Forecast Discussion
— ExtendedOverview
Dangerously hot weather will continue across much of the central U.S. through the weekend into early next week while a cold front will bring relief to the Mid-Atlantic and parts of the Southeast after a couple more very hot days on Friday and Saturday. In contrast, persistent troughing will keep much of the Pacific Northwest cool, showery, and unsettled into early next week. Locally heavy rainfall and severe weather will be possible along a frontal zone from the Midwest to the Ohio Valley, central Appalachians, and Mid-Atlantic on Friday, with additional chances farther south into the Carolinas on Saturday. Monsoonal moisture returns late week into the weekend with a tropical connection potentially leading to enhanced rainfall for parts of the Southwest into next week.
Guidance/Predictability Assessment
Deep troughing along the West Coast, highly amplified ridging over the central U.S., and more troughing along the East Coast will continue to be the dominant features of the large scale pattern into early next week. Models are generally in good agreement with the pattern through most of the weekend, but uncertainty increases leading into next week. The primary source of uncertainty seems to stem from the evolution of shortwave energies embedded within the deep troughing across the West Coast, including details on how and when those energies eject northeastward and potentially interact with the anomalously strong ridge downstream, as well as energy digging into south-central Canada.
Additionally, the evolution of the western U.S. troughing will have implications on the future track of Invest 95E. As has been the case for several runs now, the GFS continues to be an outlier with deeper and more southerly West Coast troughing, leading to more interaction with 95E and thus bringing more direct impacts to southern California and the Southwest as it tracks northward. Non- NCEP guidance (including a majority of AI/ML guidance) however generally favors less trough interaction and turns 95E sharply westward upon reaching 20-25N latitude.
Since yesterday, the preference for the fronts/pressures forecast has been to lean on a multi-model non-GFS consensus with the most weight given to the AI/ML guidance as well as the EC/GEFS ensemble means (particularly for Days 5-7 for the latter). That strategy continues with this forecast package, which does well to mitigate smaller scale differences and preserve the primary large scale features while ensuring less West Coast trough interaction with 95E.
Weather/Hazards Highlights
Intense late-summer heat will continue across the central U.S. through the weekend into next week as a large mid/upper ridge dominates the region. Before then, relief from the heat is expected this weekend for parts of the Ohio Valley, Mid-Atlantic, and Southeast as a cold front drops in from the north. The well above normal temperatures combined with high humidity and very warm overnight lows in the mid 70s will result in widespread areas of Major to Extreme HeatRisk and a concern for heat-related illnesses. Please continue to see WPC's Key Messages for more details on this long lasting heat wave.
In stark contrast from the heat across the central and eastern U.S., cooler than normal temperatures will remain in place across the Pacific Northwest through early next week as persistent clouds and showers associated with deep troughing over the West Coast linger over the region. High temperatures will mostly top out in the 50s, 60s, and 70s, which is roughly 10-15 degrees below seasonal norms.
The frontal system which will bring relief from the heat across parts of the eastern U.S. this weekend will first interact with sufficient moisture and instability to produce locally heavy rainfall and severe weather from the Midwest to the Ohio Valley, central Appalachians, and Mid-Atlantic on Friday, with additional chances farther south into the Carolinas on Saturday. The strongest storms will be capable of producing damaging winds and hail, and perhaps a few isolated tornadoes. Storms will also contain heavy rainfall rates which could lead to scattered instances of flash flooding.
Surging monsoonal moisture will foster more numerous showers and thunderstorms across parts of the Southwest and Intermountain West on Friday, with a growing potential for isolated to scattered flash flooding. More surges of moisture are likely this weekend into early next week, regardless of what happens with what becomes of Invest 95E. While the current thinking favors a track that stays far away from southern California, there is still a threat of tropical moisture enhancing monsoonal rainfall and thus leading to additional concerns for flash flooding.
Miller
Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at:
000 FXUS02 KWBC 010759 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 359 AM EDT Tue Sep 1 2026 Valid 12Z Fri Sep 04 2026 - 12Z Tue Sep 08 2026 ...Dangerous late-summer heat wave continues from the central and southern Plains to the southeast U.S. through late week... ...Pattern Overview... Dangerously hot weather will continue across much of the central U.S. through the weekend into early next week while a cold front will bring relief to the Mid-Atlantic and parts of the Southeast after a couple more very hot days on Friday and Saturday. In contrast, persistent troughing will keep much of the Pacific Northwest cool, showery, and unsettled into early next week. Locally heavy rainfall and severe weather will be possible along a frontal zone from the Midwest to the Ohio Valley, central Appalachians, and Mid-Atlantic on Friday, with additional chances farther south into the Carolinas on Saturday. Monsoonal moisture returns late week into the weekend with a tropical connection potentially leading to enhanced rainfall for parts of the Southwest into next week. ...Guidance/Predictability Assessment... Deep troughing along the West Coast, highly amplified ridging over the central U.S., and more troughing along the East Coast will continue to be the dominant features of the large scale pattern into early next week. Models are generally in good agreement with the pattern through most of the weekend, but uncertainty increases leading into next week. The primary source of uncertainty seems to stem from the evolution of shortwave energies embedded within the deep troughing across the West Coast, including details on how and when those energies eject northeastward and potentially interact with the anomalously strong ridge downstream, as well as energy digging into south-central Canada. Additionally, the evolution of the western U.S. troughing will have implications on the future track of Invest 95E. As has been the case for several runs now, the GFS continues to be an outlier with deeper and more southerly West Coast troughing, leading to more interaction with 95E and thus bringing more direct impacts to southern California and the Southwest as it tracks northward. Non- NCEP guidance (including a majority of AI/ML guidance) however generally favors less trough interaction and turns 95E sharply westward upon reaching 20-25N latitude. Since yesterday, the preference for the fronts/pressures forecast has been to lean on a multi-model non-GFS consensus with the most weight given to the AI/ML guidance as well as the EC/GEFS ensemble means (particularly for Days 5-7 for the latter). That strategy continues with this forecast package, which does well to mitigate smaller scale differences and preserve the primary large scale features while ensuring less West Coast trough interaction with 95E. ...Weather/Hazards Highlights... Intense late-summer heat will continue across the central U.S. through the weekend into next week as a large mid/upper ridge dominates the region. Before then, relief from the heat is expected this weekend for parts of the Ohio Valley, Mid-Atlantic, and Southeast as a cold front drops in from the north. The well above normal temperatures combined with high humidity and very warm overnight lows in the mid 70s will result in widespread areas of Major to Extreme HeatRisk and a concern for heat-related illnesses. Please continue to see WPC's Key Messages for more details on this long lasting heat wave. In stark contrast from the heat across the central and eastern U.S., cooler than normal temperatures will remain in place across the Pacific Northwest through early next week as persistent clouds and showers associated with deep troughing over the West Coast linger over the region. High temperatures will mostly top out in the 50s, 60s, and 70s, which is roughly 10-15 degrees below seasonal norms. The frontal system which will bring relief from the heat across parts of the eastern U.S. this weekend will first interact with sufficient moisture and instability to produce locally heavy rainfall and severe weather from the Midwest to the Ohio Valley, central Appalachians, and Mid-Atlantic on Friday, with additional chances farther south into the Carolinas on Saturday. The strongest storms will be capable of producing damaging winds and hail, and perhaps a few isolated tornadoes. Storms will also contain heavy rainfall rates which could lead to scattered instances of flash flooding. Surging monsoonal moisture will foster more numerous showers and thunderstorms across parts of the Southwest and Intermountain West on Friday, with a growing potential for isolated to scattered flash flooding. More surges of moisture are likely this weekend into early next week, regardless of what happens with what becomes of Invest 95E. While the current thinking favors a track that stays far away from southern California, there is still a threat of tropical moisture enhancing monsoonal rainfall and thus leading to additional concerns for flash flooding. Miller 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, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages 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 https://www.wpc.ncep.noaa.gov/#page=ovw $$