139
FXUS10 KWNH 121837
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
236 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 MODEL EVALUATION INCLUDING FINAL 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/12Z ECMWF 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 12Z GEFS MEAN (THOUGH NOT
AS SLOW AS THE 12Z CMC, WHICH REPRESENTS THE WESTERN EDGE OF THE
GUIDANCE ENVELOPE), WHILE THE 12Z ECMWF IS STILL A TAD FASTER THAN
THE CONSENSUS, ESPECIALLY AFTER THE OPENING WAVE CROSSES NORTHERN
NEW ENGLAND. THE 12Z UKMET, UNLIKE ITS PREVIOUS RUN, IS SLOWER
THAN THE CONSENSUS FROM THE BEGINNING.
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/12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE 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 12Z UKMET IS CLOSER TO THE
CONSENSUS WITH MID LEVEL SYSTEM, WHILE THE 12Z CMC REMAINS FURTHER
EAST ACROSS SOUTH CENTRAL MT. THE 12Z ECMWF/00Z ECMWF ENSEMBLE
MEAN ARE CLOSE TO THE 12Z NAM/GFS CLUSTER BY THE END OF THE
PERIOD, LEADING SOME CREDENCE TO THAT SOLUTION. CONSIDERING THAT
THE 12Z UKMET IS NOW CLOSER TO THE CONSENSUS, FORECAST CONFIDENCE
IS CONSIDERED SLIGHTLY ABOVE 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 12Z 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
HAYES
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