Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
153 AM EST Sun Jan 2 2022
Valid 12Z Wed Jan 5 2022 - 12Z Sun Jan 9 2022
...Additional rounds of heavy coastal rain and mountain snow for
the northwestern states...
...Frigid air mass for the north-central U.S. and potential snow
for inland portions of the East Coast region late in the week...
...General Pattern Overview...
The upper level flow pattern over the nation will be rather
amplified through the end of the week with a large scale trough
over the east-central U.S. and a broad ridge over the West Coast,
before transitioning to a more quasi-zonal flow by next weekend.
Two well defined low pressure systems are expected to affect the
Great Lakes region and also the East Coast, and a third system is
possible by next weekend across the Plains and Midwest. An arctic
air mass will settle southward across much of the north-central
U.S. in the wake of the strong cold front.
...Guidance assessment and uncertainty...
The 00Z model guidance suite is in excellent synoptic scale
agreement through the majority of the forecast period with some
mesoscale timing and amplitude differences with the individual
shortwave passages. These minor differences are all within the
ensemble spread for the most part. By Friday with the East Coast
system, the 00Z GFS is slightly farther offshore with the track of
the low and thus would be less impactful in terms of rain/snow
across the Northeast. The CMC becomes faster with the shortwave
crossing the Plains by Saturday and also more amplified across the
Southeast, whereas the ECMWF/GFS suggest a flatter mid-upper flow
pattern here.
The WPC forecast was based primarily on a multi-deterministic
model blend through Thursday, and then GFS/ECMWF/some CMC along
with gradually increasing use of the ECENS and GEFS means through
next weekend.
...Sensible Weather...
The Great Lakes storm system is expected to produce widespread
light to moderate snow across Michigan and Wisconsin through early
Thursday, with some lake enhancement to the snow likely as the low
pulls away. Winds may be strong enough in some places to produce
blizzard conditions. For the system near the East Coast, there
has been a slightly southeastward trend in the axis of QPF, and
snow is likely for inland portions of the Mid-Atlantic and
Northeast and gusty winds near the coast. Heavy coastal rain and
heavy mountain snow will continue to make weather headlines across
portions of the Pacific Northwest, and also across the northern
Rockies.
Temperatures are expected to be frigid across the central/northern
Plains to the Upper Midwest through the end of the week with a
large surface high of arctic origin governing the weather pattern
for this region. Highs in the double digits below zero are once
again likely for portions of eastern Montana and into North
Dakota, and highs in the teens settling as far south as southern
Kansas on Thursday. Some abatement in the severe cold may come to
pass across this region ahead of the next arctic surge next
Sunday. Elsewhere, seasonably cold conditions are expected west
of the Continental Divide with readings generally within 10
degrees of climatological averages, and cold next weekend along
the East Coast with highs about 10 degrees below normal.
Hamrick
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