Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
344 PM EST Fri Jan 14 2022
Valid 12Z Mon Jan 17 2022 - 12Z Fri Jan 21 2022
...Major winter storm to impact the Northeast through Monday...
...Overview...
A potent closed low moving through the Mid-Atlantic as the period
starts Monday will continue to spread heavy snow into parts of the
Northeast. Behind this, general troughiness will continue across
the Great Lakes next week as the next amplified shortwave drops
through the Plains and into the East next Thursday and Friday. Out
West, a closed low off the southern California coast will weaken
as it slides East, with weak shortwaves periodically acting to
break down ridging situated over the Northwest before a stronger
shortwave tries to move in late in the week.
...Guidance/Predictability Assessment...
Models and ensembles have come into closer agreement regarding the
ongoing major winter storm as the period starts moving into the
Northeast. This lends to increased confidence in the specifics,
though some uncertainty still lingers. Most if not all of the
guidance now shows the low inland over the Mid-Atlantic Monday
morning (near Philadelphia), although the UKMET is still displaced
a little south and the GEFS mean remains a bit farther east
showing the low right along the coast. Of course, even minor
changes in the low track can have bigger effects on winter precip
and type across especially eastern portions of the Mid-Atlantic
and the Northeast.
Elsewhere, there's fairly good agreement on general and reinforced
troughing across the Great Lakes next week, with some minor
differences in the details. A stronger shortwave looks to drop
through the Plains mid to late next week and eventually into the
East. Some recent model runs (mostly the CMC) indicate another
potential low pressure area near the East Coast, but uncertainty
in the strength of this system is highly uncertain at this time.
Out West, the greatest differences begin to pop up next
Thursday-Friday with the handling of Pacific system energy into an
upper ridge off/over the West Coast. The 06z GFS is more ernest
with a shortwave through the east Pacific and even shows a closed
low off the Pacific Northwest coast next Friday. Meanwhile, the
CMC and ECMWF are both weaker and more deflects the energy over
the ridge. The ensemble means tend to favor a solution closer to
the ECMWF and CMC.
The WPC forecast for today used a composite blend of the
deterministic models days 3-5, with increasing ensemble means
thereafter to account for detail differences across the East late
period and the energy off/over the Northwest. This provided a
consistent forecast with overnight WPC continuity.
...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 on 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. For locations closer to the
coast, precipitation may start out as some brief snow, with a
changeover to sleet and 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 the Northeast 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.
For temperatures, the East should moderate back towards normal
after Monday's storm with colder temperatures moving back in by
the end of the week. The Central U.S. will start mild and above
normal early in the week, though as strong Canadian high pressure
sinks southward, will quickly trend below to well below normal
Wednesday and Thursday. Daytime highs could be near or below zero
across parts of the northern Plains and northern Mississippi
Valley. West of the Rockies should be mostly near or slightly
above normal influenced by the upper level ridge.
Santorelli/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
Hazards:
- Heavy precipitation across portions of the Northeast, Mon, Jan
17.
- Heavy snow across portions of the Northeast and the Great Lakes,
Mon, Jan 17.
- Heavy snow across portions of the Northeast and the Great Lakes,
Wed-Thu, Jan 19-Jan 20.
- Flooding occurring or imminent across portions of the Lower
Mississippi Valley, the Pacific Northwest, and the Ohio Valley.
- High winds across portions of the Northeast, Mon, Jan 17.
- Much below normal temperatures across portions of the Central
Plains, the Northern Plains, the Middle Mississippi Valley, the
Upper Mississippi Valley, the Great Lakes, and the Ohio Valley,
Wed-Sat, Jan 19-Jan 20.
- High significant wave heights for coastal portions of the
Mid-Atlantic and the Northeast, Mon, Jan 17.
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Fri, Jan 21.
- High winds across portions of the Alaska Panhandle and mainland
Alaska, Fri, Jan 21.
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