359
FXUS10 KWNH 010822
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
321 AM EST WED JAN 01 2020
VALID JAN 01/0000 UTC THRU JAN 04/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CLOSED LOW ENTERING MEXICO AND WEAKENING WEDNESDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
08Z UPDATE: NO SIGNIFICANT CHANGES NOTED WITH THE REST OF THE 00Z
GUIDANCE AND THE PREVIOUS MODEL BLEND PREFERENCE REMAINS.
LATEST GUIDANCE HAS TRENDED BETTER WITH THE CLOSED UPPER LEVEL LOW
OVER MEXICO AND ITS TRANSITION/WEAKENING OVER THE NEXT 24-36
HOURS. EARLIER DIFFERENCES BETWEEN THE GFS/ECMWF SEEM TO HAVE
LESSENED AND NOW THERE IS REASONABLE AGREEMENT AND CLUSTERING WITH
THE EARLY 00Z GUIDANCE. BEYOND 36 HOURS, THE ENERGY BECOMES
ABSORBED INTO THE DEVELOPING LONGWAVE POSITIVELY TILTED TROUGH
ACROSS THE CENTRAL US ASSOCIATED WITH INCOMING SHORTWAVE ENERGY
FROM THE PAC NW AND CENTRAL ROCKIES. OVERALL, GIVEN THE IMPROVED
CONSISTENCY AND MODEL AGREEMENT, A GENERAL MODEL BLEND IS
PREFERRED.
...AMPLIFYING LONGWAVE TROUGH ACROSS THE CENTRAL U.S. THURSDAY
EVENING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 03.00Z, THEN GEFS/ECENS
MEAN BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
08Z UPDATE: THROUGH 60 HOURS /03.18Z/ THERE IS FAIRLY GOOD
AGREEMENT NOW BUT STILL DIFFERENCES WITH THE NORTHERN STREAM
CLOSED LOW/SHORTWAVE. HERE THE NAM IS STILL TOO FAST/DEEP WHILE
THE ECMWF/GFS OFFER A SLOWER, MORE SOUTHERLY SOLUTION. THE
OPERATIONAL RUNS OF THE GFS/ECMWF ARE NOTABLY STRONGER THAN THEIR
ENSEMBLE MEANS, SO WILL CONTINUE TO FAVOR A GEFS/ECENS MEAN BLEND
FOR DAY 3.
A LONGWAVE TROUGH WILL DEVELOP OVER THE GREAT PLAINS THURSDAY INTO
FRIDAY WITH ITS ASSOCIATED SURFACE LOW TRACKING FROM THE SOUTHERN
PLAINS TOWARD THE OHIO VALLEY AND GREAT LAKES. THERE REMAINS
FAIRLY GOOD AGREEMENT ALOFT WITH THE 500 MB HEIGHT EVOLUTION BUT
SIZABLE DIFFERENCES AT THE SURFACE WITH THE LOW TRACK/STRENGTH
FROM 03.00Z ONWARD. THE ECMWF AND ECENS LOW PLOTS ARE ON THE
SOUTHERN/SOUTHEASTERN SPREAD, WHILE THE GEFS/CMCE ARE FURTHER
NORTH/NORTHWEST. THESE DIFFERENCES BECOME AMPLIFIED BY THE END OF
THE FORECAST PERIOD, WITH A MUCH BELOW FORECAST CONFIDENCE BY DAY
3. AS SUCH, WILL LEAN ON THE GEFS/ECENS FOR DAY 3 GIVEN THE
FORECAST SPREAD.
...SHORTWAVE TROUGH AND SURFACE LOW APPROACHING PACIFIC NORTHWEST
FRIDAY/SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/NAM
CONFIDENCE: SLIGHTLY BELOW AVERAGE
08Z UPDATE: THE ECMWF REMAINS TOO SLOW WITH THE INITIAL SURFACE
LOW IMPACTING PORTIONS OF BRITISH COLUMBIA, WHEREAS THE REST OF
THE MODELS SHOW FAIRLY GOOD CLUSTERING (AND HAVE TRENDED TOWARD
THE FASTER GFS/NAM IDEA). WITH THE SECONDARY LOW SWINGING THROUGH
TOWARD THE END OF THE FORECAST PERIOD, THE UKMET IS NOTICEABLE
WEAKER COMPARED TO THE REST OF THE GUIDANCE AND IS CONSIDERED AN
OUTLIER. THE GFS/NAM STILL LOOK REASONABLE AND EVEN SOME
COMPONENTS OF THE CMC APPEAR USEFUL THROUGH DAY 3.
THERE REMAINS A FAIR AMOUNT OF SPREAD AND TIMING DIFFERENCES WITH
THE APPROACH OF THE NEXT SHORTWAVE TROUGH FOR THE PACIFIC
NORTHWEST IN THE FRIDAY/SATURDAY TIME FRAME. THE TREND HAS BEEN
FOR A FASTER SOLUTION WITH THE LOW TRACK, WHICH FAVORS THE GFS/NAM
COMPARED TO THE NON-NCEP SOLUTIONS WHICH ARE SLOWER.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
TAYLOR
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