836 FXUS21 KWNC 151819 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT October 15 2026 SYNOPSIS: Multiple models depict a robust storm developing in the lee of the Rockies late in week-1 which has the potential to drop heavy precipitation on portions of the Plains and Mississippi Valley early in week-2, especially in southern parts of the region. Farther west, precipitation from this storm is expected to coincide with below normal temperatures, increasing the potential for heavy snow across much of the Rockies, especially the higher elevations. As this system develops and pushes eastward, periods of high winds are possible over a large part of the central Contiguous U.S. (CONUS). HAZARDS Slight risk of heavy precipitation for much of the southern halves of the Great Plains and Mississippi Valley, Fri-Sat, Oct 23-24. Slight risk of heavy precipitation for North Dakota and northern Minnesota, Fri, Oct 23. Slight risk of high winds for most of the Plains and a large portion of the Mississippi Valley, Fri-Sat, Oct 23-24. Slight risk of heavy snow for much of the Rockies, Fri-Sat, Oct 23-24. DETAILED SUMMARY FOR SUNDAY OCTOBER 18 - THURSDAY OCTOBER 22: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR FRIDAY OCTOBER 23 - THURSDAY OCTOBER 29: Models continue to depict a 500-hPa trough over or near the southwestern CONUS, which is expected to induce lee cyclogenesis over the High Plains starting late in the week-1 period and continuing for the first few days of week-2. The most likely location for a surface low to spin up is over the Central/Northern High Plains, according to the ECENS, GEFS, and CMCE ensembles. This system has the potential to bring a variety of hazards to large portions of the central CONUS. The combination of shortwave energy and associated moisture wrapping around the base of the trough, and tropical moisture streaming up from Mexico (from what is currently Tropical Storm Simon and/or Hurricane Trudy over the eastern Pacific) is predicted to result in widespread heavy snowfall (4-6 inches or more) across a large portion of the Rockies. This is indicated by the 6z deterministic GFS run, the GEFS SWE tool, and uncalibrated snowfall amounts depicted by the ECENS and GEFS model ensembles, and overlaps the colder air that is forecast to be drawn in behind the departing storm system. Therefore, a slight risk of heavy snow is forecast for much of the higher elevations of the Rockies, from Oct 23-24. As the surface low pressure center deepens and moves across the Northern Plains and into Manitoba, the associated cold front is predicted to advance out over the Plains to its south. Two slight risk areas of heavy precipitation are designated. The northern area includes North Dakota and northern Minnesota, accompanying the surface low pressure center, and is valid for Oct 23. The second southern area includes much of the southern halves of the Plains and Mississippi Valley, valid Oct 23-24, which is closer to the supply of low-level Gulf and Atlantic moisture, but also includes moisture from the eastern Pacific. These precipitation areas depict where the Probabilistic Extremes Tool (PET) tools and uncalibrated precipitation forecasts generally indicate close to an inch of precipitation over a 3-day period and amounts in excess of the 85th climatological percentile. Surface pressure gradients associated with this system start off quite strong, favoring enhanced winds over much of the country's midsection. The PETs from the ECENS and GEFS reflect this, indicating at least a 20% chance of 3-day maximum winds exceeding the 85th percentile over portions of the northern and central CONUS early in the forecast period, with some areas exceeding 25 mph. The 06z and 12z deterministic GFS model runs predict wind speeds of about 35 mph just west and north of the low pressure center as it tracks across eastern Colorado and western Nebraska. A broad area is therefore highlighted with a slight risk of high winds, posted for days 8-9 (Oct 23-24) from the eastern foothills of the Rockies through portions of the Mississippi Valley, based on pattern recognition, and where tools modestly highlight increased chances for high winds at certain locations and times. The risk declines as the surface system pulls eastward. Model solutions depict persistent troughing at the surface and aloft over Alaska and adjacent areas through much of the forecast period. Strong winds and heavy precipitation are expected to affect southcentral and Southeast Alaska at times, but stormy weather is not unusual in these areas during early autumn, and normal precipitation approaches one inch per day in a few spots. Since hazards thresholds are not likely to be exceeded, no associated hazards are posted at this time for Alaska. FORECASTER: Anthony Artusa $$