[UPDATED: SEPTEMBER] NOAA Winter 2024-25 Early Forecast: La Niña Returns and What That Means For the Ski Season - SnowBrains (2024)

On Thursday, September 19, the NOAA updated its long-range seasonal forecasts for next winter, giving snow lovers an early glimpse into what 2024/25 might hold.

• Related: Farmers’ Almanac 2024-25 Winter Forecast: Cold, Wet, Snowy Winter Ahead…. But Where?

Based on the outlook discussion, here’s the early winter 2024-25 outlook.

The updated winter outlook the Northwest is likely to see above-normal snowfall, making it a prime destination for winter 2024-25. In contrast, the Southwest may experience below-normal precipitation, leading to less snow at resorts. The Northern Plains and Great Lakes regions are forecasted to have increased snowfall, while the Northeast could also benefit from above-normal precipitation, although warmer temperatures might affect lower elevation snow quality. Overall, a weak La Niña is anticipated, which typically brings wetter conditions to the north and drier conditions to the south, influencing snowfall patterns across the country.

Northwest (Pacific Northwest, Northern Rockies)

Temperature: Temperatures are expected to be near normal or slightly below normal.

Precipitation/Snowfall: Good news for powder hounds! The Northwest is likely to see above-normal precipitation, which could translate to increased snowfall for ski resorts in this region. This favorable outlook extends from late fall through winter.

Southwest (California, Nevada, Utah, Colorado)

Temperature: Warmer than average temperatures are anticipated, with the highest probability in the Southwest.

Precipitation/Snowfall: Unfortunately, below-normal precipitation is expected across much of the south-central and southwestern United States. This could mean less snowfall for many ski areas in these states.

Northern Plains and Upper Midwest

Temperature: Temperatures will likely be below normal, especially as winter progresses.

Precipitation/Snowfall: There’s an increased chance of above-normal precipitation across the country’s northern tier, including the Great Lakes region. This could result in good snow conditions for ski resorts in states like Minnesota, Wisconsin, and Michigan.

Northeast and New England

Temperature: The eastern seaboard is expected to have above-normal temperatures.

Precipitation/Snowfall: The outlook is promising for skiers and snowboarders in this region. Above-normal precipitation is favored for the Great Lakes and Northeast. While warmer temperatures might affect snow quality at lower elevations, higher-elevation resorts could see significant snowfall.

Alaska

Temperature: Southeastern Alaska will likely experience below-normal temperatures, while northwestern Alaska may see above-normal temperatures.

Precipitation/Snowfall: Southeast Alaska might see below-normal precipitation, potentially impacting snow conditions at ski areas. However, northwestern Alaska is favored to receive above-normal precipitation.

Overall Outlook

The anticipated development of a weak La Niña influences the winter forecast. This typically brings wetter conditions to the Northwest and northern tier of the United States, which could benefit many ski resorts in these areas. However, the Southwest and southern regions may face drier conditions, potentially leading to less favorable snow conditions.

Here’s the discussion in full from the NOAA, followed by outlook maps for the season:

Prognostic Discussion for Long-Lead Seasonal Outlooks NWS Climate Prediction Center College Park MD 830 AM EDT Thu Sep 19 2024 SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS El Niño Southern Oscillation (ENSO)-neutral conditions are present, as equatorial sea surface temperatures (SSTs) are near-to-below average in the central and eastern Pacific Ocean. During the last four weeks, negative SST anomaly changes prevailed across the western and central equatorial Pacific Ocean. As such, a La Niña Watch is in effect, with La Niña favored to emerge in September-November (SON) (71% chance) and is expected to persist through January-March (JFM) 2025. However, chances of a moderate to strong La Niña are currently less than 50% through the Fall and Winter. ENSO-neutral conditions are favored to re-emerge by the February-April (FMA) 2025 season. The October-December (OND) 2024 temperature outlook favors above normal temperatures for the southern two-thirds of the Contiguous United States (CONUS), the eastern third of the CONUS, and northwestern Alaska. The largest probabilities (greater than 60 percent) of above normal temperatures are forecast across much of the Southwest and parts of the Rio Grande Valley and southern High Plains. Conversely, a weak tilt toward below normal temperatures is indicated for Southeast Alaska, parts of the southern Mainland, and parts of the Alaska Peninsula. The OND 2024 precipitation outlook depicts enhanced probabilities of below-normal precipitation amounts across much of the south-central and southwestern CONUS as well as most of Southeast Alaska and parts of the southern Mainland. The greatest chances (greater than 50 percent) of below-normal precipitation are forecast for much of the Rio Grande Valley and much of the Southern High Plains, where probabilities of below exceed 50 percent. Above-normal precipitation is more likely for the northwestern CONUS, the Great Lakes and Northeast, and much of northwestern Mainland Alaska. Equal chances (EC) are forecast for areas where probabilities for each category of seasonal mean temperatures and seasonal accumulated 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 during August 2024, with near-average sea surface temperatures (SSTs) observed across most of the equatorial Pacific Ocean. The weekly Niño indices did not change substantially during the month, with the latest weekly index values varying between +0.1°C (Niño-4) and -0.2°C (Niño-3.4, 3, and 1+2). Below-average subsurface temperatures were also similar to those in early August. Negative temperature anomalies continued to dominate across most of the subsurface equatorial Pacific Ocean. Low-level wind anomalies were easterly over most of the equatorial Pacific, and upper-level wind anomalies were easterly over the east-central Pacific. Convection was slightly enhanced over parts of Indonesia and was near average near the Date Line. Both the Southern Oscillation index and the equatorial Southern Oscillation indices were positive. Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral. Since late August, the Real-time Multivariate Madden Julian Oscillation (RMM) index observations show the Madden Julian Oscillation (MJO) signal has struggled to fully propagate out of the Maritime Continent. The signal has regained amplitude in the past week, but still has shown little sign of eastward propagation. Dynamical models have come into better agreement favoring an eastward propagating Western Pacific MJO event during the next few weeks, with several ensemble members maintaining the signal with a moderate to high amplitude as it enters the Western Hemisphere. Upper-level velocity potential forecasts from the models remain somewhat mixed in regards to the evolution and strength of the MJO, with the European Centre for Medium-Range Weather Forecasts (ECMWF) favoring more robust activity heading into October. Despite some uncertainties, conditions are expected to become more conducive for tropical cyclone development over the tropical Americas. PROGNOSTIC DISCUSSION OF SST FORECASTS The most recent International Research Institute (IRI) for Climate and Society plume forecast of the Niño-3.4 SST index predicts a weak and a short duration La Niña, as indicated by the Niño-3.4 index values less than -0.5°C. This month, the latest North American Multi-Model Ensemble (NMME) guidance was relied upon, which predicts La Niña to emerge in the next couple of months and continue through the Northern Hemisphere winter. The continuation of negative subsurface temperatures and enhanced low-level easterly wind anomalies supports the formation of a weak La Nina. In summary, La Niña is favored to emerge in SON (71% chance) and is expected to persist through JFM 2025. PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS Dynamical model forecasts from the NMME, the Coupled Forecast System Model Version 2 (CFSv2) , the Copernicus (C3S) multi-model ensemble system were used extensively for the first six leads when they are available, as was the objective, historical skill weighted consolidation and Calibration, Bridging, and Merging (CBaM) guidance, that combines both dynamical and statistical forecast information. Additionally, the official ENSO forecast depicts probabilities of La Niña that are higher than climatological probabilities through the upcoming winter. This anticipated La Niña signal played a role in the construction of these outlooks. However, the anticipated La Niña is likely to be weak, which may temper some of its impacts. At later leads, decadal trends in temperature and precipitation were increasingly relied upon in creating the seasonal outlooks. PROGNOSTIC DISCUSSION OF OUTLOOKS - OND 2024 TO OND 2025 TEMPERATURE Above-normal temperatures are favored throughout a majority of the southern and eastern CONUS and northwestern Alaska during OND. Conversely, below normal temperatures are more likely for much of southern Alaska. EC of below, near, or above normal temperatures are forecast for the northwestern and north-central CONUS. This EC area is due to weak or conflicting signals among temperature tools. Probabilities of above-normal temperatures are reduced slightly relative to last month across parts of the north-central CONUS to the Southeast due to a trend toward a colder solution in the temperature consolidation coupled with a low confidence EC forecast for the month of October across many of these areas. Above normal temperatures remain likely (greater than 60 percent) across the Southwest, due to good agreement among both dynamical and statistical guidance. The area of favored above-normal temperatures are expanded to include much of California due to a stronger signal in this month’s consolidation. Guidance is similar across much of Alaska relative to last month. Increased probabilities of below-normal temperatures are indicated for southern parts of the state, aided in part due to an anticipated cooler than normal October and the potential impacts of La Niña, especially later in the season. Above-normal temperatures remain favored for northwestern Alaska due to recent trends and observed below normal sea ice extent. From November-December-January (NDJ) through JFM, impacts from the predicted La Niña continue as above normal temperatures are favored across the Southern CONUS and the Eastern Seaboard while enhanced below normal temperature probabilities persist across southeastern Alaska and expand northwestward toward the central Mainland and southeastward to the northwestern and north-central CONUS by December-January-February (DJF). By FMA, the potential impacts of La Niña begin to wane as ENSO-neutral conditions become increasingly likely. Below-normal temperatures favored for much of Alaska disappear by April-May-June (AMJ) and from all of the CONUS by May-June-July (MJJ). Thereafter, the forecast pattern increasingly reflects trends with above-normal temperatures generally favored across most of the southern and eastern CONUS next spring, expanding to most of the West Coast by the Summer and to the remainder of the CONUS next fall. Across Alaska, a quick transition toward milder than normal conditions is predicted with above-normal temperatures favored for almost the entire state by late Spring and through the Summer and much of next Fall. PRECIPITATION Model and statistical guidance remains generally consistent from previous months depicting elevated probabilities of below normal precipitation for much of the southern CONUS, and increased chances of above normal precipitation for the Pacific Northwest, Great Lakes, and parts of the Northeast during OND. However, despite dynamical models favoring below-normal precipitation in the Southeast, EC is indicated due to the potential for tropical activity early in the season and increased probabilities for a wet October. Precipitation consolidation guidance has trended wetter across the northern tier of the CONUS, resulting in an expansion of elevated above-normal precipitation probabilities across parts of the northern High Plains and Great Lakes relative to last month. However, due to a lack of dynamical model support, EC remains forecast across most of the north-central CONUS. A slight tilt toward below-normal precipitation is indicated for parts of southeastern Alaska, based primarily on dynamical model guidance from the CFSv2 and a dry signal derived from natural analogs to the current ENSO state. Conversely, above-normal precipitation is favored for northern and western Alaska due to trends with support from C3S and CBaM output.EC is indicated for most of the rest of the forecast domain as signals for the various dynamical and statistical tools are too weak or conflicting to issue a forecast with a sufficient degree of confidence. As we progress further into late fall and through the winter, dynamical and statistical guidance persist with a dry signal across the southern CONUS and southeastern Alaska, consistent with a La Niña signature. An expansion of enhanced above normal precipitation probabilities is noted across the northern CONUS, peaking in coverage during the winter months. A wet signal is also favored to persist across northwestern Alaska and expand southward from the Great Lakes across much of the east-central CONUS later in the winter through the Spring, consistent with dynamical model guidance and trends . Thereafter, trends become the dominant factor with increased chances of above normal precipitation generally indicated across parts of the Northeast and parts of the Mid-Atlantic in the Summer and shifting southward along the Mid-Atlantic Coast by early Fall. Conversely, trends favor a dry pattern for much of the Southwest during early spring shifting northward to the Northern Rockies by late Spring, with increased chances of dryness for parts of the Northern and Central Plains next summer as well. As dryness potentially expands into the northern and central Plains next summer, a corresponding weak tilt toward above normal precipitation makes a brief appearance for parts of the Southwest Monsoon Region during June-July-August (JJA) and July-August-September (JAS). Thereafter, the area of enhanced probabilities of below-normal precipitation begins to recede over the west-central CONUS, based primarily on combined statistical guidance from trends and ENSO. By next Fall, a small area of favored above-normal precipitation appears in the northwestern CONUS due to combined statistical guidance from trends and ENSO. Above-normal precipitation is also favored for much of northern Alaska late Spring and early Summer and shifting to southeastern Alaska by the Fall, consistent with trends . FORECASTER: Scott Handel

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