361
FXUS10 KWNH 091659
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1258 PM EDT TUE JUN 09 2020
VALID JUN 09/1200 UTC THRU JUN 13/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z PRELIMINARY MODEL EVALUATION INCLUDING PREFERENCES AND
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...TROUGH LIFTING THROUGH THE CENTRAL PLAINS BEFORE ABSORBING INTO
A CLOSED LOW NORTH OF THE GREAT LAKES...
...OCCLUDED LOW LIFTING INTO THE GREAT LAKES AND COLD FRONT MOVING
ACROSS THE EASTERN CONUS THROUGH FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC THROUGH THURSDAY
NON-CMC AND NON-NAM FRIDAY
CONFIDENCE: AVERAGE
A CLOSED LOW INITIALLY OVER THE CENTRAL PLAINS WILL EJECT
NORTHEASTWARD AND OPEN AS IT BECOMES ABSORBED INTO A LONGWAVE
TROUGH/CLOSED LOW CENTERED NORTH OF THE GREAT LAKES THURSDAY
MORNING. AN OCCLUDED LOW PRESSURE WILL LIFT NORTHEAST BENEATH
THIS, WITH THE ACCOMPANYING COLD FRONT PUSHING EAST TO BE ALONG OR
JUST OFF THE ATLANTIC COAST FRIDAY MORNING. THE GUIDANCE IS IN
REASONABLY GOOD AGREEMENT WITH THE EVOLUTION OF THESE FEATURES
DESPITE A COMPLEX PATTERN, WITH ONLY THE CMC BEING OUTSIDE THE
ACCEPTABLE ENVELOPE AS IT IS TOO WEAK AND TOO SLOW WITH THE
PROGRESSION OF THE WEAKENING UPPER TROUGH AND SURFACE COLD FRONT.
INTO FRIDAY, THE NAM BECOMES A STRONG OUTLIER WITH THE STRENGTH OF
THE LONGWAVE TROUGH THAT BUILDS IN BEHIND THE COLD FRONT, SO
DESPITE BEING USABLE D1-D2, IT IS REMOVED FROM THE PREFERRED BLEND
BY D3.
..CRISTOBAL REMNANTS
~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE 12Z NCEP AND 00Z NON-NCEP GUIDANCE REMAINS TIGHTLY CLUSTERED
TO THE TRACK AS CRISTOBAL ACCELERATES N/NE INTO CANADA BY
WEDNESDAY NIGHT. ALTHOUGH THE NAM BECOMES SLOWER THAN THE TRACK
AND THE CONSENSUS LATE D2, BY THIS TIME ANY IMPACTS FROM CRISTOBAL
SHOULD BE WELL REMOVED FROM THE CONUS, AND AS SUCH A GENERAL MODEL
BLEND IS SUGGESTED.
...CLOSED LOW OFF BRITISH COLUMBIA AND ASSOCIATED LONGWAVE TROUGH
DIGGING ONSHORE THE WEST COAST THROUGH FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/ECENS WITH LIGHT WEIGHT OF THE CMC/UKMET
CONFIDENCE: BELOW AVERAGE
CLOSED LOW OFF BRITISH COLUMBIA IS PROGGED TO SPIN NEARLY IN PLACE
THROUGH THURSDAY BEFORE BEGINNING A SLOW JOG SOUTHEAST TOWARDS THE
COAST FRIDAY. SOUTH OF THIS FEATURE, A LONGWAVE TROUGH EXTENDING
FROM THE CLOSED LOW WILL PROGRESS GRADUALLY EASTWARD TOWARDS THE
WEST COAST, WITH AN EMBEDDED SHORTWAVE APPROACHING CA/OR D3. THERE
IS CONSIDERABLE SPREAD, ESPECIALLY BY D3, IN THE PLACEMENT OF THIS
SHORTWAVE, LIKELY DUE TO A WIDE LATITUDINAL SPREAD IN THE POSITION
OF THE CLOSED LOW AT THAT TIME. THE NCEP GUIDANCE IS GENERALLY
FURTHER SOUTH WITH THE CLOSED LOW OFF BC, AND FASTER WITH THE
PROGRESSION OF THE TROUGH INTO CA, WHILE THE NON-NCEP GUIDANCE IS
FURTHER NORTH OFF BC AND THEN SLOWER WITH THE PROGRESSION OF THE
TROUGH. THE GFS HAS BEEN A FAST OUTLIER, AND IS EVEN FASTER AT
12Z, WHILE THE 12Z NAM HAS ALSO SPED UP A BIT FROM ITS PREVIOUS
ITERATION. MEANWHILE THE NON-NCEP GUIDANCE HAS BEEN GRADUALLY
SLOWING, AND SEEMS TO BE MORE TIGHTLY CLUSTERED. AN APPROACH
FAVORING THE 00Z/ECENS SEEMS BEST AT THIS POINT, WITH SOME WEIGHT
INCLUDED OF THE OTHER NON-NCEP MODELS, BUT CONFIDENCE IS BELOW
AVERAGE DUE TO SPREAD AND RUN-TO-RUN INCONSISTENCY.
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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