934 FXUS02 KWBC 130552 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 152 AM EDT Tue Oct 13 2026 Valid 12Z Fri Oct 16 2026 - 12Z Tue Oct 20 2026 ...Broad frost/freeze threats across the northern/central U.S. late week into early next week... ...Overview... The period begins Friday with a deep trough moving through the Great Lakes/Ohio Valley and into the Northeast Friday and Saturday. A strong cold front and chilly surface high pressure behind it will bring frost/freeze concerns to a broad area advancing from the Plains into the Midwest and the East this weekend and early next week. Gusty winds will also accompany the surface low as it moves from the Great Lakes into the Northeast Friday and Saturday. Meanwhile, an upper low will meander over the Southwest this weekend before weakening and its energy getting pulled eastward by another weak shortwave through the northern U.S.. The next trough moves into the West by Monday bringing periods of rain and high elevation snow across much of the Northwest. ...Guidance/Predictability Assessment... Model guidance continues to show good agreement through much of the period, with some uncertainty in the timing and details of individual systems. An amplified shortwave will push a strong surface low ahead of it from the Great Lakes on Friday to Atlantic Canada by Saturday. Latest guidance shows only minor timing differences now with this. There is some uncertainty as well with the weakening upper low over the Southwest as its energy gets pulled through the Central Plains and Mid-South by a northern stream shortwave early next week, but this should not be accompanied by impactful weather. Out West, guidance continues to show some timing differences with the trough as it approaches the coast and then also the details as it deepens over the West early next week. The WPC forecast tonight used a blend of the deterministic guidance Days 3-5, increasing the ensemble mean inclusion to 50 percent of the blend Days 6 and 7 amidst some larger uncertainty. This generally maintained good continuity with the previous WPC forecast and was consistent with the National Blend of Models. ...Weather/Hazards Highlights... Return flow around a high over the Gulf and moisture from what is currently Hurricane Simon may continue to bring some locally heavy rainfall to parts of the southern High Plains through Friday, with a WPC Marginal Risk in place. Farther north, areas of rain are forecast into the Great Lakes and Northeast with a surface low later this week. The pattern will be favorable for lake effect/enhanced rain and even snow across the Great Lakes region to Interior Northeast through Friday- Saturday, along with upslope precipitation in the Appalachians. High winds are possible behind the surface low/cold front track across the Great Lakes Friday, into the higher elevations of the Northeast Saturday, and also behind the tail end of the front in the Southwest to southern High Plains. Showers and storms are possible in Florida, with amounts potentially increasing by the weekend with the front passing through. Elsewhere, the Pacific Northwest into the northern Intermountain West and Rockies should see increasing precipitation chances into Sunday and Monday ahead of the next upper trough. But overall a drier pattern is in store by the weekend into early next week for much of the remainder of the country. Above normal temperatures across the Southeast at the end of the short range period may moderate and linger into Friday. Then, Canadian high pressure is forecast to gradually track across the country behind the cold front into the weekend, cooling temperatures for the central and eastern U.S. and providing fairly broad frost/freeze threats. Meanwhile, the West Coast could see above normal temperatures, including some highs near and above 90 for parts of coastal California again by late week. Above average temperatures are likely to spread into the north-central U.S. over the weekend with the Western trough cooling temps along the coast by next Monday. Santorelli Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages are at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw $$