Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1105 AM EST Sun Jan 03 2021
Valid 12Z Wed Jan 06 2021 - 12Z Sun Jan 10 2021
...Overview...
A progressive synoptic pattern will persist over the CONUS through
next weekend with activity focused on the Pacific Northwest. By
midweek, there will be an exiting system off New England while a
southern system over the south-central Plains shifts east,
possibly lifting northeastward along/off the Northeast coast
Friday/Saturday. In the West, a series of systems persists,
producing notable coastal rain and mountain snow north from
northern California. An even farther south tracking system may
cross Texas on Sunday. Temperatures will generally be near to
above normal thanks to continued influx of Pacific air that will
keep arctic air in Canada though a succession of farther tracking
systems would allow more seasonable air to push down the central
CONUS.
...Guidance/Predictability Assessment...
Global guidance continues to depict varied solutions with the
succession of shortwave features out of the Pacific and whether
the northern or southern portions of the waves will dominate. The
key with south-central Plains/Mid-South low is potential
interaction with northern stream energy descending from the Great
Lakes Thursday, interacting with the low over the Mid-Atlantic
Friday night as indicated by the 00Z ECMWF and UKMET or if it
remains a southern stream low as indicated by the 06Z GFS/CMC.
Despite this being a change to consensus, preference for now is
with the ECMWF/UKMET solutions through Day 5. Uncertainty then
increases for Days 6/7 with the resulting trough pattern/surface
low pattern in the Northeast. For now, broad troughing is forecast
for the Northeast for next weekend with inclusion of the somewhat
similar 00Z ECENS mean and 06Z GEFS mean. Next weekend, the 00Z
ECMWF/GFS are in decent agreement with a farther south tracking
low over the Desert Southwest to Texas (while the CMC is farther
inland/north) with the GFS a little more progressive.
...Weather/Threats Highlights...
The Pacific Northwest will continue to see systems arrive about
every other day through Days 3-7 with the heaviest likely on
Friday. Multi-day precipitation totals should exceed several
inches in many areas (especially west of the Cascades) with
considerable snowfall in the Cascades. Expect windy conditions and
variable snow levels (though not too low) as the systems move
through. Low pressure in the Southern Plains will move eastward as
an expanding area of rain precedes the front (and some snow on the
north side of the system in the marginally cold air mass). As the
system reaches the coast, it may turn northeastward and spread
some rain/snow over the Mid-Atlantic region Fri-Sat into New
England Sat-Sun. The preferred 00Z ECMWF solution favors a more
out to sea track, but uncertainty remains. Influx of of Gulf
moisture ahead of the far southern low track next weekend would
set up a heavy rain threat for east-central Texas Sunday.
Temperatures will be well above normal along the Canadian border
by about 10-25 degrees, especially for overnight lows, through
next week. Modestly above normal temperatures can be expected for
most of the rest of the CONUS into late next week with a general
cooling pattern to modestly below normal temperatures as
successive lows track farther south.
Jackson
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