Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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177 FXUS63 KDTX 231723 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 123 PM EDT Thu May 23 2024 .KEY MESSAGES... - Friday brings more nice weather to kick off the holiday weekend, mostly sunny with highs in the lower 80s. - Showers and thunderstorms move in Friday night (60-70%) and continue into Saturday morning. - Rain ends Saturday afternoon through Saturday night. - Showers are likely again with a chance of thunderstorms Sunday afternoon and Sunday night. - The Memorial Day outlook calls for cool temperatures with showers likely Monday and Monday night. && .AVIATION... Mainly clear sky conditions today with the exception of a few diurnal cumulus and some high cirrus. High pressure to the south keeps stable, dry conditions in place. Westerly winds remain gentle through the rest of the day today, with occasional gusts reaching 15 knots. Light and variable winds in the early morning hours tomorrow as the center of the high pressure centers overhead. Winds flip to become southeasterly tomorrow behind the high, with skies remaining clear. The next system is expected to move in Friday night/Saturday morning and bring showers and storms, although the start time for these storms remains just outside the TAF period for now. DTW THRESHOLD PROBABILITIES... * None && .PREV DISCUSSION... Issued at 327 AM EDT Thu May 23 2024 DISCUSSION... Northern periphery of a high pressure system under relatively zonal mid-level flow will ensure dry weather today under plenty of sunshine, allowing temperatures to rise into the upper 70s, up to about 80 degrees for a high. Once afternoon mixing commences, dew points drop into the low to mid 40s as wind speeds increase, gusting around 20-25 mph for most locations, up to around 30 mph for the Tri- Cities and northern Thumb. This will make for a comfortable day despite temperatures still a little above normal values for this time of year. Water vapor imagery highlights an upper-level wave now entering Wyoming, which will progress into the Dakotas tonight, amplifying an upper-level ridge across the Great Lakes. The amplitude of the ridge will reach its peak over Michigan by tomorrow afternoon, bolstering subsidence and bringing clear skies for the first half of the day. Not much change to the overall thermal profile, but very subtle warm air advection will help support highs in the lower 80s with light winds. Mid to upper-level clouds will then start to fill in from the west derived from upstream activity associated with the approaching wave. A piece of shortwave energy just ahead of the main vort lobe will bring the chance for showers and thunderstorms Friday night into Saturday morning. Moisture transport vectors are maximized over SE MI just ahead of this wave, bringing a quick window to see h850 dew points increase to around 12C. But between the tail-end of the hi-res suite, the degree of moisture transport (and thus instability) does display larger variations, with better confidence for meaningful CAPE residing over the southwest portion of the state. Shower and storm potential will more than likely remain elevated across SE MI, or will have limited surface based CAPE to work with. High pressure builds in behind this wave bringing another period of dry weather later in the day Saturday into Sunday, but dry weather will likely be short-lived with a low pressure system that is expected to fill in somewhere across the western Great Lakes or southeast into the northern Ohio River Valley. A southern stream upper-level wave will come onshore around Baja California and will aid in cyclogenesis around the TX/OK panhandles, where low pressure will then push towards the Great Lakes. This will bring another chance for widely scattered to numerous showers and possible embedded thunderstorms, pending the final position of the low. If the low tracks into northern lower, as per the ECMWF, the warm sector will drop showalter indices will drop below 0 with the rising instability. The solutions that target southern MI will have less favorable chances for thunderstorms. In either case, the large scale forcing, including the mid-level wave and a window for favorable left exit jet streak dynamics, will support likely PoPs (60-70%) for late Sunday into Monday morning. Continued rain chances (50-60%) hold through the remainder of Monday with moisture wrapping around the low, interacting with the trailing upper-level wave. MARINE... Low pressure slows over Ontario today with modest southwest gradient winds. Winds then flip to the east over the weekend and remain modest as a surface ridge builds. Another wave ejects across the Upper Midwest Friday into Saturday with a secondary low developing along the system`s cold front. Active pattern continues early next week with additional Small Craft Advisories possible across Saginaw Bay. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....BC DISCUSSION...AM MARINE......LM You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.