669
FXUS10 KWNH 010451
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1150 PM EST TUE DEC 31 2019
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
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
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
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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