660
FXUS10 KWNH 181632
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1231 PM EDT WED MAR 18 2020
VALID MAR 18/1200 UTC THRU MAR 22/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEP TROUGH/CLOSED LOW IMPACTING THE WEST
...LOW PRESSURE CROSSING THE CENTRAL PLAINS INTO THE UPPER GREAT
LAKES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS AS THEY LIFT THE CLOSED
MID LEVEL SYSTEM OVER OF THE GREAT BASIN DURING THU. THE SHORT
WAVE HELPS DEEPEN SURFACE LOW PRESSURE FORMING OVER EASTERN CO
AROUND 19/12Z, WHICH THEN TRACKS ACROSS THE CENTRAL PLAINS INTO
THE UPPER GREAT LAKES THU INTO FRI. THROUGH THAT TIME, THE 12Z
NAM/GFS ARE CLOSE TO THE CONSENSUS WITH THE TRACK OF THE SURFACE
LOW, BUT GRADUALLY BEGIN TO DIVERGE FROM THE CONSENSUS, MOVING
ACROSS EASTERN QUEBEC BY THE END OF THE PERIOD.
BY CONTRAST, THE 00Z ECMWF/ECMWF MEAN ARE A BIT WEAKER AND FURTHER
SOUTH WITH THE TRACK OF THE SURFACE LOW, TAKING IT ACROSS THE BAY
OF GASPE BY 21/00. BASED ON ITS CONSISTENCY, A BLEND OF THE 12Z
GFS/00Z ECMWF IS PREFERRED WITH THIS SYSTEM, THOUGH THE DIVERGENCE
IN TRACK AFTER THE SYSTEM REACHES EASTERN CANADA RESULTS IN ONLY
AVERAGE FORECAST CONFIDENCE.
..SERIES OF MID LEVEL TROUGHS CROSSING THE NORTHERN HIGH PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF
CONFIDENCE: AVERAGE
THE 12Z NAM /GFS ARE CLOSE TO THE CONSENSUS WITH THE FIRST SHORT
WAVE IN THE SERIES TRACKING FROM CENTRAL MANITOBA INTO THE UPPER
GREAT LAKES THROUGH 20/12Z. AFTER THAT TIME, THE 12Z NAM BECOMES
FASTER THAN THE CONSENSUS WITH THE LEAD SHORT WAVE. THE NEXT SHORT
WAVE IN THE FLOW CROSSES THE NORTHERN PLAINS FRI NIGHT INTO SAT
MORNING. THE 12Z NAM BECOMES FASTER AND DEEPER WITH THIS SYSTEM,
WHILE THE 00Z CMC IS THE SLOWEST WITH THE SHORT WAVE.
WITH BOTH SYSTEMS, THE 12Z GFS/00Z ECMWF ANCHOR FAIRLY CONSISTENT
TIMING WITH BOTH SHORT WAVES, SO THIS PAIR IS PREFERRED FOR BOTH
SYSTEM. HOWEVER, GIVEN THE SPREAD IN THE REMAINDER OF THE GUIDANCE
(ESPECIALLY WITH THE SECOND SHORT WAVE), FORECAST CONFIDENCE IS
AVERAGE.
..MID LEVEL TROUGH OVER SOUTHERN CA SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: SLIGHTY ABOVE AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING A CLOSED MID
LEVEL LOW FROM 32N 136W AT 19/00Z THAT WEAKENS INTO A MID LEVEL
TROUGH AND REACHES SOUTHERN CA BY 21/12Z. THE 00Z UKMET REMAINS
THE SLOWEST AND DEEPEST WITH THIS SYSTEM, AND REPRESENTS THE
WESTERN EDGE OF THE GUIDANCE ENVELOPE. WITH A TIGHTLY CLUSTERED
SOLUTION WITH THIS SYSTEM IN PLACE, A NON-UKMET SOLUTION IS
PREFERRED WITH SLIGHTLY ABOVE AVERAGE 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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