFF OF THE EAST COAST.
HOWEVER, THE 00Z CMC TRENDED SLOWER, TOWARD THE REMAINING MODEL
CONSENSUS. THEREFORE, THE BETTER ENSEMBLE CLUSTERING AGREES BEST
WITH A NON 00Z NAM BLEND OF GUIDANCE.
...CLOSED MID-LEVEL LOW REACHING THE SOUTHWESTERN U.S. EARLY
SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS, 00Z ECMWF, 12Z UKMET, 00Z CMC BLEND
CONFIDENCE: AVERAGE
THE ENSEMBLES HAVE BEEN TRENDING SLOWER WITH THE CLOSED LOW FRIDAY
INTO SUNDAY MORNING ACROSS THE SOUTHWEST. THE LATEST GUIDANCE
SHOWS THE 12Z CMC MUCH FASTER THAN THE LATEST CLUSTERING OF
DETERMINISTIC AND ENSEMBLE GUIDANCE. HOWEVER, THE 00Z CMC SLOWED
DOWN NEAR THE 00Z GFS TIMING WHILE THE 00Z UKMET SLOWED DOWN
RELATIVE TO ITS 12Z CYCLE. THE 00Z NAM LOOKS A BIG STRONGER THAN
THE REMAINING CONSENSUS BUT APPEARS REASONABLE WITH TIMING.
THE REASONABLY WELL CLUSTERED 00Z GFS, 00Z CMC, 00Z ECMWF AND 12Z
UKMET APPEAR BEST, STAYING AWAY FROM THE SLOWER 00Z UKMET AT THIS
TIME GIVEN LESS SUPPORT FOR ITS TIMING. GIVEN TRENDS OVER THE PAST
24 HOURS, PREFER TO STAY IN THE MIDDLE TO SLOWER SIDE OF THE
GUIDANCE, WHICH IS IN LINE WITH MUCH OF THE 00Z DETERMINISTIC
GUIDANCE.
..MID-LEVEL SHORTWAVE NEARING THE PACIFIC NORTHWEST ON SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z NAM BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
LARGE DIFFERENCES IN THE DETERMINISTIC GUIDANCE EXIST WITH A
SHORTWAVE FORECAST TO NEAR THE PACIFIC NORTHWEST ON SUNDAY. THE
00Z NAM IS RATHER FLAT ALOFT AND FEATURELESS AT THE SURFACE WHILE
THE 12Z ECMWF/UKMET/CMC ARE RATHER WRAPPED UP WITH THE MID-LEVEL
SHORTWAVE AND SURFACE REFLECTION. THE 00Z ECMWF/UKMET/CMC TRENDED
TOWARD THE LATEST ENSEMBLE MEANS KEEPING THE 00Z NAM AS AN
UNLIKELY OUTLIER. THE ENSEMBLE MEANS ARE IN REASONABLE AGREEMENT
AND APPEAR TO MATCH BEST TO A NON 00Z NAM BLEND WITH THE 00Z GFS A
BIT SLOWER AND SLIGHTLY WEAKER.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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