Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
333 PM EST Sun Jan 16 2022

Valid 00Z Mon Jan 17 2022 - 00Z Wed Jan 19 2022

...A deep low pressure system will continue to spread heavy snow northward
across the upper Ohio Valley through the lower Great Lakes and the higher
elevations of New England through Monday...

...Snow will change over to a period of sleet/freezing rain before
changing over to rain across interior Mid-Atlantic and the lower
elevations of New England...

...Some heavy downpours, thunderstorms, and high winds can be expected to
impact the coastal sections of the Mid-Atlantic up through New England
into Monday...

A low pressure system continues to expand and intensify as it moves across
the southeastern U.S. and begins to turn toward the northeast up the
Eastern Seaboard. Arctic air already in place across the central and
eastern U.S. will work in concert with this dynamic system to deliver a
wide swath of more than a foot of heavy snow northward across the upper
Ohio Valley through the lower Great Lakes, as the storm center is forecast
to track up the interior section of the East Coast through Monday. Closer
to the track of the storm center, snow that initially falls is expected to
change over to a period of sleet and/or freezing rain before changing over
to plain rain across interior Mid-Atlantic and up through the lower
elevations of New England. Along the spine of the Appalachians, snow is
forecast to change over to a period of sleet and/or freezing rain as the
storm center approaches. The mixed precipitation should then change back
to snow following the passage of the storm center. Heavy wet snow is
expected across the higher elevations of New England through much of
Monday. Near the immediate coast, some heavy downpours, possibly
thunderstorms, together with high winds can be expected to precede the
storm center as it tracks up the Mid-Atlantic through New England into
Monday.

The center of the deep low pressure system is forecast to move into
southeastern Canada Monday night. This will change the precipitation to
all snow followed by gradual tapering off of the snow Monday night. Much
improved weather is expected to arrive on Tuesday for the Northeast but
the size of the departing system will keep winds blustery.

Meanwhile, a cold front across southern Canada will dip toward the
northern Plains. An Alberta clipper is forecast to form on the front on
Monday and then move toward the Great Lakes on Tuesday. Lingering snow
across the Great Lakes will pick up in intensity on Tuesday as the clipper
approaches. Farther west, accumulating snow is also forecast across
northern Minnesota and northeastern North Dakota. Arctic air behind the
cold front will then surge into the northern Plains on Tuesday. Upslope
snow is forecast to develop and intensify over the northern High Plains
into the northern Rockies on Tuesday as an arctic high pressure system
slides down from western Canada.

Weak onshore flow combined with upper-level energy will develop light rain
and higher elevation snow over parts of the Pacific Northwest Monday
evening into Tuesday. Moreover, lingering upper-level energy slowly
approaching California from the Pacific is forecast to produce scattered
areas of rain Monday evening into Tuesday for southern California.
Meanwhile, a new low pressure system is forecast to form over the southern
Plains on Tuesday. No rainfall is expected with this system. In fact,
dry conditions with a warming trend is forecast for southern Plains on
Tuesday.

Kong
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
158 PM EST Sun Jan 16 2022

Valid 12Z Wed Jan 19 2022 - 12Z Sun Jan 23 2022

...Cooled South to East Coast Snow/Ice Threat with frontal/coastal
low genesis late week...

...Pattern Overview...

A series of impulses will carve out and reinforce a broad mean
trough over the central and eastern states during the extended
period while the upper ridge amplifies offshore the West Coast.
The leading shortwave will track over the Great Lakes region into
the Northeast by Thursday with one behind it digging into the
South Friday and then pulling offshore the Mid-Atlantic/Southeast
region Saturday. This pattern will be conducive for precipitation
to spread across the higher terrain of the Northern and Central
Rockies through Friday and precipitation to span from
Texas/western Gulf Coast, Deep South, Southeast to the
Mid-Atlantic and push eastward beyond the weekend into next early
next week.


...Guidance/Predictability Assessment and Weather
Highlights/Hazards...

Previously, it was noted that there is significant forecast spread
and run to run uncertainty with this latter feature and associated
mid-winter weather focus with frontal wave/coastal low genesis.
The 06Z/12Z guidance continues to have notable spread on the
placement/track of the secondary shortwave feature. In turn, the
QPF placement varies significantly as well, especially across the
Gulf states, Southeast and Southern Appalachia. To combat these
differences, a general blend of the GFS/GEFS mean/CMC/ECWMF/EC
ensemble means were used through all time periods. This provide a
middle ground approach and helped maintain continuity from the
previous forecast cycle.

There is good agreement with an organized low pressure system set
to dig into the north-central U.S. and subsequently track moving
eastward along the U.S./Canadian border through Thursday. This
should bring some snow to the Great Lakes then northern New
England, with locally higher totals expected near typical lake
enhancement areas as cold high pressure sweeps down across the
central and eastern U.S. in the wake of the low in a pattern with
above normal predictability for these features. As the Arctic
blast reaches the southern tier states a wavy cold front will
encounter Gulf moisture to fuel an emerging area of precipitation
up from the South/Southeast. This pattern will be favorable for an
enhanced swath of overrunning snow/ice on the northern periphery
of activity later in the week. This wave may develop into a robust
coastal low/winter storm that tracks up the East Coast.
Meanwhile, The West could see some light precipitation through the
period, particularly over the Pacific Northwest and into the
Northern Rockies as weakening systems cross the region, with
mainly dry conditions elsewhere.

Campbell/Schichtel