625
FXUS10 KWNH 190513
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1213 AM EST SUN JAN 19 2020
VALID JAN 19/0000 UTC THRU JAN 22/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SURFACE LOW/TRAILING COLD FRONT EXITING THE NORTHEAST EARLY
TODAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.
..SHORTWAVE/FRONT CLIPPING THE PACIFIC NORTHWEST BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z UKMET BLEND
CONFIDENCE: ABOVE AVERAGE
THE GUIDANCE MOSTLY AGREES WELL WITH A QUICK MOVING PACIFIC
SHORTWAVE TROUGH EARLY MONDAY WHOSE IMPACTS WILL BE GREATER INTO
BRITISH COLUMBIA THAN WASHINGTON. ONLY THE 12Z UKMET (WHICH
TRENDED FASTER THAN PREVIOUS CYCLES) STANDS OUT WITH A FASTER
TIMING THAN THE REMAINING STRONG CONSENSUS.
..AMPLIFYING SHORTWAVE CROSSING THE MIDWEST SUNDAY/MONDAY
..CLOSED LOW EVOLUTION OVER THE SOUTHEAST BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
TIMING DIFFERENCES WITH THIS PROGRESSIVE, BUT VIGOROUS, NORTHERN
STREAM SHORTWAVE BEGIN TO SHOW UP IN THE LATEST MODEL GUIDANCE ON
MONDAY. HOWEVER, ITS RELATED IMPACTS ARE LIKELY FELT MORE BY
TUESDAY ACROSS THE COAST OF THE SOUTHEAST AS A POTENTIAL CLOSED
LOW DEVELOPS. THE ENSEMBLES HAVE SHOWN GOOD AGREEMENT WITH THE
TIMING OVER THEIR PAST 4 1200Z CYCLES, BUT WAVER WITH NORTH/SOUTH
PLACEMENT OF THE VORTICITY MAX.
THE 00Z NAM IS THE MOST AGGRESSIVE WITH A SLOWER AND RATHER STRONG
SURFACE REFLECTION JUST OFF OF THE SOUTHEAST COAST. THE 00Z GFS
WAS NOTABLY FASTER THAN THE REMAINING MODEL CONSENSUS AND THE 12Z
CMC WAS ON THE NORTH SIDE WITH THE CLOSED LOW. SOMEWHERE NEAR THE
12Z ECMWF/UKMET IS CONSIDERED BEST AT THIS TIME GIVEN PLACEMENT
TOWARD THE MIDDLE OF THE SPREAD.
..SOUTHERN STREAM SHORTWAVE CROSSING CALIFORNIA BY MONDAY
...ENERGY CROSSING THE SOUTHWEST ON TUESDAY AND REACHING THE GREAT
PLAINS ON WEDNESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/00Z NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
SOUTHERN STREAM SHORTWAVE ENERGY WILL BE CROSSING SOUTHERN AREAS
OF CALIFORNIA ON MONDAY AHEAD OF A DEEP UPPER TROUGH/CLOSED LOW
OFFSHORE OF THE PACIFIC NORTHWEST. THIS ENERGY WILL THEN EJECT
QUICKLY DOWN ACROSS THE SOUTHWEST ON TUESDAY. THE 12Z UKMET ENDS
UP BEING SLOWER AND DEEPER THAN THE REMAINING SUITE BY TUESDAY
WHILE THE 00Z GFS BECOMES A CLEAR, FAST OUTLIER WHEN COMPARED TO
ENSEMBLE GUIDANCE AND THE REMAINING DETERMINISTIC GUIDANCE. WHILE
SOME LATITUDE DIFFERENCES EXIST BETWEEN THE 12Z ECMWF AND 00Z NAM,
A BLEND OF THESE TWO APPEARS TO BE CLOSEST TO THE FAVORED MIDDLE
GROUND OF THE LATEST ENSEMBLE MEANS.
...DEEP UPPER TROUGH/CLOSED LOW ARRIVING ACROSS THE PACIFIC
NORTHWEST BY TUESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/00Z NAM BLEND
CONFIDENCE: AVERAGE
WHILE TIMING OF THIS SYSTEM IS IN RELATIVELY GOOD AGREEMENT, WITH
ONLY THE 12Z CMC SHOWING SOMEWHAT SLOWER, THERE ARE LATITUDE
DIFFERENCES WITH THE CENTER OF THE CLOSED LOW AND RELATED SURFACE
LOW. ENSEMBLE LOW PLOTS HAVE CLUSTERED CLOSER TO ONE ANOTHER
COMPARED TO PREVIOUS CYCLES, BUT MODERATE DIFFERENCES REMAIN. THE
00Z GFS APPEARS TO BE TOO FAR SOUTH HOWEVER, AND WILL NOT BE
INCLUDED AS PART OF THE PREFERENCE. THE 00Z NAM APPEARS REASONABLE
BUT SHOULD BE BLENDED WITH THE 12Z ECMWF GIVEN THE PLACEMENT OF
THE ECMWF MEAN. A 12Z ECMWF/00Z NAM BLEND WILL FIT BEST AT THIS
TIME WITH ENSEMBLE MEMBER CLUSTERING FOR THIS SYSTEM IMPACTING THE
WESTERN U.S.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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