Updated Discussion from Bing:
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
730 pm update...
Issued winter weather advisory for row of counties west of the
winter storm warning since we are forecasting advisory amounts
and decision makers need the information this evening regarding
travel, school and other closures this evening. Also we bumped
up snow amounts in grids to better match neighboring offices
snowfall for our statewide and regional partners and also to
match WPC amounts better. 18Z guidance from the NAM 3km and the
2.5 km Canadian have come in with heavier snow west to near
I-81 with amounts in the 8-12" inch range in the western part of
our winter storm warning area. I also bumped up snow amounts
from Otsego and Delaware counties south to northeast Pa where
these higher resolution models have a solid 10-20". Both of
these models did very well with last Friday`s snowstorm. The 18z
GFS has backed off a bit with snow amounts running 6"-12" east
of a Rome NY to Towanda, Pa line with the highest in the Poconos
to Delaware/Sullivan Counties in NY.
We are also concerned with snowfall intensity late Wednesday
morning into afternoon/evening. Snowfall rates could reach 3"
per hour in our eastern areas, east of I-81. I look for where
the 700 mb temperature gradient sets up and of course this leads
to strong frontogenetic forcing and intense snow banding. The
18Z GFS has this gradient between the lower Hudson valley and
Upper Mohawk Valley. The 18z NAM has this gradient moving across
central NY Wednesday but really tightening up over the
Catskills by 00z Thursday. This again suggests very heavy snow
just the northwest of this. The NAM 3km, which is too fine of
resolution to look at thermal fields, has 2-3" per hour rates
which supports the 12km NAM thermal fields and frontogenetical
forcing. This all suggests strong forcing which would support
heavier snow in the Catskills, Delaware/Otsego/Sullivan counties
in NY and northeast PA. In these areas I upped amounts to
10-16"... locally 20 inches. Now west of this area there will be
a drop off in snow amounts which really is difficult to
determine exactly where the 6-12 inch amounts fall off to a few
inches. Right now we are running this line from Oneida Lake to
Owego, NY and far eastern Bradford County in PA.
One more point, we are not expecting a wet snow from this storm
as thermal profiles all have temperatures between -5C to-15C in
the snow production zone from MSV to AVP on BUFKIT which have
the warmest profiles in our forecast area. So even if surface
temperatures are close to freezing, temperatures aloft will be
cold enough to make for a more powdery snow than a wet snow. We
are looking at snow to liquid ratios of 12-13 inches of snow to
1 inch of liquid.
Updated grids, snow amounts and winter weather message to
reflect changes. Previous discussion is below