763 FXUS21 KWNC 091747 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT October 09 2026 SYNOPSIS: Renewed mid-level low pressure favors the return of anomalous cold air over the eastern contiguous U.S. (CONUS), supporting increased chances for much below normal temperatures and first fall frosts and/or freezes over parts of the Northeast, northern Mid-Atlantic, and Great Lakes. In the wake of the predicted frontal system, a more tranquil pattern is expected, reducing the risk of additional weather related hazards later in the week-2 period. Over Alaska, weak cyclonic flow over the Gulf of Alaska supports above-normal precipitation and periods of high winds for parts of the Southern Mainland and Southeast, though conditions are expected to remain below hazard thresholds. HAZARDS Slight risk of much below normal temperatures for Northeast, and parts of the Great Lakes, Appalachians, and Mid-Atlantic, Sun-Mon, Oct 18-19. DETAILED SUMMARY FOR MONDAY OCTOBER 12 - FRIDAY OCTOBER 16: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR SATURDAY OCTOBER 17 - FRIDAY OCTOBER 23: The hazards perspective largely remains on track since yesterday. The latest 0z guidance from the ECENS and GEFS ensembles continues to feature 500-hPa troughing shifting eastward and digging over the eastern U.S., with an amplified ridge axis centered throughout much of the western CONUS and western Canada upstream. At the surface, a mean low pressure system and a large frontal boundary is expected to sweep across much of the eastern two thirds of the CONUS, with a fairly strong mean surface high descending from the Canadian Prairies late next week. The extent of cold air advection favored is fairly impressive, where there is good ensemble agreement featuring double digit 24-hour temperature drops from the Southern Plains to the Northeast early in the period. While this looks to bring a rush of cold air to promote first fall frost and/or freezes for the higher latitudes of the CONUS early in the period, the drier air looks to abate any heavy precipitation risks, and temperatures are also favored to moderate fairly quickly as much of the anomalous high surface pressure looks to weaken and settle over much of the central and eastern U.S. Concurrently, expanding mid-level positive height departures are favored aloft, and the pattern overall appears to be quite tranquil and free of hazardous weather risks for much of the CONUS later in the week-2 period. With renewed northeasterly flow aloft favored downstream of the amplified ridge axis, a slight risk of much below normal temperatures is posted over northeastern CONUS for Oct 18-19. While Probabilistic Extreme Tools (PETs) from the GEFS and ECENS show strongest signals for minimum temperatures falling below the 15th climatological percentile further south across Southern Plains, there is a large coverage of 20% chances that well delineate the frontal boundary extending into the northeastern CONUS, where chances for subfreezing temperatures are highest. Climatologically, first fall freezes generally occur between late September through mid-October for this part of the country, though any temperatures dipping to near freezing levels may still trigger cold temperature advisories for areas that have not experienced their first frost and/or freezes early in the period. For precipitation, the slight risk of heavy precipitation is discontinued today based on a reduction of signals in the raw and calibrated probabilistic tools from both the GEFS and ECENS. Some enhanced precipitation amounts may linger along the frontal boundary over the eastern U.S., though it appears the highest, potentially heavy amounts will have timed off by the start of week-2. Despite the predominately drier conditions favored, it is worth noting that any additional precipitation amounts during week-2 may worsen already saturated ground conditions and trigger localized flooding following heavy rainfall from Hurricane Isaias and its remnants over many parts of the southeastern CONUS during week-1. PETs also show increased signals for wind speeds exceeding the 85th percentile across parts of the eastern U.S., though wind speeds are expected to remain below hazard thresholds with the mean surface high weakening in the wake of the frontal boundary. Over Alaska, much of the troughing favored late in week-1 remains favored to deamplify by the outset of week-2. While there remains some weakly residual cyclonic flow over the Gulf of Alaska to promote unsettled weather, tools continue to become less supportive of precipitation and winds exceeding hazard thresholds, and the slight risks of heavy precipitation and high winds are discontinued in the updated outlook. Given some potential for additional tropical cyclone activity in the western Pacific during week-2, any recurving tropical disturbances becoming absorbed in the extratropical westerlies and amplifying the mid-level pattern over the northern Pacific will continue to be monitored. FORECASTER: Nick Novella $$