The definitive pattern break will arrive courtesy of a dynamic jet stream shift occurring across the upper troposphere. Meteorologists tracking 250-millibar wind patterns have observed a major jet streak, a localized pocket of wind speeds exceeding 130 knots, diving out of south-central Canada.
This upper-level energy will carve out a deep trough over the Midwest, eroding the western shoulder of the blocking ridge. As the trough advances, it drags a sharp surface cold front across the continent. Behind this boundary, dew points will plunge from the humid mid-70s down into the crisp upper-40s and lower-50s.
The collision of these two contrasting air masses may produce a final line of strong to severe storms along the leading edge of the front. Once that line sweeps offshore late on October 5, the persistent moisture tap will be severed. Winds shifting out of the northwest will usher in stable, dry continental air, ending the sequence of torrential rains.
