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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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233 FXUS63 KDTX 120344 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1144 PM EDT Sun Aug 11 2024 .KEY MESSAGES... - Isolated showers today and tomorrow. - Mostly dry mid-week with daytime high temperatures in the low 80s. - Rain chances increase late week into the weekend. && .AVIATION... Mainly clear skies are expected overnight into Monday morning with SCT-BKN cu/strato-cu developing Monday afternoon as a shortwave encroaches on the area near peak heating. A few showers will also be possible in this scenario. Westerly winds will continue, but with less gustiness as pressure gradient diminishes into tomorrow. For DTW/D21 Convection... No thunderstorms are expected. DTW THRESHOLD PROBABILITIES... * Moderate for cigs at or below 5000 ft Monday afternoon. && .PREV DISCUSSION... Issued at 359 PM EDT Sun Aug 11 2024 DISCUSSION... Cool thermal trough remains over the region with the center of the mid/upper level closed low moves eastward just north of Lake Ontario. As this low moves further out of the central Great Lakes, the weakly forced cyclonic flow containing widely scattered light showers will target mainly the Thumb region this evening. Diminishing shower chances with a decreasing cloud trend from west to east during the overnight. Lows by early tomorrow morning fall into the low to mid 50s for most locations. Lower level temperatures gradually moderate tomorrow helping bring daytime temperatures up several degrees compared today with most areas will be in the upper 70s. A few locations should achieve 80 degrees, especially across the Detroit Metro area and parts of the Saginaw Valley. A favorably timed shortwave during peak heating Monday will have very weak surface instability/steep low level lapse rates to work with, which may be enough to generate isolated to widely scattered light showers. Will introduce a 15-20% PoP, but enough stability within the confluent northwest flow may be enough to keep conditions dry. Similar scenario for Tuesday as models depicting another weak shortwave diving S/SE through the central Great Lakes with an associated weak surface reflection. Increased low-level lapse rates and potentially some weak diurnal instability could support another day of isolated to widely scattered light rain showers. Will have 15-20% PoPs during the afternoon again, but stability may very well prevent much if any precipitation. Mid-week will see surface high pressure settle into the New England region as ridging builds over the western Great Lakes. This will lead to quiet weather conditions Wednesday and Thursday. Airmass recovery is muted by the southeast flow around the high pressure at the surface and persistent north/northwest flow aloft. Temperatures at 925-850 mb increase only a few degrees and offer daytime highs Wednesday and Thursday in the low 80s. Chances increase for more appreciable rainfall during Thursday night into the weekend, but there remains plenty of differences in the overall evolution of the low. The difference being a more progressive wave or if a closed upper low develops in or around the Great Lakes and lingers. NBM paints a broad swath of medium range PoPs from Thursday night through the weekend given the uncertainty in the long range models. Adjustments to timing of precipitation likely during this period as models come into better agreement. MARINE... The low pressure system now over Quebec will send one last trough through the eastern Lakes today. This trough running up against the high pressure system lifting northward into the southern Great Lakes will keep some gustiness around this afternoon. High pressure should win out tonight and take hold across the region which will then persist through the first half of the week. Winds will drop off with gusts below 15 knots through this time. There will be a slight chance of a shower or two mainly across Lake St. Clair and Lake Erie as diurnally forces showers drift southeast toward those bodies of water. Otherwise a quiet forecast for the marine areas. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....DG DISCUSSION...AA MARINE.......DRK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.