273
FXUS10 KWNH 011858
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 PM EST WED JAN 01 2020
VALID JAN 01/1200 UTC THRU JAN 05/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW ENTERING MEXICO AND WEAKENING THROUGH THURSDAY
NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z GFS BLEND
CONFIDENCE: AVERAGE
TIMING DIFFERENCES CONTINUE TO EXIST WITH THIS SYSTEM WITH THE 12Z
GFS FASTEST WHILE THE 00Z ECMWF/CMC ARE SLOWER. SLIGHT ADJUSTMENTS
IN THE 12Z ECMWF/UKMET/CMC SHOW BETTER SUPPORT FOR A NON 12Z GFS
TIMING. ENSEMBLE SPAGHETTI PLOTS CONTINUE TO TREND SLOWER THROUGH
THEIR 00Z/01 CYCLE. PREFER TO STAY TOWARD THE MIDDLE OF THE LATEST
DETERMINISTIC SPREAD GIVEN PLACEMENT CLOSER TO THE MIDDLE OF THE
ENSEMBLE DISTRIBUTION.
...AMPLIFYING LONGWAVE TROUGH ACROSS THE CENTRAL U.S. THURSDAY
EVENING...
...DEVELOPING SURFACE CYCLONE FROM MIDWEST TO EAST COAST FRIDAY TO
SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/12Z ECMWF BLEND THROUGH 00Z/04
12Z NAM/GFS/ECMWF BLEND 00Z/04-00Z/05
CONFIDENCE: BELOW AVERAGE
LARGE UNCERTAINTY EXISTS WITH THIS SYSTEM GIVEN COMPLEX
INTERACTIONS OF SEVERAL VORTICITY MAXIMA WITHIN TWO STREAMS OF
FLOW. ENSEMBLE SPREAD IS LARGER THAN AVERAGE AND RUN TO RUN
CONSISTENCY HAS BEEN POORER THAN USUAL. THE 12Z GFS IS UNSUPPORTED
WITH A BROADER LONGWAVE TROUGH AXIS OVER THE CENTRAL U.S. ON
FRIDAY COMPARED TO THE REMAINING AVAILABLE GUIDANCE. THE 12Z GFS
ALSO ENDS UP WITH A MORE DEVELOPED SURFACE REFECTION CROSSING INTO
THE OHIO VALLEY COMPARED TO THE REMAINING GUIDANCE. AS THE TROUGH
CONTINUES TO ADVANCE DOWNSTREAM, THE 00Z ECMWF SLOWS SIGNIFICANTLY
WITH THE 500 MB TROUGH AXIS COMPARED TO THE LATEST ENSEMBLE AND
REMAINING DETERMINISTIC GUIDANCE. THE 12Z GFS HOWEVER, BEGINS TO
ALIGN BETTER WITH THE GEFS/ECMWF MEANS AND WITH THE 12Z NAM TO
SOME DEGREE. ALSO WORTH NOTING IS THAT THE 12Z ECMWF ADJUSTED
FASTER WITH THE LONGWAVE TROUGH PROGRESSION AND CLOSER TO THE
BROAD CONSENSUS CONCERNING THE SURFACE LOW TRACK. THEREFORE,
BEYOND 00Z/04, A BLEND INCLUDING THE 12Z GFS AND 12Z ECMWF WITH
THE 12Z NAM IS PREFERRED. THE 12Z UKMET/CMC REMAIN TOWARD THE
EDGES OF THE ENSEMBLE DISTRIBUTION WITH THEIR SURFACE EVOLUTION
BETWEEN THE OHIO VALLEY AND THE EAST COAST AND ARE NOT RECOMMENDED.
...SHORTWAVE TROUGH AND SURFACE LOW APPROACHING PACIFIC NORTHWEST
FRIDAY/SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
TIMING DIFFERENCES CONTINUE TO AFFECT THE PACIFIC NORTHWEST WITH
THE NEXT POTENT SHORTWAVE TO REACH THE REGION FRIDAY NIGHT. THE
12Z GFS IS FASTER AND ON THE QUICKER EDGE OF THE ENSEMBLE
GUIDANCE. MEANWHILE, THE 00Z UKMET/ECMWF ARE SLOWER BUT THEIR 12Z
RUNS SPED UP. THE 12Z CMC SLOWED DOWN RELATIVE TO ITS PREVIOUS 00Z
CYCLE. THE 12Z NAM AND 12Z ECMWF ARE BETTER FITS FOR THE MIDDLE
GROUND. TRENDS HAVE OVERALL BEEN FASTER COMPARED TO YESTERDAY BUT
THE 12Z GFS CONTINUES TO APPEAR TO OUTPACE THE VAST MAJORITY OF
MODELS.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
OTTO
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