Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
151 PM EST Mon Dec 02 2024

Valid 00Z Tue Dec 03 2024 - 00Z Thu Dec 05 2024

...Locally heavy lake-effect snow will continue off the Great Lakes...

...Low pressure to approach Great Lakes region by Wednesday bringing
strong winds and a reinforcing shot of Arctic air to the northern Plains
and Midwest...

...Below normal temperatures will continue through the middle of the week
across much of the East, with above normal temperatures across the West...

Cold high pressure dropping southeast across the Midwest will be filtering
south down across the Mid-South and into much of the Southeast going
through the middle of the week which will keep temperatures across much of
the East below normal. In fact, some high temperatures across the southern
Appalachians and interior of the Southeast will be as much as 10 to 20
degrees below normal. Cold air meanwhile will continue to foster some
areas of locally heavy lake-effect snow downwind of the Great Lakes, with
as much as 6 to 12+ inches of additional snow possible through Tuesday,
and especially off Lake Erie impacting northwest Pennsylvania and far
western New York.

A new storm system though will be intensifying and approaching the Great
Lakes region by Wednesday. This will bring areas of strong winds to much
of the northern Plains and Midwest region by Wednesday morning, and these
winds will overspread the Great Lakes region by Wednesday night. A
reinforcing shot of Arctic air will be arriving as well behind a strong
cold front. This will also gradually reload the prospects for new rounds
of lake-effect snow later in the week downwind of the Great Lakes.

Across areas of southern Texas and the broader northwest Gulf Coast
region, a weak area of low pressure will be focusing close to the coast
and should help bring some resurgence of moisture northward across the
region going through the middle part of the week. This moisture coupled
with proximity of a front will bring a threat for some locally heavy
showers and thunderstorms, with some of the heaviest rainfall potential
expected across far southeast Texas and Louisiana where a couple of inches
will be possible going through Wednesday night.

Elsewhere, much of the West will be above normal for temperatures as high
pressure aloft continues over the region. This will also keep much of the
region dry.

Orrison


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Mon Dec 2 2024

Valid 12Z Thu Dec 05 2024 - 12Z Mon Dec 09 2024

...Another blast of arctic air to bring more heavy lake-
effect/enhanced snows and possibly snow squalls near the Great
Lakes, high winds and arctic cold into the central and eastern
U.S...

...Return moist from the Gulf of Mexico could bring enhanced
rainfall across the western to central Gulf Coast states late this
week...


...Overview...

A synoptic pattern that favors upper-level troughing over the
eastern part of the North American continent will support
additional outbreaks of arctic air into the eastern two-thirds of
the U.S. The rush of arctic air behind an intensifying Alberta
clipper will favor another outbreak of heavy lake-effect snow
across the Great Lakes through Thursday along with the possibility
of snow squalls and high winds. Meanwhile, moist return flow from
the Gulf will support daily enhanced rain chances set to spread
from the western to central Gulf Coast states and parts of the
Southeast through the weekend into next Monday with uncertainty on
the timing and inland extent of the rain. Elsewhere, high pressure
will persist in the interior West before a frontal system works
through next weekend. Moderate rains will focus over the Pacific
Northwest later this week, with snow chances spreading inland
across especially favored terrain from Cascades through the
Northwest and northern Rockies next weekend with system/colder flow
progression.


...Guidance/Predictability Assessment...

Guidance today continues with a general trend for the arctic air to
rush in faster behind the intensifying Alberta clipper system that
is forecast to track east through the Northeast on Thursday.
Guidance also shows a faster southward plunge of the Arctic High
and the associated arctic air mass into the Plains. Focus will then
shift to the Gulf Coast where there is a noticeable difference
between the ECMWF and GFS solutions on the timing and inland
extent of the moisture returning from the Gulf of Mexico into the
western Gulf Coast states. The ECMWF tends to hold back the inland
progress of the rain while GFS is more aggressive. The CMC is in
between these extremes. The uncertainty on the rain may be
attributed to the uncertainty on the timing and amplitude of the
trough/upper low ejecting across northern Mexico toward Texas this
weekend. Out West, the guidance shows the upper ridge shifting
east next weekend to usher in a more cool and unsettled pattern
with some lingering uncertainty in the timing of a main/wavy cold
front to work its way across the Northwest/West.

Accordingly, the WPC medium range product suite was mainly derived
from a composite blend of 40% from the 00Z ECMWF/EC mean, 40% from
the 06Z GFS/GEFS, and 20% from the 00Z CMC/CMC mean, transitioning
to include more of their respective ensemble means starting next
weekend amid steadily growing embedded system forecast and
continuity variances. This blend yielded a solution rather
compatible with the previous WPC medium-range package. The slower
ECMWF solutions with the QPF across the western Gulf Coast region
were preferred late in the forecast period.


...Weather/Hazards Highlights...

Another outbreak of heavy lake-effect snow is likely across the
Great Lakes behind an intensifying clipper low pressure system
on Thursday. Influx of colder air aloft behind the system is also
raising the possibility of snow squalls downwind from the Great
Lakes, as well as high winds across a wider domain down into the
Ohio Valley, Appalachians, and across the Mid-Atlantic. Locally
very heavy snow accumulations will be possible in favored downwind
locations, and travel conditions will likely be hazardous,
especially on Thursday. Snow will also be possible elsewhere in the
Northeast as the clipper system moves through, especially in the
higher terrain of the Appalachians. Conditions should improve
briefly late this week, but another low pressure system will bring
another chance for wintry precipitation to the region next weekend.

The rest of the nation will be mainly dry this week with a couple
exceptions. Moist returning from the Gulf will result in daily
rain chances along the western Gulf Coast and into portions of the
South. While there will likely be some instability to support
locally heavier downpours, no threat areas are depicted in the WPC
Excessive Rainfall Outlook. However, given the uncertainty on how
the upper trough across northern Mexico will be lifted and ejected
into Texas this weekend, there is a possibility for a band of heavy
rain to set up somewhere across eastern Texas this weekend if the
upper trough evolves between the ECMWF and GFS scenarios. The heavy
rain axis may then trail southwest toward the western Gulf Coast
and tap additional moisture from the Gulf next Monday.

Precipitation chances will also return to the Northwest by next
weekend as a Pacific frontal system approaches and works steadily
inland. This will act to produce a more cooler and unsettled
airmass across much of the West, with moderate rains over the
Pacific Northwest and some terrain enhancing snows inland across
the Northwest and northern Rockies.

Temperatures will drop below normal for parts of the north-central
to eastern U.S. this week as a cold front ushers in another blast
of Arctic air. Daytime highs from the Upper Midwest into the East
could be 10-20 degrees below normal. Elsewhere, temperatures will
be mild for this time of year, generally near to slightly above
average with this milder air gradually expanding east with time.

Kong/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
300 AM EST Mon Dec 02 2024

Valid 00Z Tue Dec 03 2024 - 00Z Tue Dec 10 2024

Guidance reasonably agrees in support of only limited shower
activity and moisture in a weak flow with land-sea breezes and
upper ridging aloft through midweek. More southerly responding
winds will then act to increase moisture across the region ahead
of an approaching frontal boundary as an amplified upper trough
passes to the north of the state. The front may slowly move
southeastward across the state starting Thursday and
lingering/stalling later week into the weekend. This should lead
to increasing rain chances and some gusty post-frontal winds. This
frontal boundary will gradually dissipate next weekend, but
residual moisture will likely linger through the weekend. Forecast
spread increases at these longer time frames, but given upstream
upper ridge amplitude over the west-central Pacific common in
guidance, favor the approach/digging of an amplified upper trough
and another wet surface front toward the state later weekend into
early next week, more in line with best clustered guidance from
the 00 UTC ECMWF/Canadian and trends from the 00 UTC UKMET versus
the less amplified 00 UTC GFS.

Schichtel

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
738 PM EST Mon Dec 2 2024
Day 1
Valid 01Z Tue Dec 03 2024 - 12Z Tue Dec 03 2024

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

Fracasso


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
738 PM EST Mon Dec 2 2024
Day 2
Valid 12Z Tue Dec 03 2024 - 12Z Wed Dec 04 2024

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

Hurley


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
738 PM EST Mon Dec 2 2024
Day 3
Valid 12Z Wed Dec 04 2024 - 12Z Thu Dec 05 2024

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

The Marginal Risk area for portions of eastern Texas and much of
western Louisiana that was inherited was removed with this update.
A fairly robust 30-40 kt LLJ will advect Gulf moisture into much of
the Mississippi Delta region and west into eastern Texas on
Wednesday. PWATs may exceed 1.75 inches, especially along the Gulf
coast. However, this is the only ingredient that is sufficient for
flooding rains. Instability, while non-zero...will be meager,
struggling in most areas to get to 500 J/kg of MUCAPE. This will be
the primary limiting factor against flooding, as a lack of
instability should keep most of the rain as stratiform. Secondly,
much of the eastern half of the U.S., including eastern Texas and
Louisiana have been very dry lately, so stream and creek beds are
running low. The drawn out period of mostly light rain in this
area will therefore mostly be beneficial. While embedded convective
cells could briefly cause locally heavy rain, the dry conditions
and high FFGs should mitigate any flooding. Finally, at the tail
end of the event late Wednesday night into Thursday, cold frontal
passage will push any heavy rain south and out of where the
heaviest rains are expected over central Louisiana. This too should
diminish the flooding potential.

As always, increases in the guidance for rainfall amounts in the
next couple days or greater instability could require a reissuance
of the Marginal, but for now the rainfall in the guidance likely
falls in the sub-Marginal 0-5% chance category area-wide.

Wegman

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Mon Dec 2 2024


Another outbreak of heavy lake-effect snow is likely across the
Great Lakes behind an intensifying clipper low pressure system
on Thursday. Influx of colder air aloft behind the system is also
raising the possibility of snow squalls downwind from the Great
Lakes, as well as high winds across a wider domain down into the
Ohio Valley, Appalachians, and across the Mid-Atlantic. Locally
very heavy snow accumulations will be possible in favored downwind
locations, and travel conditions will likely be hazardous,
especially on Thursday. Snow will also be possible elsewhere in the
Northeast as the clipper system moves through, especially in the
higher terrain of the Appalachians. Conditions should improve
briefly late this week, but another low pressure system will bring
another chance for wintry precipitation to the region next weekend.

The rest of the nation will be mainly dry this week with a couple
exceptions. Moist returning from the Gulf will result in daily
rain chances along the western Gulf Coast and into portions of the
South. While there will likely be some instability to support
locally heavier downpours, no threat areas are depicted in the WPC
Excessive Rainfall Outlook. However, given the uncertainty on how
the upper trough across northern Mexico will be lifted and ejected
into Texas this weekend, there is a possibility for a band of heavy
rain to set up somewhere across eastern Texas this weekend if the
upper trough evolves between the ECMWF and GFS scenarios. The heavy
rain axis may then trail southwest toward the western Gulf Coast
and tap additional moisture from the Gulf next Monday.

Precipitation chances will also return to the Northwest by next
weekend as a Pacific frontal system approaches and works steadily
inland. This will act to produce a more cooler and unsettled
airmass across much of the West, with moderate rains over the
Pacific Northwest and some terrain enhancing snows inland across
the Northwest and northern Rockies.

Temperatures will drop below normal for parts of the north-central
to eastern U.S. this week as a cold front ushers in another blast
of Arctic air. Daytime highs from the Upper Midwest into the East
could be 10-20 degrees below normal. Elsewhere, temperatures will
be mild for this time of year, generally near to slightly above
average with this milder air gradually expanding east with time.

Kong/Schichtel

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Mon Dec 2 2024


Another outbreak of heavy lake-effect snow is likely across the
Great Lakes behind an intensifying clipper low pressure system
on Thursday. Influx of colder air aloft behind the system is also
raising the possibility of snow squalls downwind from the Great
Lakes, as well as high winds across a wider domain down into the
Ohio Valley, Appalachians, and across the Mid-Atlantic. Locally
very heavy snow accumulations will be possible in favored downwind
locations, and travel conditions will likely be hazardous,
especially on Thursday. Snow will also be possible elsewhere in the
Northeast as the clipper system moves through, especially in the
higher terrain of the Appalachians. Conditions should improve
briefly late this week, but another low pressure system will bring
another chance for wintry precipitation to the region next weekend.

The rest of the nation will be mainly dry this week with a couple
exceptions. Moist returning from the Gulf will result in daily
rain chances along the western Gulf Coast and into portions of the
South. While there will likely be some instability to support
locally heavier downpours, no threat areas are depicted in the WPC
Excessive Rainfall Outlook. However, given the uncertainty on how
the upper trough across northern Mexico will be lifted and ejected
into Texas this weekend, there is a possibility for a band of heavy
rain to set up somewhere across eastern Texas this weekend if the
upper trough evolves between the ECMWF and GFS scenarios. The heavy
rain axis may then trail southwest toward the western Gulf Coast
and tap additional moisture from the Gulf next Monday.

Precipitation chances will also return to the Northwest by next
weekend as a Pacific frontal system approaches and works steadily
inland. This will act to produce a more cooler and unsettled
airmass across much of the West, with moderate rains over the
Pacific Northwest and some terrain enhancing snows inland across
the Northwest and northern Rockies.

Temperatures will drop below normal for parts of the north-central
to eastern U.S. this week as a cold front ushers in another blast
of Arctic air. Daytime highs from the Upper Midwest into the East
could be 10-20 degrees below normal. Elsewhere, temperatures will
be mild for this time of year, generally near to slightly above
average with this milder air gradually expanding east with time.

Kong/Schichtel

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Mon Dec 2 2024

Valid 00Z Tue Dec 03 2024 - 00Z Fri Dec 06 2024

..Great Lakes...
Day 1...

Reinforcing shortwave trough axis over the Ohio Valley this
afternoon will continue to round the longwave trough axis over the
Northeast by tracking near the VA/NC line tonight before moving
offshore. Flow will continue to be NNWly over the Lakes tonight
before shifting more westerly on Tuesday ahead of the next
approaching shortwave.

Michigan Lake Effect...
NNWly 850mb flow up to 20 kts over Lakes Superior and Michigan
will continue to support locally heavy snow over the eastern U.P.
and along the western shore of the L.P. into far northern IN. Day 1
PWPF for >4" is 40-70% around Grand Traverse Bay and far SW MI to
the IN border.

Eastern Lake Effect...
NWly flow will continue to produce heavy LES over the Chautauqua
Ridge from fetch over Lake Huron and then over Lake Erie. Day 1
PWPF for at least 6" is 60-80% over that portion of extreme western
NY with probabilities dropping off toward Erie PA. Banding off
Lake Ontario is also expected to continue for the Syracuse area
into tonight with an additional 4" possible.

Day 2...
High pressure currently centered over ND will shift down the Mid-
Mississippi Valley Tuesday with a more amplified ridge extending
north over the Great Lakes. Behind this ridge axis, flow over Lakes
Michigan and Superior quickly shifts to the SW which ends the LES
bands from overnight. However, as this new fetch saturates, warm
air advection induced snow develops across the U.P. Tuesday night,
particularly as a surface low ahead of the next wave approaches
Lake Superior from the NW late early D2 and pivots east Wednesday.
The air remains cold enough for SWly flow driven lake enhanced
snow into the far eastern U.P. Day 2 PWPF for >6" is high (>70%)
for the far eastern U.P. and medium (40-60%) for the Keweenaw
Peninsula.


The ridge axis does not shift over the eastern Great Lakes until
early Wednesday morning, so LES will continue and essentially
shift back toward a single- band appearance on SWly flow, though
the warm air advection makes for a wetter snow than recent days.
Day 2 PWPF for >4" is 20-50% around the Chautauqua Ridge with low
probs for the south towns of Buffalo. Higher probs (50-70%) are
found near the Tug Hill Plateau.


Day 3...
The low over Ontario further develops and sends a strong cold front
over the Great Lakes Wednesday into Thursday. 850mb temps quickly
drop into the DGZ behind the front, so LES resumes with a vengeance
on NWly flow through the day over Michigan and that night/Thursday
morning for the eastern Great Lakes. Snow-liquid ratios would
normally rise to around 20:1 or higher, but very strong 850mb winds
of 40-55 kts could fracture dendrites and lead to areas of blowing
snow. Day 2-3 PWPF >6" is >80% for NWly snow belts across the
northern U.P. and the northern L.P. Marginal thermals for snow and
warm air advection limit eastern Great Lakes snow Wednesday, but
quickly shifts snowy overnight. Day 3 PWPF for >6" is around 60-80%
off Lake Erie and prolonged moderate snow over the Tug Hill makes
for >90% probs there.

Additionally, snow squalls are likely along and just behind a
strong cold front crossing the Upper Great Lakes on Wednesday and
into the L.P. of Michigan by Wednesday night as 3-6 km AGL lapse
rates rise to around 7 C/km underneath the arctic airmass.This
could lead to intense multi- band convective squalls enhanced by
flow off Lake Superior and Lake Michigan Wednesday evening.
Potential also exists for snow squalls across the northern Mid-
Atlantic and Northeast by Thursday, but timing and mode is more
uncertain. Either way, gusty winds with maximum values exceeding 40
mph are likely to be widespread and persistent between the
northern Plains and central Apps/Northeast, which could lead to
lowering visibility where snow is falling and where fresh snow
cover exists.

LES looks to continue over the eastern Great Lakes on the NWly
flow into Friday.


...New England...
Day 3...

The upper low tracks across northern Lake Huron Wednesday night
with strong warm air advection and increasing precip into an
initially cold airmass over New England allowing moderate to
locally heavy snow over the terrain of the Greens/Whites/and much
of Maine. The low crosses ME on Thursday when there is a greater
snow threat for interior New England. Day 3 PWPF for >6" 30-60% for
the higher terrain of VT/NH, with a corridor of 60-80% extending
from the central highlands to northern portions of ME. The low
crosses ME on Thursday when there is a greater snow threat for
interior New England.


...Southern Appalachians...
Day 1...

A clipper-type trough currently over the Ohio Valley shifts to
eastern TN by this evening. Upslope flow enhances precip which is
cold enough for snow and SLRs around 17-18:1 to produce 30-60%
probs for >4" snow tonight for mainly the western slopes of the
Great Smokey Mtns. Enough lift directly beneath the shortwave
could also lead to minor snowfall accumulations (<1") Tuesday
morning across central NC/SC.


The probability of significant ice across the CONUS is less than
10 percent.


Snell/Jackson

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Mon Dec 2 2024

Valid 12Z Thu Dec 05 2024 - 12Z Mon Dec 09 2024

...Another blast of arctic air to bring more heavy lake-
effect/enhanced snows and possibly snow squalls near the Great
Lakes, high winds and arctic cold into the central and eastern
U.S...

...Return moist from the Gulf of Mexico could bring enhanced
rainfall across the western to central Gulf Coast states late this
week...


...Overview...

A synoptic pattern that favors upper-level troughing over the
eastern part of the North American continent will support
additional outbreaks of arctic air into the eastern two-thirds of
the U.S. The rush of arctic air behind an intensifying Alberta
clipper will favor another outbreak of heavy lake-effect snow
across the Great Lakes through Thursday along with the possibility
of snow squalls and high winds. Meanwhile, moist return flow from
the Gulf will support daily enhanced rain chances set to spread
from the western to central Gulf Coast states and parts of the
Southeast through the weekend into next Monday with uncertainty on
the timing and inland extent of the rain. Elsewhere, high pressure
will persist in the interior West before a frontal system works
through next weekend. Moderate rains will focus over the Pacific
Northwest later this week, with snow chances spreading inland
across especially favored terrain from Cascades through the
Northwest and northern Rockies next weekend with system/colder flow
progression.


...Guidance/Predictability Assessment...

Guidance today continues with a general trend for the arctic air to
rush in faster behind the intensifying Alberta clipper system that
is forecast to track east through the Northeast on Thursday.
Guidance also shows a faster southward plunge of the Arctic High
and the associated arctic air mass into the Plains. Focus will then
shift to the Gulf Coast where there is a noticeable difference
between the ECMWF and GFS solutions on the timing and inland
extent of the moisture returning from the Gulf of Mexico into the
western Gulf Coast states. The ECMWF tends to hold back the inland
progress of the rain while GFS is more aggressive. The CMC is in
between these extremes. The uncertainty on the rain may be
attributed to the uncertainty on the timing and amplitude of the
trough/upper low ejecting across northern Mexico toward Texas this
weekend. Out West, the guidance shows the upper ridge shifting
east next weekend to usher in a more cool and unsettled pattern
with some lingering uncertainty in the timing of a main/wavy cold
front to work its way across the Northwest/West.

Accordingly, the WPC medium range product suite was mainly derived
from a composite blend of 40% from the 00Z ECMWF/EC mean, 40% from
the 06Z GFS/GEFS, and 20% from the 00Z CMC/CMC mean, transitioning
to include more of their respective ensemble means starting next
weekend amid steadily growing embedded system forecast and
continuity variances. This blend yielded a solution rather
compatible with the previous WPC medium-range package. The slower
ECMWF solutions with the QPF across the western Gulf Coast region
were preferred late in the forecast period.


...Weather/Hazards Highlights...

Another outbreak of heavy lake-effect snow is likely across the
Great Lakes behind an intensifying clipper low pressure system
on Thursday. Influx of colder air aloft behind the system is also
raising the possibility of snow squalls downwind from the Great
Lakes, as well as high winds across a wider domain down into the
Ohio Valley, Appalachians, and across the Mid-Atlantic. Locally
very heavy snow accumulations will be possible in favored downwind
locations, and travel conditions will likely be hazardous,
especially on Thursday. Snow will also be possible elsewhere in the
Northeast as the clipper system moves through, especially in the
higher terrain of the Appalachians. Conditions should improve
briefly late this week, but another low pressure system will bring
another chance for wintry precipitation to the region next weekend.

The rest of the nation will be mainly dry this week with a couple
exceptions. Moist returning from the Gulf will result in daily
rain chances along the western Gulf Coast and into portions of the
South. While there will likely be some instability to support
locally heavier downpours, no threat areas are depicted in the WPC
Excessive Rainfall Outlook. However, given the uncertainty on how
the upper trough across northern Mexico will be lifted and ejected
into Texas this weekend, there is a possibility for a band of heavy
rain to set up somewhere across eastern Texas this weekend if the
upper trough evolves between the ECMWF and GFS scenarios. The heavy
rain axis may then trail southwest toward the western Gulf Coast
and tap additional moisture from the Gulf next Monday.

Precipitation chances will also return to the Northwest by next
weekend as a Pacific frontal system approaches and works steadily
inland. This will act to produce a more cooler and unsettled
airmass across much of the West, with moderate rains over the
Pacific Northwest and some terrain enhancing snows inland across
the Northwest and northern Rockies.

Temperatures will drop below normal for parts of the north-central
to eastern U.S. this week as a cold front ushers in another blast
of Arctic air. Daytime highs from the Upper Midwest into the East
could be 10-20 degrees below normal. Elsewhere, temperatures will
be mild for this time of year, generally near to slightly above
average with this milder air gradually expanding east with time.

Kong/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