Thursday Night: Mostly clear. Low: 72°F
Friday: Partly sunny, afternoon showers and thunderstorms. High: 89°F
Friday Night: Cloudy with scattered thunderstorms. Low: 68°F
Saturday: Clouds clearing through the day. High: 85°F
Saturday Night: Clear. Low: 67°F
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General Discussion:
After a hot and dry week things begin to pick up in activity as we move into Friday. Temperatures will peak near 90 degrees but salvation is coming with an approaching cold front but that also bring the threat of thunderstorms and a few could be strong to severe. Precipitation lingers through Friday night into early Saturday morning before clearing and cooler conditions Saturday evening.
-Russell
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Forecasters: Russell, Franciscus, Nightingale, Daniel
Date Issued: 08/29/2024 5:00 PM CDT
Technical Discussion:
Key Messages:
-Warm and humid conditions give way to evening thunderstorms. Some may pose a marginal damaging wind or hail threat.
-A weakening trough to the north will delay cold air advection towards the end of the forecast period. The front itself will pass late evening Friday.
-Things clear through Saturday, but increasing moisture at the surface may lead to patchy fog into Sunday morning.
A stout upper-level ridge continued to progress to the east southeast leaving us with ever so slightly cooler temperatures and an increased risk for showers and thunderstorms. A weakening trough is currently sliding across northern CONUS and is responsible for the impending cold front and thunderstorms. Temperatures moderate as the forecast progresses bringing us back to near average conditions.
Currently, an expansive line of showers and thunderstorms exists from northern Minnesota down to New Mexico associated with the approaching cold-front thanks to the large mid-latitude cyclone across southern Canada. As the afternoon progressed dewpoints decreased thanks to mixing bringing us to a more comfortable 67F compared to the previous days of 75F+. Winds are consistent from the south helping in keeping our temperatures warm.
A large upper-level trough progresses eastward through tonight into Friday across the southern Providences of Canada. A fairly large, but weak cold front propagating ahead of it will swing through the area bringing the necessary forcing to spark scattered thunderstorms. Dewpoints will remain in the mid-60s ahead of the front, paired with favorable low-level lapse rates are a few of the indicators that storms may pose a marginal severe threat. High DCAPE favors damaging winds, but weak shear may support an isolated incident of hail. Upon the passage of the cold front Friday evening, sinking air will reduce precipitation coverage but slowing of the front may allow additional development particularly along the I44 corridor. PWAT values are approaching 2″ and paired with slow storm motion flash flooding remains a concern where multiple storms track over the same areas.
Behind the front, cold air will initially remain locked up across the northern plains thanks to the collapse of the upper-level trough and slowing progression of the cold front. In tune with that, the slowing progression of the front introduces some question on precipitation timing, particularly ending. Moisture values will remain high, but sinking air found behind most fronts may prevent further development. Models highlighted a proceeding shortwave that may provide just the right forcing to kick storms off if we can see enough recovery following the front. Things clear into Saturday but remaining moisture at the surface and weak surface winds may promote patchy fog into early Sunday morning so future forecasters should monitor that risk.
-Russell, Franciscus, Nightingale, Daniel