Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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212 FXUS63 KDTX 230727 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 327 AM EDT Thu May 23 2024 .KEY MESSAGES... - Comfortable weather with low humidity today. A little breezy with winds gusting around 20-25 mph, up to 30 mph closer to the Tri- Cities and Thumb this afternoon. - A brief warm-up is expected Friday with a 60 to 70% chance for showers and storms late Friday into early Saturday. - Slightly cooler conditions early next week with additional showers and storms likely late Sunday into Monday. && .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. && .PREV DISCUSSION... Issued at 1223 AM EDT Thu May 23 2024 AVIATION... A significant spoke of absolute vorticity pushed across the forecast area between 00-04Z. Subsidence in the wake of the shortwave and loss of daytime heating has caused the cumulus to dissipate this evening. Relatively neutral temperature advection with increasing confluent flow aloft will result in low sky fraction the duration of tonight. A cooler and drier morning is expected to result in a slow development of boundary layer cumulus late Thursday morning. DTW THRESHOLD PROBABILITIES... * None && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...AM MARINE......LM AVIATION.....YO You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.