Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
154 AM EST Mon Jan 3 2022
Valid 12Z Thu Jan 6 2022 - 12Z Mon Jan 10 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 the weekend.
An organized low pressure system is expected near the East Coast
to close out the week, and another low affects the Great Lakes by
Saturday night into Sunday. 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 very good synoptic scale
agreement through Saturday with some mesoscale timing and
amplitude differences with the individual shortwave passages. One
of the main differences is with the 00Z GFS by depicting a more
offshore track with the East Coast low and thus much less
impactful for the Northeast, and this was also the case with
yesterday's GFS run. By Sunday, the GFS becomes considerably
stronger with a potential closed low over the West Coast region,
which does not have much ensemble support. The greatest
differences by day 7 are apparent this same general region, whilst
the trough over the East has good model agreement.
The WPC forecast was based primarily on a multi-deterministic
model blend through Friday, and then gradually increasing use of
the ECENS and GEFS means through next weekend and into Monday.
...Sensible Weather...
There will be multiple Pacific storm systems that will affect the
Pacific Northwest and inland across portions of the Great Basin
and the Northern Rockies. This will result in heavy rain and
heavy mountain snow for Thursday and Friday, with a potential
atmospheric river event for northern Oregon and southwest
Washington during this time. A drying trend should commence in
time for the weekend across much of the West as high pressure
builds back into the region. Meanwhile, widespread light to
moderate precipitation is likely across the eastern third of the
U.S. in association with the East Coast low on Friday, with heavy
snow possible for portions of the Appalachians. More showers and
storms are likely to make a return to the Gulf Coast region by
Sunday ahead of the next front.
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. Subzero highs are once again likely for portions
of eastern Montana, North Dakota, and northern Minnesota, and
highs in the teens settling as far south as Kansas on Thursday.
Some abatement in the severe cold may come to pass across this
region on Saturday ahead of the next arctic surge Sunday, which is
not expected to be as intense as the earlier arctic blast.
Elsewhere, seasonably cold conditions are expected west of the
Continental Divide with readings generally within 10 degrees of
climatological averages, and mild across the southern Plains and
Deep South with highs running 5 to 15 degrees above average this
weekend.
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