116
FXUS10 KWNH 010746
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 AM EST SAT FEB 01 2020
VALID FEB 01/0000 UTC THRU FEB 04/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...EVOLUTION OF TROUGH OVER EASTERN HALF OF THE U.S. THROUGH
SUNDAY...
...COASTAL LOW TRACKING NORTH OFFSHORE OF NEW ENGLAND LATE
SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
MODELS WERE STILL MAKING SOME RUN TO RUN SHIFTS IN TERMS OF HOW
MUCH ENERGY WILL BE PART OF THE NORTHERN STREAM PORTION OF THE
MID-LEVEL TROUGH THAT AFFECTS PARTS OF THE NORTHEAST LATER THIS
COMING NIGHT. DOWNSTREAM OF THE TROUGH AXIS, SURFACE CYCLOGENESIS
IS EXPECTED TO OCCUR OFF OF THE MID-ATLANTIC OR NEW ENGLAND COAST
LATER TODAY. THE GFS WAS STILL A BIT STRONGER THAN THE UKMET
WHILE THE CANADIAN WAS MORE AMPLIFIED RESULTING IN THE BASE OF ITS
TROUGH BEING DEEPER AND MORE SOUTHERLY. THINKING IS THAT A BLEND
OF THE 01/00Z GFS AND NAM WILL WORK WITH THE 01/00Z ECMWF WILL
WORK TO MINIMIZE SOME OF THESE DIFFERENCES AND MAINTAINING A
MIDDLE GROUND.
REGARDING THE OFFSHORE SURFACE LOW, THERE IS GOOD AGREEMENT WITH
TRACK UNTIL THE LOW IS OFFSHORE OF NOVA SCOTIA, WITH A GFS/ECMWF
BLEND WORKING WELL FOR BOTH POSITION AND TIMING.
...PACIFIC NORTHWEST ATMOSPHERIC RIVER LEADING A LONGWAVE TROUGH
PUSHING INTO THE WEST ON SUNDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF NON 01/00Z GFS GUIDANCE
CONFIDENCE: AVERAGE
..06Z UPDATE
THE 01/00Z NON-NCEP GUIDANCE SHOWED GOOD RUN TO RUN CONTINUITY SO
NO CHANGE IN PREFERENCES WAS NECESSARY.
..PREVIOUS DISCUSSION
THERE IS REASONABLE AGREEMENT WITH THE EVOLUTION OF A LONGWAVE
TROUGH ACROSS THE WEST COAST INTO THE GREAT BASIN INTO EARLY NEXT
WEEK. THERE 01/00Z GFS MAINTAINED CONTINUITY WITH ITS PREVIOUS
RUN, WHICH MEANT THAT IT REMAINED A BIT QUICKER THAN THEN MODEL
CONSENSUS WITH THE LEADING EDGE OF THE TROUGH BY EARLY SUNDAY.
MODEL DETERMINISTIC MODELS CLUSTER BETTER WITH THE 31/12Z ECMWF
AND UKMET. A NON 12Z GFS BLEND OF GUIDANCE LOOKS REASONABLE FOR
THE WESTERN U.S. TROUGH SINCE DIFFERENCES AMONG THE NON-GFS
DETERMINISTIC GUIDANCE ARE MINOR.
...LEADING SHORTWAVE TRACKING THROUGH SOUTHERN CANADA ON SUNDAY
WITH ACCOMPANYING SURFACE LOW...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
..06Z UPDATE
NO CHANGES WERE MADE TO THE PREVIOUS PREFERENCES BASED ON A GOOD
CONTINUITY AND SUPPORT FROM THE ENSEMBLES...
..PREVIOUS DISCUSSION
WEAK HEIGHT FALLS MOVING EASTWARD ACROSS SOUTHERN CANADA ON SUNDAY
AND SUNDAY NIGHT BE ACCOMPANIED BY A WEAK AREA OF LOW PRESSURE AT
THE SURFACE. THE 01/00Z GFS REMAINED A BIT FASTER THAN THE 31/12Z
ECMWF...WITH OTHER GUIDANCE IN REASONABLY CLOSE PROXIMITY. STILL
THINK THAT THE MODEL DIFFERENCES ARE SMALL ENOUGH THAT A GENERAL
MODEL BLEND SHOULD WORK.
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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