478
FXUS10 KWNH 051657
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1156 AM EST SUN JAN 05 2020
VALID JAN 05/1200 UTC THRU JAN 09/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SHORTWAVE TROUGH TRACKING ACROSS THE GREAT LAKES/NORTHEAST
THROUGH LATE MON...
..WEAK SURFACE LOW MOVING THROUGH SOUTHERN CANADA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.
..SPLIT-FLOW TROUGH NEAR THE PACIFIC NORTHWEST TODAY
..ENERGY REACHING THE GREAT LAKES/NORTHEAST TUE/WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM, 00Z ECMWF AND 00Z UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
AS SHORTWAVE ENERGY MAKES ITS WAY EAST INTO THE GREAT LAKES REGION
ON TUESDAY, THERE ARE DIFFERENCES WITH THE HANDLING OF THE 500 MB
TROUGH. THE 12Z GFS IS DISPLACED NORTH WITH THE CORE OF THE BASE
OF THE TROUGH IN THE VICINITY OF WESTERN ONTARIO NOTED MID-DAY
TUESDAY. THE 00Z CMC IS DISPLACED SLIGHTLY SOUTH AND SLOWER THAN
THE REMAINING CONSENSUS. FAIRLY GOOD AGREEMENT IN THE ENSEMBLES
EXISTS FOR A BLEND NEAR THE 12Z NAM, 00Z ECMWF AND 00 UKMET.
..SOUTHERN STREAM TROUGH/LOW NEAR THE TN VALLEY BY TUE
..SURFACE LOW IMPACTING THE MID-ATLANTIC/NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM AND 00Z ECMWF
CONFIDENCE: AVERAGE
WHILE MODEL DIFFERENCES ARE RATHER MINOR WITH THIS SYSTEM, A
MODEST AMOUNT OF SPREAD REMAINS IN THE ENSEMBLES AND RUN TO RUN
CONSISTENCY IN THE GUIDANCE HAS NOT BEEN GREAT. THE 12Z GFS STANDS
OUT FIRST WITH A FASTER 500 MB TROUGH PROGRESSION TOWARD THE EAST
COAST, PERHAPS DUE TO MORE SEPARATION IN THE FLOW WITH THE
NORTHERN COMPONENT OF THE LARGER SCALE TROUGH AXIS TRACKING
THROUGH SOUTHERN CANADA.
AMONG THE NON 12Z GFS GUIDANCE, SPECIFICALLY CONCERNING THE 850 MB
LOW, FROM LATE TUESDAY INTO WEDNESDAY, THE 12Z NAM IS ON THE SOUTH
SIDE OF THE DETERMINISTIC GUIDANCE WHILE THE 00Z ECMWF/UKMET/CMC
ARE NORTH. THE 12Z GFS IS ALSO SOUTH LIKE THE NAM, BUT AGAIN IS
FASTER THAN IDEAL. A BLEND BETWEEN THE 12Z NAM AND 00Z ECMWF IS
CONSIDERED BEST FOR THIS SYSTEM AT THIS TIME, BUT ADJUSTMENTS IN
FUTURE CYCLES APPEAR POSSIBLE GIVEN THE CHANGES SEEN LEADING TO
TODAY'S RUNS.
...SHORTWAVE/FRONTS APPROACHING THE PACIFIC NORTHWEST MON AND
TUE...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 00Z UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
YET ANOTHER IN A SERIES OF SHORTWAVE TROUGHS WILL ARRIVE ACROSS
THE PACIFIC NORTHWEST LATE MONDAY INTO TUESDAY. INITIALLY A WARM
FRONT WILL CROSS THE REGION AHEAD OF THIS ENERGY, WITH THE MAIN
TROUGH CROSSING BY LATE TUESDAY. MODEL AGREEMENT WITH THE WARM
FRONT IS NOW GOOD, BUT THE 00Z UKMET IS FASTER WITH THE MID-LEVEL
SHORTWAVE ALONG THE WEST COAST. THE FASTER TIMING OF THE 00Z UKMET
CARRIES OVER DOWNSTREAM INTO INTERIOR PORTIONS OF THE WEST AND IS
A NOTABLE FASTER SOLUTION IN THE SPAGHETTI ENSEMBLE PLOTS THROUGH
WEDNESDAY. WHILE NOT A COMPLETE OUTLIER, PREFER TO STICK NEARER TO
THE BETTER ENSEMBLE/DETERMINISTIC CLUSTERING AWAY FROM THE 00Z
UKMET. TIMING DIFFERENCES AMONG THE NON 00Z UKMET GUIDANCE ARE
PRESENT (00Z ECMWF A BIT FASTER) BUT ARE RELATIVELY MINOR.
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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