007 FXUS02 KWBC 200600 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 200 AM EDT Mon Apr 20 2026 Valid 12Z Thu Apr 23 2026 - 12Z Mon Apr 27 2026 ...Overview... A fairly active and evolving spring pattern across much of CONUS as a Pacific mid/upper-level trough continues to move east across the Rockies/Plains before ejecting eastward into the Midwest by late week. This system will bring very strong winds and widespread precipitation, including low elevation rain and heavy mountain snow. As the trough and its associated surface low interacts with surging Gulf moisture over the central U.S., episodes of heavy rain and severe weather will become more likely Thursday and Friday. The system will bring periods of anomalous warmth and late-season cool intrusions as below average temperatures expand from the western U.S. to the central U.S. behind a strong eastward advancing cold front. ...Guidance/Predictability Assessment... Model guidance remains in generally good agreement on the large- scale evolution of the the ridge over central U.S. moving eastward, while the Pacific system and amplified trough lifts into western/central U.S. Later in the period, model spread persist mostly with the upper low/trough in respect to the timing and amplitude of the embedded shortwaves and associated surface features. This includes differences in placement of frontal zones and the track of developing systems emerging from the west. The ensemble means continue to smooth some of the small scale differences amongst the deterministic models. The GFS continues to show higher run-to-run variability and some noticeable differences in respect to shortwave troughs. The forecast incorporated a blend of models for the initial period, but gradually phased in the ensembles by Day 5. ...Weather/Hazards Highlights... The ridge over eastern U.S. will break down and shift offshore, as the Pacific system and amplified trough continues to digs across western U.S. into central U.S. This will bring unsettled conditions across the Rockies, Plains, and Midwest. Multiple embedded shortwaves rotating within and around the base of the trough will bring periods of widespread low elevation rain and mountain snow, with locally heavy precipitation possible along favored terrain. Accumulating snow will primary be confined to higher elevations, with impacts limited to high mountain passes and mountain towns. In addition, strong gusty winds are expected across much of central U.S. as the system moves across into the Plains and Mississippi Valley through the week. The deepening Pacific system ejects eastward into the Plains by Thursday, supporting the eastward progression of a cold front. The cold front will interact with warm Gulf moisture and unstable airmass, which will support a corridor of showers and thunderstorms across the Plains into much of eastern U.S. through the weekend. The combination of the large scale forcing and increasing instability along and ahead of a strengthening surface low and strong cold front, will support widespread clusters of strong to severe thunderstorms capable of producing heavy rainfall and isolated flash flooding over the Central/South Plains and parts of the Mississippi Valley. This flooding threat is highlighted by a Marginal Risk in the Day 4/Thursday ERO. Given increasing soil moisture from previous bouts of convection, an upgrade to a Slight Risk is not out of the question in future updates. As the front moves further east, flood risk shifts into the Ohio/Tennessee Valley on Friday. This flooding threat is highlighted by a Marginal Risk in the Day 5/Friday ERO. Elsewhere, a relatively weak cold front will continue to push through the Ohio Valley, Mid-Atlantic, and Northeast on Thursday, bringing chances for isolated to scattered showers. Otherwise, much of the Desert Southwest and Southeast will be mainly dry through the end of the week, before the cold front drops into the Southern Plains/Mississippi Valley by Friday and over the Southwest by the weekend, which may bring showers and thunderstorms Friday into the weekend. Below normal temperatures over much of western U.S. will expand east into Northern/Central Plains and Rockies by the end of the week and parts of Mississippi Valley by the weekend. Parts of the Northern Plains/Rockies will drop to 15-20 degrees below normal, where highs will be within the 40s over the northern Rockies on Thursday and will gradually spread into the Northern Plains by Friday. Ahead of the frontal system, above average temperatures will persist through Friday across parts of central U.S. into much of eastern U.S. before temperatures moderate into the weekend. Over into the Pacific Northwest, temperatures will begin to trend slightly above average late in the period. Oudit 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 $$