FXUS63 KDTX 062322 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 722 PM EDT Sat Jul 6 2024 .KEY MESSAGES... - Isolated showers remain be possible this evening, generally north of I-94. Some rumbles of thunder cannot be ruled out. - The holiday weekend closes out with dry weather Sunday under partly sunny sky. - Hot Monday with highs in the upper 80s. Shower and thunderstorm chances return Monday and Tuesday. && .AVIATION... We are still dealing with isolated pop up showers. As we continue to lose diurnal heating, these showers will gradually dissipate. Tonight into Sunday morning, look for winds to become light/variable and/or calm as high pressure continues to slowly moves into the region. Could see another round of BR or HZ develop tonight. However, probabilistic data is not overly excited at seeing vsbys fall below 3-4SM. Sunday will feature light westerly winds, with the development of lake breeze boundaries that will bring wind shifts late in the day to KDET/KDTW/KYIP/KMBS. For DTW/D21 Convection...Widely scattered showers will dissipate around/shortly after sunset. DTW THRESHOLD PROBABILITIES... * Low for ceilings at or below 5000 ft late tonight and on Sunday. && .PREV DISCUSSION... Issued at 346 PM EDT Sat Jul 6 2024 Pop up showers remain a consideration through tonight. Temperatures have creeped up into the mid-to-upper-70s across the CWA today. Isolated showers have already begun to develop, and further development is expected throughout the evening. The best chances for showers remains north of I-69, where CAPE values of 500 J/kg are currently in place. 0-3km lapse rates of 7 C/km are the most favorable ingredient for shower development currently, and not much else supports anything more organized. CAPE values are not expected to increase through the evening, and low shear values are a problem for updrafts trying to organize further. PWAT values struggle to reach 1", and showers that do develop are not expected to bring more than a few hundreths of an inch. Warmer air at the 600mb level will advect in this evening and bring lapse rates of around 5 to 5.5 C/km, below the moist adiabatic lapse rate and as a result, cutting off convective access to the upper levels. With updraft potential limited to the lower levels of the atmosphere, thunder is not expected with these showers. However, an isolated rumble of thunder cannot be ruled out. High pressure ridge fills in briefly on Sunday keeping dry conditions and few to scattered clouds through the day. As a result temperatures will reach the 80s across the CWA tomorrow with urban areas likely to push 85 degrees or better. The next chance for rain comes Monday ahead of a weak front that will pass through. The combination of frontal forcing and daytime heating will produce decent chances for showers and storms. Hi-res models remain out of range at this time, but looks from global models resolve CAPE values between 1000-1500 J/kg. Trough axis will line up as well and place a jet streak over the lower peninsula, giving the area a shot at some decent speed shear of 30-40 knots. Beyond Monday, models struggle to convincingly resolve rain chances through the rest of the week. One of the main disagreements in the deterministic models is the evolution of the negatively tilted trough through the week. The ECMWF for example, keeps the trough axis slightly further to the northwest than models like the GFS. This is especially important when considering the potential for the remnants of Tropical Storm Beryl to be picked up and brought over the southern part of the CWA. Regardless of if Beryl makes its way over the area or stays to the southeast, the setup will allow for warm, moist air to advect in, pushing dew points into the upper 60s/low 70s and PWATs up to 2 inches. As a result, available moisture in combination with daytime heating still provide chances for showers to pop up in the mid-to-late week time frame even if the more robust system stays to the southeast. MARINE... Light winds and low waves accompany the weak pressure gradient in place through this weekend. Apart from a stray shower this afternoon or early evening, dry conditions will prevail through Sunday as an area of weak high pressure builds in over the Ohio Valley. Southerly wind of around 10 knots then develops on Monday ahead of the next frontal system moving in from the Midwest. This system will bring scattered showers and storms late Monday into Tuesday as it tracks through. Slightly cooler northerly flow follows for the mid-week. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....JA DISCUSSION...BC MARINE.......TF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.