356 FXUS02 KWBC 070639 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 139 AM EST Sat Mar 7 2026 Valid 12Z Tue Mar 10 2026 - 12Z Sat Mar 14 2026 ...Multi-day heavy rain/flooding and severe weather from the south-central to east-central U.S. into next week... ...Pattern Overview... The medium range period begins Tuesday with an active and complex split-flow regime featuring a closed upper-low near Baja California moving eastward and an amplifying trough digging from the Northwest into the Central U.S.. The interaction of these two features will result in widespread rainfall, including the potential for severe weather, from the south-central U.S. into the Ohio Valley. Some snow or mixed precipitation is possible on the northern edge of the precipitation shield from the Great Lakes into the interior Northeast. An Atmospheric River may bring moderate to heavy precipitation to the Pacific Northwest Wednesday into Thursday with high wind threats especially across the Rockies and High Plains. ...Guidance/Predictability Assessment... The latest guidance is showing increasing agreement on the large scale pattern across the CONUS for the medium range period. The greatest area of uncertainty remains with the timing and strength of the Baja California upper low as it moves into the Southern Plains and phases with the northern stream amplifying trough. Models are generally trending a bit faster with this system over recent runs. Despite minor differences, a general blend of the deterministic guidance served as a good starting point for the first half of the forecast period. Increased weighting of the ensemble means for the Friday and Saturday forecast to dampen somewhat the individual deterministic guidance and provide a good middle ground to the forecast, especially regarding a deeper surface low near the Great Lakes/Northeast late in the period. ...Weather/Hazards Highlights... Return flow from the Gulf and instability ahead of the Baja upper low will help fuel a multi- day heavy rain event with potential severe thunderstorms and flooding threats. Flood threats may also build with each round of rain given a repeating pattern with training potential. A Marginal Risk area for excessive rainfall is highlighted from the southern Plains into the Midwest for Tuesday. Activity should gradually shift eastward on Wednesday with a Marginal Risk ERO from the lower Mississippi Valley into the Ohio Valley. SPC is also highlighting severe weather potential in similar regions for both days. Rainfall will expand into the Eastern U.S. ahead of the main frontal boundary late in the week, but the overall flood threat looks limited as the frontal boundary should be much more progressive at that time. Some snow or wintry mix is possible on the northern edge of the precipitation shield from the Great Lakes into the interior Northeast. A couple of shortwaves should keep the Pacific Northwest wet through much of the period. The heaviest rainfall should be associated with a modest Atmospheric River as it enters the region Wednesday. Heavy snows are possible in the higher elevations, with even some light rain/snow mix possible at lower elevations on Tuesday into Wednesday as temperatures could be cold enough in the mornings. Deep systems and tight pressure gradients will support high winds, especially for the Northwest-Rockies-High Plains through much of the week. Gusty winds may also accompany the cold front as it slides through the Midwest and into the East mid to late week. A significant springtime warm-up is expected ahead of the front from the Ohio Valley into the Northeast with daytime highs 20 to 30 degrees above normal with daily widespread records. Values should moderate back towards normal by Friday following the frontal passage. Above normal temperatures are also expected to expand with time across the Southwest into the Plains and the South with below normal temperatures across the far northern tier. 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 $$