Extended Forecast Discussion NWS Weather Prediction Center College Park MD 255 PM EDT Wed Jun 08 2022 Valid 12Z Sat Jun 11 2022 - 12Z Wed Jun 15 2022 ...Dangerous/Record heat for the Southwest/Great Basin to Texas into the weekend to shift into the east-central U.S. next week... 19Z Update: The 12Z model guidance suite is in very good synoptic scale agreement through about Monday. Some minor differences become apparent with the CMC by early next week with a more amplified solution across the East Coast region. By next Tuesday, the GFS is stronger with the closed low exiting the Northern Rockies, and shortwave energy reaches the Upper Midwest sooner than the slower CMC/ECMWF by Wednesday. The southern U.S. upper ridge and the accompanying heat is probably the most confident part of the forecast. In terms of QPF, there is a stronger signal for heavier rain across North Dakota for Sunday night ans into Monday as the surface low becomes better organized and focuses moisture. The previous forecast discussion is appended below for reference. /Hamrick ...Pattern Overview and Sensible Weather/Threat Highlights... The upper pattern over the nation is set to amplify with trough development to the West Coast and downstream over the East/Northeast to sandwich ridging from the Southwest to the south-central U.S. this weekend. Amplified troughing will work inland over an unsettled/cooling West early next week as downstream ridging builds into the east-central U.S.. Despite transitional flow, guidance is offering a strong signal for a wet period for the East into the weekend with widespread showers/strong thunderstorms and possible local runoff issues as a organizing low pressure system works through the Mid-Atlantic/Northeast and a wavy trailing front settles into the Southeast. Moderating post-frontal temperatures/moisture into early next week will starkly contrast extreme heat spreading over the period from the Southwest/Great Basin and Texas to the east-central U.S. that may challenge daily records. Meanwhile, unsettled/wet weather seem set to spread from the Pacific Northwest to the northern Rockies where some high elevation snows are possible. In this flow, there is also a growing signal for heavier rains with some local runoff concerns for the northern Great Basin/Rockies this weekend as deeper moisture from the Pacific advects inland. Flow downstream over northern Plains/Upper Midwest into next week will increasingly favor periodic strong MCS activity with heavy downpours as uncertain impulses track across the northern periphery of the ridge. ...Guidance and Predictability Evaluation... The WPC medium range product suite was primarily derived from a composite blend of best clustered pattern, system, temperature profile and QPF guidance of the 12 UTC ECMWF/UKMET and GEFS/NAEFS/ECMWF ensemble means along with the 01 UTC National Blend of Models (NBM) for days 3-5 (Saturday-Monday) before leaning on the ensemble means as forecast spread and model run to run continuity issues grow into days 6/7 (next Wednesday/Thursday). Newer 00 UTC guidance remains in line with this scenario in a pattern with overall near average forecast uncertainty. Schichtel 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