580 FXUS02 KWBC 240656 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 255 AM EDT Tue May 24 2022 Valid 12Z Fri May 27 2022 - 12Z Tue May 31 2022 ...Weather Pattern Overview... A large scale upper trough with a possible embedded closed low will be crossing the eastern U.S. through Friday and into Saturday, and this will sustain a surface cold front that should exit the East Coast by the weekend. Meanwhile, another trough enters the northwestern U.S. by the end of the week with a brief upper ridge ahead of it across the Rockies and the High Plains. Models suggest this trough will deepen as it crosses the West this weekend with surface cyclogenesis across the northern Plains this weekend. In response to the digging upper trough, an upper ridge should build across the eastern U.S. along with warmer temperatures. This general amplified pattern is forecast to persist into early next week. ...Model Guidance and Preferences... The 00Z model guidance is trending more towards a slower and potentially closed upper low solution across the Ohio Valley for the Friday-Saturday time period, with the past few runs of the GFS consistently on the slower side of the model consensus. The CMC is now on the faster side and has less of a closed low signal compared to the ECMWF/GFS/UKMET. Therefore, the WPC forecast through Saturday focused more towards the ECMWF/CMC/UKMET as a starting point. Out West, the guidance shows good timing agreement on the initial shortwave into the West late this week, but differ with the evolution into the weekend, with the GFS stronger and the CMC/ECMWF a little slower. The WPC forecast trended towards the ensemble means for the second half of the period to account for this uncertainty and generally shows good continuity with the previous WPC forecast as well. ...Sensible Weather/Threat Highlights... The majority of the heavy rainfall should be over by Friday, although a corridor of showers and storms is expected across the East Coast states ahead of a weakening cold front. There is the potential for some repeated rounds of convection with heavy rain across portions of the Carolinas based on some of the latest model guidance, but right now the potential for any flooding appears marginal. Patchy areas of heavy rainfall are also possible across portions of the Northeast, although the system should be more progressive here. By this weekend, showers and storms increase in coverage across the Northern Plains and Upper Midwest in response to a developing low pressure system over the north-central U.S. Some late season high elevation snow is also possible across the Northern Rockies for the Sunday and Monday time period. Temperatures will warm up considerably across the Plains by the end of the week with highs reaching well into the 90s from Kansas to the Gulf Coast, and some low-mid 100s across western Texas. The heat builds eastward to include the Ohio Valley and eventually the East Coast through the weekend and into early next week, compliments of the building upper ridge and southerly flow ahead of the storm system over the Plains. Much cooler weather arrives for the Pacific Northwest by Friday, and the below normal temperatures encompass the Northern Rockies and Northern Plains as the upper trough moves in behind the cold front. 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, experimental excessive rainfall outlook, winter weather outlook probabilities and heat indices 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 $$ $$