516 FXUS07 KWBC 312050 PMD30D Prognostic Discussion for Monthly Outlook NWS Climate Prediction Center College Park MD 300 PM EST Wed Dec 31 2025 30-DAY OUTLOOK DISCUSSION FOR JAN 2026 The January 2026 Monthly Temperature and Precipitation Outlooks are updated considering input from the Climate Prediction Center (CPC) Extended Range and Subseasonal Outlooks, and shorter-term (days 1-7) forecasts of precipitation from the Weather Prediction Center (WPC). Dynamical model guidance from GEFSv12, ECMWF, and CFSv2 for the 6-10 day, week 2, and weeks 3-4 periods, recent monthly CFSv2 forecasts of temperature and precipitation, and experimental monthly forecasts of temperature and precipitation from extended runs of the GEFSv12 and ECMWF models are utilized. Impacts from background climate states, such as the El Nino Southern Oscillation (ENSO) are considered. La Nina is currently present, with equatorial sea surface temperatures (SSTs) remaining below average across the central and east-central Pacific Ocean and the latest weekly Nio 3.4 index reaching -0.7 degrees C. While these conditions have persisted since September 2025 and remain in weak La Nina territory, a transition to ENSO-neutral is most likely during the January-February-March 2026 period with a 68% probability. The Madden-Julian Oscillation (MJO) is expected to remain weak and disorganized through early January, as dynamical models favor little to no reemergence of coherent subseasonal activity. Most forecasts depict the MJO within the unit circle at low amplitude, and any potential renewed activity later in the month would likely occur over the Western Pacific. Given this uncertainty and predicted weak MJO signals, the MJO is not a significant contributor to the updated forecast. While La Nina influence is expected, the event's weakness allows teleconnections to be potentially overshadowed by intra-monthly variability, increasing forecast uncertainty. A complex, transient, and uncertain height pattern is forecast during January. Although dynamical model ensemble means show good agreement for early January, with troughing over Alaska, the West Coast, and the East, and weak positive heights over the central Contiguous United States (CONUS), model solutions quickly diverge. By mid-month, ridging develops over Alaska and the East with troughing over the West, and the pattern is forecast to shift eastward. Week 3-4 dynamical model forecasts were previously more uncertain, but recent models have aligned to favor ridging over Alaska and the western U.S. and troughing over the northern tier and New England (with some differences in position and strength of height anomalies between models). Overall, the transient nature of this pattern adds significant uncertainty to the January outlook, particularly for precipitation. Much of the CONUS is forecast to experience above-normal temperatures in early January before a transient mid-month, leading to ridging in the West and troughing in the Northeast by late January, which may bring cooler temperatures to the North and East. The January 2026 Monthly Temperature Outlook depicts a broad area of favored above-normal temperatures across the Western, Southern, and Southeastern U.S., with the highest probabilities over the Southwest and Southern Plains. Conversely, below-normal temperatures are favored for the Great Lakes, Northeast, and much of central, eastern, and southeastern Alaska. Equal-chances (EC) of above, below, and near-normal temperatures stretch from the Northern High Plains through the Central Plains and into the Mid-Atlantic. Compared to the initial outlook, above-normal temperature probabilities are expanded to cover the western third of the CONUS. Despite the mid-month transient phase that may bring milder conditions to the West, strong monthly model agreement supports enhanced probabilities for above-normal temperatures. Over the Southeast, above-normal temperature probabilities are weakened and compressed southward as updated guidance suggests late-month troughing that may bring cooler temperatures to the North and East, and potentially further South, though the position of the transition between above-normal and below-normal is somewhat uncertain. Below-normal probabilities are expanded eastward toward the Northeast given troughing in the second half of January. Over Alaska, a weak below-normal signal is maintained based on monthly dynamical models, despite a mid-month period of ridging that may bring temporary warmth. The January 2026 Monthly Precipitation Outlook favors above-normal precipitation from the Northwest and Northern Rockies to the Southwest coast, with below-normal conditions over western Texas and the Southeast. For Alaska, above-normal precipitation is indicated for central regions, while the southern coast leans below normal. While there are some regions where probabilities are higher and reach 50 to 60% chances, probabilities are low and broad areas of EC are depicted as the Precipitation Outlook is comparatively more uncertain than the Temperature Outlook. While early-month forecasts from the CFSv2 showed strong La Nina-like signals for monthly precipitation, recent guidance has become more uncertain as the transient pattern for January emerges. The first half of January favors above-normal precipitation for much of the U.S., but the monthly mean as a whole remains less certain due to the weak La Nina and intra-monthly variability. Despite the uncertainty, the above-normal precipitation probabilities, consistent with typical La Nina teleconnections, are maintained in the updated Outlook given consistency across the month of January in models, as well as in monthly dynamical model forecasts. A weak tilt toward above-normal precipitation is extended into southern California and western Arizona given above normal precipitation for this region in WPC forecasts for days 1-7, and strong above-normal probabilities in CPC 6-10 and 8-14 day Outlooks that may be enough to tilt the month toward above-normal overall, as well as lower precipitation climatologies. Below-normal probabilities in the Southwest and Texas are significantly reduced spatially due to forecasted above-normal precipitation in early January and inconsistent signals in models throughout the month. Below-normal precipitation probabilities are maintained in the Southeast, but modified slightly based on updated model forecasts. Notably, the La Nina-associated above-normal precipitation previously indicated over the Great Lakes and Ohio Valley has been removed in favor of EC. Monthly models now suggest a below-normal tilt for this region, however, early month weakly above-normal precipitation probabilities, the potential for individual storms, and lake-effect snow precludes a definitive below-normal forecast. Finally, a tilt toward below normal precipitation is maintained over the southern coast of the Mainland and Southeast Alaska due to decadal trends, La Nina, and dynamical model support. Models are mixed for the Mainland, but indicate a weak tilt toward above normal precipitation over the center of the state. ****************************************************************************** ***** Previous mid-month discussion below ***** ****************************************************************************** The January 2026 Monthly Temperature and Precipitation Outlooks are constructed by considering the La Nina base state, as well as dynamical climate models and integrated statistical tools. Equatorial sea surface temperatures (SSTs) remain below average across the Central and East-Central Pacific Ocean, with SST departures in the Nio 3.4 region reaching -0.7 degrees C. These below-average SSTs have persisted since September 2025, and we are firmly within weak La Nina territory. Furthermore, atmospheric anomalies over the tropical Pacific Ocean are consistent with La Nina, consequently, we expect La Nina teleconnections during January 2026. In contrast, the Madden-Julian Oscillation (MJO) remains more uncertain, as models suggest destructive interference from a strong Kelvin Wave may hinder its re-emergence. The January 2026 Outlooks are primarily shaped by the La Nina background state, dynamical climate models, local SST anomalies, sea ice, and land surface conditions (where appropriate). An experimental multiple linear regression (MLR) tool which estimates the influences of the El Nio Southern Oscillation (ENSO), MJO, and decadal trends is utilized, as is a consolidation that includes influence of ENSO, decadal trends, and calibrated North American Multi-Model Ensemble (NMME) output. Weeks 3-4 forecasts from the Global Ensemble Forecast System version 12 (GEFSv12), the European Centre for Medium-Range Weather Forecasts (ECMWF), and Coupled Forecast System version 2 (CFSv2) models that cover the period to about mid-January were also considered. Impacts from the MJO, along with land surface variables such as snow cover, will be re-evaluated at the end of the month for the updated version of this Outlook. The January 2026 Temperature Outlook features increased chances of below-normal temperatures for much of Mainland Alaska, all of Southeast Alaska, and stretching from the Northern Rockies to the Upper Mississippi Valley. Above-normal temperatures are more likely for the Southern Tier of the Contiguous United States (CONUS), covering much of the Southwest, Four Corners, Southern Plains, Southeast, and Mid-Atlantic. Equal Chances (EC) of above-, near-, and below-normal temperatures are forecast for Western and Northern Alaska, the Northwest, much of Northern and Central California, the Central Plains, Great Lakes, and New England. A mid-level height pattern typical of La Nina has been established and is forecast to persist into at least mid-January per week 3-4 dynamical models. A blocking high has been a significant feature over the North Pacific and Aleutians, with downstream mid-level low pressure residing over eastern Alaska and portions of the Northwest. Above-average mid-level heights cover much of the Southern Tier and Eastern CONUS. The pattern reflected in the January 2026 Temperature Outlooks is consistent with La Nina expectations, though it has been modified based on available guidance. Probabilities for below-normal temperatures are highest over Southeast Alaska and adjacent areas of southeastern Mainland Alaska, reaching 50 to 60%, given consistency among various tools. Monthly forecasts for Alaska from NMME, C3S, and CFSv2 align with shorter-term week 3-4 forecasts in favoring these cooler conditions. Probabilities are also enhanced, reaching 50 to 60%, over Southern New Mexico, Texas, Louisiana, and Florida. This is driven by strong agreement between dynamical models and higher-probability signals in the shorter-term week 3-4 forecasts. While decadal trends and certain tools like the CFSv2 tilt toward above-normal temperatures over the Northern Coast of Alaska, EC is indicated because early to mid-January is forecast to be at least slightly below-normal, and sea ice is present along the coast. Similarly, while La Nina often brings below-normal temperatures to the Northern Tier of the CONUS, sometimes including the Northwest, the NMME, C3S, and CFSv2 monthly outlooks are generally above-normal along the western third of the country. Furthermore, should the MJO become more coherent, it could introduce more variability, such as cooler temperatures in the West, though this influence is currently highly uncertain. EC is thus favored over much of the West and Northwest as we cannot discount the possibility of cooler air extending further West and South. Similarly, models are warm over the central CONUS, however, it is not unheard of during January and La Nina years to see cold air intrusions reach further South, as such we tilt toward EC over the central CONUS and will re-assess in the monthly update. In addition, uncertainty is high in the central CONUS in a consolidation of statistical tools (which include influence of trend and ENSO), and NMME, which adds to our uncertainty here. Finally, guidance was mixed and inconsistent over the Great Lakes and New England, which also led to a tilt toward EC. Because this La Nina is currently weak, increased variability and uncertainty are possible for some regions, which also supports EC. While some regions in the January Temperature Outlook remain uncertain due to the variability of weak La Nina teleconnections, the precipitation pattern is more consistent across various tools, closely resembling the expected La Nina signature. Above-normal precipitation is favored for the Northwest, Northern Rockies, Great Lakes, and much of the Ohio and Middle Mississippi Valleys. Western Alaska also leans above-normal. Drier conditions are more likely across the Southwest, Southern Plains, and much of the Southeast. A weak tilt toward below-normal precipitation is also indicated over much of the southern coast of Mainland Alaska and all of Southeast Alaska. While the NMME and C3S favor below-normal precipitation up much of the West Coast, reaching into the Northwest in some models, recent forecasts from CFSv2 tilt above-normal for the month of January over the Northwest. Moreover, week 3 and week 4 dynamical models forecast at least 40 to 50% chances of above-normal precipitation over the Northwest. As such, we have minimized the region of below-normal precipitation forecast by some of the multi-model ensembles, confining it more to southeastern California. Given the uncertainty regarding how far South the moisture may reach, much of California is designated as EC. Above-normal precipitation is also indicated for the Great Lakes, Ohio Valley, and parts of the Middle and Lower Mississippi Valleys and the Tennessee Valley , which is a typical La Nina signature. These two areas of above-normal precipitation are connected by a weak (33 to 40%) chance of above-normal precipitation that is supported by the NMME and C3S. The below-normal precipitation favored over the southern tier is consistent with models and La Nina, though some uncertainty exists over parts of Texas and Louisiana as it is currently unclear how far south any above-normal precipitation might reach. Finally, over Alaska, decadal trends and La Nina support the forecast for below-normal precipitation over the southern coast of the Mainland and Southeast Alaska, while dynamical models like the NMME, C3S, and CFSv2 favor above-normal precipitation for much of the western Mainland. FORECASTER: Johnna Infanti The climatic normals are based on conditions between 1991 and 2020, following the World Meteorological Organization convention of using the most recent 3 complete decades as the climate 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. The next monthly outlook...for Feb ... will be issued on Thu Jan 15 2026 These outlooks are based on departures from the 1991-2020 base period. $$