…Atmospheric river to bring low elevation rain and high elevation snow
to the West through the weekend…
…Increasingly wet pattern forecast to develop over the eastern U.S. this
weekend…
…Mild and much above average temperatures will persist across most of
the country…
A slow moving frontal boundary will move into the Pacific Northwest
tonight and direct a plume of Pacific moisture at the West Coast, which
will be the next atmospheric river to impact the West. Moisture will
spread from the coast across the Intermountain West, resulting in
widespread low elevation rain and high elevation snow. Heavy rain with
intense rain rates could produce instances of flooding in coastal Oregon
and northern California, and there is a Slight Risk of Excessive Rainfall
(level 2/4) for this region on Saturday and Sunday. Heavy mountain snow
could cause moderate to major impacts for the higher elevations of the
Cascades and northern Rockies. Heavy snow combined with strong winds could
lead to blowing and drifting snow with reduced visibility, and travel
conditions may be very difficult to impossible. The recent wet weather
pattern across the Northwest and likelihood of additional widespread heavy
precipitation amounts this weekend will result in increasing stream flows
and soil saturation levels, leading to an increasing threat of river
flooding, and rock and mudslides.
Precipitation is also forecast to spread across the eastern U.S. this
weekend as a series of frontal systems move northeast from the Lower
Mississippi Valley to the Great Lakes and Northeast. The first frontal
system will bring rain to the Lower Mississippi, Tennessee, and Ohio
Valleys and mixed wintry precipitation to the Upper Midwest today. Rain
will spread towards the East Coast as another frontal system develops over
the Lower Mississippi Valley on Saturday, and rain will continue through
Sunday as the second system tracks northeast. Rain will likely be
beneficial for many areas that are experiencing drought conditions,
especially in the Lower Mississippi Valley and along the East Coast.
However, locally heavy rain may also result in isolated instances of flash
flooding.
While stormy weather dominates the West and East, much of the Central U.S.
and Southwest will remain dry through the weekend.
Most of the nation will experience much above average temperatures over
the weekend, with high temperatures reaching 15-25 degrees above average
and low temperatures reaching 20-30 degrees above average. This will be a
continuation to the above average pattern for areas west of the
Mississippi River, but a reversal of the overall below average pattern
that has dominated areas east of the Mississippi during December. This
much above average pattern will support the potential for record high
morning low temperatures across the Midwest, Mid-Atlantic, and Northeast.
Dolan
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php