929
FXUS10 KWNH 251840
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 PM EDT WED MAR 25 2020
VALID MAR 25/1200 UTC THRU MAR 29/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..EAST COAST SURFACE LOW TONIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
BOTH THE 12Z NAM/GFS ARE CLOSE TO THE MODEL CONSENSUS WITH THE
SURFACE LOW DEVELOPING ALONG THE MID ATLANTIC THIS AFTERNOON.
EVENTUALLY, THE 12Z NAM BECOME A BIT DEEPER AND SLOWER WITH THE
SURFACE LOW, AS IT REPRESENTS THE WESTERN EDGE OF THE SOLUTION
ENVELOPE. GIVEN THE TIGHT CLUSTERING WITH THIS SYSTEM, A GENERAL
MODEL BLEND IS PREFERRED, WITH ABOVE AVERAGE CONFIDENCE.
..SURFACE LOW CROSSING THE MID ATLANTIC STATES THU NIGHT/FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 12Z NAM/GFS ARE CLOSE TO THE CONSENSUS WITH THE SURFACE WAVE
THAT DEVELOPS ON THE FRONT OVER THE OH VALLEY THU NIGHT. AS THE
WAVE REACHES THE NORTHERN MID ATLANTIC COAST, IT BEGINS TO DEEPEN,
AND THERE IS SOME SPREAD ON HOW QUICKLY THIS MIGHT OCCUR. WITH
LITTLE IN THE WAY OF MID LEVEL SUPPORT, THE DIFFERENCES IN
DEVELOPMENT TIMING/PLACEMENT MAY BE DUE TO DIABATIC HEATING
EFFECTS FROM THE GULF STREAM. ONCE THE SURFACE WAVE REACHES THE
GULF STREAM, THERE IS GENERALLY GOOD MODEL AGREEMENT WITH THE
STRENGTH AND TRACK OF THE LOW. A GENERAL MODEL BLEND IS PREFERRED
WITH THIS SYSTEM, THOUGH THE TIMING DIFFERENCES CONCERNING WHEN
THE WAVE STARTS TO DEEPEN RESULT IN ONLY SLIGHTLY ABOVE AVERAGE
FORECAST CONFIDENCE.
...LONG WAVE TROUGH TRACKING FROM THE WEST COAST TO THE CENTRAL
PLAINS...
...SURFACE LOW MOVING FROM EASTERN CO INTO THE MID/UPPER MS
VALLEY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
WHILE THE 12Z NAM/GFS REMAIN CLOSE TO THE CONSENSUS WITH THE TRACK
AND TIMING WITH THE POSITIVELY TILTED LONG WAVE TROUGH OVER CA
THIS AFTERNOON, THE 12Z NAM SEEMS TO DEVELOP THE SURFACE LOW TOO
FAR SOUTH (AS DOES THE 12Z CMC), AT LEAST WHEN COMPARED WITH THE
CONSENSUS, AND ENDS UP EAST OF THAT CONSENSUS. THE 12Z GFS REMAINS
CLOSE TO THE CONSENSUS (AS WELL AS 12Z GEFS AND THE 00Z ECMWF
ENSEMBLE MEAN) WITH THE SURFACE LOW, AND CLUSTERS WELL WITH THE
12Z ECMWF. THE 12Z UKMET REMAINS ED ITS FORWARD MOVEMENT AND IS
CLOSE TO THE GFS/ECMWF SOLUTIONS.
BASED ON THE ABOVE, A 12Z GFS/12Z ECMWF/UKMET BLEND IS PREFERRED.
SINCE ONLY THE 12Z NAM/12Z CMC ARE NOT CLOSE WITH THE POSITION OF
THE SURFACE LOW LATE, FORECAST CONFIDENCE IS SLIGHTLY ABOVE
AVERAGE.
SHORTWAVE AND SURFACE COLD FRONT APPROACHING PACIFIC NORTHWEST SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/12Z ECMWF BLEND
CONFIDENCE: AVERAGE
THERE IS A FAIR AMOUNT OF SPREAD WITH THE SYSTEM AS IT TRACKS FROM
SOUTH OF THE GULF OF AK TOWARD THE PACIFIC NORTHWEST TOWARD THE
END OF THE PERIOD. THE 12Z NAM SEEMS TO BE TOO FAST, AND HAS BEEN
ACCELERATING WITH THIS SOLUTION. THE 12Z GFS HAS SLOWED ITS
PROGRESS, THOUGH IT IS NOT AS SLOW AS THE 12Z ECMWF. NOT
SURPRISINGLY, THE ENSEMBLE MEANS SUPPORT THEIR PARENT MODELS,
SUGGESTING THAT THERE IS STILL SOME WAY TO GO BEFORE THE MODEL
DIFFERENCES CAN BE RECTIFIED. BASED ON THIS, A BLEND OF THE 12Z
GFS/12Z ECMWF IS PREFERRED, BUT GIVEN THE SPREAD, FORECAST
CONFIDENCE IS AVERAGE AT BEST.
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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