…Long duration lake-effect snow event continues downwind of the Great
Lakes…
…Pacific system brings another round of locally heavy coastal rains and
higher elevation snow to the northwestern U.S./Rockies Friday into
Saturday….
…Arctic air surges south from the Northern Plains through the central
and eastern U.S….
Strong northwesterly winds on the southwest side of a low pressure system
lingering over southeastern Canada will lead to continued lake-effect snow
bands downwind of the Great Lakes through the end of this week and into
the weekend. The heaviest snow is expected downwind of Lakes Ontario and
Erie, where total snowfall amounts in the 2-4 feet range will be possible
under the most persistent bands. Some moderate to locally heavy snowfall
will be possible downwind of Lakes Superior and Michigan as well, though
this should taper off by Saturday. An upper-level shortwave and
accompanying cold front sweeping through the Midwest will also bring some
light wintry precipitation chances through Friday morning before some much
more substantial accumulating snowfall in the central Appalachians into
the day Friday. Winter weather-related advisories have been issued for
snow totals of 6-12 inches. Snow should taper off by Saturday morning.
In the West, ongoing coastal rain, a lower elevation rain/snow mix, and
higher elevation snow will begin to ramp back up into Thursday evening and
overnight as yet another upper-level wave/Pacific System move into the
Pacific Northwest bringing additional moisture from the Pacific to the
coast and inland. Locally heavy rainfall is most likely through Friday for
upslope regions along the coastal ranges of southwestern Oregon and
northern California as well as inland along the Sierra in northern
California. Some isolated instances of flooding will be possible. Heavy,
accumulating snowfall is expected in the Cascades and Sierra as well as
the northern Rockies Friday, spreading into the central Rockies by
Saturday as the system continues inland. Snowfall totals over a foot are
likely for the higher mountain peaks. A mix of light to moderate rain and
some snow will pass inland through the Great Basin Friday and Friday
night, with little to no accumulations expected. Moist, upslope flow ahead
of the system as it passes over the Rockies will bring some heavy,
accumulating snowfall to the northern High Plains as well beginning Friday
afternoon and continuing into the day Saturday. This system will lead to
impactful winter weather from the central Plains eastward through the
Middle Mississippi/Ohio Valleys and eventually the Mid-Atlantic mostly
after the current forecast period Saturday evening, though some wintry
precipitation may begin for the central Plains by late Saturday afternoon.
A stagnant pattern featuring a strong upper-level low over southeastern
Canada/the northeastern U.S. will begin to settle in late this week and
last well beyond the current forecast period, bringing a stretch of below
average, chilly Winter temperatures to much of the central and eastern
U.S. These conditions are already spreading through the Northern Plains
and Midwest, with forecast highs Friday in the single digits and teens in
the northern Plains and the teens to 20s in the Midwest. Gusty winds will
bring wind chills as low as -30 degrees for portions of the northern
Plains Friday morning. The surge of colder air will reach the East Coast
by Saturday with highs in the teens and 20s for New England, the 20s and
30s in the Mid-Atlantic, the 30s and 40s in the Carolinas, and the 40s and
50s in the Southeast. Highs in Florida will be in the 50s and 60s outside
of South Florida, and Freeze and Frost-related advisories are in effect
for the northern Peninsula as lows dropping into the low 30s could damage
local vegetation. In stark contrast, conditions over the western and
south-central U.S. will be above average and mild for most locations, with
40s and 50s for the Pacific Northwest and Interior West, 50s and 60s for
California and the southern Rockies/Plains, and 60s and 70s in the
Southwest.
Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php