090 FXUS02 KWBC 161824 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 224 PM EDT Thu Apr 16 2026 Valid 12Z Sun Apr 19 2026 - 12Z Thu Apr 23 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 a cooler airmass by Sunday, and continuing into 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, and mostly beneficial, 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... Model agreement on the large scale pattern and evolution remains good through much of the period with plenty of uncertainty still on the details and timing of individual systems. The main focus today was with the upper low off the West Coast going into early next week, with recent runs of the GFS continuing to be slightly farther offshore than the better consensus made up of the CMC/ECMWF/UKMET/EC-AIFS and GEFS/ECENS ensemble means. The 12z run of the GFS today did come in faster, which increases confidence in the current faster consensus. The evolution of this low as it enters the West and opens in the middle to latter part of next week is much more uncertain, and the CMC is notably faster/farther east than the preferred consensus. The WPC forecast for tonight was based on a general model blend for the first half of the period, but more heavily weighted towards the ensemble means Days 6 and 7 to help mitigate the differences noted above. For the most part, this maintained continuity with the previous WPC forecast and the 13z NBM served as a very reasonable starting point for the sensible weather grids across the CONUS, with mostly minor adjustments noted. ...Weather/Hazards Highlights... A strong cold front reaching the East Coast on Sunday/Day 4 is expected to be accompanied by a corridor of showers and some thunderstorms. Moderate to locally heavy rainfall is expected for the Northeast U.S. but appears to be progressive enough to limit the flood potential. The trailing portion of this front may linger through Monday across parts of south Texas, and with anomalous moisture in place, went ahead with a marginal risk ERO both Sunday/Day 4 and Monday/Day 5. Out West, 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 Sunday and Monday, but for the most part this should be beneficial with only localized flooding impacts expected. Still, maintained a Marginal Risk area on Monday/Day 5 for parts of northern California where soil moisture is near or above normal. Mountain snow will also be commonplace for the higher terrain of the Sierra and the Cascades, and extending eastward to include for the northern Rockies. The record breaking early season heat wave for much of the eastern U.S. will come to an end by Sunday as a strong cold front brings a return to much cooler conditions. The anomalous warmth should then be confined mainly to the coastal Carolinas and southward into Florida on Sunday 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 Sunday and Monday nights. The central and southern Plains heat back up as highs reach well into the 80s from western Texas to Nebraska by Tuesday, and this warmth then spreads eastward again to the Mid-Atlantic and Southeast U.S. with highs from the middle 70s to the middle 80s by Wednesday, but less extreme compared to the hot temperatures in the short range period. 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 $$