312 FXUS21 KWNC 161921 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EST January 16 2026 SYNOPSIS: A developing area of mid-level low pressure over south-central Canada and the western contiguous U.S. (CONUS) increases the risk of multiple weather related hazards including anomalously cold winter temperatures along the northern tier of the CONUS, and high wind and high elevation snow over the Interior West. Surface low development in the lee of the Rockies may potentially trigger heavy precipitation and low elevation heavy snowfall across portions of the Midwest during the period. In the central Pacific, there is an increased chance of Kona low development potentially impacting parts of Hawaii, with enhanced precipitation and occasional high wind gusts HAZARDS Moderate risk of much below normal temperatures for much of the Northern Plains, Upper Mississippi Valley, and western Great Lakes, Sat-Mon, Jan 24-26. Slight risk of much below normal temperatures for portions of the Northern Intermountain, Northern Rockies, Northern and Central Plains, Upper and Middle Mississippi and Ohio Valleys, Great Lakes, Mid-Atlantic, and Northeast, Sat-Wed, Jan 24-28. Slight risk of heavy snow for portions of the Great Lakes and Central Appalachians, Sat-Fri, Jan 24-30. Slight risk of heavy snow for the higher elevations of the Northern Great Basin and Northern Rockies, Sat-Wed, Jan 24-28. Slight risk of heavy snow for portions of the Northern and Central Plains, Mississippi and Ohio Valleys, Great Lakes, Mid-Atlantic, and the Northeast, Sat-Mon, Jan 24-26. Slight risk of high winds for much of the Interior West and western High Plains, Sat-Wed, Jan 24-28. Slight risk of heavy precipitation for parts of the Mississippi, Ohio, and Tennessee Valleys, Appalachians, and Southeast, Sat-Mon, Jan 24-26. DETAILED SUMMARY FOR MONDAY JANUARY 19 - FRIDAY JANUARY 23: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR SATURDAY JANUARY 24 - FRIDAY JANUARY 30: Model ensembles are in good agreement with the synoptic setup at the outset of week-2, with fairly amplified mid-level ridging over the Bering Sea and Alaska, and a broad trough downstream with negative 500-hPa height anomalies stretching all along the U.S.-Canada border, and weak positive height anomalies over the Southeastern U.S. However, as the forecast period progresses solutions between the GEFS and ECMWF diverge quite a bit with respect to the synoptic evolution over the North Pacific and West Coast, with the GEFS building a stronger ridge centered on the coast, while the ECWMF builds a weaker ridge a bit further to the east. The models are in much better agreement further east, favoring a persistent trough centered over eastern Canada, which paired with the upstream ridge provides a good setup for an incursion of very cold Arctic air into the CONUS east of the Rockies, along with the potential for hazardous precipitation. Over the northern tier of the CONUS, strong mean surface high pressure and accompanying Arctic air is favored to descend southward from the Canadian Prairies early in week-2, and the . Probabilistic Extreme Tools (PETs) from the GEFS and ECMWF have come into much better agreement with regard to the southern extent of the cold potential, there is still substantial spread with regard to just how far the coldest air will push southward. While the GEFS limits 40% chances of minimum temperatures falling below the 15th percentile much closer to the Canadian border compared to ECMWF, it is notable that the 20% chances in the GEFS extend well to the south into the Southern Plains and Mississippi Valley. This represents continued support and consistency with the southern reach of anomalous cold in the ECMWF PET where the potential for hazardous cold is indicated. A slight risk area of much below normal temperatures is maintained over much of the Northern and Central Plains, as well as the Mississippi and Ohio Valleys, valid Jan 24-28, with a shorter duration as the mid-level troughing shifts eastward by middle of week-2 and ridging builds over the West Coast, resulting in weaker signals from the PETs.. The coldest signals in the PETs remain established across the Upper Midwest and northern Great Lakes, with the ECMWF becoming supportive of high risk hazard designation, now depicting 50-60% chances for minimum temperatures falling below the 15th percentile. However, the warmer GEFS shows a more limited area with 40% chances, so a moderate risk of much below normal temperatures remains issued for Jan 24-26, and no high risk hazard is issued. Despite this weaker signal, the GEFS has been trending colder, and the uncalibrated ECMWF continues to depict 30-40% chances for wind chill values to fall below -40deg F. therefore the moderate risk of much below normal temperatures valid Jan 24-26 has been expanded southward and westward to include more of the Northern Plains and Upper Midwest. Due to the potential for one or more shots of cold air over the northern tier, the combination of pure lake effect snow and/or lake enhanced snow over the Great Lakes, supports the continuation of a slight risk of heavy snow downwind of the Lakes and into the Central Appalachians for all of week-2. Model guidance continues to indicate surface low development in the lee of Rockies at the outset of week-2 with moist return flow from the Gulf of America increasing the likelihood of heavy precipitation, however the greatest potential for heavy precipitation is beginning to shift into the week-1 period. Good agreement exists in daily precipitation tools depicting enhanced totals over the Ohio and Tennessee Valleys early in the period. Signal from the PETs has reduced somewhat, but continues to depict broad coverage of at least 20% chances of 3-day precipitation to exceed the 85th percentile early in the forecast period. The moderate risk of heavy precipitation is removed in the updated outlook, but the broader slight risk area remains posted for Jan 24-26. With the aforementioned anomalous cold air expected to dig southward from the northern tier of the CONUS, any enhanced moisture being entrained into a frontal system is expected to be conducive for accumulating snowfall along the backside of the tracking surface low. Although the uncalibrated ECMWF and GEFS are not quite supportive of snowfall amounts reaching hazards criteria, a slight risk of heavy snow is posted for much of the Midwest for Jan 24-26 based on the predicted baroclinicity in the region and several deterministic solutions. Relative to yesterday, this slight risk area is also expanded further to the south in the Plains and Mississippi Valley based on the aforementioned southerly solutions of the anomalously cold air, with coverage also including the Ozarks and Southern Appalachians as well as much of the Northeast based on increased snowfall signals associated with the storm track. Mixed wintry precipitation is possible along/near the interface of the slight heavy precipitation and heavy snow risk areas. Based on continued agreement among the GEFS, ECMWF, and Canadian ensembles in regards to the development of negative height departures over the Interior West, slight risks of high elevation heavy snow and high winds remain posted for the region, valid through Jan 28 before mid-level heights begin to build across the western CONUS later in week-2. Both the Snow Water Equivalent (SWE) and wind PETs maintain increased chances for values exceeding the 85th percentile through the middle of the period. Across the Pacific Northwest, the ECMWF Integrated Vapor Transport (IVT) tool depicts an increasing Atmospheric River (AR) potential late in week-2 which is supported in the ECMWF PET with 20% chances of 3-day amounts exceeding the 85th percentile and 2 inches from northern California to western Washington during days 12-14. The GEFS IVT is beginning to show some signal, but the GEFS PET is void of any precipitation threat. As a result, no associated hazards are posted, but this potential will be reassessed as any AR related risks may come into better focus. No hazards are issued over Alaska. The strong ridging over the north Pacific and into the Mainland remains favorable for the above-normal temperatures with a tilt in the odds for above-normal precipitation. Should the mid-level ridge axis remain amplified and shift westward, this would allow for more cross polar flow with colder temperatures developing across the Mainland and any temperature trends will continue to be monitored. With persistent troughing favored underneath strong ridging forecast over the northern Pacific, one or more Kona lows may develop and impact parts of Hawaii during week-2. There is considerable uncertainty regarding the location, evolution, and magnitude of any hazardous conditions, but there is general agreement that precipitation over most of the state will be above normal for week-2. Potential impacts include periods of heavy precipitation, high winds, and significant waves. FORECASTER: Danny Barandiaran $$