Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EST Mon Feb 17 2025

Valid 12Z Mon Feb 17 2025 - 12Z Wed Feb 19 2025

...A surge of arctic air will bring record cold temperatures further
southward into the mid-section of the country through the next few days...

...Potential of a winter storm increasing from the central Plains to the
mid-Mississippi Valley Tuesday into Wednesday morning...

...Mountain snow and lower-elevation rain across the Pacific Northwest and
northern Rockies will have a lull on Tuesday before another Pacific system
brings the next round of unsettled weather into the Pacific Northwest
Tuesday night...

...Snow gradually tapers off in New England today behind a big storm but
lake-effect snow and blustery conditions continue...

A large and intense low pressure system is beginning to move away from New
England after dumping moderate to locally heavy snow along with a swath of
freezing rain across New England. Even though the wintry precipitation
will largely taper off today, the huge circulation of the deep cyclone
will continue to funnel strong and gusty winds across the entire Northeast
and the Great Lakes through the next couple of days. Lake-effect snow
will once again make its presence known along the Snow Belt downwind from
the Great Lakes. In addition, blizzard warnings remain in effect into
this afternoon along the western slopes of the central Appalachians due to
snow falling under very gusty upslope flow forced by the slowly departing
storm. The enhanced snowfall is expected to taper off later today as an
arctic high pressure system begins to usher colder and drier air into the
region.

Meanwhile, the aforementioned high pressure system will continue to push a
large pool of arctic air from Canada down into the mid-section of the
country through the next few days. Temperatures of 40 degrees below
normal near the Canadian border this morning will plunge into the central
High Plains by Tuesday. This means that actual temperatures will remain
colder than -30 degrees for the next couple of mornings near the Canadian
border while high temperatures may not top the zero-degree mark as far
south as northern Kansas by Tuesday afternoon. Wind chill temperatures
will reach dangerously cold levels between -30 and -60 degree over the
northern Plains.

Farther west, a Pacific system will continue to bring mountain snow and
lower-elevation rain from the Pacific Northwest to the northern Rockies
today but a lull is expected on Tuesday before another Pacific system
brings the next round of unsettled weather into the Pacific Northwest by
Tuesday night. Meanwhile, upslope snowfall north of the arctic front
across the northern Rockies will be carried downstream into the
north-central Plains today. As the arctic high pressure system from
Canada pushes further southward, a low pressure wave is forecast to
develop along the arctic front. In response, snow will become heavier and
more widespread across the central Plains along with gusty winds on
Tuesday. A swath of freezing rain/sleet can also be expected to develop
farther south across Oklahoma to Arkansas later on Tuesday into Tuesday
night. Rain showers will also expand in coverage across eastern Texas
with the possibility of strong thunderstorms developing closer to the Gulf
Coast of Louisiana Tuesday night into Wednesday morning. Meanwhile,
moderate to heavy snow will spread farther east, likely reaching into the
Tennessee and Ohio Valleys whereas the wintry mix could move into the
interior Deep South early on Wednesday.

Kong


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
211 AM EST Mon Feb 17 2025

Valid 12Z Thu Feb 20 2025 - 12Z Mon Feb 24 2025


...Intense Central to Eastern U.S. Arctic Blast this week...


...Guidance/Predictability Assessment...

The WPC medium range product suite was primarily derived from
composite of reasonably clustered medium to larger scale guidance
of the 18 UTC GFS and the 12 UTC ECMWF/UKMET/Canadian models valid
for Thursday and Friday. Opted to switch to a composite of best
clustered guidance of the 18 UTC GEFS mean and the 12 UTC
ECMWF/Canadian ensemble means by next weekend amid growing forecast
spread. The blend process tends to smooth the increasingly numerous
smaller scale system differences over time as consistent with
individual predictability. This solution maintains good WPC product
continuity and seems mainly in line with latest 00 UTC guidance.

...Weather/Hazards Highlights...

An exiting coastal storm with lift robustly offshore the East
Coast Thursday as mainly a maritime threat, but high winds and
surf will impact eastern New England along with a threat of wrap-
back snow. In the wake of this storm, quite an impressive Arctic
airmass is taking hold over the central and eastern U.S. this week
with advent of strong Canadian high pressure. Entrenched cold air
will maintain some lake effect snows and offer a widespread Extreme
Cold threat. Numerous record temperatures are likely from the
South- Central Plains through the Mid-Lower Mississippi Valley and
The South. Temperatures anomalies into Thursday will range from 30
to 40 degrees below normal over the Central Plains/Mid-Mississippi
Valley, with widespread values 10-20 degrees below normal over much
of the central and eastern U.S. The airmass will slowly moderate
late week through next weekend. While no strongly organized storm
system is evident Thursday through next Monday, the approach of
several uncertain impulses may produce some light and unheralded
but locally disruptive wintry weather in the Arctic airmass.
Periodic moderate rainfall is more likely over the Gulf in closer
proximity to a persistent and slow moving/wavy frontal zone through
this forecast period, but will with more uncertainty also try to
work onshore into the cooled Gulf Coast states.

Upstream, several organized shortwaves/frontal systems will dig
through the West later this week. A main lead system in this
period will bring a swath of terrain/Mountain enhanced snow
Thursday over the north-central Intermountain West/Rockies. The
pattern becomes increasingly favorable for longer fetch moisture
feed to fuel rounds of moderate to heavy low elevation rain and
mountain snow primarily into the Pacific Northwest, but also inland
to the northern Rockies next weekend into early next week.

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
240 AM EST Mon Feb 17 2025

Valid 00Z Tue Feb 18 2025 - 00Z Tue Feb 25 2025

A blend of reasonably well clustered model and ensemble guidance
seems to offer a solid forecast basis for much of the upcoming
week. The blending of compatible guidance tends to smooth-out
numerous lingering smaller scale differences as consistent with
individual predictability. An area of enhanced moisture will feed
into the western islands over the next couple of days and link
with moisture focusing in advance of a front approaching from the
northwest. These on ongoing per radar. This offers potential for
some locally heavy downpours. High pressure cells bridging to the
north of the state over the next week should favor moderate island
trades that may temprarily ease late week. Expect limited rainfall
chances under an upper ridge.

Schichtel

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1021 AM EST Mon Feb 17 2025
Day 1
Valid 12Z Mon Feb 17 2025 - 12Z Tue Feb 18 2025

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

Gallina


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1021 AM EST Mon Feb 17 2025
Day 2
Valid 12Z Tue Feb 18 2025 - 12Z Wed Feb 19 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG PORTIONS OF
THE CENTRAL GULF COAST...

Strengthening southwesterly winds ahead an amplifying upper level
shortwave and an associated cold front are expected to draw deeper
moisture into parts of the Gulf Coast, with PWs climbing to around
1.5 inches. This moisture along with increasing lift and
instability may be sufficient for heavy rainfall rates. Models
offer a modest signal for training storms ahead of a surface low
that is forecast to develop and advance east along the coast
Wednesday morning. This may help support localized heavy rainfall,
with some potential for isolated flash flooding, especially in
urbanized areas.

Pereira

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1021 AM EST Mon Feb 17 2025
Day 3
Valid 12Z Wed Feb 19 2025 - 12Z Thu Feb 20 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF NORTHERN FLORIDA AND SOUTHERN GEORGIA...

Surface low developing along the central Gulf Coast on Day 2 will
continue to track east early in the period, before tracking
northeast along the Southeast Coast later in the day. Training
storms, with potentially heavy rainfall rates fueled by deep
moisture (PWs 1.5-1.75 inches) ahead of the wave and along its
trailing cold front, may produce locally heavy amounts and an
isolated flash flooding threat on Wednesday.

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
211 AM EST Mon Feb 17 2025


An exiting coastal storm with lift robustly offshore the East
Coast Thursday as mainly a maritime threat, but high winds and
surf will impact eastern New England along with a threat of wrap-
back snow. In the wake of this storm, quite an impressive Arctic
airmass is taking hold over the central and eastern U.S. this week
with advent of strong Canadian high pressure. Entrenched cold air
will maintain some lake effect snows and offer a widespread Extreme
Cold threat. Numerous record temperatures are likely from the
South- Central Plains through the Mid-Lower Mississippi Valley and
The South. Temperatures anomalies into Thursday will range from 30
to 40 degrees below normal over the Central Plains/Mid-Mississippi
Valley, with widespread values 10-20 degrees below normal over much
of the central and eastern U.S. The airmass will slowly moderate
late week through next weekend. While no strongly organized storm
system is evident Thursday through next Monday, the approach of
several uncertain impulses may produce some light and unheralded
but locally disruptive wintry weather in the Arctic airmass.
Periodic moderate rainfall is more likely over the Gulf in closer
proximity to a persistent and slow moving/wavy frontal zone through
this forecast period, but will with more uncertainty also try to
work onshore into the cooled Gulf Coast states.

Upstream, several organized shortwaves/frontal systems will dig
through the West later this week. A main lead system in this
period will bring a swath of terrain/Mountain enhanced snow
Thursday over the north-central Intermountain West/Rockies. The
pattern becomes increasingly favorable for longer fetch moisture
feed to fuel rounds of moderate to heavy low elevation rain and
mountain snow primarily into the Pacific Northwest, but also inland
to the northern Rockies next weekend into early next week.

Schichtel

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
211 AM EST Mon Feb 17 2025


An exiting coastal storm with lift robustly offshore the East
Coast Thursday as mainly a maritime threat, but high winds and
surf will impact eastern New England along with a threat of wrap-
back snow. In the wake of this storm, quite an impressive Arctic
airmass is taking hold over the central and eastern U.S. this week
with advent of strong Canadian high pressure. Entrenched cold air
will maintain some lake effect snows and offer a widespread Extreme
Cold threat. Numerous record temperatures are likely from the
South- Central Plains through the Mid-Lower Mississippi Valley and
The South. Temperatures anomalies into Thursday will range from 30
to 40 degrees below normal over the Central Plains/Mid-Mississippi
Valley, with widespread values 10-20 degrees below normal over much
of the central and eastern U.S. The airmass will slowly moderate
late week through next weekend. While no strongly organized storm
system is evident Thursday through next Monday, the approach of
several uncertain impulses may produce some light and unheralded
but locally disruptive wintry weather in the Arctic airmass.
Periodic moderate rainfall is more likely over the Gulf in closer
proximity to a persistent and slow moving/wavy frontal zone through
this forecast period, but will with more uncertainty also try to
work onshore into the cooled Gulf Coast states.

Upstream, several organized shortwaves/frontal systems will dig
through the West later this week. A main lead system in this
period will bring a swath of terrain/Mountain enhanced snow
Thursday over the north-central Intermountain West/Rockies. The
pattern becomes increasingly favorable for longer fetch moisture
feed to fuel rounds of moderate to heavy low elevation rain and
mountain snow primarily into the Pacific Northwest, but also inland
to the northern Rockies next weekend into early next week.

Schichtel

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
323 AM EST Mon Feb 17 2025

Valid 12Z Mon Feb 17 2025 - 12Z Thu Feb 20 2025


...Great Lakes...
Days 1-2...

Behind the exiting winter storm, cyclonic flow will remain over
the Great Lakes with 805mb temps < -20C. NW to WNW flow will favor
the typical MI belt regions but with an emphasis over the eastern
U.P. due to persistent light to moderate snow and especially
downwind of Lake Ontario. There, an intense single band may set up
today into Oswego and just north of Syracuse with some wavering N-S
into Tuesday. Two-day totals could exceed 18" (WPC probs > 50%)
with intense snowfall rates of 2-3"/hr. Strong pressure gradient in
place will keep winds elevated as well, creating blowing and
drifting of snow with especially hazardous whiteout conditions
within the band. Snow will gradually wind down into day 3.


...Pacific Northwest/Rockies/Northern High Plains...
Days 1-2...

An active Pacific jet will maintain unsettled weather into the
Northwestern U.S. for the next 24 hours or so over the Cascades
into the northern Rockies. Height falls will continue moving inland
this morning with modest snows following along out of the Cascades
and into the Bitterroots/western MT this evening. East of the
Continental Divide a very cold air mass will be in place thanks to
high pressure over Canada that pushes southward through the Plains,
setting up upslope flow into western MT. Snow totals will be light
to modest in the higher elevations where WPC probabilities for at
least 8 inches of snow are >70%. Over central MT, light snow due
to upslope/easterly flow is expected from Billings to Kalispell but
WPC probabilities for an additional 4 inches are low (<40%) in the
lower elevations. As the height falls move into the Plains, snow
will gradually diminish on Tuesday.

Day 3...

The next system will enter the Pacific Northwest starting Tuesday
Night with some periods of snow for the Cascades, including into
the passes. Moisture plume will aim into Oregon but then move
quickly inland, helping to spread snow into the Northern Rockies
throughout the day on Wednesday (especially into the Blue Mountains
and into the central Idaho ranges). WPC probabilities for >6" of
snowfall are high (>70%) in these areas.



...Central Plains/Mid-MS Valley/Mid-South...
Days 1-2...

The anomalous IVT responsible for periods of heavy snow in the
Rockies will accompany a period of 700mb WAA over the Central
Plains. The combination of 700mb FGEN and an accelerating 250mb jet
aloft will support a stripe of light/moderate snow from the Black
Hills southeastward through NE and into the Lower Missouri River
Valley today, weakening later today. Then tonight, the stronger
500mb shortwave trough tracking across the Central Rockies will
gradually deepen while upper-level diffluence increases at the nose
of a 250mb jet streak rounding the base of the Central Rockies
trough, setting up another area of snow from NW to SE. By early
Tuesday morning, KS will be within the entrance region of the upper
jet which will help promote an area of snow across central KS
where lower-level FGEN is maximized. Temperatures will be cold
behind an Arctic front, which should allow for SLRs ~15:1
especially in healthier bands. This area of snow will move
southeastward and increase in intensity into southeastern KS and
southern MO late Tue afternoon/evening where the 00Z CAM guidance
shows the potential for 1-1.5"/hr rates (per WPC snowband tool). By
early Wednesday the snow may diminish in intensity into KY as the
upper jet reorients itself and shifts focus to the Gulf coast,
setting up the coastal part of this event farther east. WPC
probabilities of at least 4 inches of snow are high (>70%) from
central KS eastward into MO and extreme southern IL. Within this
region, WPC probabilities for at least 8 inches of snow are
moderate (40-70%), especially over southern MO.

To the south of this swath of snow, cold surface temperatures
beneath >0C air aloft will promote an area of sleet and freezing
rain over central OK eastward into AR. A few hundredths of an inch
of icing is possible, especially into the Ouachita Mountains.


...Central/Southern Appalachians/Mid-Atlantic...
Day 3...

The next phase of the system moving out of the Mid-MS Valley has
been in quite a bit of flux. Question revolves around the timing
and amount of interaction between the shortwave responsible for the
snow across KY/northern TN and the lead height falls ahead of the
upper low over the western Great Lakes/Corn Belt. A surface wave
should develop near the Gulf coast by early Wed and track eastward
then east-northeastward just off the Southeast coast to become the
new focus for QPF. Models have been wavering quite a bit on the
amount of development and how close to the coast this may be,
influencing how much QPF to surge into the southern Mid-Atlantic.
Overall trend continues to be a flatter and drier system and have
trended that way tonight.

Nevertheless, there is confidence in the wave development and at
least light to moderate QPF that will spread into the Southeast and
southern Mid-Atlantic from the system. The result will be a swath
of snow over southern and southeastern VA and northern NC with an
area of sleet and potentially significant freezing rain to the
south over eastern NC where QPF will be plentiful. WPC
probabilities for at least 4 inches of snow are >50% across
southern/southeastern VA. Over NC, where the cold air in place
behind the departing system Sunday will be overrun with >0C air
aloft, the icing potential is significant. WPC probabilities for at
least 0.25" ice are at least 30% but may rise in future updates.


Fracasso



...Winter Storm Key Messages are in effect. Please see current
Key Messages below...

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_2.png

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
211 AM EST Mon Feb 17 2025

Valid 12Z Thu Feb 20 2025 - 12Z Mon Feb 24 2025


...Intense Central to Eastern U.S. Arctic Blast this week...


...Guidance/Predictability Assessment...

The WPC medium range product suite was primarily derived from
composite of reasonably clustered medium to larger scale guidance
of the 18 UTC GFS and the 12 UTC ECMWF/UKMET/Canadian models valid
for Thursday and Friday. Opted to switch to a composite of best
clustered guidance of the 18 UTC GEFS mean and the 12 UTC
ECMWF/Canadian ensemble means by next weekend amid growing forecast
spread. The blend process tends to smooth the increasingly numerous
smaller scale system differences over time as consistent with
individual predictability. This solution maintains good WPC product
continuity and seems mainly in line with latest 00 UTC guidance.

...Weather/Hazards Highlights...

An exiting coastal storm with lift robustly offshore the East
Coast Thursday as mainly a maritime threat, but high winds and
surf will impact eastern New England along with a threat of wrap-
back snow. In the wake of this storm, quite an impressive Arctic
airmass is taking hold over the central and eastern U.S. this week
with advent of strong Canadian high pressure. Entrenched cold air
will maintain some lake effect snows and offer a widespread Extreme
Cold threat. Numerous record temperatures are likely from the
South- Central Plains through the Mid-Lower Mississippi Valley and
The South. Temperatures anomalies into Thursday will range from 30
to 40 degrees below normal over the Central Plains/Mid-Mississippi
Valley, with widespread values 10-20 degrees below normal over much
of the central and eastern U.S. The airmass will slowly moderate
late week through next weekend. While no strongly organized storm
system is evident Thursday through next Monday, the approach of
several uncertain impulses may produce some light and unheralded
but locally disruptive wintry weather in the Arctic airmass.
Periodic moderate rainfall is more likely over the Gulf in closer
proximity to a persistent and slow moving/wavy frontal zone through
this forecast period, but will with more uncertainty also try to
work onshore into the cooled Gulf Coast states.

Upstream, several organized shortwaves/frontal systems will dig
through the West later this week. A main lead system in this
period will bring a swath of terrain/Mountain enhanced snow
Thursday over the north-central Intermountain West/Rockies. The
pattern becomes increasingly favorable for longer fetch moisture
feed to fuel rounds of moderate to heavy low elevation rain and
mountain snow primarily into the Pacific Northwest, but also inland
to the northern Rockies next weekend into early next week.

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