FXUS02 KWBC 100646 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 246 AM EDT Tue Mar 10 2026 Valid 12Z Fri Mar 13 2026 - 12Z Tue Mar 17 2026 ...Record warmth across the Southwest late week into next week... ...Heavy snow/wind threats Northwest/Rockies to the Great Lakes... ...Pattern Overview... The upcoming medium range period should remain fairly amplified and active through the period. A deepening cyclone over the Great Lakes will bring some snow and gusty winds across the region on Friday. A clipper system behind this one across the Northern tier will bring high wind threats across the Rockies and High Plains into the weekend, and spread moderate snowfall from the northern Plains into the Great Lakes on the north side of an ejecting low pressure system. The Pacific Northwest should be fairly active with daily heavy precipitation threats, with upper level ridging holding and building over the Southwest to bring record breaking warmth and moderate HeatRisk to some areas. ...Guidance/Predictability Assessment... Guidance remains in good agreement on the overall large scale pattern evolution through the period, but does show some considerable uncertainty in the details and timing of individual shortwaves through the northern tier. Agreement and forecast confidence has increased with an initial deeper low pressure system over the Great Lakes. Behind this, another shortwave drops into the northern Plains, but with more uncertainty in the smaller scale details and depth. This impacts frontal placement across the Central U.S. to the Midwest and exact placement of an axis of heavy snowfall to the north from the northern Plains to the Upper Midwest/Great Lakes. This shortwave will dig southward in response to a building ridge out West, resulting in a highly amplified pattern likely across the CONUS by early next week. There were not really any notable outliers in tonights guidance so the WPC forecast was able to rely on a general deterministic model blend for the first half of the period. Did increase weighting of the ensemble means to 60 percent of the blend by Day 7 just to help mitigate individual model variances. ...Weather/Hazards Highlights... An initial main low will move into the Northern Plains/Upper Midwest/Great Lakes then northern New England bringing precipitation including a swath of modest snow as well as a threat for gusty winds into Friday and Saturday. A couple of shortwaves should keep the Pacific Northwest quite wet through much of the period. The heaviest rainfall should be associated with an Atmospheric River which begins at the end of the short range period and extends into the weekend. A Marginal Risk for excessive rainfall is highlighted for southwest Washington and northwest Oregon on Friday, with a brief break in the moisture on Saturday. Heavy snows are possible in the higher elevations of the Northwest inland into the Rockies. Tight pressure gradients will also support high to damaging winds, especially for the Northwest- Rockies-High Plains from later week into the weekend. Another low pressure system will emerge into the Plains by this weekend, with increasing confidence in a swath of moderate to heavy snow to the north from the Northern Plains into the Upper Midwest and Great Lakes. There is good agreement on snow, but still considerable uncertainty in the exact axis and amounts of snow. This associated surface low and cold front will push into the East early next week with widespread precipitation expected ahead of the system. Some lake effect snow is possible downwind of the Great Lakes behind this system. Heat from the Southwest to the central Great Basin will build through the period, with widespread record breaking values possible. Moderate to very localized major HeatRisk is forecast across parts of Southern California from roughly Santa Barbara to San Diego as temperatures approach or exceed 90 degrees in some places. Above normal temperatures will overspread the south as well, with some records possible into the Southern Plains, and another brief warmup for the Midwest and the East. This will be short lived though as the next trough into the north- central U.S. early next week will bring with it below normal temperatures with daytime highs 10 to 20 degrees below normal by next Monday and Tuesday over the northern/central Plains into the Midwest and the East. 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 (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: 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 $$