Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
307 PM EDT Sat Oct 11 2025

Valid 12Z Tue Oct 14 2025 - 12Z Sat Oct 18 2025

...Locally heavy rain and flash flooding remain a threat for parts
of the Southwest next week...

...Heavier rain and mountain snow for California...


...Overview...

An amplified pattern will favor a stormy period for much of the
West with well below temperatures. This will bring modest rain to
California and significant snow for the Sierra on Tuesday
(especially above 6500ft). This will spread across the
Intermountain West midweek and perhaps linger through much of the
week as the system slowly moves eastward/northeastward. Over the
central and eastern states, the coastal storm in the short term
will pull away from the Northeast and milder air will be prevalent
as upper ridging builds ahead of the western troughing.

...Guidance/Predictability Assessment...

For the first half of the period, the models remained in good
agreement and multi-model blend sufficed as a starting point. By
around Thursday, there was a notable divergence of opinion in how
quickly to lift the western trough: most dynamical models were
quicker while the AI models/ensembles were slower. The
previous/overnight shift was nicely in between the two camps, and
have favored continuity for next Fri/Sat for now. The flow is
somewhat complicated by incoming northern stream shortwaves later
in the week next week which could modulate the shape/axis of the
trough or split it into multiple shortwaves. The 13Z NBM was the
basis for the sensible weather grids but with modification by next
Fri/Sat to account for the slower preference. In the
central/eastern states, a slower western trough would delay the
ridge axis from moving eastward but again this could be complicated
by northern stream shortwaves through eastern Canada. Confidence
in the forecast started above average with a trend to near/below
average by the end of the period.

...Weather/Hazards Highlights...

Over the Northeast, the coastal storm and its effects (blustery
winds, high surf, and above normal tides) will pull away from the
coast at the start of the period. Focus will be on the West as the
incoming upper low that will bring in the rain/snow to California
will be underway on Tuesday. A Marginal Risk in the Excessive
Rainfall Outlook is noted for areas between San Francisco and Los
Angeles. Heavy snow is likely in the Sierra above 6500-7000ft. In
addition, another Marginal Risk area exists over New Mexico where
moisture levels remain high.

Into Wednesday, the system will continue southeastward and push
the rain/snow into the Intermountain West, with a continued threat
over New Mexico where another Marginal Risk area is in place. Much
of the West will see at least some rain or snow, with snow levels
lowering as colder air moves in. Temperatures will be well below
normal Tue-Wed (by 10-20 deg) with some slight moderation for the
rest of the week, but still staying cooler than normal.

For the central states, southwesterly flow will increase the
chances of light to modest rain late Tuesday into Wednesday over
the Northern Plains into the Upper Midwest closer to the jet
stream. However, mild and moisture-laden air to the south (central
to southern Plains) will support at least isolated showers and
perhaps some storms ahead of the western/Rockies system. Much of
the Southeast will remain dry and warm through the period with
temperatures well into the 80s and low 90s (South TX).

Fracasso


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
307 PM EDT Sun Oct 12 2025

Valid 12Z Wed Oct 15 2025 - 12Z Sun Oct 19 2025


...Guidance/Predictability Assessment...

The models into the medium range period continue to show good
agreement on an amplified pattern consisting initially of a Western
U.S. deep trough and building ridge downstream from the central to
eastern states. The evolution of this, as the Western trough/low
opens up and progresses eastward, is generally in good agreement
but with some variability in the details and timing of the trough
next weekend. Around Friday, the GFS is a bit faster with a
northern stream shortwave into southern Canada and also faster and
more aggressive with a following shortwave, resulting in a deep
closed low over the Great Lakes next Sunday. The better consensus
would be for something a bit slower and more open and the WPC
forecast today weighted a bit more towards the ECMWF/CMC early
period and the ensemble means later in the period. The guidance
agrees on another amplified shortwave moving into the Pacific
Northwest late period, but again with some question on the timing.
For the sensible weather grids, the 13z NBM served as a good
starting point and basis, but with some modifications based on the
ECMWF which was the preferred model. Overall, maintained good
continuity with the previous WPC forecast.


...Weather/Hazards Highlights...

A lead short range coastal storm will be working well out to sea
across the western Atlantic by midweek but still support continued
unsettled/windy conditions over New England through late week with
impulses digging behind the system bring some lingering showers.

An incoming upper low/amplified trough slated to bring rain/snow
to California early week will lift increasingly inland across the
West/Rockies mid-late week. A Day 4/Wednesday WPC Excessive
Rainfall Outlook Marginal Risk area remains over New Mexico and
southern Colorado where leading moisture levels may fuel some
lingering local downpours with runoff issues. Upper system and wavy
frontal progression will also drive organized rain/snow over the
north-central Intermountain West/Rockies Wednesday/Wednesday night.
Much of the West will see at least some rain or snow, with snow
levels lowering as colder air moves in. Temperatures will be well
below normal into Wednesday (by 10-20 deg) with some slight
moderation for the rest of the week, but still cooler than normal.
Later period, there is also some upstream guidance signal
supporting approach of another amplified Northeast Pacific storm
system toward the Pacific Northwest/Northwest next weekend that may
offer quite unsettled flow and enhanced rainfall to monitor.

Downstream for the central states, southwesterly upper flow will
increase the chances of rain for mid-late week over the Northern
Plains into the Upper Midwest closer to the jet stream with wavy
surface system translation/genesis. Mild and more moisture-laden
air to the south over the central Plains and Mid-Mississippi Valley
will support a growing pattern with showers and thunderstorms
ahead of the western/Rockies system into Thursday/Friday. Activity
may flourish as focus shifts slowly with more uncertainty into the
east-central states into next weekend in an emerging return flow
pattern to monitor for enhanced rainfall/runoff issue potential.


Santorelli/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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
304 PM EDT Mon Oct 13 2025

Valid 12Z Thu Oct 16 2025 - 12Z Mon Oct 20 2025


...Guidance/Predictability Assessment...

The models and ensembles generally agree on the large-scale
pattern over the next week, favoring strong troughing in the West
that will slowly lift into the Plains and then push into the
Northeast by early next week. Another trough is expected to move
into the Pacific northwest late next weekend. By the Sat-Mon
period, the GFS/GEFS were generally quicker than the ECMWF/ECMWF
EPS and ECMWF- AIFS/ECMWF-EPS-AIFS by about 12 hours which is well
within tolerance for that time range. For the fronts/pressures,
utilized a multi- model/ensemble blend for the first few days of
the forecast before trending to the 00Z ECMWF ensemble mean in
order to maintain better depiction of the features vs a blend of
the ensembles. For the sensible weather grids, the NBM was
reasonable through the period.


...Weather/Hazards Highlights...

No areas were noted in the Day 4-5 Excessive Rainfall Outlooks as
the QPF across the CONUS was on the lighter side.

Lingering upper troughing in Atlantic Canada (tied to the current
coastal storm) still supports continued unsettled/windy conditions
over New England through late week with cooler than normal
temperatures to start that will slowly moderate.

The troughing and associated surface frontal boundary in the West
will promote cool and showery (with some snow at higher elevations)
conditions over the Northern/Central Rockies to start, with
broader light rain in advance of the surface low that is poised to
track from the Northern Plains into southern Canada. As the
attendant cold front passes through the Plains, moisture will
increase in advance of it through the Mid-MS Valley where rainfall
could increase by Saturday. This rainfall will continue eastward
next Sunday and Monday into the Northeast near the track of the low
pressure (and into the Southeast ahead of the cold front).
Temperatures will be mild ahead of the cold front -- well into the
70s/80s Friday from the Corn Belt to the Ozarks with 90s across
South Texas.

By late next weekend into next Monday, another system will enter
the Pacific Northwest with another round of valley rain and higher
mountain snow that will spread into the Northern Rockies.
Temperatures will again cool over Idaho southwestward to Nevada and
NorCal.


Fracasso


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EDT Tue Oct 14 2025

Valid 12Z Fri Oct 17 2025 - 12Z Tue Oct 21 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...

Lingering upper troughing in Atlantic Canada (tied to the current
coastal storm) still supports continued unsettled and borderline
windy conditions over New England through late week with cooler
than normal temperatures that will slowly moderate with time.

The troughing and associated surface frontal boundary in the West
will promote cool and showery weather (with some snow at higher
elevations) over the northern/central Rockies to start, with
broader light rain in advance of the surface low that is poised to
track from the northern Plains into southern Canada. As the
attendant cold front passes through the Plains, moisture will
increase in advance of it through the Mid-MS Valley where rainfall
could increase by Saturday. The WPC Day 5/Saturday Excessive
Rainfall Outlook (ERO) maintains a Marginal Risk area centered over
the Mid-South given favorable upper support, moisture and
instability. Given the somewhat progressive nature of the upper-
level and surface features, this rainfall will continue to spread
eastward into the Northeast later Sunday into early next week,
particularly near and along the track of a deepening/consolidating
low pressure system (and into the Southeast ahead of the cold
front). 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.

By late next weekend into early next week, another deepened system
will enter the Pacific Northwest/West Coast with another round of
valley rain and higher mountain snow that will then dig and spread
across the West and downstream to the Rockies. The Day 5/Saturday
ERO maintains a coastal Washington Marginal Risk area given a
favorable guidance signal.

Miller/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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
358 PM EDT Wed Oct 15 2025

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


...Guidance/Predictability Assessment...

The depiction of the large scale pattern by the latest model
guidance remains reasonably good to start off the medium range
period, but uncertainty increases quite a bit for Day 5 and beyond.
Given only minor differences of the strength and timing of an
eastern U.S. ridge, central U.S. trough and western U.S. ridge, a
composite blend of the 00Z EC, 00Z UKMET, 00Z CMC and 06Z GFS were
utilized for the Day 3 and Day 4 forecast. By Day 5, the trough
progged to push from the Pacific across the Pacific Northwest is
trending to be much more progressive compared to yesterday's
package. In fact, most of yesterday's guidance aside from the CMC
was on board with a much slower and more amplified solution, with a
deepening trough digging southward along the West Coast. Instead,
the more progressive solution is now looking more likely, with all
guidance including the latest machine learning guidance all
depicting this evolution fairly similarly. The latest 00Z and 06Z
runs of the GFS were slow to catch on (and thus were not used in
the composite blend for Days 5-7) but the most recent 12Z run has
joined consensus as well. Given the strength and amplitude of the
eastern U.S. ridge at the beginning of the period, the faster and
more progressive flow upstream is leading to a sharper and more
negatively tilted trough pushing from the central U.S. into the
eastern U.S. this weekend into early next week. As a result, a
stronger and more consolidated surface low is looking more likely
to track across the Great Lakes, with implications to QPF and
hazards. More on that below. Given the above, the Days 5-7 forecast
consisted of a blend that increasingly relied on the ensemble means
of the EPS, CMCE, and GEFS, which provided more stability and less
noise from individual deterministic guidance sources.

...Weather/Hazards Highlights...

A sharpening upper trough/shortwave and strengthening surface low
pressure pushing across the Great Lakes region this weekend will
draw anomalous moisture and instability northward in advance of a
cold front. PW anomalies of >200% of normal combined with
instability of 500-1500 j/kg will support an axis of heavier
rainfall across parts of the Upper Midwest, Ohio Valley and Mid-
South on Saturday. As a result, the Day 4/Saturday Excessive
Rainfall Outlook (ERO) expanded the Marginal Risk northward to
include southeast Wisconsin and southwest Michigan. The recently
introduced Slight Risk area centered over the Mid-South was
maintained given the overlap with the greatest instability and
relatively lower FFG. SPC also shows a threat for severe weather in
this pattern. The slowly progressive nature of the upper-level and
surface features will then spread organized rainfall eastward into
the East/Northeast Sunday into early next week. This will
especially be the case 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 Marginal Risk area was maintained and broadened to
capture local runoff potential into the Appalachians and parts of
the Ohio Valley.

Out West, the now more progressive trough and surface low will
quickly approach and push across the Pacific Northwest and northern
Rockies over the weekend to produce a period of moderately heavy
coastal and valley rains along with higher mountain snow. The Day
4/Saturday ERO maintains a coastal Washington Marginal Risk area
given a favorable QPF signal while our Day 4-7 Winter Weather
Outlook shows mountain snow potential inland from the Northwest to
the Northern Rockies Sunday into Monday.

Miller/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