Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
248 AM EDT Wed Oct 15 2025

Valid 12Z Wed Oct 15 2025 - 12Z Fri Oct 17 2025

...There is a chance of showers and thunderstorms over parts of the
Northern Plains to the Southern Plains and Upper Great Lakes on Wednesday
and Thursday....

...Heavy snow over parts of the Sierra Mountains on Wednesday and over the
Northern Rockies on Thursday...

On Wednesday, low pressure over the Great Basin moves northeastward into
South-Central Canada by Friday. The associated front moves from the Great
Basin to the Upper Mississippi Valley and Central Plains/Southern High
Plains by the seventeenth, Friday. The system will create rain over parts
of Central California on Wednesday. Meanwhile, rain and higher-elevation
snow will develop over the Sierra Nevada Mountains and the Great Basin on
Wednesday and the Northern Intermountain Region/the Northern Rockies on
Thursday into Friday.

Moreover, showers and thunderstorms will develop over parts of the
Central/Southern Rockies on Wednesday into Thursday morning. Further, rain
will also develop over parts of the Northern/Central Plains, the Middle
Mississippi Valley, and the Great Lakes on Wednesday. Rain will continue
on Thursday over the Northern Plains, the Middle Mississippi Valley, and
the Great Lakes. In addition, the weather will remain unsettled over the
Northern Intermountain Region and Northern Rockies on Thursday into
Friday. Additionally, weak onshore flow will help develop rain over the
Pacific Northwest on Thursday afternoon into Friday.


Ziegenfelder


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
347 AM EDT Wed Oct 15 2025

Valid 12Z Sat Oct 18 2025 - 12Z Wed Oct 22 2025


...Guidance/Predictability Assessment...

Model guidance remains in relatively good agreement during the
medium range period, handling the evolution of several large scale
trough/ridge features across the CONUS reasonably well despite a
highly amplified 500mb flow pattern. Only minor differences were
noted for Days 3 and 4, so a composite blend of the 00Z EC, 00Z
UKMET, 00Z CMC and 06Z GFS deterministic runs sufficed to begin the
period. However, larger discrepancies started cropping up by Day
5, most notably with the evolution of a potent Pacific trough that
is progged to push inland over British Columbia and the Pacific
Northwest late in the weekend into early next week. While the
EC/GFS/UKMET all had similar solutions depicting the trough digging
deeper along the West Coast, the CMC shows the trough becoming
completely sheared apart as it moves across the Pacific Northwest.
As a result of being much faster and flatter than consensus, the
00Z CMC was removed from the blend starting on Day 5 and was not
considered for the remainder of the forecast. To compensate, more
weighting was placed on the EPS and GEFS ensemble means, which
ultimately made up slightly more than 50% of the blend for Day 6
and 7. The greater weighting of the ensemble means resulted in a
more stable forecast that preserved continuity while reducing some
of the timing and positional differences that are typical for the
latter half of the medium range forecast period.

...Weather/Hazards Highlights...

As an upper trough supported and wavy cold front passes through
the Plains, moisture/instability return will increase in advance
of it through the Mid-MS Valley where rainfall should significantly
increase by Saturday. The WPC Day 4/Saturday Excessive Rainfall
Outlook (ERO) introduced a new Slight Risk area centered over the
Mid-South given favorable upper support, moisture and instability.
SPC also shows a threat for severe weather in this pattern. The
slowly progressive nature of the upper-level and surface features
will spread organized rainfall eastward into the East/Northeast
later weekend into early next week, particularly near and along the
track of a deepening/consolidating coastal low pressure system
(and more modestly into the Southeast ahead of the cold front). A
Day 5/Sunday ERO Maringal Risk area was introduced to capture local
runoff potenital into the Appalachians. Temperatures will be mild
ahead of the cold front with highs well into the 70s/80s Friday
from the Corn Belt to the Ozarks with 90s across South Texas.

Out West, another deepened system will approach/enter the Pacific
Northwest/West Coast over the weekend to produce a period of
moderately heavy coastal and valley rains along with higher
mountain snow. Activity will then dig and spread across the West
and downstream to the Rockies. The WPC Day4/Saturday ERO maintains
a coastal Washington Marginal Risk area given a favorable signal
and our Winter Weather Outlook shows mountain snow potenial inland
from the Northwest to the Northern Rockies into Monday with
passage.

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
324 AM EDT Wed Oct 15 2025

Valid 00Z Thu 16 Oct 2025 - 00Z Thu 23 Oct 2025


Model and ensemble solution continue to seem reasonably well
clustered for the main flow and features, bolstering overall
forecast confidence. Expect trades to steadily ramp-up over the
next few days and then again over the weekend as high pressure
settles to the northeast and then bridges to the north of the
state. Meanwhile, an unsettling upper low/trough settling over
the state will be a slow mover over the next few days before
shifting slowly westward. Pooling moisture and increasing lift
favor chances for some local downpours and thunderstorms in a wet
period. An upper weakness may linger over the islands into next
week, with enhanced trades favoring windward terrain activity.




Schichtel

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
319 AM EDT Wed Oct 15 2025
Day 1
Valid 12Z Wed Oct 15 2025 - 12Z Thu Oct 16 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
COLORADO AND NORTHERN NEW MEXICO...

A large mid/upper wave centered across Nevada at 12Z Wednesday will
migrate eastward during the forecast period, spreading height falls
across the central and southern Rockies. As this occurs, cooling
aloft and surface heating will foster development of a few showers
and thunderstorms across southern Colorado and northern New Mexico
especially during the afternoon and evening hours. Point forecast
soundings across the region depict fast storm motions (30-50
knots) with any developing convection, although steep lapse rates
aloft and 0.5-0.75 inch PW both suggest potential for brief heavy
rainfall especially where any backbuilding can materialize. Wet
antecedent conditions and very high streamflows (per the USGS Water
Dashboard) are suggestive of ground conditions that are readily
supportive of excessive runoff due to poor drainage. Additionally,
a few burn scars across the region could support local excessive
runoff at times. Areas of 1-2 inch rainfall totals are possible -
especially in upslope and terrain-favored areas. Isolated flash
flooding is possible in this regime.

Cook


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
319 AM EDT Wed Oct 15 2025
Day 2
Valid 12Z Thu Oct 16 2025 - 12Z Fri Oct 17 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG MUCH OF THE
MONTANA/NORTH DAKOTA BORDER...

Strengthening mid-latitude cyclone will traverse the Northern High
Plains by Thursday afternoon and beyond with a developing closed
mid-level vorticity center propagating over eastern MT to the MT/ND
border. The subsequent evolution will lead to a period of moderate
to heavy rainfall across the above areas with a prominent
deformation axis anticipated to setup along the MT/ND border. At
this juncture, instability will be lacking from a thermodynamic
sense, however the dynamical forcing and prolonged period of
enhancement with the axis of deformation will likely spur a
widespread area of moderate to heavy rainfall capable of low-end
flash flood concerns. These concerns will be suited mainly over
those urbanized zones and any low-water crossing. Totals area
expected to be a widespread 1-2" of rainfall with some localized
totals >2", likely over western and northwestern ND as the heaviest
rain will hang on there given the proxy of the surface low
progression and positioning of the axis of deformation. A MRGL risk
was maintained with a small expansion south to account for the
latest QPF trends.

Kleebauer


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
319 AM EDT Wed Oct 15 2025
Day 3
Valid 12Z Fri Oct 17 2025 - 12Z Sat Oct 18 2025

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

Kleebauer

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
347 AM EDT Wed Oct 15 2025


As an upper trough supported and wavy cold front passes through
the Plains, moisture/instability return will increase in advance
of it through the Mid-MS Valley where rainfall should significantly
increase by Saturday. The WPC Day 4/Saturday Excessive Rainfall
Outlook (ERO) introduced a new Slight Risk area centered over the
Mid-South given favorable upper support, moisture and instability.
SPC also shows a threat for severe weather in this pattern. The
slowly progressive nature of the upper-level and surface features
will spread organized rainfall eastward into the East/Northeast
later weekend into early next week, particularly near and along the
track of a deepening/consolidating coastal low pressure system
(and more modestly into the Southeast ahead of the cold front). A
Day 5/Sunday ERO Maringal Risk area was introduced to capture local
runoff potenital into the Appalachians. Temperatures will be mild
ahead of the cold front with highs well into the 70s/80s Friday
from the Corn Belt to the Ozarks with 90s across South Texas.

Out West, another deepened system will approach/enter the Pacific
Northwest/West Coast over the weekend to produce a period of
moderately heavy coastal and valley rains along with higher
mountain snow. Activity will then dig and spread across the West
and downstream to the Rockies. The WPC Day4/Saturday ERO maintains
a coastal Washington Marginal Risk area given a favorable signal
and our Winter Weather Outlook shows mountain snow potenial inland
from the Northwest to the Northern Rockies into Monday with
passage.

Schichtel

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
347 AM EDT Wed Oct 15 2025


As an upper trough supported and wavy cold front passes through
the Plains, moisture/instability return will increase in advance
of it through the Mid-MS Valley where rainfall should significantly
increase by Saturday. The WPC Day 4/Saturday Excessive Rainfall
Outlook (ERO) introduced a new Slight Risk area centered over the
Mid-South given favorable upper support, moisture and instability.
SPC also shows a threat for severe weather in this pattern. The
slowly progressive nature of the upper-level and surface features
will spread organized rainfall eastward into the East/Northeast
later weekend into early next week, particularly near and along the
track of a deepening/consolidating coastal low pressure system
(and more modestly into the Southeast ahead of the cold front). A
Day 5/Sunday ERO Maringal Risk area was introduced to capture local
runoff potenital into the Appalachians. Temperatures will be mild
ahead of the cold front with highs well into the 70s/80s Friday
from the Corn Belt to the Ozarks with 90s across South Texas.

Out West, another deepened system will approach/enter the Pacific
Northwest/West Coast over the weekend to produce a period of
moderately heavy coastal and valley rains along with higher
mountain snow. Activity will then dig and spread across the West
and downstream to the Rockies. The WPC Day4/Saturday ERO maintains
a coastal Washington Marginal Risk area given a favorable signal
and our Winter Weather Outlook shows mountain snow potenial inland
from the Northwest to the Northern Rockies into Monday with
passage.

Schichtel

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
321 AM EDT Wed Oct 15 2025

Valid 12Z Wed Oct 15 2025 - 12Z Sat Oct 18 2025

...Central Great Basin & Northern Rockies...
Days 1-2...

A potent closed upper low, which impacted California and the Sierra
to start the week is forecast to cross the central Great Basin
today before lifting across the northern Rockies on Thursday. As it
does so, it is also forecast to gradually weaken, but still
provide ample broad scale upper ascent over the region. The
greatest potential for moderate to locally heavy snow will likely
be situated directly underneath the aforementioned upper low where
the greatest lift and steepest lapse rates exist. The 00z HREF
shows this potential for 1-2"/hr snowfall rates across the high
terrain throughout north-central and northeast NV between 18Z-00Z
today as snow levels drop as low as 7,000ft.

For the northern Rockies, strong south-southwesterly upslope flow
into the WY and UT mountain ranges will provide for more longevity
of moderate high elevation snowfall ahead of the mid-upper low on
Thursday. This includes the Tetons, Absarokas, Bighorns, Wind River
Range, as well as the Wasatch and Uintas of UT. Snow levels will
start out fairly high and around 9,000ft before dropping to around
7,000ft for areas underneath the mid-upper low as it pushes
northeastward. Snow should taper off by Thursday night as the
system quickly exits into the northern Plains and dry northwesterly
flow becomes the dominant regime again for the time being.

WPC probabilities for at least 8 inches of snow for this event are
moderate-to-high (50-80%) across the Ruby Mts of northeast NV, as
well as many of the ranges surrounding Yellowstone NP, the WY
Bighorns, and the Uintas of UT. Most of these higher probabilities
reside over regions higher than 9,000ft in elevation.


The probability of significant freezing rain across CONUS is less
than 10 percent.


Snell

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
347 AM EDT Wed Oct 15 2025

Valid 12Z Sat Oct 18 2025 - 12Z Wed Oct 22 2025


...Guidance/Predictability Assessment...

Model guidance remains in relatively good agreement during the
medium range period, handling the evolution of several large scale
trough/ridge features across the CONUS reasonably well despite a
highly amplified 500mb flow pattern. Only minor differences were
noted for Days 3 and 4, so a composite blend of the 00Z EC, 00Z
UKMET, 00Z CMC and 06Z GFS deterministic runs sufficed to begin the
period. However, larger discrepancies started cropping up by Day
5, most notably with the evolution of a potent Pacific trough that
is progged to push inland over British Columbia and the Pacific
Northwest late in the weekend into early next week. While the
EC/GFS/UKMET all had similar solutions depicting the trough digging
deeper along the West Coast, the CMC shows the trough becoming
completely sheared apart as it moves across the Pacific Northwest.
As a result of being much faster and flatter than consensus, the
00Z CMC was removed from the blend starting on Day 5 and was not
considered for the remainder of the forecast. To compensate, more
weighting was placed on the EPS and GEFS ensemble means, which
ultimately made up slightly more than 50% of the blend for Day 6
and 7. The greater weighting of the ensemble means resulted in a
more stable forecast that preserved continuity while reducing some
of the timing and positional differences that are typical for the
latter half of the medium range forecast period.

...Weather/Hazards Highlights...

As an upper trough supported and wavy cold front passes through
the Plains, moisture/instability return will increase in advance
of it through the Mid-MS Valley where rainfall should significantly
increase by Saturday. The WPC Day 4/Saturday Excessive Rainfall
Outlook (ERO) introduced a new Slight Risk area centered over the
Mid-South given favorable upper support, moisture and instability.
SPC also shows a threat for severe weather in this pattern. The
slowly progressive nature of the upper-level and surface features
will spread organized rainfall eastward into the East/Northeast
later weekend into early next week, particularly near and along the
track of a deepening/consolidating coastal low pressure system
(and more modestly into the Southeast ahead of the cold front). A
Day 5/Sunday ERO Maringal Risk area was introduced to capture local
runoff potenital into the Appalachians. Temperatures will be mild
ahead of the cold front with highs well into the 70s/80s Friday
from the Corn Belt to the Ozarks with 90s across South Texas.

Out West, another deepened system will approach/enter the Pacific
Northwest/West Coast over the weekend to produce a period of
moderately heavy coastal and valley rains along with higher
mountain snow. Activity will then dig and spread across the West
and downstream to the Rockies. The WPC Day4/Saturday ERO maintains
a coastal Washington Marginal Risk area given a favorable signal
and our Winter Weather Outlook shows mountain snow potenial inland
from the Northwest to the Northern Rockies into Monday with
passage.

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