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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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005 FXUS63 KDTX 201915 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 315 PM EDT Sat Jul 20 2024 .KEY MESSAGES... * Low coverage of showers or thunderstorms both Sunday and Monday afternoon. * Greater chances for showers and thunderstorms middle of next week. && .DISCUSSION... Seasonably high amplitude flow regime will hold in place across North America into early next week before going through one more episode of amplification during the midweek prior to transitioning to a more progressive state by week`s end. The main feature of note with the next little impulse of height falls is the ribbon of concentrated moisture along the lower tropospheric front settling south across the Northern Great Lakes region today. The shearing deformation within the overall weak geopotential field will stall out across Central Lower Michigan Sunday and Monday. There will be adequate moisture pooling within this zone to support weakly capped modest instability generation (~1.5 kJ/kg MLCAPE) across the Saginaw Valley and Thumb on Sunday. Furthermore, this is the region that possesses the greatest CAPE depth, thereby the best opportunity for convective initiation. Furthermore, slightly unbalanced flow aloft in the entrance zone to tropopause level jet and near surface focus near lake-breeze features should support isolated convection during the middle and late afternoon. Coverage should remain meager given the capping layer and insufficient forcing to adiabatically erase. Quick pulse nature to the convection is expected given the lack of shear, or any flow in the column for that matter. Only minor changes to the overall setup on Monday. Mainly the decaying deformation axis will be perturbed by the meandering upper circulation, currently over the Mid-Mississippi Valley, as it wanders into the Southern Great Lakes Region. Some weak flow imbalance aloft near the leading flank of the wave should be enough to instigate isolated to scattered convective development once again. The instability axis will rotate cyclonically and recenter over interior portions of the Lower Peninsula. Greatest CAPE depth looks to exist across the Saginaw Valley south to along and west of the glacial ridge. Again, lack of shear and flow will support garden variety smaller scale pulse convection. More of the same can be expected Tuesday with continued general weak geopotential troughing and adequate diurnal destabilization. A more substantial deep tropospheric wave will pivot around the Eastern North American trough into the Great Lakes region on Wednesday. Certainly better over all forcing and better instability density in the mid-levels to support a more vigorous convective response. The flow remains rather weak; however, deep layer shear does increase sufficiently to support organized convection. && .MARINE... Influence of surface high pressure wanes through the reminder of the day as said high weakens. A weak cold front gradually sags through the region this weekend into the beginning of next week offering scattered shower and thunderstorm chances focused in the afternoon- evening each day. Winds shift to N-NE behind this front though speeds remain light at or below 10kts. Wider spread shower/storm chances don`t arrive until midweek when a trough dives out of Canada into the Great Lakes. && .PREV DISCUSSION... Issued at 124 PM EDT Sat Jul 20 2024 AVIATION... Dry and stable low level conditions persist through tonight as high pressure maintains control. This ensures VFR conditions hold, while winds remain light and variable. Broad coverage of higher based diurnal cu at scattered to perhaps briefly broken coverage will linger through the latter half of the day before fading with loss of daytime heating. For DTW/D21 Convection...No convection is expected through the TAF period. DTW THRESHOLD PROBABILITIES... * None. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...Mann MARINE.......KDK AVIATION.....MR You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.