Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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978 FXUS63 KDTX 060736 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 336 AM EDT Sat Jul 6 2024 .KEY MESSAGES... - Isolated to widely scattered showers will be possible this afternoon and 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 cloudy skies. - Hot on Monday with highs in the upper 80s. Shower and thunderstorm chances return Monday and Tuesday. && .DISCUSSION... A cold front has cleared the state as of early this morning, where dry weather now prevails in the wake of the front with temperatures presently in the mid-60s. Residual moisture and humidity will hold on today across SE MI, which will aid in the production of isolated to widely scattered shower activity. The inherited forecast looks reasonable, holding PoP chances north of I-94, with highest PoP chances (30-35%) located along and north of I-69, tied to the greater moisture and subsequently better instability. Instability and bulk shear are not favorable for sustainable activity today, holding at 500 J/kg and around 15-20 knots respectively. Additionally, a cap just under h600 will limit convective depth and coverage. However, steep low level lapse rates with the passage of multiple upper-level waves do justify the PoP potential. Cannot rule out some embedded thunderstorms, but LI values of 0 to 1 and very poor mid-level lapse rates favor rain showers. Shower and storm potential will wane with the loss of daytime heating, with lingering potential lasting through 10PM- Midnight. Highs hold in the upper 70s in the wake of the front. A weak shortwave ridge will fill in behind the departing shortwave and will bring a day of dry weather tomorrow with temperatures returning into the mid 80s for a high. The return of warmer weather is a result of multiple upper-level waves that fill in over the Plains with trough amplification taking place across the greater Plains through the early week period. Initially, this directs heat and moisture from central US downstream into the Great Lakes noted by h850 temperatures increasing from 16C Sunday evening to 18C by Monday evening. This brings daytime highs in the upper 80s, possibly reaching 90 across urban areas on Monday. Rain and thunderstorm chances are also possible Monday with the improved moisture and support from glancing shortwaves ahead of the main trough axis. The better chances for numerous to widespread showers with embedded thunderstorms will enter late Monday into Tuesday tied to the better connection with the trough, with the axis swinging over Michigan late Tuesday night. Medium range models are more muddled through the midweek period given subtleties with shortwave passages and interactions. One major consideration that models are struggling with this far out will be the upstream impacts of Tropical Storm Beryl. The latest ECMWF is much less progressive relative to the 12Z model run and pushes the system into the Ohio Valley, clipping portions of SE MI. Even less progressive is the ICON (and ICON-EPS), which pushes the center of the low right over Michigan. Regardless, not much credence is given into any one particular model solution at this time factoring in limited sampling from the upper-air network, but it is worth noting as several deterministic runs display a much less progressive solution for the 00 cycle. Closer attention will be given to the path of the system as it makes landfall somewhere over southeast TX by early Monday. && .MARINE... Low pressure departs to the eastern Great Lakes this morning but leaves a trailing trough that lingers over the local area much of the day. This feature and enough moisture wrapping around the departing system will keep scattered showers in the forecast with potential for a few thunderstorms as well. Light northwest winds develop today at generally 10 knots or below. The trough exits tonight with weak high pressure moving back in through Sunday bringing continued light winds. Southerly wind of 10 to 15 knots then develops on Monday ahead of the next frontal system moving in from the Midwest. This system will bring showers and storms late Monday into Tuesday as it tracks through. Slightly cooler northerly flow follows for the mid-week. && .PREV DISCUSSION... Issued at 130 AM EDT Sat Jul 6 2024 AVIATION... We are already starting to see haze develop behind the exiting line of showers and thunderstorms. With dewpoints still well into the low to mid 60s and calm winds expected overnight, confidence is growing that we will see haze develop. Soundings are not overly excited about seeing any fog development, as passing mid and high clouds overnight should help limit temperatures from fully bottoming out. Around/near daybreak on Saturday, expect MVFR ceilings to develop around 2.0-2.5kft. It remains possible that we could see low-end MVFR ceilings, but for not opted to hold off on mentioning any BKN- OVC cloud decks and just kept SCT mentions of this potential. By late Saturday morning and into the afternoon hours, widely scattered showers and perhaps a thunderstorm or two will be possible. Given the coverage is is very difficult to pinpoint a solid TEMPO period. So will let subsequent TAF updates refine that potential, if needed. For DTW/D21 Convection...Widely scattered showers and a thunderstorm or two are expected on Saturday. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms on Saturday. * Medium for ceilings at or below 5000 ft on Saturday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...AM MARINE.......TF AVIATION.....DG You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.