ACUS11 KWNS 210315
SPC MCD 210315
Mesoscale Discussion 0118
NWS Storm Prediction Center Norman OK
0915 PM CST Wed Feb 20 2019
Areas affected...parts of PA/NY/NJ into New England
Concerning...Winter mixed precipitation
Valid 210315Z - 210815Z
SUMMARY...A large area of wintry precipitation -- with mainly snow
across far northeast NY, much of NH and VT, and most of ME, and
transitioning to mainly freezing rain south of this area -- is
expected to spread across the discussion area overnight.
DISCUSSION...A widespread band of primarily freezing rain continues
to shift quickly eastward across central NY/eastern PA, where ice
accumulation continues. This area of precipitation will spread into
-- and across -- New England overnight, moving off the southern New
England coast and diminishing over Maine beginning prior to sunrise.
At this time, temperatures remain in the low to mid 20s across most
of eastern NY and southern New England, and in the teens to low 20s
over much of VT/NH/ME. Gradual warming in the 900 to 700 mb layer
will continue as low-level warm advection increases and secondary
surface low pressure develops offshore.
This increasing warm advection should allow a transition from
freezing rain to rain to occur across coastal southern New England
overnight, and likewise a transition from light snow to freezing
rain over the remainder of southern New England. Indeed, this
transition from snow to freezing rain is already observed at some
locales, and this trend will continue over the next few hours as
warm advection above a shallow/cold boundary layer increases.
The precipitation area is relatively fast-moving -- owing to the
fast westerly flow aloft -- and as such, overall snowfall
accumulations will be limited despite rates of 1" per hour briefly
possible in a few areas. Meanwhile, freezing rain accumulations of
over 0.05" to .10" per hour will occur for a couple of hours in some
locations, potentially resulting in hazardous road conditions in
some areas overnight.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 41657170 41317340 40707456 40607590 40937692 41747730
43107713 43907563 44667360 45097032 44546951 42787108