FXUS02 KWNH 150759 PREEPD Preliminary Extended Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Wed Apr 15 2026 Valid 12Z Sat Apr 18 2026 - 12Z Wed Apr 22 2026 ...General Overview... A welcomed pattern change is expected across the eastern half of the country in time for the weekend 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 refreshing 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 00Z model guidance suite features good overall agreement on the synoptic scale for the end of the week into the weekend, so a general deterministic model blend works well as a starting point. The UKMET is still a slower solution with the timing of the cold front reaching the East Coast this weekend, but not to the same degree as previous runs. The ensemble means were increased to about 40-50% by early next week given timing differences with the next Pacific system and northern stream shortwave energy. The NBM appeared to be a reasonable starting point for most areas of the country for temperatures, although values were raised 1-2 degrees from southern Virginia through the Carolinas where there is stronger support for highs above NBM guidance on Saturday. There was also a slight increase made within the main QPF axis ahead of the eastern U.S. cold front. ...Weather/Hazards Highlights... A strong cold front crossing the Ohio Valley, Mid-South, and into Texas 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. 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 will be valid 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 finally be coming 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. 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 $$