Extended Forecast Discussion NWS Weather Prediction Center College Park MD 345 PM EDT Thu Jul 21 2022 Valid 12Z Sun Jul 24 2022 - 12Z Thu Jul 28 2022 ...Dangerous heat wave persists over the South-Central U.S. into midweek... ...Notable heat expected to build over the Inland Northwest next week... ...Overview... The western ridge which is currently centered over the Desert Southwest is expected to steadily drift east through the middle of next week, focusing on the Southeast through the middle of next week while progressive activity persists over the northern tier states. A strong ridge developing over the northeastern Pacific through eastern Alaska Sunday/Monday shifts inland across the West Coast through the middle of next week, establishing a multi-day period of hot weather over the Northwest (with highs looking to reach 15F above normal) which looks to persist perhaps through next weekend. An initial surface front over the central CONUS by late this weekend persists into midweek, then the next cold front approaches soon thereafter. This looks to focus heavy rain potential over parts of the central/eastern U.S. and support the moderating temperature trend east of the Rockies. A period of enhanced monsoonal moisture from Sunday onward, promoting daily risk of locally heavy showers and storms that may produce instances of flash flooding. ...Guidance Evaluation/Predictability Assessment... The overall pattern is in decent agreement with some continued differences for low-predictability shortwave details within northern U.S./southern Canada, particularly by midweek. Overall the majority cluster looks good for upper ridging that establishes over the Southeast and expands over the West. The 00Z ECMWF was a notable change from its prior runs with a more prolonged heavy rain progged for the Ohio Valley area mid to late next week, though confidence in this is low given model variability. That said, the ECENS is generally between the more progressive 00Z CMCE and the less progressive 06Z GEFS means, so perhaps the placement of rain over the Ohio Valley is reasonable. The updated forecast incorporating the 00Z/06Z guidance started with an operational model blend favoring the 00Z ECMWF/CMC that transitions to the ensemble means of the 00Z ECENS/CMCE and 06Z GEFS. ...Weather/Hazards Highlights... A cold front moving into northern sections of the central/eastern U.S. will erode/end the heat wave from the north by Monday-Tuesday but not reach far enough south to lower temperatures much over and near the southern half of the Plains. The next front that reaches the northern Plains early next week looks to have a stronger southward push, bringing moderately below normal highs to the northern-central Plains Tuesday onward, but possibly not south of Kansas until Thursday at the earliest. Both fronts will focus episodes of showers and storms, with some severe weather and heavy rainfall possible. The leading front heading into the East may initially favor highest rainfall totals from the eastern Great Lakes/Ohio Valley into the Northeast/Mid-Atlantic but could also focus repeat activity as far west as the Plains as it stalls before lifting back as a warm front. The second front should produce northern Plains convection that extends south/east with time, potentially repeating activity over an already soggy Ohio Valley. Expect periods of showers and thunderstorms over portions of Florida and the Gulf Coast region. The Florida Peninsula may see somewhat higher rainfall totals around midweek as an area of enhanced moisture passes through from east to west. Over the West, persistent monsoonal moisture and various shortwave impulses will support diurnally favored showers/storms with some locally heavy rainfall over the Four Corners/Great Basin region from Sunday through at least Thursday. Guidance continues to suggest that the pattern evolution will support a more active period with greater coverage and intensity of rainfall versus the short range time frame. Potential still exists for some of this moisture to interact with central Plains fronts (one during Sunday/early next week and the second arriving around midweek) to enhance rainfall totals. Upper ridging that builds over the Northwest next week will bring multiple days of hot weather to that region, with some locations likely to see highs reach up to 10-15F or so above normal. Some daily records for highs/warm lows will be possible, particularly over Inland portions of the Northwest such as the Columbia Basin. Jackson Hazards: - Heavy rain across portions of the Central Plains, the Central Rockies, the Central Great Basin, the Southern Rockies, the Southern Plains, and the Southwest, Sun-Thu, Jul 24-Jul 28. - Heavy rain across portions of the Lower Mississippi Valley, the Central Appalachians, the Tennessee Valley, the Middle Mississippi Valley, the Southern Appalachians, and the Ohio Valley, Mon-Thu, Jul 25-Jul 28. - Heavy rain across portions of the Great Lakes, the Mid-Atlantic, the Northeast, the Central Appalachians, and the Ohio Valley, Sun, Jul 24. - Flooding occurring or imminent across portions of the Northern Plains. - Excessive heat across portions of California, the Central Great Basin, the Pacific Northwest, the Northern Rockies, and the Northern Great Basin, Mon-Thu, Jul 25-Jul 28. - Excessive heat across portions of the Southeast, the Middle Mississippi Valley, the Lower Mississippi Valley, the Southern Plains, and the Tennessee Valley, Sun-Thu, Jul 24-Jul 28. - Excessive heat across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley, Sun-Wed, Jul 24-Jul 27. - Excessive heat across portions of the Northeast, the Central Appalachians, the Tennessee Valley, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, and the Ohio Valley, Sun, Jul 24. 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