Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
207 AM EST Mon Feb 01 2021
Valid 12Z Thu Feb 04 2021 - 12Z Mon Feb 08 2021
...Midweek Southwest U.S. system to progress to the
Plains/Midwest/Northeast later week followed by major arctic
outbreak over the central and eastern U.S. by the weekend...
...Guidance/Predictability Assessment...
The WPC medium range product suite was primarily derived from a
composite blend of the 18 UTC GFS and 12 UTC ECMWF/Canadian/UKMET
Thursday/Friday along with the 01 UTC National Blend of Models.
Transitioned blend focus toward the best clustered ECMWF/Canadian
and 12 UTC NAEFS days 5-7 amid growing forecast spread to to
better depict the cold air surge potential into the states that
period in amplified flow.
...Weather/Threats Highlights...
The low ejection of a stormy lead cyclone into the Canadian
Maritimes will allow some areas along or offshore coastal New
England to have lingering brisk winds into Thursday.
Upper troughing driving through the Southwest/Rockies will produce
a swath of terrain enhanced snows into Thursday. System ejection
into the Plains still offers additional northern stream trough
phasing uncertainties and a complex frontal structure, but suspect
that a deepening low will organize and lift to the Great Lakes
into Friday. Enhanced snows are expected near and to the north of
the main cyclone track from the windy Midwest/Great Lakes to the
Northeast. Meanwhile to the south, leading warm air advection and
return Gulf moisture will combine with favorable dynamics and
forcing to fuel an expanding but progressive area of moderate
rain/convection from the east-central U.S. through the Eastern
Seaboard.
Upstream, expect a swath of heavy terrain snows are forecast from
the Northwest to the north-central Rockies late week with a series
of potent shortwaves that subsequently dig into an
emerging/amplified central U.S. upper trough position this
weekend. This will act to drive a frigid arctic airmass fully
southward through the central then eastern U.S.. Interaction with
a lingering wavy front trailing from the aforementioned lead
system over the East may favor piedmont/coastal rains and inland
snows from the OH Valley/Appalachians to the Northeast.
Schichtel
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml