580
FXUS10 KWNH 161909
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
308 PM EDT MON MAR 16 2020
VALID MAR 16/1200 UTC THRU MAR 20/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEP UPPER TROUGH/CLOSED LOW IMPACTING THE WEST
..CYCLOGENESIS OVER THE CENTRAL HIGH PLAINS WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS
NON-NAM AND NON-CMC BLEND...AFTER 60 HOURS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
19Z UPDATE: NO SIGNIFICANT CHANGES TO THE EARLIER PREFERENCE WITH
THE LATEST 12Z GUIDANCE NOW AVAILABLE.
A DEEP UPPER TROUGH AND EMBEDDED CLOSED LOW ALONG THE WEST COAST
WILL CONTINUE TO SETTLE SOUTH OVER THE NEXT COUPLE OF DAYS, AND
THEN BEGIN TO PIVOT INLAND INTO THE INTERMOUNTAIN WEST BY
WEDNESDAY WHICH WILL FOSTER LEE-SIDE CYCLOGENESIS OVER THE CENTRAL
HIGH PLAINS. THE GUIDANCE IS IN GOOD AGREEMENT THROUGH ABOUT 60
HOURS, BUT THEREAFTER A FEW OF THE MODELS DIVERGE ON THE EJECTION
OF THE MID-LEVEL ENERGY AND SUBSEQUENT SURFACE LOW DEVELOPMENT
ACROSS THE CENTRAL PLAINS. THE 12Z NAM ALONG WITH THE 00Z CMC ARE
AHEAD OF THE REST OF THE DETERMINISTIC MODELS AND ENSEMBLE MEANS,
AND ALSO THEREFORE HAVE A STRONGER/DEEPER SURFACE LOW THAT IS
FURTHER TO THE NORTHEAST COMPARED TO THE GFS/ECMWF/UKMET
SOLUTIONS. THE CONSENSUS FAVORS A SLOWER APPROACH AT THIS TIME AND
THEREFORE, BEYOND 19.00Z (60 HOURS), A NON-NAM AND NON-CMC BLEND
IS PREFERRED WHILE A GENERAL MODEL BLEND IS SUFFICIENT PRIOR TO
THAT.
..TROUGH ARRIVING OVER THE NORTHERN HIGH PLAINS WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: AVERAGE
19Z UPDATE: WITH THE REST OF THE 12Z GUIDANCE AVAILABLE, THE GFS
NOW APPEARS TO BE A BIT OF AN OUTLIER WITH THE PROGRESSION OF THE
TROUGH OVER THE NORTHERN HIGH PLAINS. THE ECMWF/UKMET SLOWED DOWN
SOMEWHAT, NOT TO THE DEGREE THAT THE NAM/CMC SUGGEST, BUT ENOUGH
TO NOW FAVOR MORE OF A NON-GFS APPROACH AT LEAST FOR THE MASS
FIELDS.
POSITIVELY TILTED NORTHERN STREAM ENERGY IS EXPECTED TO SLIP DOWN
INTO THE NORTHERN HIGH PLAINS BY MID-WEEK. AS NOTED BY THE
PREVIOUS DISCUSSION, THE 12Z NAM CONTINUES TO BE SLOWER/DEEPER
THAN THE REST OF THE GUIDANCE. THE 12Z GFS HAS SLOWED SOMEWHAT,
AND IS A BIT BEHIND ITS 06Z GEFS MEAN, BUT ISN'T AS DEEP AS THE
NAM. THE CMC MIRRORS THE NAM IDEA OF A SLOWER/DEEPER SOLUTION
WHILE THE ECMWF IS STILL A WEAKER AND MORE PROGRESSIVE SOLUTION.
ITS PHASING/INTERACTION WITH THE SOUTHERN STREAM ENERGY COMING OUT
OF THE CENTRAL ROCKIES REMAINS UNCLEAR AND LIKELY WILL DICTATE HOW
PROGRESSIVE THE EVENTUAL TROUGHING IS. FOR NOW, WILL NOT MAKE
DRASTIC BLEND PREFERENCE CHANGES, AND CONTINUE TO FAVOR A
GFS/ECMWF/UKMET BLEND. IF THE LATER 12Z ECMWF/UKMET TREND SLOWER,
THAN MORE INCORPORATION OF THE NAM AND CMC WOULD BE PLAUSIBLE.
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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