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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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869 FXUS63 KDTX 121647 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1247 PM EDT Mon Aug 12 2024 .KEY MESSAGES... - Seasonable temperatures through the mid week period. - Isolated showers possible today and Tuesday. - Rain chances increase Friday into the weekend. && .AVIATION... SE Mi remains on the eastern fringe of broad Midwest high pressure this afternoon. Cooler air still over the region gets a boost from a mid level wave and daytime heating for production of VFR cumulus. An isolated shower is also possible nearby the terminal corridor but with low predictability for any specific location. High pressure then builds more strongly overhead tonight and Tuesday. A brief period of ground fog is possible around sunrise leading up to another round of afternoon VFR instability cumulus. For DTW/D21 Convection... The weather pattern does not support thunderstorms today through Tuesday. DTW THRESHOLD PROBABILITIES... * Low for cigs at or below 5000 ft this afternoon and evening. && .PREV DISCUSSION... Issued at 310 AM EDT Mon Aug 12 2024 DISCUSSION... Mid level cyclonic flow gradually relents today, as height falls associated with a seasonably strong closed low over Quebec finally release eastward. General transition toward confluent mid level northwest flow atop weak high pressure suggests a higher degree of stability will exist across the column today. With that, daytime heating offers a window for shallow instability to emerge, with a couple hundred joules of CAPE targeted for the late day period. This may prove sufficient to yield isolated showers, highlighted primarily along the US 23 corridor given a noted weak signal of convergence. Plausible nothing develops as moisture quality remains lean within a moderately mixed profile. Temperatures take step upward within the backdrop of an increasing upper height field. Late day readings arriving closer to average, with humidity remaining manageable. Conditions largely a carbon copy for Tuesday. Loosely organized high pressure beneath persistent northwest flow ensures thermal advection remains muted, maintaining a seasonable mid August thermal profile. Potential for a modest uptick in larger scale vertical motion as shortwave energy works through the great lakes offers slightly greater convective shower potential during the peak heating cycle. Still not a great signal overall across short range model guidance, but the underlying thermodynamic profile again affords a weakly unstable profile as lapse rates steepen diurnally. Forecast maintains an isolated mention attm. Upper ridging takes control for the Wed-Thu window. No significant weather noted this period given depth of stability within this environment. An increase in the upper height field portends additional moderation of the existing airmass, but still no evidence of a more sizable warming trend with low level flow still backed to the southeast and cloud cover likely an increasing issue by Thursday. Attention Thursday night into Friday turns to an initial period of forced ascent and accompanying moisture advection associated with an organizing height fall center propagating toward the upper great lakes. Improving confidence evident within the model solution space for a meaningful response locally during this timeframe, offering an increasing probability for shower and thunderstorm production within the background of concentrated ascent above 850 mb. Potentially unsettled conditions heading into the weekend, as pv consolidates into a more organized low nearby and engages an increasingly moist and weakly unstable profile during this time. Positioning and downstream pace of the governing large scale features will dictate the scope and timing of any prospective convective episodes. MARINE... High pressure will continue to build northward across the region today pushing the last bit of influence from the Quebec low out of the Great Lakes. More stable conditions with ridging aloft and at the surface should produce favorable marine conditions across the waters through mid week with max wind gusts mostly below 10 knots and minimal wave heights. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....BT DISCUSSION...MR MARINE.......MR You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.