Sig Silber

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
1105 PM EST Wed Nov 27 2024
Valid 12Z Thu Nov 28 2024 – 12Z Sat Nov 30 2024

…Thanksgiving Day storm to push into the Northeast today spreading
rainfall and New England snowfall in its vicinity…

…Increasingly below average temperatures spill out into the Great Plains
and Mississippi Valley through the end of the week…

…Lake Effect snows continue and will expand and intensify with time…

A dynamic mid-latitude cyclone tracks near the New England coast today.
Scattered showers and thunderstorms spread into the East Coast today. A
swath of moderate to heavy snowfall is likely to develop across portions
of the interior Northeast — winter storm watches and warnings are in
effect for portions of central New England related to the heavy snow
threat.

Elsewhere, Lake Effect snow showers across the Upper Great Lakes may yield
anywhere from 4-8 inches over the northern coastline of the Upper
Peninsula of Michigan as well as northern parts of the Lower Peninsula
today. A disturbance aloft will allow for the development of a new cold
front late today which moves east and south ahead of a strong and cold
surface high. In the wake of this front, as temperatures cool further,
lake effect snows should expand and intensify as they interact with record
warm Great Lakes temperatures for late November. Several additional inches
of snow are forecast on Friday bringing 2 day snowfall totals over a foot
with isolated higher amounts possible across downwind areas of the Great
Lakes by Saturday morning. Florida will remain mild to warm.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Nov 26 2024
Valid 12Z Tue Nov 26 2024 – 12Z Thu Nov 28 2024

…Heavy snow over parts of the Sierra Nevada Mountains, Great Lakes and
Central Rockies…

…Below average temperatures in the Plains…

A moderate level atmospheric river event will accompany a surface low
pressure system as it moves into the West today. This AR will spread
anomalous moisture over southern/central California, the Great Basin and
Central Rockies. Heavy coastal and mountain rain may lead to instances of
flash flooding, particularly over the windward foothills of the southern
Sierra Nevada below 8000 feet, where excessive rainfall may cause
land/rock/mudslides. Heavy snow accumulating between 1-3 feet are possible
over the higher elevations of the southern Sierra, as well as much of the
Intermountain West and Central Rockies today. Snow diminishes over the
Sierra on Wednesday while snow showers persist over the Colorado Rockies.
Snow showers continue across the Great Lakes this week with parts of the
Upper Peninsula of Michigan and downwind areas of Lake Ontario picking up
between 4-8 inches of snow by Thursday morning.

Troughing across the northern tier states will continue to promote below
average temperatures over the next several days. High temperatures in the
teens and 20s will represent a 15-25 degree departure from normal for much
of the far Northern Plains today and Wednesday. A pair of mid-level
disturbances are expected to phase over the Central U.S. and facilitate an
arctic outbreak across the region Wednesday night into Thanksgiving
Thursday.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Nov 25 2024
Valid 12Z Mon Nov 25 2024 – 12Z Wed Nov 27 2024

…Heavy snow over parts of the Sierra Nevada Mountains, Upper Great Lakes
and Central Rockies…

…Below average temperatures in the Northern Plains; above average temps
in the Southern Plains/Lower Mississippi Valley today...

An upper-level trough will swoop into the West Coast from the northeast
Pacific early this week. This trough will direct a very anomalous
subtropical moisture plume along its base at central and southern
California today and Tuesday. A surface low pressure system will help
focus the anomalous moisture over coastal areas as well as the Sierra
Nevada. Parts of the southern Sierra below about 8000 feet may experience
instances of Flash Flooding today. Rock/mud slides and general debris flow
are some of the possible impacts from excessive rainfall in mountainous
areas. Heavy snow is probable at the higher elevations of the southern
Sierra, where 3-4 feet are forecast to accumulate with isolated higher
amounts possible by Wednesday morning. The anomalous moisture feed is also
expected to penetrate into the interior of the West. Parts of the Great
Basin will experience snow showers while heavy snow blankets the
Intermountain West and Colorado Rockies with 1-2′ (isolated 3′) likely
over the next couple of days.

Elsewhere, a pair of low pressure systems moving through the Upper
Midwest/Great Lakes will generate several inches of snow over the Upper
Peninsula of Michigan, while snow showers occur across the greater Upper
Midwest and Lower Great Lakes. Temperatures will remain above average for
one last day from the Southern Plains into the Midwest before a strong
cold front pushes through on Tuesday. Some record high temperatures (in
the mid to upper 80s) might be set over south Texas today. Highs topping
out in the teens and 20s will represent a negative 20-30 degree departure
from normal for parts of the Northern Plains today. Mild conditions
continue over much of the East Coast through Tuesday.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sun Nov 24 2024
Valid 12Z Sun Nov 24 2024 – 12Z Tue Nov 26 2024

…Heavy Snowfall for parts of the Sierra Nevada…

…Above average temperatures spread from the central U.S. into the East
while cold airmass descends into the Great Plains…

A weak low pressure system will continue directing a plume of moisture at
the West Coast over the next few days. This will likely result in coastal
and low elevation rain, while moderate to heavy snow proliferates across
the coastal ranges of Washington, Oregon and California. The heaviest
snowfall is likely to occur over portions of the Sierra Nevada, with the
southern Sierra poised to accumulate 2-3 feet with isolated higher
amounts. Snow showers will also impact the Colorado Rockies over the next
few days. Heavy rain and snow chances increase on Tuesday as another
atmospheric river event arrives across parts of central California.

Relatively zonal flow across the southern tier of the country will support
another day of above average temperatures for the Central/Southern U.S.
today. An upper trough will pickup steam over the northern tier and send a
strong cold front diving south through the Great Plains over the next 48
hours. Highs in the teens will represent 20-30 degree departures from
normal over the Northern High Plains through Monday. Temperatures will
drop precipitously, from highs in 60s and 70s today to 40s and 50s on
Monday over parts of the Southern Plains as the cold front propagates
through. The associated warm front will spread mild air across the Eastern
U.S. on Monday before the cold front arrives and drops temperatures for
the rest of the week.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sat Nov 23 2024
Valid 12Z Sat Nov 23 2024 – 12Z Mon Nov 25 2024

…Very strong Atmospheric River to produce heavy snow across the Sierra
Nevada before winding down over north/central California today…

…Above average temperatures expand across the Central U.S. this
weekend…

Moisture associated with a highly impactful and dangerous atmospheric
river event will diminish as it sags south and east through central
California today. Heavy snow is likely over much of the Sierra Nevada this
morning where anywhere between 1-2 feet are expected to accumulate when
all said and done. Upslope portions of the Sierra below 7000 feet may
experience isolated instances of flash flooding this morning before snow
levels drop on the backside of the cold front pushing through the West
this afternoon. Snow showers spread into Northern/Central Rockies this
afternoon and the Intermountain West on Sunday. Snowfall totals of 6-12
inches are probable for the aforementioned areas by the end of the weekend.

Surface high pressure extending from central Canada down to the Gulf Coast
will support below average temperatures for those regions through tonight.
Parts of the Southeast will experience low temperatures in the mid to
upper 30s which may lead to some frost/freezes. A deepening upper trough
over the north-central U.S.and Ridge over Mexico will promote above
average temperatures across the Great Plains today and Sunday before
expanding into the East by Monday. Elsewhere, mixed precipitation can be
expected to continue across portions of upstate New York and New England
today.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri Nov 22 2024
Valid 12Z Fri Nov 22 2024 – 12Z Sun Nov 24 2024

…Atmospheric river will produce one last round of heavy rain/mountain
snow and strong wind gusts across the Pacific Northwest today…

…Moderate to heavy snow for portions of the Central Appalachians today...

…Above average temperatures expand across the Central U.S. this
weekend…

Anomalous moisture supported by a deep low pressure system will continue
impacting the Pacific Northwest today. Life threatening flooding is likely
across portions of northern California, where additional amounts of 3-5″
are expected, mainly over coastal areas. As much as 4-10″ of rain are
possible for the northern Sierra Nevada. Dangerous flooding, rock slides
and debris flows remain likely today. A Moderate Risk of Flash Flooding is
in effect for upslope portions of the northern Sierra below 5000′. The
flooding risk will decrease from north to south by later today and into
tonight. Heavy mountain snow is expected over the Washington Cascades and
Northern Rockies through Saturday. Multiple feet of snow are likely to
accumulate over portions of the northern Sierra (above 7000′) by Saturday
evening. Strong winds will continue across coastal areas of northwest
California into western Washington, and over south-central Oregon. These
winds may blow down trees and power lines, and additional power outages
are possible.

A deep upper low will pivot over the Northeast and reinforce a cooler
airmass along with a relatively shallow bit of moisture into the region
today. Some rain and snow showers are expected across much of the
Northeast/northern Mid-Atlantic as a result. Heavier snow will likely
remain confined to the higher terrain of the Central Appalachians, where
between 6-12 inches are expected with locally higher amounts possible.
Snow chances diminish as the day progresses and temperatures rise. Upper
ridging over the Intermountain West and Rockies will shift eastward into
the Central U.S. this weekend where above average temperatures are likely
to follow.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Thu Nov 21 2024
Valid 12Z Thu Nov 21 2024 – 12Z Sat Nov 23 2024

…Strong atmospheric river continues to impact northern California with
heavy rain and life-threatening flooding through Friday…

…Developing storm system forecast to bring another round of gusty winds
to the Pacific Northwest on Friday with heavy mountain snow spreading
toward the northern Rockies this weekend...

…Unsettled weather expected across much of the Northeast and Great Lakes
over the next few days, including the likelihood of heavy snow in the
central Appalachians and higher elevations of northeastern Pennsylvania
and southern New York…

Impactful and for some place dangerous weather conditions will continue
through early this weekend as two separate storm systems impact the Lower
48. Starting in the West, a strong atmospheric river currently impacting
northern California is forecast to remain relatively stationary over the
next few days and produce an additional 6-12 inches of rainfall over
regions with already saturated terrain. The atmospheric river is expected
to peak in intensity today, but with moderate bouts of rain lingering
through much of Friday and snow levels finally lowering somewhat on
Saturday. In the meantime, dangerous flooding, rock slides, and debris
flows are likely, which has prompted a High Risk (level 4/4) of Excessive
Rainfall to be issued across the northern California coastline today. Be
sure to check conditions before traveling and never drive across flooded
roadways.

Aiding the surge of atmospheric moisture into northern California and the
Northwest through the end of the week is a developing storm system
forecast to swing off the Oregon and Washington coastline on Friday. A
punch of gusty winds are expected, mainly along coastal regions, could
produce rough surf and additional isolated power outages. As precipitation
lifts northward and inland along a draped stationary boundary stretching
from the northern Rockies to British Columbia, heavy snow is possible from
the Washington Cascades to the western Montana, Idaho, and northwestern
Wyoming mountain ranges through early Sunday.

November snowfall is also in the forecast for parts of the Northeast and
Great Lakes thanks to a potent upper-level low swinging over the region.
At the surface, a compact area of low pressure is currently looping around
the Great Lakes with an eventual southward trajectory over Lake Michigan
later today. Parts of eastern Wisconsin could see precipitation fall as
snow along with wind gusts up to 40 mph. Winter Weather Advisories have
been issued for snowfall amounts up to 3-4 inches. Meanwhile, a separate
area of low pressure developing near Long Island tonight is also expected
to track in a looping orientation across the Northeast through Friday,
while also producing periods of heavy snow. The greatest chances for at
least 6 inches of snowfall is found across northeast Pennsylvania and
southern New York, including the Pocono and Catskill mountains.
Additionally, a long-duration upslope snow event is underway across the
central Appalachians and anticipated to linger through at least early
Saturday. Up to a foot of snow is possible across the higher terrain of
West Virginia, Maryland, and southwest Pennsylvania. Light snow is also
expected to reach as far south as the higher ranges of North Carolina.

The central and southern U.S. can expect much more tranquil conditions as
high pressure creates a void in the unsettled weather impacting both the
East and West coasts. However, below average temperatures are forecast
from the Mississippi Valley to the Southeast as breezy northwest flow
ushers in a colder airmass. This may lead to early morning frost and/or
freeze potential across the Southeast and Lower Mississippi Valley.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Wed Nov 20 2024
Valid 12Z Wed Nov 20 2024 – 12Z Fri Nov 22 2024

…Back-to-back powerful Pacific storm systems to impact the West Coast
through the end of this week with heavy rain, life-threatening flooding,
strong winds, and higher elevation mountain snow…

…Near blizzard conditions are possible through this evening across the
northern Plains…

…Heavy snow is likely throughout parts of the central Appalachians
beginning on Thursday, with a separate burst of snowfall possible across
northeast Pennsylvania and neighboring regions of the Northeast Thursday
night into Friday...

The active November weather pattern impacting CONUS is forecast to
continue through the end of this week and bring hazardous rain, wind, and
snow for several regions. A significant Pacific storm system and strong
atmospheric river have already started pummeling the West Coast and
Northwest this morning. The very deep low pressure system churning about
300 miles off the coast of Washington is responsible for high winds
impacting much of northern California, Oregon, and Washington. These winds
have already produced numerous power outages, reports of tree damage, and
are expected to create blizzard conditions throughout the Cascades.
Fortunately these winds are expected to gradually subside by midday as the
low pressure system swings away from the region. However, a continuous
plume of ample atmospheric moisture content entering northern California
this morning is forecast to linger through the end of the week and lead to
extreme rainfall totals. Over 10 inches of rainfall across the northern
California coast and inland mountain ranges are likely to increase the
threat of life-threatening flash flooding, rock slides, and debris flows.
As this corridor of heavy rainfall lingers along a stationary boundary
extending into the Pacific Ocean, a separate area of low pressure is
forecast to develop and rapidly strengthen off the Northwest coast on
Friday. This storm will help amplify the atmospheric river streaming into
northern California through Friday morning, exacerbating the flooding
threat. WPC has issued a High Risk (level 4/4) of Excessive Rainfall on
Thursday in order to further highlight this concern. Additionally, another
round of strong winds are anticipated from this second low pressure system
throughout the Northwest to end the week. Residents and visitors residing
or traveling between northern California and Washington are advised to
check road conditions before venturing out, listen to advice from local
officials, review emergency plans, and have multiple ways of receiving
warnings.

For the central U.S. the main weather story will be found throughout the
northern Plains as heavy snow and gusty winds create near blizzard
conditions today. These hazardous weather conditions are resulting from a
slow-moving and gradually weakening low pressure system just north of the
Minnesota-North Dakota border. The greatest snowfall amounts are forecast
across North Dakota, eastern South Dakota, and northwest Minnesota, but
with additional totals today generally under 4 inches. Wind impacts should
be more widespread and extend into eastern Montana and Nebraska as maximum
gusts could exceed 60 mph through tonight. This area of low pressure is
anticipated to rapidly weaken tonight and lead to calmer conditions on
Thursday.

After an extended period of dry and tranquil weather across the Northeast,
the upper level system exiting the northern Plains today will slide
eastward and produce a chance for heavy precipitation in the form of both
rain and snow. The evolution of surface features over the next few days
are forecast to begin with a developing strong and compact low pressure
system over the Great Lakes today, while a cold front quickly pushes
eastward to the Mid-Atlantic by tonight. Showers and maybe a rumble of
thunder may accompany this cold front as rain possibly mixes with snow
spreading across the Great Lakes. By Thursday, a separate area of low
pressure forming along the aforementioned cold front is expected to deepen
and lift northward into the Northeast, while also leading to a blossoming
precipitation shield. Rain is most likely across New England where warmer
air surges from the Atlantic Ocean, but the higher elevations and area
directly underneath the cold upper low pressure system may see
precipitation fall as heavy snow. Probabilities for at least 4 inches of
snow by Friday night are high (70-90%) across northeast Pennsylvania and
the southern Catskill mountains of New York. Impactful snowfall is also
likely to be experienced throughout the Allegheny mountains of West
Virginia, Maryland, and Pennsylvania through the end of the week due to a
longer duration favorable upslope snow setup. Total snowfall amounts in
these higher elevations could add up to a foot.

Elsewhere, high pressure building into the south-central U.S. will create
dry conditions from the lower Mississippi Valley to much of the Plains,
Rockies, and Southwest. The temperature outlook features one final day of
widespread 60s and 70s along the East Coast before a strong cold front
knocks afternoon highs below average through the start of the weekend. The
coldest temperatures when compared to climatology over the next few days
are forecast across the northern Plains (highs in the 20s) and Ohio Valley
(highs in the 30s and 40s).