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
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