433 FXUS02 KWBC 151848 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 248 PM EDT Wed Apr 15 2026 Valid 12Z Sat Apr 18 2026 - 12Z Wed Apr 22 2026 ...General Overview... A pattern change is expected across the eastern half of the country as a strong cold front heralds the end of the early season heat wave. Hot temperatures across the East Coast on Saturday will be replaced by more seasonal readings by the start of next week as a Canadian surface high builds into the region. Out West, a new storm system arrives by Sunday and brings additional rain and mountain snow to the West Coast states. A broad upper ridge builds between the eastern U.S. trough and the West Coast system, but not to the same magnitude as what is currently in place across the country. ...Guidance/Predictability Assessment... The latest deterministic and ensemble guidance continues to show good synoptic agreement on the pattern evolution during the Day 4-7 period, but plenty of uncertainty in the details. There was good enough consensus on the timing of the initial cold front into the East for an equal blend of the deterministic guidance for Saturday and Sunday. After this, the focus shifts out West to an upper low moving towards California. The 00z ECMWF/ECENS were notably faster than the consensus, but some of the new 12z guidance did speed up (while the ECMWF) did slow down. Given the variability, prefer to stick closer to the GEFS mean and WPC continuity, so the latter half of the period was weighted more heavily towards those solutions. 13z NBM was a reasonable starting point for much of the forecast but did decrease QPF coverage a bit for the West since it was too heavily influenced by the faster 00z ECMWF. ...Weather/Hazards Highlights... A strong cold front crossing the Ohio Valley, Mid-South, and into Texas on Saturday is expected to be accompanied by a corridor of showers and thunderstorms. Greater coverage of convection is likely from eastern Texas to central Mississippi where better moisture convergence and instability will exist, and a Marginal Risk of excessive rainfall will remain valid here for the Day 4/Saturday outlook. There will likely be a second maxima of heavier rainfall from Ohio into Pennsylvania, and this area may eventually need a Marginal Risk area in later outlooks if amounts trend upward, but the front should be more progressive in this area as well. The Storm Prediction Center is also monitoring the northern Ohio Valley for the potential of severe weather on Saturday ahead of the front. Going into Day 5/Sunday, moderate to locally heavy rainfall is expected for the Northeast U.S. but appears to be progressive enough to limit the flood potential. However, a potential atmospheric river with the next Pacific storm system may produce enough rainfall across northern California to lead to some 1-2 inch rainfall on Sunday, and therefore a Marginal Risk area is in place here. Mountain snow will also be commonplace for the higher terrain of the Sierra and the Cascades, and lighter snows for the northern Rockies. The record breaking early season heat wave for many areas of the eastern U.S. will come to an end by Sunday as the huge upper ridge gets suppressed, and a cold front brings a return to conditions more typical of spring to begin next week. The summer- like heat will persist on Saturday from the Mid-Atlantic to Florida with highs in the upper 80s to middle 90s, and then by Sunday the anomalous warmth is confined mainly to the eastern Carolinas and southward before the entire East Coast gets relief on Monday. Conditions will turn rather chilly from Michigan to New England with highs mainly in the 40s to lower 50s, and frost/freeze conditions at night. Warmth returns to the Plains as highs reach into the 80s from western Texas to Nebraska by Tuesday. Santorelli/Hamrick 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 $$