891
FXUS10 KWNH 020423
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1222 AM EDT SAT NOV 02 2019
VALID NOV 02/0000 UTC THRU NOV 05/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CONUS THROUGH 84HRS (05/12Z)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z UKMET BLEND
CONFIDENCE: AVERAGE
A VERY BROAD GLOBAL SCALE TROUGH DOMINATES THE CURRENT CONUS
WEATHER PATTERN WITH A SIZABLE RIDGE (BECOMES CLOSED 582DM
ANTICYCLONE LATER TODAY) OVER THE NORTHEAST PACIFIC. ORIENTATION
OF THE TROUGH WILL ALLOW FOR PERSISTENT NORTHWESTERLY FLOW OPENING
UP THE CENTRAL CONUS TO COLDER ARCTIC SOURCE AIR THOUGH THE
SHORT-TERM FORECAST WITH EACH INTERNAL SMALLER SCALE SHORTWAVE
FEATURES MOVING THROUGH IT. SO FROM A LARGE SCALE PERSPECTIVE
THERE IS VERY GOOD AGREEMENT.
CURRENTLY, A DIP IN THE CORE OF THE TROUGH THE GREAT LAKES TODAY
IS WELL HANDLED IN THE GUIDANCE, AS IT SLIDES THROUGH THE
NORTHEAST SUNDAY WITH LITTLE FANFARE BESIDE LAKE EFFECT SNOW BANDS
IN THE GREAT LAKES. THE NEXT SMALL SCALE WAVE, DOES HAVE SOME
UNCERTAINTY AND MODEL SPREAD. THE 12Z ECWMF BREAKS FROM CONSENSUS
INCLUDING THE BULK OF ECENS MEMBERS SUPPORTING INCREASED SHORTWAVE
RIDGING AHEAD OF THE NEXT WAVE THAT DROPS OUT OF WESTERN CANADA ON
SUNDAY. THIS ALLOWS FOR FURTHER SOUTHWARD PRESS OF THE WAVE AND
DELAY COMPARED TO THE ENSEMBLE SUITE AND IN PARTICULAR THE 00Z GFS
AND 12Z UKMET. THE CMC IS ALSO IN LINE WITH THE GFS/UKMET FOR
THIS WAVE. THE 00Z NAM HOWEVER, IS VERY STRONG WITH THE POLAR JET
SHORTWAVE EVEN TAMPING DOWN THE RIDGE IN THE PACIFIC, WHICH DOES
NOT APPEAR METEOROLOGICALLY SOUND, GIVEN THE STRENGTH OF THE RIDGE
AND MAY BE IN LINE WITH TYPICAL NEGATIVE NAM OVER-AMPLIFICATION
BIAS. WHILE THE DIFFERENCES SHOW SMALLER EFFECTS ACROSS THE
GREAT LAKES BY MONDAY, THERE IS ENOUGH TO SUPPORT A PREFERENCE
TOWARD THE GFS/UKMET AND CMC.
THE SET UP/TIMING WITH THE AFOREMENTIONED WAVE LEADS TO TIMING
ISSUES WITH THE NEXT SHORTWAVE IN THE NORTHWEST FLOW. THIS WAVE
IS MORE OUT OF THE ARCTIC STREAM ACTING AS THE KICKER TO THE PRIOR
ONE, AND THERE IS A LARGER UNCERTAINTY TO ITS INITIALIZATION AS
WELL AS EVOLUTION AS IT DIPS INTO NW ONTARIO BY 5.00Z. THE ECMWF
BEING SLOWER WITH THE INITIAL WAVE IS VERY COMPACT/STRONG WITH
THIS KICKER. THE COMPACT NATURE IS A OUTLIER IN THE ECENS MEMBER
SUITE AND SO IS NOT FAVORED AT THIS TIME. WHILE, THE LEADING WAVE
INTO THE GREAT LAKES IS HANDLED WELL BY THE CMC, THIS ARCTIC WAVE
IS RESOLVED AS VERY COMPACT/STRONG AND THEREFORE VERY SLOW TO ROLL
SOUTHWARD, AND GIVEN THE LARGER SCALE PATTERN, THIS SEEMS UNLIKELY
AS WELL. THE UKMET/GFS SHOW SOME AMPLIFICATION/STRENGTH TO THIS
WAVE, BUT ARE WEAKER/BROADER AND MORE IN LINE TO A TYPICAL
PATTERN.
AS SUCH THE WPC PREFERENCE IS A 00Z GFS/UKMET BLEND THROUGHOUT THE
FORECAST PERIOD WITH SOME INCLUSION OF THE CMC EARLY. WHILE THE
IMPACTS TO SENSIBLE WEATHER ARE NOT LARGE, THE SPREAD AND
EVOLUTION UNCERTAINTY IS MODERATE TO HIGH AND SO CONFIDENCE IS
AVERAGE IN THE GFS/UKMET BLEND THROUGH THE SHORT-TERM FORECAST
PERIOD.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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