881
FXUS10 KWNH 040445
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1145 PM EST FRI JAN 03 2020
VALID JAN 04/0000 UTC THRU JAN 07/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..UPPER TROUGH CROSSING FROM THE MIDWEST TO THE EAST COAST
..SURFACE LOW CROSSING THE OH VALLEY TO NEW ENGLAND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
MODEL SPREAD CONCERNING THE INTERACTION BETWEEN TWO PIECES OF
ENERGY WITHIN A LONGWAVE SPLIT-FLOW TROUGH SHIFTING EASTWARD HAS
DIMINISHED CONSIDERABLY COMPARED TO PREVIOUS DAYS. THE MODELS SHOW
GOOD AGREEMENT NOW IN HAVING THE MORE DOMINANT NORTHERN STREAM
COMPONENT OF THE TROUGH GRADUALLY ABSORBING THE SOUTHERN STREAM
ENERGY AS IT ADVANCES TOWARD THE EAST COAST OVER THE NEXT DAY OR
SO. THE GUIDANCE SUPPORTS LOW PRESSURE CROSSING FROM THE OH VALLEY
THROUGH THE NORTHERN MID-ATLANTIC AND OFFSHORE SOUTHERN NEW
ENGLAND BY LATE SATURDAY, WITH LOW PRESSURE GRADUALLY DEEPENING AS
IT PULLS AWAY FROM THE NORTHEAST BY SUNDAY. MODEL SPREAD OVERALL
HAS BECOME RATHER MINIMAL WITH THIS SYSTEM, SO A GENERAL MODEL
BLEND WILL BE PREFERRED.
..SHORTWAVE TROUGH/LOW IMPACTING THE PACIFIC NORTHWEST
..ENERGY EJECTING OUT ACROSS THE PLAINS/MIDWEST BY SAT/SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS ARE IN GOOD AGREEMENT WITH THE SHORTWAVE TRACKING FROM
THE PACIFIC NORTHWEST TOWARD THE GREAT LAKES REGION BY SUNDAY
NIGHT. THE 00Z GFS BECOMES A TAD FASTER THAN THE REMAINING MODEL
GUIDANCE AS THE ENERGY ARRIVES ACROSS THE GREAT LAKES REGION, BUT
GIVEN THE FAST/PROGRESSIVE FLOW ACROSS THE CONUS IT WILL NOT BE
DISMISSED. THUS, A GENERAL MODEL BLEND WILL BE PREFERRED WITH THIS
SYSTEM.
..SPLIT-FLOW TROUGH NEAR THE PACIFIC NORTHWEST BY SUN
..CLIPPER TYPE LOW APPROACHING THE GREAT LAKES BY TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
SIMILAR TO THE ABOVE SYSTEM, MODEL SPREAD IS SMALL WITH THE
MID-LEVEL TROUGH AXIS REACHING THE PACIFIC NORTHWEST ON SUNDAY.
THIS ENERGY WILL RAPIDLY ADVANCE DOWNSTREAM WITH A WEAK LOW CENTER
CLIPPING THE NORTHERN PLAINS AND REACHING THE GREAT LAKES BY
TUESDAY. LIKE ITS PREDECESSOR, THE 00Z GFS IS SEEN AS BEING A TAD
MORE PROGRESSIVE THAN THE REMAINING MODEL SUITE, BUT FOR NOW A
GENERAL MODEL BLEND WILL BE PREFERRED.
..SOUTHERN STREAM TROUGH/LOW NEAR THE TN VALLEY BY TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z NAM/12Z UKMET AND 12Z ECMWF
CONFIDENCE: AVERAGE
THE MODELS TAKE A SHORTWAVE TROUGH IN THE SOUTHERN STREAM AND
ADVANCE IT ACROSS THE LOWER MS AND TN VALLEYS THROUGH MONDAY AND
TUESDAY ALONG WITH A WAVE OF LOW PRESSURE. THE 00Z GFS BECOMES A
BIT OF A PROGRESSIVE OUTLIER WHEREAS THE 12Z CMC APPEARS TO BE TOO
SLOW. THE GEFS MEAN AND ECENS MEAN DO NOT SUPPORT THE FAST GFS
WITH THIS SYSTEM, AND CLUSTER WELL WITH THE 00Z NAM/12Z UKMET AND
12Z ECMWF LED CLUSTER. SO, WILL PREFER A BLEND OF THE LATTER CAMP
OF SOLUTIONS AS A RESULT.
...UPSTREAM SHORTWAVE OFF OF THE PACIFIC NORTHWEST MONDAY
EVENING...
..WARM FRONTAL TIMING INTO THE PACIFIC NORTHWEST ON MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE
MODERATE SPREAD EXISTS WITH AN UPSTREAM SHORTWAVE TROUGH AXIS THAT
ARRIVES ACROSS THE PACIFIC NORTHWEST LATE MONDAY INTO TUESDAY.
INITIALLY A WARM FRONT WILL CROSS THE REGION AHEAD OF THIS ENERGY,
AND THE THE GUIDANCE HANDLES THAT RELATIVELY WELL, BUT THE 00Z GFS
IS A BIT MORE PROGRESSIVE WITH THIS, AND THE 12Z UKMET IS SLOWER.
THEN AS THE MAIN SHORTWAVE AND ASSOCIATED COLD FRONT ARRIVES ON
TUESDAY, THE 00Z NAM/GFS SOLUTIONS BOTH END UP SLOWER THAN THE
NON-NCEP MODELS. THE ENSEMBLE MEANS ARE SPLIT WITH THE GEFS MEAN
SLOWER AND THE ECENS MEAN FASTER. OVERALL, THE ECMWF IS CLOSEST TO
THE MODEL CONSENSUS, AND IS ACTUALLY A LITTLE SLOWER THAN THE
ECENS MEAN. GIVEN THE FAST OVERALL MEAN LAYER FLOW ACROSS THE
EASTERN PACIFIC AND THE CONUS, THE SLOWER SOLUTIONS PER THE
NAM/GFS DO NOT SEEM AS PLAUSIBLE, BUT FOR SURE CANNOT BE RULED
OUT. WILL PREFER THE 12Z ECMWF WITH SOMEWHAT LIMITED CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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