Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EST Sat Dec 06 2025

Valid 12Z Sat Dec 06 2025 - 12Z Mon Dec 08 2025

...Active winter weather pattern continues with snow expected across the
Northern Tier this weekend...

...Series of atmospheric rivers to usher in heavy rainfall to the Pacific
Northwest late this weekend...

Winter weather continues to make headline across multiple regions of the
Lower 48 this weekend. Through the afternoon, Winter Storm conditions are
expected to persist across portions of the Northern Rockies as a wave of
low pressure develops along an Arctic front, with an additional foot plus
of snowfall possible in higher terrain areas. By tonight, the surface low
is forecast to migrate eastward from the Rockies, which will lead to
increasing snowfall coverage in parts of the Northern Plains and Upper
Midwest. As such, the current Watch-Warning map shows a swath of Winter
Weather Advisories and an embedded Winter Storm Warning extending from
South Dakota into northwest Illinois for 4-6" (locally higher) of snow
through Sunday.

Meanwhile, the unsettled pattern in the Pacific Northwest could take a
turn for the worse as a series of Pacific storm systems increases the
heavy rain and flood threat on Monday. Scattered flash flooding is
possible across portions of western Washington and Oregon beginning Monday
as persistent rainfall in the region saturates soils, in turn converting
any additional rain to runoff very quickly. The current WPC outlook
highlights a Slight Risk of Excessive Rainfall for the region on Monday,
and a Flood Watch is in effect for the area beginning Sunday night. Stay
tuned for updates to the forecast as the heavy rainfall threat looks to
carry on into at least midweek. Elsewhere across the Continental U.S., dry
conditions are expected to continue from California to the Southern
Plains, and extending eastward to the Mid-South and Tennessee Valley.
Across the Gulf Coast region, a lingering frontal boundary off the coast
will keep rainfall chances elevated through early Sunday from southeast
Louisiana to the Florida Peninsula to southern South Carolina, with some 1
inch totals possible in some areas. In terms of temperatures, it will be
quite cold from the Northern Plains to the Northeast with a big dip in the
jet stream and multiple cold frontal passages heralding the arrival of a
polar airmass. Some subzero overnight lows are likely across portions of
the Dakotas and into Minnesota, especially by Sunday/Monday morning in the
wake of the next arctic front.

Asherman/Kebede


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
117 AM EST Sat Dec 6 2025

Valid 12Z Tue Dec 09 2025 - 12Z Sat Dec 13 2025


...Multi-day heavy precipitation threat for the Pacific Northwest
early to mid next week due to a potent & persistent Atmospheric
River...


...Overview...
A broad upper level trough with reinforcing shortwaves will
continue to dominate across the eastern two-thirds of the lower 48
during the medium range period, with broad ridging generally
preferred near the West Coast. Strong westerly flow over the broad
ridge will bring a wavering atmospheric river into the Northwest
with heavy rain and high elevation snow next week, along with
potential for high winds. Cold weather and clipper systems will be
favored in this pattern east of the Rockies.


...Guidance/Predictability Assessment...
Guidance continues to show general agreement with mid-larger scale
systems and the overall pattern evolution for much of this forecast
period, but there remains some uncertainty in the details of the
timing of flow embedded multiple shortwaves that will focus
sensible weather impacts locally. For the most part a multi-model
deterministic model blend works well for Tuesday-Wednesday, with
favored blend including some of the 05/12z NAEFS the ECMWF
ensemble means for later next week amid growing forecast spread,
particularly across the southern Plains and Southeast. The 01z UTC
NBM seems to provide a solid forecast basis for most mass fields
through the period. However, NBM QPF was modified upwards later
next week over the Great Lakes and Northwest midweek given
the then available guidance early in the medium range period.


...Weather/Hazards Highlights...
The incoming atmospheric river across the Northwest looks strong
and relatively persistent from the 8th possibly into the 11th, with
some wavering in the axis across western WA and western OR.
Precipitable water values approaching 1.5" not far offshore with
50+ kts of low- level inflow from the Pacific promises days of
heavy rains, potentially 5"+ locally per day. Significant multi-
day precipitation totals are possible both with coastal rain and
high elevation snows across the Cascades. The Slight Risk was
maintained for day 4/9-10th with a new Slight Risk area added for
day 5/10-11th per coordination with the PDX/Portland OR and
SEW/Seattle WA forecast offices.

Elsewhere, clipper systems will bring rounds of precipitation,
mainly snow, over a cold northern Plains and Midwest, Great
Lakes/Appalachians, and the Northeast next week. Aforementioned
surface cyclo/fronto genesis will act to enhance wrapping activity
and especially Lake Effect with system passages. Wavy and stalling
trailing fronts lingering down near southern Florida and into the
Gulf may also focus uncertain rain chances over/offshore next week.

Tuesday will be cold across the East, with 10-15F cold anomalies at
that point. While a general thaw is noted Wednesday, the beginning
of a colder air mass invades the northern Plains with 10F cold
anomalies noted, before intensifying and expanding from the
northern Plains southeast across the Midwest and towards the
Southern Appalachians with 15F+ cold anomalies across a broader
swath east of the Rockies Thursday into next Saturday. The West
and portions of the High Plains will experience 15-20F warm
anomalies next week underneath upper ridging.


Roth/Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
157 AM EST Sat Dec 6 2025

Valid 00Z Sun 07 Dec 2025 - 00Z Sun 14 Dec 2025

A cold front in association with a deep trough and cutoff low
west of the state should weaken and retrograde as an easterly wave
this weekend. Winds should moderate back to normal easterly
trades this weekend with the usual windward shower paradigm
expected. A compact cut off low will meander east and northeast of
the state as late as Wednesday but is forecast to have minimal,
if any, impact on precipitation amounts across Hawai'i before it
moves east, out of the picture.

Another cold front moves into the western main islands late Wednesday
at the leading edge of a positively tilted trough. While timing
is no longer a factor, the guidance now allows the front to sweep
cleanly through the main Hawaiian Islands by next Saturday. There
is some difference as to where a closed/occluded low sets up
within the trough, with the GFS a bit farther south with its
cyclone which could bring cooler/drier air across the state. A
compromise position for the deep layer low, north of the 00z GFS,
is currently preferred. In any event, moderate to heavy
showers/thunderstorms are expected to accompany the frontal
passage, though expected rainfall doesn't appear to be excessive
at the present time as the front is forecast to be progressive.

Roth

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
230 AM EST Sat Dec 6 2025
Day 1
Valid 12Z Sat Dec 06 2025 - 12Z Sun Dec 07 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Wegman

Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
230 AM EST Sat Dec 6 2025
Day 2
Valid 12Z Sun Dec 07 2025 - 12Z Mon Dec 08 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

The inherited Marginal Risk aligned roughly along the
Florida/Georgia line was removed with this update. A stalled out
front over the area will act as a focal point for a corridor of
mostly light to moderate rain through the day Sunday. Instability
will be near zero, so any convection will be brief. Fast storm
motion along the front due to an approaching 130 kt jet will ensure
that any elevated convection will be short-lived. Finally, soils in
the area are well below normal. The dry soils in this area will
support any light rain being soaked right into the soil. This too
will temper any flooding threat. Due to all of the above factors,
the flooding threat was determined to be less than 5 percent, with
the highest risk in the Jacksonville urban area.

Wegman

Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
230 AM EST Sat Dec 6 2025
Day 3
Valid 12Z Mon Dec 08 2025 - 12Z Tue Dec 09 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
PACIFIC NORTHWEST...

The first in a series of Pacific lows will move into the coast of
the Pacific Northwest on Monday. The combination of multiple days
of heavy rain as low after low moves into the coast will slowly
increase the flooding threat in western Washington and western
Oregon. The slow increase of the flooding threat is due to the
area's general favorability for rainfall to quickly run off,
resulting in a much higher threshold of heavy rain before there
are flooding concerns. The trailing cold front south of a strong
low that will move into British Columbia will be the focus for the
heavy rain as abundant Pacific moisture slams into the coastal
ranges and Cascades through the period. Soil moisture levels in
this area are around normal for this time of year, but repeated
days of heavy rain will cause the soils to saturate entirely. Thus,
once the soils are saturated, all additional rainfall will convert
to runoff very quickly. Moisture from the tropics will track
northeast around the northwestern periphery of an expansive
subtropical high off the California coast. This abundance of
Pacific moisture from the tropics will support the elevated flash
flooding threat over much of the upcoming workweek.

Very few changes were needed to the inherited Marginal and Slight
Risks. The Slight Risk area was trimmed away from Washington's
mountains, as the dominant precipitation type at the higher
elevations will be snow on Monday morning. Both risk areas were
also expanded south across west- central Oregon due to small
southward adjustments in much of the guidance supporting heavy rain
extending further south in Oregon.

Wegman

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
117 AM EST Sat Dec 6 2025

The incoming atmospheric river across the Northwest looks strong
and relatively persistent from the 8th possibly into the 11th, with
some wavering in the axis across western WA and western OR.
Precipitable water values approaching 1.5" not far offshore with
50+ kts of low- level inflow from the Pacific promises days of
heavy rains, potentially 5"+ locally per day. Significant multi-
day precipitation totals are possible both with coastal rain and
high elevation snows across the Cascades. The Slight Risk was
maintained for day 4/9-10th with a new Slight Risk area added for
day 5/10-11th per coordination with the PDX/Portland OR and
SEW/Seattle WA forecast offices.

Elsewhere, clipper systems will bring rounds of precipitation,
mainly snow, over a cold northern Plains and Midwest, Great
Lakes/Appalachians, and the Northeast next week. Aforementioned
surface cyclo/fronto genesis will act to enhance wrapping activity
and especially Lake Effect with system passages. Wavy and stalling
trailing fronts lingering down near southern Florida and into the
Gulf may also focus uncertain rain chances over/offshore next week.

Tuesday will be cold across the East, with 10-15F cold anomalies at
that point. While a general thaw is noted Wednesday, the beginning
of a colder air mass invades the northern Plains with 10F cold
anomalies noted, before intensifying and expanding from the
northern Plains southeast across the Midwest and towards the
Southern Appalachians with 15F+ cold anomalies across a broader
swath east of the Rockies Thursday into next Saturday. The West
and portions of the High Plains will experience 15-20F warm
anomalies next week underneath upper ridging.


Roth/Schichtel

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
117 AM EST Sat Dec 6 2025

The incoming atmospheric river across the Northwest looks strong
and relatively persistent from the 8th possibly into the 11th, with
some wavering in the axis across western WA and western OR.
Precipitable water values approaching 1.5" not far offshore with
50+ kts of low- level inflow from the Pacific promises days of
heavy rains, potentially 5"+ locally per day. Significant multi-
day precipitation totals are possible both with coastal rain and
high elevation snows across the Cascades. The Slight Risk was
maintained for day 4/9-10th with a new Slight Risk area added for
day 5/10-11th per coordination with the PDX/Portland OR and
SEW/Seattle WA forecast offices.

Elsewhere, clipper systems will bring rounds of precipitation,
mainly snow, over a cold northern Plains and Midwest, Great
Lakes/Appalachians, and the Northeast next week. Aforementioned
surface cyclo/fronto genesis will act to enhance wrapping activity
and especially Lake Effect with system passages. Wavy and stalling
trailing fronts lingering down near southern Florida and into the
Gulf may also focus uncertain rain chances over/offshore next week.

Tuesday will be cold across the East, with 10-15F cold anomalies at
that point. While a general thaw is noted Wednesday, the beginning
of a colder air mass invades the northern Plains with 10F cold
anomalies noted, before intensifying and expanding from the
northern Plains southeast across the Midwest and towards the
Southern Appalachians with 15F+ cold anomalies across a broader
swath east of the Rockies Thursday into next Saturday. The West
and portions of the High Plains will experience 15-20F warm
anomalies next week underneath upper ridging.


Roth/Schichtel

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
246 AM EST Sat Dec 6 2025

Valid 12Z Sat Dec 06 2025 - 12Z Tue Dec 09 2025

...Central Rockies..
Day 1...

500mb height falls, the divergent left-exit region of a strong
250mb jet streak, and a plume of anomalous PWATs (above the 90th
climatological percentile per ECMWF) are all working together to
produce heavy mountain snow from the Wasatch, Uinta, and Wind River
ranges to the Rockies of southern WY and much of CO. Upslope
enhancement will be focused along the Wasatch and CO/WY Rockies
through this morning. As the core of the best moisture content
exits east this afternoon, snow will gradually taper off Saturday
night. WPC probabilities sport high chances (>70%) for additional
snowfall totals >12" in the Wasatch above 8,000ft and CO/WY
Rockies above 9,000ft. WPC's WSSI highlights Moderate Impacts at
these listed elevations with some localized Major Impacts in the
more remote peaks of the UT, WY, and CO Rockies.


...Pacific Northwest & Northern Rockies...
Days 1-3...

The Pacific Northwest and Northern Rockies will continue to contend
with the lingering effects of the ongoing atmospheric river (AR)
through the remainder of the day Saturday. WPC probabilities show
high chances (>70%) for additional snowfall totals >8" in the more
remote reaches of the WA Cascades, the Bitterroots, Lewis Range,
and as far south as the peaks of the Absaroka and Tetons. A brief
ridge of high pressure builds in Saturday night before the round
of Pacific moisture arrives Sunday morning. Temperatures will be a
little milder this time around, confining most snowfall to the more
remote reaches of the Cascades. Pacific moisture will spill over
into the Northern Rockies Sunday night as the next atmospheric
river arrives on Monday. The Monday AR will be more intense with a
plume of >99th climatological PWATs engulfing much of the Pacific
Northwest by Monday afternoon. While the moisture influx is more
extensive, the strength of the WAA will keep snowfall to the more
remote reaches of the Cascades. However, moisture that spills over
into the Bitterroots and Lewis Range will have enough cold air to
support locally heavy snowfall. Over this weekend and through
Monday, WPC probabilities show moderate-to-high chances (50-80%)
for snowfall totals >12" in the WA Cascades above 5,000ft and along
the Lewis Range, which does include Glacier NP. Expect any
mountain passes that remain open to contend with potential closures
this weekend and into early next week.

...Northern Plains & Midwest...
Days 1-2...

Height falls ahead of an approaching 500mb vorticity maximum will
coincide with the divergent left-exit region of a 250mb jet streak
over the Northern Plains to support the development of low pressure
early this morning. A narrow band of 850mb WAA and FGEN over
eastern MT will pivot south and east towards southern ND and become
responsible for the initial band of snow this morning. As low
pressure deepens, a more organized 850mb low will form over
southern SD and central NE. A strengthening 850mb LLJ will direct a
surge of WAA in the 850-700mb layer ahead of the 850mb low.
Combined with a healthy 290K isentropic ascent amid SWrly flow, and
a moistening DGZ will ensue over southeast SD, northern IA, and
southern MN and periods of heavy snow will develop. WPC's Snowband
Probability Tracker depicts the potential for >1"/hr snowfall
rates over southeast SD beginning around midday and continuing over
northern IA through Saturday evening. After 00Z Sunday, the 850mb
low will weaken, taking on a positive tilt and becoming an open
wave. Light-to-moderate snow is expected through Saturday night
over northern IL and southern WI (including the Milwaukee and
Chicago metro areas), with light snow possible across the Great
Lakes on Sunday.

WPC probabilities show northern IA as having the best odds of
seeing the heaviest snowfall of the event with moderate chances
(40-60%) for snowfall totals >6". Probabilities suggest I-35
located north of Des Moines and south of I-90 have low chances
(10-20%) for localized amounts over 8". Elsewhere, the area
spanning Sioux Falls on south and east through southern MN and
eastern ND all sport >50% chances for >4" of snowfall. The WSSI
shows Minor Impacts from the Sioux Falls area of southeast SD to as
far east as the Milwaukee/Chicago metro areas due to the snowfall
Saturday night into Sunday morning. Across eastern MT and southwest
ND, WPC probabilities show low- to- moderate chances (30-50%) for
snowfall >2", but probabilities for >4" are generally <10%,
implying that most totals are likely to range between 1-4" through
Saturday afternoon.

It is worth noting bitterly cold temperatures will follow in wake
of this system Saturday night and through Sunday. By Sunday
morning, temperatures will be in the single digits across much of
the Midwest and lows below zero Sunday night. Any snow that falls
will likely stick around for a couple days, resulting in daily
recurrences of icy roads and the potential for black ice.

...Great Lakes & Northeast...
Days 1-3...

A series of upper level disturbances tracking across the Great
Lakes and into the Northeast will cause both LES bands and some
synoptically-focred snow across these regions this weekend and into
early next week. Some LES streamers off Lakes Superior, Erie, and
Ontario will keep accumulating snow in the forecast in the usual
snow belts of Michigan's U.P., the "Tip of the Mitt" in Michigan,
and across western NY. By Sunday morning the upper trough
responsible for the Midwest storm on Saturday will make its way
through these regions with light-to-moderate snowfall across
Michigan and much of the Northeast (minus the I-95 corridor
megalopolis). Most snowfall totals will range between 1-4",
although some of the LES belts may manage to see some snowfall
totals eclipse 4" on Sunday. It is possible an inverted trough axis
over the Gulf of Maine could produce locally heavy snow along the
coast of ME, but the trough is a progressive one and should limit
totals from being overly heavy (1-4" most likely). Lastly, while
high pressure builds in over the Northeast on Monday, an Alberta
Clipper makes its way toward the Upper great Lakes by Monday
evening with more light-to-moderate snow expected.

WPC probabilities over the next three days (Sat-Sun-Mon) show
moderate-to-high chances (50-80%) for snowfall totals >4" in the
typical LES belts of Michigan's U.P., northern Michigan, and
downwind of Lakes Erie and Ontario. When it comes to >8" of
snowfall, it is the eastern Michigan U.P. and northwest Michigan
where low-to-moderate chances (30-50%) are present. The WSSI shows
Minor Impact potential downwind of Lakes Erie and Ontario, which
does include the Buffalo metro area.

...Southern Appalachians...
Days 2-3...

A quick moving 500mb trough will track from the TN Valley Sunday
night to the Southeast Coast by Monday afternoon. 500mb PVA ahead
of the upper trough will be paired with easterly low-level flow
that allows for some upslope enhancement along the southern
Appalachians. Snow will be at its heaviest Monday morning but taper
off by Monday evening. WPC probabilities show low-to-moderate
chances (30-50%) for snowfall totals >2" in portions of the VA/NC
Blue Ridge and Potomac Highlands of WV. Some localized totals could
top 4" in the VA/NC Blue Ridge.


Mullinax

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
117 AM EST Sat Dec 6 2025

Valid 12Z Tue Dec 09 2025 - 12Z Sat Dec 13 2025


...Multi-day heavy precipitation threat for the Pacific Northwest
early to mid next week due to a potent & persistent Atmospheric
River...


...Overview...
A broad upper level trough with reinforcing shortwaves will
continue to dominate across the eastern two-thirds of the lower 48
during the medium range period, with broad ridging generally
preferred near the West Coast. Strong westerly flow over the broad
ridge will bring a wavering atmospheric river into the Northwest
with heavy rain and high elevation snow next week, along with
potential for high winds. Cold weather and clipper systems will be
favored in this pattern east of the Rockies.


...Guidance/Predictability Assessment...
Guidance continues to show general agreement with mid-larger scale
systems and the overall pattern evolution for much of this forecast
period, but there remains some uncertainty in the details of the
timing of flow embedded multiple shortwaves that will focus
sensible weather impacts locally. For the most part a multi-model
deterministic model blend works well for Tuesday-Wednesday, with
favored blend including some of the 05/12z NAEFS the ECMWF
ensemble means for later next week amid growing forecast spread,
particularly across the southern Plains and Southeast. The 01z UTC
NBM seems to provide a solid forecast basis for most mass fields
through the period. However, NBM QPF was modified upwards later
next week over the Great Lakes and Northwest midweek given
the then available guidance early in the medium range period.


...Weather/Hazards Highlights...
The incoming atmospheric river across the Northwest looks strong
and relatively persistent from the 8th possibly into the 11th, with
some wavering in the axis across western WA and western OR.
Precipitable water values approaching 1.5" not far offshore with
50+ kts of low- level inflow from the Pacific promises days of
heavy rains, potentially 5"+ locally per day. Significant multi-
day precipitation totals are possible both with coastal rain and
high elevation snows across the Cascades. The Slight Risk was
maintained for day 4/9-10th with a new Slight Risk area added for
day 5/10-11th per coordination with the PDX/Portland OR and
SEW/Seattle WA forecast offices.

Elsewhere, clipper systems will bring rounds of precipitation,
mainly snow, over a cold northern Plains and Midwest, Great
Lakes/Appalachians, and the Northeast next week. Aforementioned
surface cyclo/fronto genesis will act to enhance wrapping activity
and especially Lake Effect with system passages. Wavy and stalling
trailing fronts lingering down near southern Florida and into the
Gulf may also focus uncertain rain chances over/offshore next week.

Tuesday will be cold across the East, with 10-15F cold anomalies at
that point. While a general thaw is noted Wednesday, the beginning
of a colder air mass invades the northern Plains with 10F cold
anomalies noted, before intensifying and expanding from the
northern Plains southeast across the Midwest and towards the
Southern Appalachians with 15F+ cold anomalies across a broader
swath east of the Rockies Thursday into next Saturday. The West
and portions of the High Plains will experience 15-20F warm
anomalies next week underneath upper ridging.


Roth/Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw