…Unsettled weather to persist across the Northwest U.S. into early next
week with much colder temperatures and heavy snowfall across the Cascades,
northern Great Basin, northern Rockies and northern High Plains…
…An atmospheric river will continue to stream across northern and
central California with heavy rains and areas of flooding possible through
Tuesday…
…Storm system crossing the Great Lakes region to bring accumulating
snowfall to parts of the Northeast…
…Record high temperatures are expected across portions of the Southwest
out through the Southern Plains through the middle of the week…
A deep layer cyclone will continue to impact the Pacific Northwest and the
northern Rockies through Tuesday with unsettled weather expected. Moist
onshore flow into the higher terrain coupled with cold air filtering south
from British Columbia will drive heavy accumulating snowfall across the
Cascades and especially interior mountain ranges. The atmospheric river
that is bringing heavy rainfall to areas of northern California is being
steered up the larger scale pattern northeastward up across areas of
southern and eastern Oregon, and into the southwest facing slopes of the
northern Rockies which should lead to heavy snowfall accumulations and
including even some lower elevation locations. For the Cascades, generally
an additional 6 to 12 inches of snow is expected through early Wednesday,
with amounts over a foot expected from the terrain of northern California
into the northern Rockies. The deep layer fetch of Pacific moisture
overrunning Arctic air combined with upslope flow east of the Continental
Divide will allow for heavy snowfall in the northern High Plains. The
atmospheric river bringing the flooding threat for northern and central
California should persist through Tuesday as a stationary front lingers.
A couple waves of low pressure rippling along the front coupled with
upslope flow into the higher terrain should yield an additional 5 to 10
inches of rain. A Slight Risk of excessive rainfall remains northern and
central California through Tuesday.
A frontal system traversing the Great Lakes region will bring a swath of
accumulating snow across portions of northern New York and northern New
England Monday evening into Tuesday. Several inches of new snow
accumulation is expected. This system will pull away through southeast
Canada tonight with a trailing cold front then crossing the region and
bringing a renewed surge of cold air. Warm air aloft overrunning a
returning warm front over this cold airmass is expected to lead to
widespread, impactful freezing rain event from the Midwest across the
Lower Peninsula of Michigan into the Mid-Atlantic States Wednesday and
into southern New England Thursday. In addition to the dangerous travel
conditions this may cause, the highest ice storm potential (with 1/4 inch
or greater ice accretion) is expected from western Maryland northward into
the Laurel Highlands of Pennsylvania, where scattered power outages and
tree damage is most likely.
An arctic high pressure system settling south from Canada across much of
the northern tier of the Lower 48 will cause temperatures to fall well
below average. Across the northern High Plains, temperatures will be as
much as 15 to 30 degrees below normal, with daytime highs locally staying
below zero. South of the front, very warm temperatures are expected
across much of the southern tier of the country. Temperatures should
reach well into the 80s across the interior of the Southwest and the
southern Plains, with record high temperatures expected.
Roth
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
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