487
FXUS10 KWNH 121648
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 PM EDT TUE MAY 12 2020
VALID MAY 12/1200 UTC THRU MAY 16/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION INCLUDING INITIAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW OVER ALBERTA TRACKING TO THE UPPER GREAT LAKES
THU...THEN ACROSS NORTHERN NEW ENGLAND FRI...
...SURFACE LOW MOVING FROM THE NORTH CENTRAL US WED NIGHT INTO
NORTHERN NEW ENGLAND FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/00Z ECMWF/00Z UKMET BLEND
CONFIDENCE: AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS WITH THE CLOSED MID
LEVEL LOW AS IT TRACKS OUT OF ALBERTA WED AS IT MOVES ACROSS THE
UPPER GREAT LAKES THU NIGHT. AFTER THAT TIME, THE 12Z GFS SLOWS
WHEN COMPARED TO THE CONSENSUS AND THE 00Z GEFS MEAN (THOUGH NOT
AS SLOW AS THE 00Z CMC, WHICH REPRESENTS THE WESTERN EDGE OF THE
GUIDANCE ENVELOPE), WHILE THE 00Z ECMWF BECOMES FASTER THAN THE
CONSENSUS, ESPECIALLY AFTER THE OPENING WAVE CROSSES NORTHERN NEW
ENGLAND. FOR THE MID LEVEL SYSTEM, GIVEN THE SPREAD, THE 12Z
NAM/00Z ECMWF/00Z UKMET IS THE PREFERRED BLEND.
AT THE SURFACE, THERE IS EVEN MORE SPREAD CONCERNING THE PLACEMENT
OF THE LOW OVER NORTHERN NEW ENGLAND THU INTO FRI. FOR THE MOST
PART, THE SURFACE LOW IS FAIRLY WEAK, AND IN THIS SCENARIO, IT IS
NOT CLEAR WHERE ALONG THE LOW LEVEL BAROCLINIC ZONE THE LOW
DEVELOPS. BECAUSE OF THE SPREAD IN THE SURFACE LOW POSITION,
FORECAST CONFIDENCE IS ONLY AVERAGE.
....CLOSED MID LEVEL LOW OFF THE PACIFIC NORTHWEST COAST
THU...MOVING INTO THE NORTHERN ROCKIES FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING THE CLOSED MID
LEVEL LOW FROM THE PACIFIC NORTHWEST COAST THU MORNING ACROSS THE
NORTHERN ROCKIES DURING FRI. THE 00Z UKMET CLOSES THE MID LEVEL
SYSTEM DOWN AS IT MOVES OVER ID EARLY FRI, WHILE THE 00Z CMC ALSO
ATTEMPTS TO CLOSE THE MID LEVEL SYSTEM, BUT FURTHER EAST ACROSS
SOUTH CENTRAL MT. THE 00Z ECMWF/ECMWF ENSEMBLE MEAN ARE CLOSE TO
THE 12Z NAM/GFS CLUSTER BY THE END OF THE PERIOD, LEADING SOME
CREDENCE TO THAT SOLUTION. HOWEVER, GIVEN THE SPREAD WITH RESPECT
TO THE 00Z UKMET/CMC, FORECAST CONFIDENCE IS ONLY AVERAGE.
..BROAD MID LEVEL TROUGH OVER NORTHERN MEXICO THU/FRI
..SURFACE LOW OVER EASTERN NM/WEST TX FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING A DEVELOPING
LONG WAVE TROUGH ACROSS NORTHWEST MEXICO THU NIGHT, WHICH THEN
BECOMES A BROAD TROUGH ACROSS NORTHERN MEXICO TOWARD THE END OF
THE PERIOD. IN FACT, OUTSIDE OF THE 00Z CMC (WHICH IS A BIT FASTER
THAN THE CONSENSUS), THERE IS GENERALLY GOOD CLUSTERING WITH THIS
FEATURE.
THERE IS A BIT MORE SPREAD CONCERNING THE PLACEMENT OF THE SURFACE
LOW ACROSS EASTERN NM/FAR WEST TX BY THE END OF THE PERIOD.
HOWEVER, THE SURFACE LOW IS FAIRLY WEAK, AND A GENERAL MODEL BLEND
SHOULD SUFFICE WITH SLIGHTLY ABOVE AVERAGE FORECAST CONFIDENCE.
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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