Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
242 AM EST Fri Jan 13 2023

Valid 12Z Fri Jan 13 2023 - 12Z Sun Jan 15 2023

...Another couple rounds of heavy rain and snow for the West as the
Atmospheric River pattern continues...

...Snow continues across northern New England Friday along with a period
of freezing rain/sleet...

...Unseasonably warm temperatures to start the weekend for the High Plains
as conditions turn chilly in the South...

The ongoing unsettled weather in the West associated with the active
Atmospheric River pattern unfortunately continues into this weekend with
another couple rounds of heavy precipitation forecast. Lower elevation
valley/coastal rain and high elevation mountain snow is already ongoing
this morning in the Pacific Northwest and will spread into California
through the day Friday as another Pacific storm system approaches the
coast. This system will stall and weaken as ridging builds inland over the
West, keeping overall rain/snow totals relatively lighter compared to
other recent systems. One exception will be for coastal northern
California/southern Oregon where a stream of higher Pacific moisture
oriented roughly parallel to the coast will remain in place over the
region, leading to longer duration showers and heavier rainfall rates of
0.5"+ per hour. A Slight Risk of Excessive Rainfall (level 2/4) is in
place as extremely wet antecedent conditions on top of the additional
rainfall will lead to some flooding concerns. A more intense surge of
moisture is expected on Saturday ahead of a stronger Pacific storm system
that will move inland through the day. A broader Slight Risk of Excessive
Rainfall is in place for both coastal northern California, where rainfall
will continue from Friday, as well as upslope regions of the Sierra. Flood
watches are also in effect for the Sacramento and San Joaquin Valleys.
Rainfall totals will range between 1-2" along the coast and interior
valleys, with upwards 3-5" possible in the more favorable upslope regions
outlined by the Slight Risk areas, which may lead to a few instances of
flooding and the risk of mudslides. Very heavy snow is forecast for the
Sierra, with 2-3+ feet possible by early Sunday.

Moisture will also begin to spread further inland over the West as ridging
over the region begins to break down Saturday. Precipitation over most
lower elevation valley locations will start as snow Saturday before
transitioning into a wintry mix of sleet and snow for the Great Basin and
Northern and Central Rockies, with little to no accumulations forecast.
Higher elevation mountain locations, particularly from central Idaho south
into Nevada and the Four Corners region, can expect snow totals through
Sunday morning of 4-8", locally higher. Temperatures overall will remain
rather mild with ridging in place ahead of the storm system on Saturday.
Highs Friday and Saturday will range between the 40s and 50s for the
Pacific Northwest, Great Basin, Rockies, and northern/central California
and between the 60s and 70s for southern California and the Desert
Southwest.

Rain and snow will linger through Friday for portions of the Midwest,
Appalachians, and East Coast as a cold front passes through this morning.
Any additional rainfall totals should be light outside of coastal Maine,
where a Flood Watch remains in effect through Friday afternoon. Some
moderate snow totals of 2-4 inches, locally higher, are forecast in
favorable Lake Effect locations in the Lower Great Lakes, the Adirondacks
in New York, and portions of the central/southern Appalachians. Higher
snow totals of 8-12 inches are possible for northern Maine and the Great
Smokey Mountains. Some sleet and light accumulations of freezing rain will
be possible for northern New England as warmer air pushes northward ahead
of the cold front Friday morning/afternoon before changing back over to
all snow following the passage of the front Friday evening.

High temperatures will remain rather chilly across the South behind the
frontal passage, with 40s inland and 50s for locations closer to the Gulf
and Atlantic Coasts. Highs in Florida on Saturday will drop into the 50s
with lows below freezing possible Sunday morning in the Panhandle and
northern Florida Peninsula. Meanwhile, in the center of the country,
conditions will be unseasonably warm and a bit breezy with large scale lee
troughing in place east of the Rockies. Highs for the Northern/Central
High Plains will be in the 50s and 60s with some 70s possible into the
Southern High Plains. Temperatures further east over the Midwest and
Plains will start a bit cooler Friday with 20s and 30s to the north and
40s and 50s to the south. Temperatures warm up by 10 to 20 degrees on
Saturday as conditions moderate following the cold front passage. 

Putnam

Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php