Day 4-8 Convective Outlook
Issued: · Valid: –
Summary
Severe thunderstorms are possible throughout the eastern United States from Thursday through Friday, with potential severe weather also occurring in the southern High Plains, the upper Mississippi Valley, and Arizona during that time. Additional severe weather risks may affect the Midwest and Great Lakes region through early next week.
Product Text
000 ACUS48 KWNS 030830 SWOD48 SPC AC 030829 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0329 AM CDT Mon Aug 03 2026 Valid 061200Z - 111200Z ...DISCUSSION... ...Day 4/Thursday... Broad troughing is forecast from the northern Plains through the Great Lakes with a series of disturbances moving through that airflow pattern. Elsewhere, an elongated vorticity ribbon will progress from the central and southern Appalachians into the Northeast. At the surface, a front initially from the southern Great Lakes into the southern Plains is forecast to weaken. Over the eastern CONUS, southerly winds will maintain a broad corridor of 70+ F dewpoints along and east of the Appalachians, which will contribute to moderate instability by afternoon. Aided by the approach of the disturbance aloft, thunderstorms are expected to increase in coverage through the afternoon with some severe weather possible. Generally weak vertical shear and the absence of a coherent front in the region lead to uncertainty in where the greatest threat may materialize. An isolated severe threat may also develop along the front from the Ozark Plateau into the southern High Plains, and in AZ during the afternoon and evening. ...Day 5/Friday... An intense mid/upper-level low is expected to evolve over central Canada with upper highs situated over the Great Basin and off the Mid-Atlantic Coast. Between those features, corridors of stronger mid-level flow are forecast from the northern Rockies into the northern Plains, and to a lesser extent over the Northeast. Some severe weather threat may again materialize from the Mid-Atlantic into southern New England in the vicinity of a surface trough. However, the strongest vertical shear is forecast to be displaced to the north of the stronger instability, leading to uncertainty in the extent of the severe weather threat. Isolated severe storms also appear possible along a front moving into the upper MS Valley. ...Days 6-8/Saturday through Monday... The various 00Z ensemble means indicate an upper low initially over Hudson Bay shifting east into northern QC with persistent ridging over the southern CONUS. Between those features, a belt of enhanced mid-level flow is forecast across the northern tier of states with some signal for continued troughing through Sunday over the Great Lakes into the OH Valley. At the surface, there is ensemble member clustering in surface low positions over the northern Plains along a front extending into the upper Great Lakes. There is a model signal for the front to continue into the Great Lakes and Midwest, where some severe weather threat appears possible. A separate severe weather risk may also persist from the Mid-Atlantic into New England. ..Mead.. 08/03/2026