AVIATION

Southeast Michigan will remain under the influence of an expansive high pressure system today. There will be some eastward movement of the sfc high today. This will simply transition the light winds to a more SSE direction during the afternoon.

For DTW/D21 Convection...There is no chance of thunderstorms through the TAF period.

DTW THRESHOLD PROBABILITIES...

* None.

PREV DISCUSSION
Issued at 347 AM EDT Sat Jul 27 2024

DISCUSSION...

High pressure is parked over the eastern Great Lakes and the Ontario peninsula where it will remain through the day as mid-level ridging crests over the region and maintains broad subsidence. There will be some pockets of cirrus at times as a weak wave passes to our east, but otherwise abundant sunshine is expected. This leads to high temps in the lower to mid 80s with warm mid-levels ensuring stable and dry conditions through the day and into tonight. Light southerly wind will gradually nudge dew points toward the lower 60s by this evening, raising the floor for low temps tonight into Sunday morning to around 60.

Prototypical mid summer weather continues Sunday as the mid-level ridge holds on overhead between an incoming trough from the west and a coastal low developing off the Mid-Atlantic. The surface high will be displaced farther east thus southerly warm/moist advection is expected to send highs into the upper 80s to near 90 with humidity increasing to more noticeable levels with dew points in the lower to mid 60s. Enough capping remains present through the day to offer a dry forecast but will see increasing clouds as upper level moisture streams in ahead of the trough moving in from the Mississippi Valley. Can't entirely rule out an evening pop-up shower as ridging begins to break down, but guidance continues to hold the arrival of deeper moisture until after midnight.

Additional moisture advection and ascent ahead of the inbound trough will bring the start of a more unsettled pattern on Monday with scattered showers and thunderstorms looking increasingly likely for the afternoon and evening. CAPE on the order of 1000 J/kg may lead to a few stronger updrafts but 0-6km bulk shear will be very weak at around 10 kt. The resultant pop-up storm mode offers little threat of severe weather but slow storm motion and PWATs increasing to around 1.75 inches may lead to localized heavy downpours. Not everyone will see rain with weak/disorganized forcing generally keeping coverage limited. With more clouds expected through the day, high temps should hold in the mid 80s.

Similar unsettled conditions continue into Tuesday as broad troughing continues to spread overhead with heat and humidity sticking around at the surface. A shortwave working across northern Ontario will provide a little reinforcement of the wave and looks to send a weak cold front across the state. This offers slightly higher PoPs owing to the more coherent low-level forcing, but organized severe weather chances again look low with very little wind shear and the main threat would be heavy rainfall. Warmth and humidity typical of late July and early August likely persists through the rest of the week with additional shower and thunderstorm chances each day given an unstable and generally uncapped air mass.

MARINE...

Resident surface high pressure settles eastward today over the southern Ontario peninsula. Improvement of the local pressure gradient yields a slight uptick in southerly winds with time today.
Peak gusts could reach 20-25 knots for portions of north-central Lake Huron while the rest of the central Great Lakes generally hold AOB 10 knots ensuring favorable maritime conditions. The surface ridge breaks down Sunday maintaining relatively weak southerly flow before attention turns to a shortwave trough approaching from the west Monday morning. This initial wave is expected to flatten/weaken upon arrival, but the transition to a hotter and more humid airmass should still promote the development of some afternoon thunderstorms. A well-defined surface low pressure system crosses into the Upper Midwest from the Canadian Prairies before tracking across Lake Superior Tuesday. The low features an attendant cold front draped south of the circulation which may extend into the regional waterways and help promote additional storms Tuesday. Any stronger storms that develop early next week could lead to locally higher winds/waves.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.