Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1222 PM EDT Tue Mar 12 2019
Valid Mar 12/1200 UTC thru Mar 16/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Preferences and Confidence
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...Overall CONUS...
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Preference: 12z GFS and 00z ECMWF blend
Confidence: Above average
Current GOES-16/17 WV Mosaic depicts a very strong/compact closed
low over the Lower Colorado River with well defined features,
including well shaped subtropical jet and western branch of low
level warm conveyor. Further northwest, a similar polar jet
structure resides on the eastern side of a sharpening/digging
shortwave crossing into SW OR/N CA at this time. This upstream
wave will continue to dig with a strong undercutting jet through
the desert southwest further amplifying (with negative tilt) the
closed low leading to rapid lee cyclogenesis deepening in E CO/W
KS Wed. Models are coming into solid agreement, enough to start
discerning smaller scale differences. The 12z NAM is a bit north
and west with the surface low track through the Plains, but is not
substantially out of phase through until the cyclone reaches the
Upper Midwest/Northern Great Lakes Fri. Here, the NAM is draws
energy (a bit colder thermally too) southward sharper leading to
some increased spread in mass fields. Similar but on the opposite
side, the CMC is slow to draw the northern stream energy south
across MN, leading to a slight slowing of the shearing deep closed
low in the Great Lakes relative to the 12z GFS/00z ECMWF and
ensemble suite. The 00z UKMET is also a bit fast ejecting into
the Great Lakes as well as the northern stream energy digging
faster than other guidance would support as well. This leads to a
fairly confident 12z GFS/00z ECMWF blend (mainly after Thurs).
This blend should also work throughout the remainder of the CONUS
in the short-term. The shortwave currently over ND will slide
over the ridge in the Great Lakes and through New England with
lower fanfare. Similarly, a shortwave emerging from the Pacific
Thursday will reach CA and start to settle into a broader trof
with a potential closed decameters at 5H at 84hrs. Here a
GFS/ECMWF blend will suffice, though ensembles (CMC/UKMET too)
would suggest a more consolidated closed feature nearer the ECMWF
solution, so weighting that direction in the blend seems prudent
for CA/Southwest at the end of day 3.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Gallina