Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
159 AM EST Fri Jan 14 2022
Valid 12Z Mon Jan 17 2022 - 12Z Fri Jan 21 2022
...Major winter storm to lift over the Northern Mid-Atlantic/lower
Great Lakes and Northeast Monday...
...Guidance/Predictability Assessment...
Models and ensembles have come into closer agreement in the day
3-5 (Mon-Wed) including a major winter storm to bolster forecast
confidence. The WPC product suite this period was mainly derived
from a GFS/ECMWF/UKMET/Canadian composite along with the 01 UTC
National Blend of Models. WPC continuity is well maintained.
Predictabilty seems marginally above normal into days 6/7
(Thu-next Fri), but forecast spread does increase in particular
with the handling of Pacific system energies into an upper ridge
built off the West Coast. Recent ECMWF/UKMET runs bring more upper
troughing through this ridge into the Northwest than the Canadian
and especially the GFS that deflect energies more over the ridge.
Suspect ridge amplitude should hold on the more amplified side of
the full envelope of solutions given initial strength, perhaps
closest to the 06 UTC GEFS mean.
...Weather Highlights/Hazards...
A major winter low developing over the weekend seems set to lift
from the northern Mid-Atlantic/lower Great Lakes through the
Northeast Monday. This will present a continuing full array of
weather hazards and threats. Heavy wrapping snows will spread in
earnest along/on the backside of the deepening low and west of the
I-95 corridor into interior areas given track. For locations
east/along I-95 (including the major metro areas), precipitation
may start out as accumulating snow, with a changeover to sleet
then rain as warmer air filters in from the east. Gusty winds
surrounding the surface low may create high waves off the coast
leading to possible coastal flood concerns along the Northeast
coastline.
After the main low exits northeast of the U.S. by Tuesday, another
low pressure system is forecast to track over the north-central
U.S. in response to a mid-upper shortwave and bring some snow to
the Upper Midwest and Great Lakes then northern New England, with
possibly higher totals near typical lake enhancement areas. The
West could see some light precipitation during the period,
particularly over the Pacific Northwest and into the Northern
Rockies, with mainly dry conditions elsewhere. Rain may develop
across the Lower Mississippi Valley and Southeast for mid-later
next week with modest return Gulf flow with induced wave passages.
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