156 FXUS21 KWNC 111814 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT October 11 2026 SYNOPSIS: Cold surface high pressure is expected over the eastern Contiguous U.S. (CONUS) early in week-2, increasing the chances for much below normal temperatures in parts of the Northeast, upper Mid-Atlantic, and Appalachians the first day of the period (Oct 19). The first frosts and/or freezes of the season are possible in parts of coastal and southern New England, the northern Mid-Atlantic, and much of the Appalachians before temperatures quickly moderate. Farther west, heavy rainfall is possible across the central and western Gulf Coast region, where a southerly fetch of moist tropical air may interact with a lingering frontal boundary. Over Alaska, mid-level troughing and cyclonic flow is expected much of week-2 in the Gulf of Alaska, supporting periods of above-normal precipitation and high winds from the south-central Mainland through Southeast Alaska, but conditions are expected to remain below hazard thresholds. HAZARDS Slight risk of much below normal temperatures for southern New England, parts of the northern Mid-Atlantic, and much of the Appalachians, Sun, Oct 19. Slight risk of heavy precipitation along the central and western Gulf Coast and adjacent sections of eastern Texas and central Louisiana, Sun-Thu, Oct 19-23. DETAILED SUMMARY FOR WEDNESDAY OCTOBER 14 - SUNDAY OCTOBER 18: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR MONDAY OCTOBER 19 - SUNDAY OCTOBER 25: The hazards perspective largely remains on track since yesterday. As week-2 begins, the latest 0z European ensemble (ECENS) and GEFS means show a 500-hPa trough moving away from the northeastern CONUS, with an upstream 500-hPa ridge extending from the western and central CONUS into southern Canada. Between these features, a cold surface high is expected across the eastern CONUS, accompanied by subnormal temperatures. This has the potential to bring the first frosts and/or freezes of the season to some of the higher latitudes of the eastern CONUS, and a slight risk for much below normal temperatures is posted in these regions for day 8 (Oct 19), avoiding parts of Upstate New York and interior New England where near- to below-freezing temperatures have already occurred. ECENS Probabilistic Extremes Tool (PET) shows chances for minimum temperatures below the 15th climatological percentile range from 20 percent along the spine of the Appalachians to more than 40 percent across central and eastern Maine. The ECENS PET also shows chances for subfreezing temperatures topping 20 percent in many areas from West Virginia and western Virginia northward, with odds exceeding 50 percent across upstate New York and most of New England. Thereafter, mid-level ridging quickly builds in from the west, quickly increasing temperatures. The GEFS shows the cold air lingering in the east a little longer, and holds the strongest signal farther to the south. On day 8 (Oct 19), the GEFS PET shows at least a 30 percent chance for minimum temperatures below the 15th percentile extending as far west as the lower Great Lakes, the Ohio Valley, and part of the Lower Mississippi Valley, with odds exceeding 50 percent across the southern Mid-Atlantic and South Atlantic regions. The GEFS PET also holds on to higher chances for subfreezing temperatures farther south and west, with chances topping 40 percent as far south and west as the highest elevations near the northern Tennessee/North Carolina border. The official outlook favors a compromise of these two forecasts, leaning toward the ECENS faster timing but extending farther south to where the GEFS shows significant chances for subfreezing temperatures. In any case, the mid-level ridge to the west quickly builds into the northeastern CONUS, accompanied by increasing surface temperatures and ending the increased potential for cold weather. Farther west, as surface high pressure moves eastward out of the eastern CONUS, southerly low-level flow is expected to bring an anomalous push of tropical moisture northward into the central and western Gulf Coast States. This moisture-laden air has the potential to interact with a weak frontal boundary lingering across this region, increasing the chances for heavy rainfall. The ECENS and GEFS PETs both show marginally enhanced chances (over 20 percent) for 3-day rainfall totals to exceed the 15th climatological percentile and 1 inch along and near the Gulf Coast from Texas through southern Louisiana, extending northward at times into eastern Texas and central Louisiana. There is a lot of uncertainty regarding the timing, location, and evolution of any heavy precipitation that develops, with significant model divergence. The latest 12z and 0z runs of the dynamical European model (ECMWF) show this area receiving over 2 inches of rain through the middle of week-2, with amounts topping 5 inches in a few spots. Other models are more muted, however, including the 0z ECENS which only shows .75 to 1.5 inches and confines that to the immediate coastline. The dynamical European Artificial Intelligence Forecast System (ECMWF-AIFS) drops 1 to 2 inches of rain on many locations as well, but are not in agreement on where the heaviest amounts fall, nor how far north heavy rain may occur. Meanwhile, the AIGFS shows only a few tenths of an inch at best, and the dynamical GFS confines heavy amounts to a relatively small part of southeastern Texas. Despite the uncertainty, a sufficient number of tools highlight increased chances for heavy rain to support posting a slight risk of heavy precipitation for much of the northern and western Gulf Coast, extending inland as far as eastern Texas and central Louisiana, although a few models bring heavier amounts farther north. The PETs and most models show lesser amounts after the middle of week-2, so the slight risk of heavy precipitation is removed then. Over Alaska, mid-level troughing remains favored late week-1 centered over the Gulf of Alaska, and the ensemble means today show the potential for a weakened 500-hPa trough to remain in place throughout the period, or potentially reload farther to the west. In either case, a fairly weak cyclonic mid-level flow is maintained over the Gulf of Alaska, which favors unsettled weather from the south-central Mainland through Southeast Alaska. Given how high precipitation normals are in this region during October, it seems unlikely that amounts will reach hazards thresholds, and the weak nature of this system does not favor high winds reaching hazards thresholds either. But there is the potential for any tropical cyclones that develop in the active western Pacific to recurve northward and become incorporated into the extratropical westerlies, resulting in a more amplified mid-level pattern with precipitation enhanced by the incursion of tropical moisture. No hazards are posted at this time, but the mid-level pattern over the northern Pacific will continue to be monitored. FORECASTER: Rich Tinker $$