Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
155 PM EST Tue Jan 04 2022
Valid 12Z Fri Jan 07 2022 - 12Z Tue Jan 11 2022
...General Pattern Overview...
The upper level pattern over the continental U.S. through the
beginning of next week should remain fairly amplified but also
progressive. A strong shortwave trough and associated nor'easter
will exit the East Coast Friday, and this should give way to a
Canadian surface high and cold weather settling across the
east-central U.S. in the wake of the strong cold front. Inland
progression of an early Friday Pacific Northwest system will bring
a drier trend to that region as upper ridging builds over the West
by Sunday-Monday. Meanwhile by the weekend the flow ahead of
Plains low pressure and a trailing cold front will support an
expanding area of rain from the Gulf Coast into at least the
Tennessee Valley. Also another surge of arctic air will reach the
north-central U.S. behind the system.
...Guidance/Predictability Assessment...
There was reasonably good agreement for significant features in
the 00Z-06Z models/ensembles. The large scale of the eastern
trough by early next week suggests better than average
predictability while there is some uncertainty with shortwaves
that may try to move into/around the upper ridge building into the
West. Details become somewhat ambiguous over and near the
southwestern U.S. by the first half of next week as solutions
diverge for what becomes of smaller-scale energy in the
southernmost part of the upper trough crossing the West during the
weekend as well as another feature that approaches from the
Pacific. A blend of the latest operational models represented
consensus ideas from Friday into Sunday and incorporating some
weight of the 06Z GEFS/00Z ECMWF means along with the 06Z GFS and
00Z ECMWF/CMC reflected the continued large scale agreement while
accounting for the uncertainty near the Southwest next week. The
resulting forecast yielded good continuity.
Guidance is finally better clustered for the deepening storm that
tracks from off the New England coast into the Canadian Maritimes
late this week. Today's GFS runs are stronger versus a number of
prior runs while the consistently strong ECMWF has nudged its
track a bit to the east over the past couple days. New guidance
still shows various ideas for the weak shortwave energy that may
linger over the Southwest by late weekend/early next week with the
GFS still weakest/most progressive and 00Z ECMWF the most
concentrated. The 00Z ECMWF's handling of that feature likely
plays a role in its greater deflection of approaching Pacific
energy versus what most other models and means show. 12Z ECMWF
trends are favorable compared to other guidance.
...Hazards/Sensible Weather Highlights...
After an active period of weather during the short range period
across the Pacific Northwest, some lingering rain and mountain
snow is still likely from northern California to western
Washington, and snow for the Northern Rockies, on Friday. A
drying trend should commence in time for the weekend across much
of the West as high pressure builds back into the region.
Meanwhile, an intensifying nor'easter off the New England Coast on
Friday may produce some snow over eastern/northern New England in
particular (amounts very sensitive to exact track) along with
lingering snow showers over the rest of the Northeast. New
England may see a brief period of brisk to strong winds behind
this system. Gulf moisture ahead of a Plains cold front should
spread rain and thunderstorms from the Lower Mississippi Valley
into the Tennessee Valley/southern Appalachians this weekend with
lesser amounts of rain extending farther north. Some locally
moderate to heavy activity is possible but confidence in specifics
is fairly low at this time. Areas from the upper Great Lakes into
the Northeast could see wintry weather, either exclusively or
before a changeover to rain. Parts of the Great Lakes may see
lake effect snow behind the passing front.
Temperatures will be quite cold across the central/northern Plains
to the Upper Midwest on Friday with a large surface high of arctic
origin governing the weather pattern for this region. Lows may be
20-30F below normal while highs 15-20F or so below normal may
extend as far southeast as the Tennessee Valley and southern
Appalachians. Expect some moderation of the severe cold over the
Plains/Midwest on Saturday ahead of the next arctic surge that
reaches into the northern tier states by Sunday-Monday. The
second surge may not be quite as intense as its predecessor but
temperatures could still be 15-25F below normal over some areas.
From Friday into Sunday above normal temperatures will progress
from the southern Plains into the Deep South with greatest
anomalies of plus 20-25F possible at some locations for highs on
Saturday and morning lows on Sunday. Seasonably cold conditions
are likely west of the Continental Divide with readings generally
within 10 degrees of climatological averages, though locally a
little more than that on the warm side of normal for lows on
Friday-Saturday.
Rausch/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