733
FXUS05 KWBC 161231
PMD90D
Prognostic Discussion for Long-Lead Seasonal Outlooks
NWS Climate Prediction Center College Park MD
830 AM EDT Thu Oct 16 2025

SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

A La Nia Advisory was issued in early October as conditions representing the
cold phase of the El Nio Southern Oscillation (ENSO) have developed. The
expectations are for a relatively weak and short lived event through winter
2025-2026 before easing back to ENSO-neutral by early Spring. The most common
La Nia impacts contribute to the outlook during the late autumn and winter
months.



The temperature outlook for Nov-Dec-Jan (NDJ) 2025-2026 favors above-normal
seasonal mean temperatures for much of the contiguous U.S. (CONUS) with the
exception of most of the northern tier of the country where Equal-Chances (EC)
of either of the three categories is forecast. The highest odds of warmer than
normal conditions are located in the Southwest, southern High Plains, and
coastal areas of northwestern Alaska. Below-normal seasonal mean temperatures
are favored for the Alaska Panhandle.



There is an elevated likelihood of above-normal seasonal precipitation amounts
for the Pacific Northwest and northern California eastward to the northern
Rockies and Plains and western Great Lakes in the NDJ 2025-2026 precipitation
outlook. Drier-than-normal conditions are most likely for the southern tier of
the U.S. from the Southwest eastward to southern Texas and the Southeast. For
Alaska, above-normal precipitation is favored for western areas of the state
and below-normal precipitation is favored for the Alaska Panhandle.

BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS
Note:  For Graphical Displays of the Forecast Tools Discussed Below See:
http://www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

La Nia conditions exist in the tropical Pacific Ocean as shown by both oceanic
and atmospheric indicators. Below-normal sea surface temperatures (SSTs) exist
along the equator from 160 E to near the South America coast. Within this area
are regions of SST anomalies less than -0.5 degrees C. The latest weekly value
of the Nino3.4 SST index is -0.3 degrees C. The most recent ocean heat content
values indicate colder than normal water from the surface to about 175 meters
in depth from 150 W to 90 W indicating a reservoir to maintain La Nia
conditions from the ocean perspective. Anomalous convection and lower- and
upper-level winds in the tropical Pacific atmosphere are consistent with La
Nia conditions.



Another area of anomalous SSTs is present in the north Pacific Ocean where a
large region of above-normal temperatures exists from near Japan eastward to
the central North America coast. The largest departures at this time are
centered along the Date Line from approximately 30 - 50 degrees N.



A current review of snow cover across the northern hemisphere indicates lots of
variability across the domain with substantial areas of both positive and
negative snow cover anomalies present. The status of the land surface state
across the CONUS shows the majority of the CONUS and Hawaii under at least
abnormally dry conditions with severe, extreme and exceptional drought present
for much of the western CONUS, parts of the Ohio Valley, mid-Mississippi
Valley, and New England.



The Quasi-Biennial Oscillation (QBO) is currently in its easterly phase and
will remain so throughout the winter into Spring 2026.

PROGNOSTIC DISCUSSION OF SST FORECASTS

The CPC objective, skill weighted consolidation and North American Multi-Model
Ensemble (NMME) Nino3.4 SST outlooks are consistent in forecasting continuing
La Nia conditions into the late winter before transitioning to ENSO-neutral in
early Spring 2026. ENSO-neutral is favored to continue through Spring into
Summer 2026.

PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS

Physical subseasonal to seasonal (S2S) climate drivers considered in these set
of outlooks include the current La Nia conditions and associated potential
winter impacts, the state of the QBO and its relationship with La Nia and the
stratospheric polar vortex, and coastal SSTs in some areas. Above-normal SSTs
across the northern Pacific ocean are also considered in preparing the outlook.



The NMME and C3S dynamical model ensemble systems and their participant models
were utilized as well as statistical forecast tools and long term temperature
and precipitation trends.

PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2025 TO NDJ 2026

TEMPERATURE

The NDJ 2025-2026 temperature outlook favors above-normal seasonal mean
temperatures for much of the CONUS with the exception of most of the northern
tier of the country where Equal-Chances (EC) of either of the three categories
is forecast. This is consistent with the majority of the statistical, hybrid
(CBaM), and dynamical model guidance. The highest odds of warmer than normal
conditions in the CONUS are located in the Southwest and the southern High
Plains where the above tools, La Nia impacts and long term trends align. For
Alaska, later sea ice formation and consequently positive temperature trends
support elevated odds for above-normal temperatures for much of the northern
and western areas of the state. Potential La Nia impacts, primarily later in
the season, along with NMME dynamical model support favors a slight tilt to
below-normal temperatures for the Alaska Panhandle. EC is forecast across much
of the northern tier of the CONUS due to favored high variability over this
three month season.



The evolution of the temperature outlooks from Dec-Jan-Feb (DJF) 2025-2026
through Feb-Mar-Apr (FMA) 2026 depict enhanced odds for below-normal
temperatures from parts of the Pacific Northwest eastward across the northern
Rockies, northern Plains, upper Mississippi Valley, and the far western Great
Lakes. Maximum coverage of favored below-normal temperatures occurs during
Jan-Feb-Mar (JFM) and FMA 2026. This area recedes during Mar-Apr-May (MAM)
2026.



Highlighted favored warmer than normal temperatures across much of the CONUS
forecast in NDJ 2025-2026 decreases in coverage and likelihood over this same
period. More modest probabilities for favored above-normal temperatures are
confined to the southern tier and much of the East Coast of the CONUS during
JFM and FMA 2026. Later in MAM 2026, elevated odds of above-normal temperatures
increase in coverage across both the western CONUS and Eastern Seaboard.



The forecasts over the period from late autumn through winter and early Spring
2026 described above are based on a number of factors and considerations. These
include typical La Nia impacts across the seasons of DJF 2025-2026 through FMA
2026. Given retraction of the East Asian jet (on average) and potential
subsequent ridging/blocking in the north Pacific Ocean, troughing and colder
than normal conditions often impact eastern Alaska as well as much of the
western and north-central CONUS. Also, in these seasons long-term temperature
trends are neutral or negative in some of these areas. For the central U.S.,
statistical forecast tools are consistent with a significant weakness or
absence in the forecast of warmer than normal conditions indicated by most of
the NMME and C3S dynamical model ensemble systems - most likely an
overrepresentation of positive temperature trends in this region where observed
trends do not indicate this.



Two additional considerations when preparing the outlook included the (1)
current abnormally warm north Pacific SSTs and (2) how the current easterly
phase of the QBO may impact the strength of the stratospheric polar vortex.
Extratropical SSTs can change very quickly due to variations in the storm track
and so typically are not a reliable predictor of climate variability. With La
Nia conditions in place, typical anomalous ridging or blocking in the north
Pacific could lead to some persistence of these positive SSTs in some regions.
Although highly uncertain, any impact would most likely be consistent with
typical La Nia temperature anomalies (i.e. potentially colder than average
temperatures in areas of the north-central CONUS).



The stratospheric polar vortex is weaker typically during winters when both La
Nia and an easterly QBO phase are in place - which is favored to be the case
this year. A weaker stratospheric polar vortex can lead to Sudden Stratospheric
Warming (SSW) events and a more meridional or wavy jet stream in general. This
makes it more likely for Arctic air outbreaks consistent with a negative Arctic
Oscillation (AO) and so potential cold air penetrating the northern Hemisphere
continental areas. Even if this is the case, Arctic air can enter either the
western or eastern hemisphere. Nevertheless, this set of conditions does
slightly elevate the potential for colder temperatures in the central and
eastern U.S., so also supports favored below-normal temperatures in the upper
Midwest and the considerable area of EC in the interior central CONUS and parts
of the Northeast during JFM and FMA 2026.



For Alaska, the outlooks over this period highlight an enhanced likelihood for
above-normal temperatures for northern and western coastal areas of the state.
Favored below-normal temperatures increase in coverage from that depicted in
NDJ 2025-2026 in the Alaska Panhandle to include parts of southeastern Mainland
Alaska in DJF 2025-2026, JFM 2026 and FMA 2026 with the maximum extent in
coverage forecast for the latter two seasons.



The outlooks from Apr-May-Jun (AMJ) 2026 onwards are based on the ENSO-OCN
forecast tool which is based on the "perfect prog" forecast from the CPC
Nio3.4 SST consolidation (ENSO component) and long term temperature trends
(Optimal Climate Normal). Given the ENSO-neutral forecast from this guidance,
the forecast maps are primarily based on long term temperature trends.

PRECIPITATION

For precipitation, there is an elevated likelihood of above-normal seasonal
precipitation amounts for the Pacific Northwest and northern California
eastward to the northern Rockies, Plains and western Great Lakes during the NDJ
2025-2026 season. Drier-than-normal conditions are most likely for the southern
tier of the U.S. from the Southwest eastward to southern Texas and the
Southeast. For Alaska, above-normal precipitation is favored for western areas
of the state and below-normal precipitation for the Alaska Panhandle.



Moving through the winter seasons to early Spring 2026, the evolution of the
precipitation outlooks from NDJ 2025-2026 through FMA 2026 shows a continuation
of favored above-normal precipitation across the northern tier eastward to the
Great Lakes through JFM 2026 with an extension to include the Ohio Valley from
DJF 2025-2026 through FMA 2026. Highest odds for above-normal precipitation are
for the northern Rockies and High Plains especially during DJF 2025-2026.
Common La Nia impacts and evolution supported by statistical, hybrid, and
dynamical model forecast guidance form the basis for these outlooks. Above
normal SSTs in the north Pacific are used to increase coverage somewhat beyond
typical La Nia impacts during NDJ 2025-2026, primarily in November.



For below-normal precipitation, forecast coverage and probabilities increase
along the southern tier of the U.S. and maximize during JFM and FMA 2026. La
Nia and associated NMME and C3S model guidance support these outlooks. Both
these signals (wetter and drier) recede during the MAM 2026 season.



For Alaska, the outlooks over this period continue to highlight an enhanced
likelihood for above-normal precipitation for western areas of the state with
below-normal precipitation favored for both areas in southeastern Mainland
Alaska and the Alaska Panhandle during DJF 2025-2026 and JFM 2026.



Similar to temperature, the outlooks from Apr-May-Jun (AMJ) 2026 onwards are
based on the ENSO-OCN forecast tool which is based on the "perfect prog"
forecast from the CPC Nio3.4 SST consolidation (ENSO component) and long term
precipitation trends (Optimal Climate Normal). Given the ENSO-neutral forecast
from this guidance, the forecast maps are primarily based on long term
precipitation trends.

FORECASTER: Jon Gottschalck

The Climatic normals are based on conditions between 1991 and 2020, following
the World Meterological Organization convention of using the most recent 3
complete decades as the climatic reference period.  The probability anomalies
for temperature and precipitation based on these new normals better represent
shorter term climatic anomalies than the forecasts based on older normals.

For a description of of the standard forecast tools - their skill- and the
forecast format please see our web page at
http://www.cpc.ncep.noaa.gov/products/predictions/long_range/tools.html
(Use Lower Case Letters)
Information on the formation of skill of the CAS forecasts may be found at:
http://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Outlook/outlook.shtm
l
(use lowercase letters)
Notes - These climate outlooks are intended for use prior to the start of their
valid period.  Within any given valid period observations and short and medium
range forecasts should be consulted.

This set of outlooks will be superseded by the issuance of the new set next
month on Nov 20 2025


1991-2020 base period means were implemented effective with the May 20, 2021
forecast release.
$$