Atmospheric Rivers

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri Mar 15 2024
Valid 12Z Fri Mar 15 2024 – 12Z Sun Mar 17 2024

…Heavy mountain snow continues throughout the Four Corners region into
this weekend…

…Severe thunderstorm and excessive rainfall chances shift south into the
Southeast and Gulf Coast States…

…Mild weather continues across the Pacific Northwest and East Coast…

A meandering closed upper low spinning over the Desert Southwest will
continue to funnel moisture northward into the Four Corners region and
create additional chances for heavy mountain snow through the weekend.
Snow chances will diminish today across the central/southern High Plains
as upslope flow weakens, but mountainous terrain of the central and
southern Rockies can expect an additional 1 to 2 feet of snow through
Sunday. The higher elevations of southern Utah and Arizona can also expect
snowfall accumulations over a foot, which will create hazardous driving
conditions. Winter Storm Warnings and Winter Weather Advisories remain in
effect for these regions.

Farther east, waves of low pressure and an associated cold front are
forecast to slide south and east today while stretching from the
Mid-Atlantic to the Southern Plains. Heavy rain and scattered
thunderstorms will accompany this system, with the greatest chances for
severe weather and/or flash flooding located across parts of the Mid-South
and south-central Texas. For these areas, thunderstorms could be strong
enough to contain damaging wind gusts and isolated tornadoes. Meanwhile,
the primary risk across south-central Texas is expected to be associated
with large hail and scattered flash flooding. By this weekend, the
aforementioned frontal boundary is forecast to stall along the Gulf Coast
and southern Texas, resulting in additional chances for heavy rain that
could lead to scattered flooding concerns from south-central Texas to
southern Mississippi.

The other notable weather system to impact the Lower 48 will be a potent
low pressure system passing to the north of the Great Lakes on Saturday
and nearing Maine on Sunday. The greatest impacts are anticipated to be
associated with gusty winds across the Great Lakes and decreasing
temperatures throughout the Upper Midwest by Sunday. Additionally, periods
of lake effect snow could be locally heavy across the U.P. of Michigan
downwind of Lake Superior. Otherwise, strong southerly flow on the eastern
side of this system will keep much of the East Coast mild with high
temperatures mainly in the 60s and 70s. The other warm spots over the next
few days include the Pacific Northwest and Southeast, where a few daily
record highs are possible. Parts of western Washington and Oregon may see
highs into the mid-70s, while mid-to-upper 80s are found throughout the
Sunshine State.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Wed Mar 13 2024
Valid 12Z Wed Mar 13 2024 – 12Z Fri Mar 15 2024

…Heavy snow develops over central Colorado Wednesday night into Thursday
followed by rain/mountain snow across the Four Corners to the southern
High Plains Thursday into Friday…

…Strong to severe thunderstorms possible from the Midwest to the
southern Plains from this evening into Thursday…

…Strong to severe thunderstorms with a slight risk of excessive rainfall
expected Thursday evening into early Friday from the southern Plains to
the Mid-South...

An amplifying upper-level trough digging into the western U.S. is
gradually pushing the unsettled weather out of the Pacific Northwest into
the Intermountain region. The interaction of the upper trough with colder
air filtering southward is setting the stage for a long-duration snow
event from the central Rockies and down into the Four Corners over the
course of the next few days. The precipitation will first be focused over
the central Rockies from this evening into Thursday when wet snow is
forecast to be the heaviest across the Front Range of Colorado where a few
feet of new snow could fall. Lesser amounts are expected in adjacent
areas but one to two feet of wet snow is possible down into the High
Plains at locations such as Boulder and Denver, Colorado. Hazardous to
very difficult travel is expected as heavy snow and intense snow rates at
times (1-2 inches plus per hour) will lead to deteriorating travel
conditions beginning Wednesday and Wednesday night across the
central/southern Rockies and beginning across the Four Corners region
Thursday night.

A second phase of the winter storm will then impact the Four Corners
Region beginning Thursday night, as the upper trough closes off into a
slow-moving upper low. Waves of heavy snow will impact the terrain areas
north of the Mogollon Rim and northeast toward the San Juans and southern
Colorado Rockies. Snow probabilities for 8 inches are moderate to high
(greater than 50%). Localized totals above a foot are possible for the
higher terrain.

On the warm side of the system, low relative humidity and gusty winds will
continue to raise the danger of wildfires to locally extreme levels from
the Texas Panhandle to western Texas today. The dry environment in the
Plains states will initially limit the formation of showers and some
thunderstorms across the mid-Mississippi Valley into the Midwest.
However, as a low pressure system develops and tracks across the central
Plains towards the Midwest, influx of moisture from the Gulf of Mexico is
forecast to organize an area of enhanced rainfall across Arkansas and
neighboring areas Thursday evening into early Friday when severe weather
is possible. The heavy rain and severe weather threat will then shift
northeast toward Tennessee by Friday morning as the trailing cold front
associated with the low pressure system approaches from the west. The low
pressure system itself will bring widespread moderate to locally heavy
rain with a slight threat of severe weather across the Midwest tonight,
followed by the southern half of the Great Lakes on Thursday, and into New
England Friday morning. The rain may mix with wet snow over the upper
Midwest tonight and over interior New England Friday morning.

As the winter storm develops over the western U.S., much of the eastern
U.S. will enter an extended period of very warm and pleasant weather.
High temperatures in the 60s and 70s from the Ohio Valley to the
Mid-Atlantic states will be 20-25 degrees above normal for this time of
year.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Mar 12 2024
Valid 12Z Tue Mar 12 2024 – 12Z Thu Mar 14 2024

…One more day of unsettled weather across the Pacific Northwest and
northern California before the precipitation gradually tapers off on
Wednesday…

…Mountain snows spreading into the northern and central Rockies on
Wednesday before heavy snow develops over central Colorado Wednesday
night…

…Fire danger across the southern High Plains will be followed by chance
of severe thunderstorms across the north-central Plains later on Wednesday
as rain may change over to wet snow in the nearby High Plains…

…Anomalously warm temperatures to expand eastward from the Upper Midwest
into the Ohio Valley, Mid-Atlantic and Northeast through Wednesday…

A gradual shift in the large-scale upper-level pattern across the U.S.
will bring unsettled weather that has been impacting the Pacific Northwest
in recent days progressively eastward into the central U.S. by Wednesday
night. The final in a series of Pacific fronts and low pressure systems
will push onshore into the West Coast today, bringing additional mountain
snow and lower-elevation rain with one to possibly two feet of new snow
along the Cascades. As the main upper trough presses eastward through the
western U.S. the next couple of days, areas along the West Coast will have
a chance to gradually dry out on Wednesday. Meanwhile, the main batch of
moisture will penetrate farther inland in the form of mountain snow
pushing into the northern to central Rockies on Wednesday. The upper
trough will also help develop a low pressure system over the central High
Plains on Wednesday. The interaction of the upper trough with the
intensifying low pressure system will begin to organize and focus an area
of moderate to heavy snow over central Colorado by early on Thursday. By
Thursday morning, snow could be falling in earnest over the mountainous
terrain into the Front Range and nearby High Plains of central Colorado.

On the warm side of the low pressure system, low relative humidity and
gusty winds will continue to raise the danger of wildfires across central
to southern High Plains today, followed by a more southward focus from the
Texas Panhandle to western Texas on Wednesday. The dry environment in the
Plains states will initially limit the formation of showers and some
thunderstorms across the mid-Mississippi Valley into the Midwest today
into early on Wednesday. However, as the low intensifies, influx of
moisture from the Gulf of Mexico is forecast to organize an area of
enhanced rainfall over the vicinity of Nebraska Wednesday night as the
storm center passes just to the southeast. Some of the enhanced rainfall
could be accompanied with severe weather. In addition, there is a
possibility that the western portion of the enhanced rainfall would change
over to wet snow early on Thursday if additional cold air wraps around the
storm center.

Across the eastern U.S., the departure of a strong surface low near Nova
Scotia into the western Atlantic will allow the gusty winds to moderate
further across the northern Mid-Atlantic and Northeast today. Breezy
conditions are likely to remain for northern New England into Tuesday
night, but overall improvement is expected. High pressure over the
southern U.S. will slide eastward over the next couple of days, allowing
winds to return from the south, bringing warmer temperatures northward.
The greatest departures from normal highs will remain over the Upper
Midwest and Great Lakes region on Tuesday which may cause a few record
daily maximum temperatures to be broken, but the magnitude of the
anomalous warmth is likely to be lower on today compared to Monday. High
temperatures in the 60s to lower 70s will expand eastward through
Wednesday across the Ohio Valley and portions of the northern Mid-Atlantic
into the Northeast, roughly 15 to 25 degrees above mid-March averages.
With the warmer weather will come the threat for thunderstorms across
portions of the central U.S. Some severe thunderstorms will be possible
ahead of a dryline from eastern Oklahoma/Kansas into western Missouri on
Tuesday with a broader risk across some of these same areas on Wednesday.
Again, the prevailing dry environment will initially limit the intensity
of the storms.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Mar 11 2024
Valid 12Z Mon Mar 11 2024 – 12Z Wed Mar 13 2024

…Heavy wet snow will continue into the morning hours on Monday across
the higher elevations of the northern New England and portions of the
lower Great Lakes…

…Unsettled weather is expected to persist across the Pacific Northwest
and into the northern Rockies with multiple rounds of lower-elevation rain
and higher elevation snow…

…Fire danger to increase across the central and southern High Plains
from very dry conditions, gusty winds, and warm temperatures…

A deep low pressure system centered over Downeast Maine early this morning
will be slow to move away into the Canadian Maritimes. The ongoing heavy
wet snow associated with this system is expected to linger across the
higher terrain from the Adirondacks of New York, up across the Green and
White Mountains of Vermont and New Hampshire respectively. Meanwhile, the
cold air pouring southeast over the lower Great Lakes will sustain heavy
lake-effect snow shower activity with squalls locally across upstate New
York into the morning of today before they gradually taper off during the
afternoon. The snow will likely taper off to snow showers and flurries by
tonight across northern Maine. Nevertheless, the strong and gusty winds
are expected to persist into Tuesday as the large circulation of the low
pressure system will take time to depart.

In the wake of the low pressure system, a large dome of high pressure will
build across the South and into the Southeast while taking its time to
slide off into the Atlantic. Temperatures over the next couple of days
will be well above normal especially across the central and northern
Plains and the Midwest before gradually advancing into the Great Lakes and
Ohio Valley. The return of dry weather coupled with increasingly gusty
winds and low relative humidity will promote an increased risk of
wildfires. In fact, the Storm Prediction Center has highlighted large
areas of the central and southern High Plains in an elevated to critical
fire danger area. This will include the panhandles of Texas and Oklahoma
where devastating fires occurred a couple weeks ago.

Meanwhile across the Pacific Northwest, multiple low pressure systems
arriving from the Pacific will bring frequent rounds of precipitation
onshore and then farther inland into the northern Rockies through the next
couple of days. Moderate to locally heavy rain is expected for the coastal
ranges with heavy snow over the higher elevations of the Cascades,
northern Sierra Nevada, and the Sawtooth, Bitterroot, and Teton ranges of
the northern Rockies. The Cascades will likely receive the heaviest
snowfall totals where as much as 1 to 2 feet of new snow can be expected.

Temperatures are expected to begin rebounding rather quickly for much of
the East and the South by later Tuesday as milder air from the Plains and
Midwest advances east together with warm air beginning to return north
from the Gulf of Mexico. High temperatures across portions of eastern
South Dakota, Minnesota, Iowa, and Wisconsin are forecast to be as much as
30 to 40 degrees above normal on today and Tuesday with temperatures
approaching or locally exceeding 70 degrees. Some cities will likely be
warm enough to see their daily high temperature records either tied or
broken today.

Meanwhile, a cooling trend is expected across the western U.S. as colder
air associated with an upper trough pushes inland to bring moderate to
locally heavy mountain snow into the central Rockies by early Wednesday
while the West Coast begins to dry out. Farther east, a low pressure
system is forecast to develop over the central to southern High Plains
Tuesday night. The dry environment in the vicinity will initially limit
the formation of showers and some thunderstorms across the mid-Mississippi
Valley into the Midwest early on Wednesday. Some light snow could brush
the northern Plains near Canadian border early Wednesday ahead of a
clipper system.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sat Mar 09 2024
Valid 12Z Sat Mar 09 2024 – 12Z Mon Mar 11 2024

…Heavy rain and some severe weather expected to move across the
Southeast today followed by heavy rain and strong winds across the
Mid-Atlantic and southern New England tonight into Sunday morning…

…Wet snow and strong winds across northern New England from tonight
through much of Sunday followed by lake-effect snows across the lower
Great Lakes into Monday morning…

…Frequent rounds of lower-elevation rain and mountain snow expected to
reach the Pacific Northwest through the next couple of days…

A complex interaction among a cold air mass dipping into the mid-section
of the country, an amplifying upper-level trough, moist air from the Gulf
of Mexico ingesting into the South, and a subtropical jet stream will
bring widespread increment weather through the eastern U.S. into Sunday.
The heaviest rainfall is expected to be found across the Southeast where
some of the thunderstorms could become severe. The Weather Prediction
Center has a Slight Risk of excessive rainfall forecast for the eastern
Carolinas for today. The low pressure center that forms and intensifies
along the southern front is forecast to track up the East Coast and reach
southern New England by early on Sunday. Areas from central Appalachians
into southern New England are expected to see a period of moderate to
occasionally heavy rain later today into early Sunday as the low pressure
center passes just to the southeast. Farther inland, colder air wrapping
around the intensifying storm will support wet snow across northern New
England during the same time period. This will be followed by lake-effect
snows across the lower Great Lakes into Monday morning when colder air
pours in behind the big low. Strong and gusty winds will expand and then
engulf the entire northeastern U.S. as the big low intensifies further and
begins to exit into the Canadian Maritimes by Monday morning.

In the wake of the storminess in the East, high pressure will take over
the entire central and southern U.S. with dry conditions persisting into
the new work week. The dry weather will extend into much of the western
U.S. as well. However, moisture associated with the next Pacific system
is forecast to reach the Pacific Northwest in a hurry today in the form of
lower-elevation rain and mountain snow for rather high elevations. More
systems arriving from the Pacific will result in frequent rounds of
precipitation persisting across the western portions of Washington,
Oregon, and down into northern California. The Cascades and higher
terrain of northern California will likely receive a couple more feet of
new snow through Monday.

Temperatures will generally be cooler than normal across the South but
above normal across the North. The East will be milder than normal today
ahead of the intensifying low pressure system before colder air surges
into the region on Sunday. Temperatures across the West will average near
normal.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EST Fri Mar 08 2024

Valid 12Z Fri Mar 08 2024 – 12Z Sun Mar 10 2024

…Snow gradually tapering off over the central High Plains as well as
central/southern Rockies…

…Threat of flash flooding and severe weather expected to sweep across
the Deep South to the Southeast through the next couple of days…

…An intensifying low pressure system will bring locally heavy rain and
strong winds from the Ohio Valley to New England late Saturday into
Sunday…

…Wet snow expected across the Great Lakes to northern New England late
Saturday to Sunday as next round of rain and mountain snow reaches the
Pacific Northwest…

Upper-level moisture arriving from the eastern Pacific in association with
a subtropical jet stream will interact with a cold air mass dipping into
the mid-section of the country through the next couple of days. This
interaction will result in active to locally severe weather to move from
west to east across many areas of the eastern half of the country through
Sunday morning. In addition, lower-level moisture from the Gulf of Mexico
will be ingested into the system. These complex interactions will result
in an axis of heavy rain and possibly severe weather to blossom later
today across the lower Mississippi Valley, spreading through the Deep
South Friday night, and then through the Southeast on Saturday.
Meanwhile, a low-level disturbance that has been sustaining locally heavy
snow over the central High Plains is forecast to weaken and allow the snow
there, as well as the snow over the central to southern Rockies, to
gradually taper off today into this evening. By Saturday, a low pressure
center is forecast to consolidate over the Ohio Valley when the system
intensifies more rapidly and tracks northeastward into the lower Great
Lakes Saturday night. Locally heavy rain and increasingly strong and
gusty winds are expected to develop from the Ohio Valley to New England
late Saturday into Sunday. Colder air wrapping around the low pressure
center is expected to change the rain to wet snow from across the Great
Lakes to portions of northern New England especially for the higher
elevations.

Much of the Great Plains will dry out on Saturday behind the low pressure
system as a high pressure system takes over. The dry weather will extend
into much of the western U.S. However, moisture associated with the next
Pacific system is scheduled to reach the Olympic Peninsula later today
with rain for the lower elevations and snow for rather high elevations.
The rain and mountain snow will expand southward across Oregon and into
northern California on Saturday into Saturday night. The Cascades will
see snow picking up intensity on Saturday as the next batch of moisture
getting ready to reach the coastline of the Pacific Northwest by early on
Sunday.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Thu Mar 07 2024
Valid 12Z Thu Mar 07 2024 – 12Z Sat Mar 09 2024

…Storm system to bring the threat of flash flooding and severe weather
to the Southern Plains Thursday, spreading eastward into the Lower
Mississippi Valley and Southeast Friday…

…Areas of moderate to heavy snow expected for the Central Rockies/High
Plains Thursday…

…Another Critical Risk of Fire Weather Thursday for the Southern High
Plains…

…High temperatures remain above average and Spring-like for the eastern
U.S. with below average temperatures in the West…

A complex weather system evolving over the central U.S. will bring showers
and thunderstorms with the threat of severe weather and flash flooding to
the Southern Plains/Southeast, a risk of wildfires in the High Plains, and
some areas of heavy snow over the Rockies/Central High Plains over the
next couple of days. Upper-level troughing approaching from the west will
help to deepen/organize a low pressure/frontal system over the Southern
Plains, further reinforced by a Pacific system moving in from the West.
Southerly moist Gulf return flow ahead of a sharpening dryline will bring
increasing shower and thunderstorm chances to the Southern Plains
beginning as early as Thursday morning. Increasing deep-layer shear with
the approach of the upper-level trough as well as sufficient CAPE will
bring the threat for a few severe thunderstorms, and the Storm Prediction
Center has highlighted central Texas and western Oklahoma/south-central
Kansas with Slight Risks of Severe Weather (level 2/5) for some instances
of large hail along with damaging winds and an isolated tornado. In
addition, the increasing moisture will lead to some heavier downpours, and
the threat for a couple rounds of storms evolving downstream over north
Texas Thursday evening has prompted a Slight Risk of Excessive Rainfall
(level 2/4) for some scattered instances of flash flooding, particularly
for urban areas in the DFW metroplex. Very dry conditions will exist west
of the dryline over the Southern High Plains, which when combined with
warm temperatures and gusty winds has prompted a Critical Risk of Fire
Weather (level 2/3) form the Storm Prediction Center. To the northwest, a
secondary frontal system pushing southward will bring much colder air into
the Central Rockies/High Plains. Areas of moderate to heavy snow are
expected to continue through the day Thursday for portions of the Central
Rockies, particularly along the Front Range in Colorado. In addition,
confidence has increased in a round of snow bands moving through portions
of northeastern Colorado into western Nebraska bringing heavy snow rates
of 1-2″+ per hour and several inches of accumulating snow, with Winter
Storm Warnings now in effect. The snow should come to an end for the High
Plains into Friday morning, with chances in the mountains shifting
southward into the Southern Rockies.

The system will continue eastward Friday, with an expanding area of shower
and thunderstorms spreading into the Midwest, Lower Mississippi Valley,
and Southeast. A reinforcing influx of more anomalous moisture flowing
northward with a warm front from the Gulf will bring a higher threat for
more widespread heavy downpours compared to Thursday, with the expectation
that clusters of storms will bring repeated rounds of rainfall along the
frontal boundary into Friday night. A Moderate Risk of Excessive Rainfall
(level 3/4) has been introduced from east-central Alabama into northern
Georgia where wet antecedent conditions from the night before will further
help increase the threat for some scattered to numerous instances of flash
flooding, particularly for urban areas in the greater Atlanta region. A
broader Slight Risk is in place from the Lower Mississippi Valley eastward
through the Southern Appalachians. Another round of severe weather is also
expected, with a Slight Risk of Severe Weather stretching from eastern
Texas/southeastern Oklahoma through the Lower Mississippi Valley and
towards the central Gulf Coast. Large hail, damaging winds, and a few
tornadoes are all possible.

Elsewhere, the noted Pacific system eventually reaching the Plains will
first move eastward from California into the Great Basin/Southwest on
Thursday, with some light to moderate rain/snow showers for the Great
Basin and a few thunderstorms in the deserts of the Southwest. Some light
to moderate showers will taper off through the day Thursday in southern
New England as a frontal system departs the region, with the potential a
bit of snow may mix in. Some additional light snowfall accumulations will
be possible further north into Maine. Showers and thunderstorms will also
continue in South Florida Thursday ahead of a cold front. Finally, an
approaching Pacific system will bring increasing precipitation chances to
the Pacific Northwest later Thursday and into Friday morning.

Temperature wise, highs will remain above average for much of the eastern
U.S. ahead of the frontal systems approaching from the west over the
Plains. Highs will range from the 40s and 50s in the Upper Midwest east
through the Great Lakes and New England; the 50s and 60s from the Middle
Mississippi Valley east through the Ohio Valley and into the Mid-Atlantic;
and the 60s and 70s from the Lower Mississippi Valley into the Southeast.
Portions of the Central/Southern Plains will be above average Thursday,
with highs in the 50s and 60s in the Central Plains and 70s and 80s in the
Southern Plains. Cold fronts passing through with the central U.S. system
will bring some much cooler temperatures Friday, with highs dropping to
the 40s and 50s for western portions of the Plains. The Northern Plains
will recover Friday following a chilly day Thursday, with highs in the 20s
and low 30s rising into the upper 30s and 40s. Temperatures will generally
remain below average in the West, with 30s and 40s for the Pacific
Northwest and Great Basin, 50s and 60s for California, and 60s and 70s
into the Southwest.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Wed Mar 06 2024
Valid 12Z Wed Mar 06 2024 – 12Z Fri Mar 08 2024

…Wet Wednesday in store from the Ohio/Tennessee Valleys to the East
Coast, with locally heavy rainfall and the risk of scattered flash
flooding along the I-95 urban corridor…

…Showers and thunderstorms expected along the California coast
Wednesday…

…Strengthening storm system in the Plains to bring showers and
thunderstorms with the threat of severe weather Thursday…

…Above average temperatures persist for much of the central/eastern U.S.
as conditions remain below average in the West…

Wet weather will continue for portions of the eastern U.S. from the
Ohio/Tennessee Valleys eastward to the East Coast in a complex pattern.
Ongoing showers will continue along a slow moving cold front stretching
from the Interior Northeast southwestward through the Ohio Valley,
expected to make little eastward progress today and eventually stalling
along the Appalachians. Meanwhile, a combination of upper-level energies
and associated waves of low pressure along a quasi-stationary frontal
boundary draped along the East Coast southwestward through the Southeast
will spread showers and thunderstorms northeastward through the day
Wednesday from the Southeast into the Mid-Atlantic and New England. A
couple axis of locally heavier rainfall are forecast to occur to the east
of the low pressure waves where enhanced very moist, onshore flow from the
Atlantic will exist. Slight Risks of Excessive Rainfall (level 2/4) are
outlooked for the North Carolina Outer Banks and for the coastal
Mid-Atlantic into southern New England, from New Jersey northeastward to
far southwest Maine. Areal average rainfall totals of 1-2″, locally 3″,
may lead to some scattered instances of flash flooding, especially for
urban areas along the I-95 corridor. In addition, some locally heavy
downpours will be possible in South Florida ahead of the trailing frontal
boundary. The front/low pressure waves will begin to push away from the
coast overnight Wednesday into Thursday morning, with rain chances
lingering longest into the day Thursday in New England. Some wintry
precipitation will mix in for portions of New England as colder air
spreads southward behind the departing system, and some light snow
accumulations will be possible into Maine.

In the West, an upper-level low/Pacific frontal system will move southward
along the California coast and eventually inland, bringing showers and
storms to the area Wednesday. Some locally heavy rainfall will be possible
through southern California, which may lead to some isolated flash
flooding concerns given the very sensitive conditions still in place over
the area after recent heavy rainfall events. Some snow showers will linger
through portions of the higher elevations of the southern Pacific
Northwest/northern California and northern Great Basin, but will come to
an end as moisture flow follows the Pacific system southward. A light
wintry mix for the central Great Basin and showers for the Desert
Southwest will follow the system as it progresses eastward on Thursday.

Precipitation chances will also increase for the center of the country as
a couple different systems pass through the region. To the north, an
upper-level wave will help to deepen/organize a low pressure system over
the Northern Plains, forecast to lift northeastward through the Upper
Midwest and into Canada Wednesday-Thursday. Some light showers will be
possible ahead of the system, but more precipitation is expected to follow
in the colder air on the backside of the system track along the Canadian
border. Some light to moderate snow accumulations are expected through
Thursday morning from northern North Dakota into northwestern Minnesota.
Further south, the upper-level trough over the West will approach the
Central/Southern Plains from the west, helping to induce lee cyclogenesis
along the Rockies and organize/strengthen a frontal system over the Plains
by Thursday. A broad area of showers and thunderstorms is expected in the
warm sector ahead of the system over the Central/Southern Plains into the
Middle/Lower Mississippi Valley as moist Gulf return flow spreads
northward, especially into Thursday evening/night. Strengthening deep
layer shear as stronger winds arrive with the approach of the upper-level
trough may lead to some severe thunderstorms, with the Storm Prediction
Center highlighting western Oklahoma into northwest/central Texas in a
Slight Risk (level 2/5) for the threat of some large hail as well as
damaging winds and an isolated tornado. Some locally heavy downpours and
an isolated risk of flash flooding will exist more broadly across the
region as well. Finally, the system will bring some moderate higher
elevation/mountain snow to portions of the Central Rockies, with some
lighter snow mixing in for the Central High Plains.

A familiar pattern of above average temperatures for central/eastern
portions of the country and below average temperatures in the West looks
to continue for at least the next couple of days. Highs for many locations
will be upwards of 10-20 degrees above average from the Plains to the East
Coast. Forecast highs generally range from the 40s and 50s from the Upper
Midwest east through the Great Lakes and New England; the 50s and 60s from
the Central Plains east through the Middle Mississippi/Ohio Valleys into
the Mid-Atlantic; and the 60s and 70s from the Southern Plains east
through the Lower Mississippi Valley into the Southeast and Florida. A
pocket of much colder temperatures in the 20s and 30s behind a cold front
in the far Northern Plains will begin to spread southward following the
front, with highs dropping into the 30s and 40s for portions of the
Northern/Central Plains Thursday after a warmer Wednesday. Forecast highs
in the West range from the 30s and 40s in the Pacific Northwest and Great
Basin, the 50s and 60s in California, and the 60s and 70s in the Desert
Southwest.