082
FXUS10 KWNH 101843
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 PM EDT WED JUN 10 2020
VALID JUN 10/1200 UTC THRU JUN 14/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z FINAL MODEL EVALUATION INCLUDING PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SHORTWAVE AND ASSOCIATED SURFACE LOW LIFTING INTO CANADA
TONIGHT...
...DEEPENING EASTERN CONUS TROUGH AND COLD FRONT THROUGH FRIDAY
NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL BLEND THROUGH FRIDAY
ECENS/GEFS D3
CONFIDENCE: AVERAGE
19Z UPDATE: 12Z NON-NCEP CAMP STILL LACKS MUCH IN THE WAY OF
RUN-TO-RUN CONSISTENCY, ALTHOUGH THE 12Z ECMWF DOES NOW MATCH UP
BETTER BY D3 WITH THE PREFERRED MEANS BLEND. THE UPDATED GEFS MEAN
REMAINS WELL CLUSTERED TO THE ECENS AND NOW THE ECMWF, SO NO
CHANGES SUGGESTED.
PREVIOUS DISCUSSION:
THROUGH FRIDAY, THE GLOBAL MODELS ARE IN VERY GOOD AGREEMENT IN
THE EVOLUTION OF A WEAKENING SHORTWAVE AND ASSOCIATED SURFACE LOW
LIFTING THROUGH THE UPPER MIDWEST AND INTO CANADA, SO A GENERAL
MODEL BLEND IS REASONABLE. LATE FRIDAY AND SATURDAY, THE NORTHEAST
GETS VERY MESSY AS 4 INDIVIDUAL SHORTWAVES INTERACT IN SOME
FASHION ACROSS SOUTHEAST CANADA. THESE WILL LIKELY CONGEAL INTO A
LARGER CLOSED LOW/GYRE WHICH WILL THEN AMPLIFY A LONGWAVE TROUGH
ACROSS THE EASTERN CONUS. THERE IS LITTLE AGREEMENT IN THE
DETERMINISTIC MODELS INTO D3 AS TO HOW THIS WILL EVOLVE, ALTHOUGH
THE ECMWF IS A CLEAR STRONG OUTLIER, WHILE THE GFS IS BY FAR THE
MOST PROGRESSIVE. WITHOUT ANY CLEAR INDICATOR AS TO WHICH
SHORTWAVE WILL BECOME DOMINANT, WHICH WOULD LEAD TO A MORE
DEFINITIVE EVOLUTION OF THE TROUGH AMPLIFICATION, FEEL A BLEND
TOWARDS THE GEFS/ECENS MEANS IS MOST REASONABLE. THIS WILL WASH
OUT SOME OF THE FINER PRECIP DETAILS, ESPECIALLY ALONG THE
SOUTHEAST COAST WHERE THE STALLING FRONT COULD FIRE CONVECTION,
BUT FOR AMPLITUDE AND PLACEMENT OF THE MEAN TROUGH PREFER TO HEDGE
TOWARDS THE MEANS DUE TO WIDELY VARYING DETERMINISTIC SOLUTIONS AT
THIS TIME.
...LONGWAVE TROUGH OFF THE WEST COAST AND SHORTWAVE LIFTING
ONSHORE CALIFORNIA BY THE WEEKEND...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON GFS
CONFIDENCE: SLIGHTLY BELOW AVERAGE
19Z UPDATE: THE PREVIOUS CONCERNS ABOUT THE CMC HAVE BEEN REMOVED
AS THE 12Z ITERATION WAS VERY TIGHTLY CLUSTERED TO THE PREFERRED
BLEND. THE GFS REMAINS A PROGRESSIVE OUTLIER, BUT THE REMAINING
GUIDANCE IS USABLE.
PREVIOUS DISCUSSION:
THE GUIDANCE IS BECOMING AT LEAST SOMEWHAT BETTER ALIGNED WITH A
SUBTLY MORE PROGRESSIVE SOLUTION INTO THE WEST COAST. THE
IMPORTANT SHORTWAVE ROTATING THROUGH THE BASE OF THE LONGWAVE
TROUGH EXTENDING FROM A CLOSED LOW OFF THE BC COAST WILL TILT
NEGATIVELY AND LIFT ONSHORE LATE FRIDAY INTO SATURDAY. THERE
REMAIN TIMING DIFFERENCES OF THIS FEATURE, MOST NOTABLY THE GFS
CONTINUES TO BE THE FASTEST WITH THE EJECTION OF THE SHORTWAVE TO
THE NORTHEAST. THE GEFS MEAN IS ALSO ON THE FAST EDGE OF THE
ENSEMBLE CLUSTER. HOWEVER, SINCE THE OTHER GUIDANCE HAS SPED UP AT
LEAST SOMEWHAT, USING THE GEFS MEAN IS REASONABLE THROUGH 60
HOURS. THEREAFTER, THE CMC BECOMES A STRONG OUTLIER WITH THE
AMPLITUDE OF THE SHORTWAVE AS IT PIVOTS INTO THE GREAT BASIN
SATURDAY, LEAVING THE ECENS/ECMWF/NAM/UKMET/GEFS AS THE PREFERRED
BLEND.
WEISS
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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