807
FXUS10 KWNH 131629
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1129 AM EST MON JAN 13 2020
VALID JAN 13/1200 UTC THRU JAN 17/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..LARGE SCALE PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 36HRS THEN
00Z ECMWF/UKMET/ECENS MEAN
CONFIDENCE: AVERAGE
THROUGH ABOUT 48 HOURS, LARGE SCALE TROUGHING AND CLOSED UPPER LOW
SETTLES OVER INTERIOR WESTERN CANADA WITH SEVERAL IMPULSES
IMPACTING PORTIONS OF THE PACIFIC NORTHWEST TO CENTRAL PLAINS AND
GREAT LAKES REGIONS. BEYOND THAT TIME FRAME, A MORE SIGNIFICANT
SHORTWAVE TROUGH MOVES ACROSS THE PACIFIC NW AND THEN EXTENDS
THROUGHOUT THE WEST COAST WHILE A PROGRESSIVE SHORTWAVE TRACKS
THROUGH THE NORTHEAST U.S. THE SOUTH-CENTRAL US TO SOUTHEAST U.S.
IS EXPECTED TO BE GENERALLY UNDER ZONAL TO RIDGING. THE 12Z
GUIDANCE HAS TRENDED TIGHTER WITH THE EVOLUTION AND PROGRESSION OF
THE POLAR VORTEX WHERE THE GFS NOW IS NOT AS FAST/PROGRESSIVE
AHEAD OF THE OTHER MODELS AS PREVIOUSLY SEEN. THOUGH BEYOND 36-42
HOURS, IT DOES SHEAR OUT THE ENERGY FASTER ACROSS SOUTHERN CANADA
AND THE GREAT LAKES REGIONS. THIS PUTS THE SURFACE LOW TRACK A
STEP AHEAD OF THE REST OF THE GUIDANCE, THOUGH GENERALLY ALONG THE
SAME TRACK FROM THE CENTRAL PLAINS TO EASTERN GREAT LAKES BY 60
HOURS.
AS THE UPPER LOW LOSES INFLUENCE AND MOVES EAST ACROSS THE CONUS,
A PATTERN CHANGING SHORTWAVE AMPLIFIES OVER THE GULF OF ALASKA AND
NORTHEAST PACIFIC OCEAN. WITH A SLOWER CLOSED LOW (AS WELL AS
NORTH), THE ECMWF PUMPS THE DOWNSTREAM RIDGE ACROSS THE NORTHWEST
AND RAPIDLY DEVELOPS A CLOSED LOW/DEEP SURFACE CYCLONE ALONG THE
PACIFIC NW COAST INTO VANCOUVER ON DAY 3. WHILE, THE OPERATIONAL
ECMWF/CMC ARE ON THE FASTER SIDE, GIVEN THE DOWNSTREAM INFLUENCES,
PREFER THE ECENS MEAN SOLUTION GREATEST THOUGH THE OPERATIONAL 12Z
GFS IS FURTHER SOUTH/SLOWER NEAR THE 12Z NAM. THE EVOLUTION AND
SPREAD IS NOT TERRIBLE FOR THE END OF DAY 3 FOR SUCH AN UPSTREAM
WAVE THROUGH A RELATIVE DATA VOID THAT A NON-NAM BLEND MAY WORK
BEST WEIGHTED STRONGEST TO ECENS MEAN, THEN ECMWF/CMC/UKMET.
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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