444
FXUS10 KWNH 281650
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 PM EDT TUE APR 28 2020
VALID APR 28/1200 UTC THRU MAY 02/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION INCLUDING INITIAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...DEVELOPING LONG WAVE TROUGH AND SURFACE LOW TRACKING FROM THE
MID MS VALLEY TO THE NORTHERN MID ATLANTIC...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE 12Z NAM/GFS ARE CLOSE WITH SHORT WAVE ENERGY TRACKING FROM
EASTERN MT THAT DROPS INTO A DEVELOPING LONG WAVE TROUGH ACROSS
THE MID MS VALLEY THROUGH 30/00Z. AFTER THAT TIME, THE 00Z NAM
BECOMES SLOWER THAN THE CONSENSUS, WITH THE GREATEST DIFFERENCE
OCCURRING OVER THE NORTHERN MID ATLANTIC TOWARD THE END OF THE
PERIOD. THE 12Z GFS REMAINS CLOSER TO THE CONSENSUS AS THE CLOSED
MID LEVEL SYSTEM CROSSES THE OH VALLEY, THEN BECOMES FASTER WITH
THIS SYSTEM BY 02/00Z. THE DIFFERENCES WITH THE 12Z NCEP GUIDANCE
APPEAR TO BE DRIVEN BY HOW THE CLOSED MID LEVEL SYSTEM INTERACTS
WITH SHORT WAVE ENERGY DROPPING INTO IT ACROSS THE OH VALLEY AND
NORTHERN MID ATLANTIC. BY CONTRAST, THE 00Z ECMWF/UKMET ARE MORE
CONSISTENT WITH THE MID LEVEL SYSTEM, ENJOYING THE SUPPORT OF THE
00Z ECMWF ENSEMBLE MEAN.
THE 12Z NAM/GFS ALSO EXHIBIT THEIR RESPECTIVE ISSUES WITH THE
SURFACE LOW ASSOCIATED WITH THE MID LEVEL SYSTEM, WITH THE 12Z GFS
LOOKING TOO FAST AND TOO FAR SOUTH WITH THE SYSTEM BY 02/00Z.
THOUGH THE 00Z ECMWF/UKMET FORM A LOOSE CONSENSUS WITH THE MID
LEVEL AND SURFACE SYSTEMS, THERE REMAINS A FAIR AMOUNT OF SPREAD
IN THE SOLUTIONS. BASED ON THIS, FORECAST CONFIDENCE IS SLIGHTLY
BELOW AVERAGE.
...SHORT WAVE ENERGY AFFECTING THE PACIFIC NORTHWEST TO THE
NORTHERN PLAINS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF/00Z UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS TAKING SHORT WAVE
ENERGY NEAR 42N 138W AT 29/12Z AND WEAKENING IT AS IT APPROACHES
VANCOUVER ISLAND NEAR 30/12Z. AFTER THIS TIME, BOTH MODELS DIVERGE
FROM THE LOOSE CONSENSUS, WITH THE 12Z NAM TAKING THE BULK OF THE
SHORT WAVE ENERGY INTO ALBERTA AND MANITOBA. THE 12Z GFS REMAINS
CLOSER TO THE 00Z ECMWF/00Z UKMET, KEEPING THE SHORT WAVE ENERGY
CLOSER TO THE INTERNATIONAL BORDER, REACHING THE NORTHERN PLAINS
BEFORE 02/00Z. SOME OF THE SPREAD COULD BE TIED TO HOW A SECOND
SHORT WAVE APPROACHING THE PACIFIC NORTHWEST LATE INTERACTS WITH
THE FIRST SHORT WAVE, CAUSING SOME DIVERGENCE IN THE SOLUTIONS.
BASED ON THE INCREASING SPREAD WITH TIME, FORECAST CONFIDENCE IS
SLIGHTLY BELOW AVERAGE.
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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