Prognostic Discussion for Long-Lead Seasonal Outlooks 
NWS Climate Prediction Center College Park MD 
830 AM EDT Thu Oct 17 2024 
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS 
 
El Niño Southern Oscillation (ENSO)-neutral conditions remain present, as 
equatorial sea surface temperatures (SSTs) are near-to-below average in the 
central and eastern Pacific Ocean. A La Niña Watch remains in effect, with La 
Niña favored to emerge during September-November (SON) 2024 (60% chance) and is 
forecast to persist through January-March (JFM) 2025. Any La Niña event that 
develops this autumn is favored, however, to be a weak short duration event. 
 
The November-January (NDJ) 2024-2025 temperature outlook favors above-normal 
seasonal mean temperatures for most of the Contiguous United States (CONUS) 
from the Southwest eastward to include most of the central U.S. and all of the 
eastern CONUS. The largest probabilities (greater than 60 percent) of above 
normal temperatures are forecast for parts of the Southwest. There also is an 
enhanced likelihood of above-normal temperatures for northern Alaska. 
Below-normal temperatures are most likely for much of southern Alaska. 
 
The NDJ 2024-2025 precipitation outlook depicts enhanced probabilities of 
below-normal seasonal total precipitation amounts along most of the southern 
tier of the CONUS and for parts of southeast Mainland Alaska and Alaska 
Panhandle. The greatest odds of below-normal precipitation (greater than 50 
percent) are forecast for parts of the Southwest and Southern Plains. Slight 
tilts toward above-normal precipitation is depicted for parts of the Pacific 
Northwest, northern Rockies, central Great Lakes, and western and northern 
Alaska. 
 
Equal chances (EC) are forecast for areas where probabilities for each category 
of seasonal mean temperatures and seasonal total precipitation amounts are 
expected to be similar to climatological probabilities. 
 
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 
 
ENSO-neutral continued through early October 2024, with near-average sea 
surface temperatures (SSTs) observed across the equatorial Pacific Ocean as a 
whole. The equatorial central Pacific SSTs, however, have cooled recently and 
negative anomalies of greater than -0.5 degrees C for the equatorial region 
from 165 W to 125 W are evident. In fact, the latest weekly Niño-3.4 index 
value is now -0.5 degrees C. Below-average subsurface ocean temperatures remain 
in place with cooler than normal conditions from approximately 160 W to 90 W to 
a depth of about 150 m. Low-level wind anomalies are easterly over the 
east-central equatorial Pacific, and upper-level wind anomalies are westerly 
over the eastern Pacific. Convection has been near average over Indonesia and 
slightly suppressed over the Date Line. 
 
Then MJO has been active during September into October and aided a trade wind 
surge across the central Pacific in early September. The MJO is forecast to 
remain active for at least the rest of October and another trade wind surge 
supporting cooling of SSTs in the central Pacific is possible in late October. 
 
SSTs at higher latitudes remain warmer than normal for most areas of the 
mid-Pacific, Atlantic, and Indian Oceans. Enhanced upwelling along the U.S. 
West Coast has allowed negative SST anomalies to develop in parts of this 
region and below-normal ocean surface temperatures are evident in parts of the 
Gulf of Alaska and the Bering Sea. 
 
Drought conditions have rapidly expanded across much of the CONUS during late 
summer and early autumn especially for areas in the central U.S. 
 
PROGNOSTIC DISCUSSION OF SST FORECASTS 
 
Taken collectively, statistical and dynamical model forecast guidance of the 
Niño3.4 index favor the development of a weak and most likely short duration La 
Niña event. Some statistical model forecasts do favor a continuation of 
ENSO-neutral into and through winter 2024-2025. Dynamical model guidance 
predictions tend to support weak La Niña conditions to develop, including the 
majority of participant models from the NMME and C3S forecast suites. Most 
recent observations and the forecast guidance noted above favor La Niña to 
emerge during SON (60% chance) and is expected to persist through JFM 2025. 
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS 
 
The development of potential La Niña conditions in the atmosphere-ocean system 
in the Pacific contributed to the outlooks from NDJ 2024-2025 through FMA 2025. 
Although typical La Niña impacts are less likely to occur during a weak event 
(currently favored), La Niña still tilts the odds in the outlook forecast 
probabilities. Coastal SSTs and constructed analogue forecasts keyed to current 
soil moisture anomalies are utilized in preparation of the outlooks at early 
leads. Dynamical model guidance from the NMME and C3S prediction suites (first 
5 and 3 leads respectively), statistical forecast tools, long-term temperature 
and precipitation trends , and an objective, historical skill weighted 
combination of much of the above guidance strongly contributed to the final 
outlooks. 
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2024 TO NDJ 2025 
 
TEMPERATURE 
 
The NDJ 2024-2025 temperature outlook favors above-normal seasonal mean 
temperatures for much of the contiguous U.S. (CONUS) to include the Southwest, 
central Rockies, the central and Southern Plains, Southeast, Ohio Valley, 
mid-Atlantic and Northeast. Highest odds for warmer than normal conditions is 
forecast for the Southwest and southern Plains. The temperature outlook for 
this season is primarily based on dynamical model guidance from the NMME and 
C3S prediction suites and long term positive temperature trends  across much of 
the country. 
 
Expectations for the development of La Niña conditions contributed to the 
temperature outlooks and their evolution from DJF 2024-2025 through FMA 2025. 
Even though the La Niña event is favored to be a weak and shorter duration 
event at this time, typical winter season impacts influence the outlook during 
these seasons with below-normal temperatures most likely from the Pacific 
Northwest eastward to the northern Plains beginning in DJF 2024-2025 through 
FMA 2025 and potentially lingering for parts of the Pacific Northwest and 
northern Rockies in MAM 2025. Enhanced odds for above-normal temperatures 
forecast in NDJ 2024-2025 gradually decrease in coverage and magnitude across 
the CONUS through FMA 2025 for areas of the western CONUS, Midwest, Great 
Lakes, Ohio Valley and Northeast. Some statistical model guidance including the 
ENSO-OCN forecast tool and composites taken over the 1991-2023 period for 
combined weak La Niña and ENSO-neutral winter seasons support this outlook 
evolution. 
 
Negative temperature trends  for the north-central U.S. - especially centered 
near the month of February - played a considerable role in the outlooks. The 
official outlooks deviate significantly in some areas in the north-central 
CONUS from the majority of the NMME and C3S dynamical model guidance. Given 
weak ENSO forcing this winter, variability within the winter seasons is most 
likely to be above-average and greater than last winter. The variance from key 
subseasonal modes of variability from both the Tropics (e.g., MJO, etc.) and 
higher latitudes/stratosphere (i.e., AO/NAO, etc.) is likely to dominate the 
eventual seasonal mean temperature anomalies rather than more persistent 
periods during the winter. Positive temperature trends  in the dynamical model 
guidance may be overemphasized in the model predictions in these regions 
resulting in warmer solutions overall for the winter seasons from DJF through 
FMA 2025 as the observed temperature trends  are either neutral or negative in 
most areas. 
 
For Alaska, over these seasons, dynamical model guidance is in overwhelming 
agreement between models and consistent with typical La Niña related impacts. 
Below-normal temperatures are most likely for south-central and Southeast 
mainland Alaska as well as for the Alaska Panhandle through MAM 2025 with the 
maximum forecast coverage during JFM 2025. Above-normal temperatures are 
favored for northwest Alaska during this period with the greatest odds during 
NDJ 2024-2025 due to more open water (below-normal sea ice extent) and 
anticipated warmer than normal SSTs. 
 
Progressing through the spring and summer months of 2025, the outlooks 
primarily rely on the forecast consolidation of statistical model guidance and 
long-term temperature trends  with high uncertainty in the future evolution of 
ENSO. Forecast coverage for above-normal temperatures is greatest during the 
late spring and summer seasons of MJJ and JJA 2025. 
 
PRECIPITATION 
 
The NDJ 2024-2025 precipitation outlook favors above-normal seasonal total 
precipitation amounts for portions of the Pacific Northwest, northern Rockies, 
Michigan, and northern and western Alaska. Drier-than-normal conditions are 
most likely for the southern tier of the U.S. with the highest odds forecast 
for the Southwest and Southern Plains. For Southeast Mainland Alaska and the 
northern Alaska Panhandle, a slight tilt toward drier than normal conditions is 
forecast through MAM 2025. 
 
As noted above, the favored development of La Niña conditions approaching the 
winter and consistent dynamical model forecast guidance is the basis for the 
outlook. Moving through the FMA 2025 season, the enhanced likelihood of 
above-normal precipitation in the Great Lakes and Ohio Valley regions expands 
in coverage and probabilities increase maximizing in the southern Great Lakes 
and northern Ohio Valley area in JFM 2025. Positive precipitation trends  also 
contribute strongly to these outlooks for some areas in the Midwest and Great 
Lakes. 
 
Favored below-normal precipitation across the south through FMA 2025 remains 
generally consistent with the forecast coverage and odds greatest for JFM 2025. 
The majority of the dynamical model guidance from the NMME and C3S model suites 
highlight substantially elevated odds for below-normal precipitation for the 
Far West (i.e., California/Nevada) for the winter seasons through FMA 2025. 
Given the anticipated generally weak ENSO forcing, this seems overdone, 
especially since some of the dynamical model guidance can sometimes 
overemphasize ENSO impacts during weaker events. 
 
Given the lack of a clear, reliable ENSO signal after this winter/early spring, 
longer lead outlooks are primarily based on long term precipitation trends  and 
depict low forecast coverage. The longer lead precipitation outlooks during the 
warm season generally have low forecast skill. 
 
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 Cas e 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 21 2024 
 
 
1991-2020 base period means were implemented effective with the May 20, 2021 
forecast release. 
$$