529
FXUS10 KWNH 270446
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1246 AM EDT FRI MAR 27 2020
VALID MAR 27/0000 UTC THRU MAR 30/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...MID-LEVEL TROUGH TRACKING FROM THE WEST COAST TO THE UPPER
MIDWEST AND INTO QUEBEC BY MONDAY MORNING...
...SURFACE LOW MOVING FROM EASTERN CO INTO THE MID/UPPER MS VALLEY
AND ONTARIO/QUEBEC...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF/12Z CMC (LESS WEIGHT BY LATE
SATURDAY)
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
MODELS ARE COMING INTO BETTER AGREEMENT WITH RESPECT TO A
MID-LEVEL TROUGH TRACKING ACROSS THE SOUTHWEST INTO THE MIDSECTION
OF THE COUNTRY THURSDAY INTO EARLY FRIDAY. HOWEVER, THE GUIDANCE
STARTS TO DIVERGE ONCE THE MID-LEVEL WAVE BECOMES A CLOSED LOW IN
THE CENTRAL PLAINS. THE 00Z NAM IS TOO PROGRESSIVE AND FARTHER
NORTH WITH BOTH THE MID LEVEL LOW AND SURFACE LOW. CONVERSELY, THE
12Z UKMET IS TOO SLOW AND THUS THE SURFACE LOW LAGS BEHIND.
MEANWHILE, THE 00Z GFS/EC/CMC ARE IN LOCKSTEP THROUGH MUCH OF THIS
STORM SYSTEMS EVOLUTION; THOUGH THE CMC IS WEAKER AND DOES START
TO OUTPACE THE REST OF THE GUIDANCE LATER SATURDAY INTO SUNDAY.
THE MIDDLE OF THE ROAD WOULD SUPPORT THE DETERMINISTIC 00Z GFS/12Z
EC FALLING IN LINE WITH BOTH OF THEIR CORRESPONDING ENSEMBLE MEANS
WHILE ALSO KEEPING THE 12Z CMC IN THROUGH THE FIST HALF OF DAY 2.
IT SHOULD BE NOTED THAT WHILE THE TRACK OF THIS SYSTEM IS IN
FAIRLY GOOD AGREEMENT WITH THE BLEND OF CHOICE, THE 12Z EC MAY BE
A BIT TOO STRONG WITHIN THE 500MB/850MB LEVELS WHICH COULD IMPACT
THERMAL PROFILES.
...SHORTWAVE TROUGH AND SURFACE COLD FRONT APPROACHING PACIFIC
NORTHWEST SATURDAY WITH THE TROUGH AXIS DIVING INTO THE SOUTHWEST
BY SUNDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-00Z NAM/12Z UKMET BLEND
CONFIDENCE: AVERAGE
THERE REMAINS SOME MODEL DIFFERENCES WITH RESPECT TO A TROUGH AXIS
APPROACHING THE PACIFIC NORTHWEST. BOTH THE 00Z NAM AND 12Z UKMET
CONTINUE TO BE MORE PROGRESSIVE WITH THE TROUGH AXIS AND SHORTWAVE
ENERGY MOVING INTO THE SOUTHWEST BY LATE SUNDAY. THE 00Z GFS AND
12Z ECMWF ARE REASONABLE OUTER BOUNDS IN TERMS OF TIMING AND
AMPLITUDE AND ARE IN DECENT AGREEMENT WITH THEIR ENSEMBLE MEANS.
THE 12Z CMC IS A NICE MIDDLE GROUND BETWEEN THE GFS/EC.
THEREFORE, THIS SUPPORTS A BLEND OF THE 00Z GFS, 12Z EC AND THE
12Z CMC.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
PAGANO
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