882
FXUS10 KWNH 041714
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1214 PM EST SAT JAN 04 2020
VALID JAN 04/1200 UTC THRU JAN 08/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..UPPER TROUGH CROSSING FROM THE MIDWEST TO THE EAST COAST
..SURFACE LOW NEAR NEW ENGLAND TODAY/TONIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.
...SHORTWAVE EJECTING OUT ACROSS THE PLAINS, REACHING THE GREAT
LAKES BY SUN NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM, 12Z GFS, 00Z ECMWF BLEND
CONFIDENCE: ABOVE AVERAGE
THERE REMAIN SOME MINOR PLACEMENT DIFFERENCES WITH THE MID-LEVEL
SHORTWAVE AS IT NEARS THE GREAT LAKES. THE 00Z UKMET AND 00Z CMC
ARE FARTHER SOUTH WITH THE 500 MB TROUGH AXIS, WHEREAS THE
ENSEMBLE MEANS ARE IN GOOD AGREEMENT SUPPORTING THE REASONABLY
SIMILAR 12Z NAM, 12Z GFS AND 00Z ECMWF.
..SPLIT-FLOW TROUGH NEAR THE PACIFIC NORTHWEST BY SUN
..CLIPPER TYPE LOW APPROACHING THE GREAT LAKES BY TUE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
TIMING AND LATITUDINAL DIFFERENCES SHOW UP WITH THE NORTHERN
PORTION OF A MID-LEVEL TROUGH AMPLIFYING THROUGH THE CENTRAL TO
EASTERN U.S. MONDAY NIGHT. THE 12Z NAM AND 00Z CMC ARE SLOWER
WHILE THE 00Z UKMET IS DISPLACED NORTHWARD WITH THE VORTICITY
MAXIMA COMPARED TO THE ENSEMBLE MEANS AND REMAINING DETERMINISTIC
GUIDANCE. THE 12Z GFS AND 00Z ECMWF ARE THOUGHT TO BE CLOSER TO
THE MIDDLE OF THE MODEL SPREAD AND ARE PREFERRED AT THIS TIME.
..SOUTHERN STREAM TROUGH/LOW NEAR THE TN VALLEY BY TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z NAM, 00Z ECMWF AND 00Z UKMET
CONFIDENCE: AVERAGE
THE SOUTHERN PORTION OF A BROADENING MID-LEVEL TROUGH OVER THE
EASTERN TWO THIRDS OF THE NATION MONDAY NIGHT INTO TUESDAY IS
EXPECTED TO COINCIDE WITH A WEAK SURFACE LOW TO CROSS THE
TENNESSEE VALLEY. THE 12Z GFS BECOMES SIGNIFICANTLY FASTER BY
TUESDAY MORNING WHILE THE 00Z CMC SHOWS SLOWEST OF THE
DETERMINISTIC GUIDANCE. THE 12Z NAM, 00Z ECMWF AND 00Z UKMET SHOW
GOOD AGREEMENT AND ARE FAVORABLY POSITIONED WITH RESPECT TO THE
ENSEMBLE MEANS.
..SHORTWAVE/FRONTS APPROACHING THE PACIFIC NORTHWEST TUE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS, 00Z UKMET BLEND
CONFIDENCE: AVERAGE
MODERATE SPREAD CONTINUES TO EXIST WITH A SHORTWAVE TROUGH TO
APPROACH THE PACIFIC NORTHWEST LATE MONDAY INTO TUESDAY. A WARM
FRONT IS FORECAST TO REACH WESTERN BRITISH COLUMBIA AND COASTAL
WASHINGTON MONDAY MORNING AS A LOW NEARS JUST NORTH OF VANCOUVER
ISLAND. THERE ARE SOME MINOR PLACEMENT DIFFERENCES WITH THE
SURFACE LOW, THE 00Z UKMET IS TOWARD THE SOUTHERN SIDE OF THE
DETERMINISTIC SPREAD WHILE THE 00Z CMC IS FARTHER NORTH. THE 12Z
NAM, 12Z GFS AND 00Z ECMWF ARE IN REASONABLE AGREEMENT HERE.
HOWEVER, LARGER DIFFERENCES SHOW UP DUE TO THE APPROACHING
SHORTWAVE TO THE WEST. WITH THIS FEATURE, THE 00Z ECMWF WAS FASTER
WHILE THE 12Z NAM WAS WEAKER WITH THE TROUGH. THE 00Z CMC WAS
CONSIDERED A BIT SLOW WITH THE FEATURE WHILE THE 12Z GFS AND 00Z
UKMET SHOWED REASONABLE AGREEMENT TO ONE ANOTHER AND A BLEND OF
THE LATEST ENSEMBLE MEANS. THEREFORE, A BLEND OF THE 12Z GFS AND
00Z UKMET WILL BE PREFERRED WITH THIS SYSTEM GIVEN DIFFERENCES
FROM THE 00Z UKMET'S SURFACE LOW INFLUENCE IS FELT FARTHER NORTH
AWAY FROM WASHINGTON.
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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