Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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004 FXUS63 KDTX 241752 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 152 PM EDT Mon Jun 24 2024 .KEY MESSAGES... - High temperatures in the upper 70s to lower 80s today are right around normal for mid to late June leading to a pleasant day with low humidity. - Showers and thunderstorms become active again early Tuesday morning. These storms are not expected to reach severe intensity but could produce locally heavy rainfall. - An additional round of thunderstorms is possible Tuesday night into early Wednesday, mainly south of I69. There is Marginal Risk of severe thunderstorms during this time. - Cooler and less humid air moves back into the area late Wednesday and lasts through Thursday. && .AVIATION... High pressure maintains dry and VFR conditions this evening with weak and variable winds organizing out of the south to southwest tonight in response to an approaching frontal system from the upper Midwest. Mid/high clouds will increase overnight ahead of this system but will remain VFR. Confidence is increasing on a thunderstorm complex to emerge from the system and track eastward into the area Tuesday morning. Instability will be weak this far east, so expect the storms to be elevated and weakening as they move through mainly between 10z and 15z. The main impacts will be lowered visibility in heavy downpours and an isolated strong wind gust. Warmer air arrives on a breezy southwest wind Tuesday afternoon with a slight chance for additional convection to develop as the cold front moves through late. For DTW/D21 Convection...Adjusted the Tuesday morning TSRA window an hour earlier to 13-16z based on latest hi-res trends. Considered adding a PROB30 TS mention for potential late Tuesday afternoon convective redevelopment but confidence remains too low with model soundings showing stability/capping concerns. DTW THRESHOLD PROBABILITIES... * Medium for ceilings aob 5kft Tuesday after after 12z. * Medium in thunderstorms Tuesday morning mainly 13-16z. Low confidence late Tuesday afternoon. && .PREV DISCUSSION... Issued at 403 AM EDT Mon Jun 24 2024 DISCUSSION... A stray shower remains possible until shortly after sunrise as the overachieving mid level low pressure system exits into Ontario. It is followed by a short wave ridge/surface high pressure combination that takes over conditions for the rest of today through tonight ensuring dry weather. Nearly full sun also helps lift temperatures into the lower 80s across the area with the exception of cooler readings near Lake Huron, still right around normal for late June and with low humidity. A mostly zonal long wave pattern keeps smaller scale wave structures progressive across Canada and the northern tiers of states during the mid week period. The first short wave system is already organizing over the Canadian Prairie provinces today where ongoing convection stays mostly north of the border as the low pressure system reaches northern Ontario tonight. The system has a broad warm front and warm sector extending southward into the upper Midwest that will support a well organized low level jet focused into the Great Lakes late tonight into Tuesday. Model projections are in good agreement on 850 mb wind reaching 50 kts from the central Plains into the warm frontal zone late tonight leading to strong mid level moisture transport and destabilization. QPF fields from regional and global models blossom as a result and are supported by MCS development across the range of hi-res solutions. Consistent from earlier forecast cycles is the pronounced south to north instability axis feeding into the low pressure center which also sets up a sharp gradient into Lower MI by sunrise Tuesday. Surface based CAPE is almost nonexistent in SE MI Tuesday morning while MUCAPE drops off below 1000 J/kg which leads to a pronounced weakening of any organized convection while elevated moisture transport maintains numerous to widespread coverage of showers and other thunderstorm clusters across Lower MI until the low to mid level moisture axis builds fully into the Great Lakes by afternoon. The SPC Day 1 outlook reflects these trends and the General Thunder outlook is in good shape for SE MI. A transition from nocturnal to surface based convective potential occurs Tuesday afternoon as the warm sector of the system surges into the Great Lakes. Afternoon temperatures reach the upper 80s as surface Td returns to around 70 in SW flow ahead the initial cold front/prefrontal trough. This boundary becomes the focus for round 2 of storms affecting Lower MI late Tuesday through Tuesday night. The regional/global models help frame a wide range of hi-res CAM solutions by suggesting surface based development is limited by capping 700 mb temperatures until a new cycle of the low level jet forcing occurs Tuesday night. The question then becomes how far north into Lower MI will this activity be able to reach before the trough/front sweeps the pattern south/east by Wednesday morning. Probability is highest at the Ohio border and then tapers off toward the I69 corridor. The potential for severe intensity drops off from west to east across the southern Great Lakes reflecting the potential for greater MCS-type organization earlier in the night. A chance of showers and sub-severe storms lingers into Wednesday morning until the primary cold front moves through SE MI by afternoon. High pressure then builds in aggressively for Thursday but the progressive larger scale pattern already has a very similar low pressure system organizing in the Plains and Midwest. This system is projected to bring a new thunderstorm pattern into the Great Lakes by Friday. MARINE... A lingering trough draped along the long axis of Lake Huron will pull away to the east today as high pressure builds across the region. Northerly winds will persist today being on the eastern edge of the high, but by this evening winds will go calm as the center of the high passes overhead. The next low pressure system starts developing upstream over the Plains/Midwest today and will pass through the region Tuesday and Tuesday night. This will bring the next chances of showers and thunderstorms and an uptick in southwest winds Tuesday which may necessitate another Small Craft Advisory. HYDROLOGY... An active pattern of thunderstorms returns to Lower Michigan by Tuesday morning as warm and humid air surges back into the region. Most SE Michigan locations will see at least a period of showers during the morning as thunderstorms decrease intensity while moving in from the west. Rainfall totals average 0.25 to 0.5 inch with localized amounts up to 1 inch possible. The Tuesday morning activity is followed by a break in the afternoon until the next round of storms becomes possible Tuesday night into Wednesday morning. Current forecast trends suggest this round of rainfall occurs mainly south of I69 across metro Detroit to the Ohio border. Additional totals up to 1 inch are possible with this activity until it exits the area by Wednesday afternoon. The potential for flooding in each event is greater where repeated rounds of storms occur over the same area making ponding of water on roads and in prone low lying areas possible. The Tuesday and Wednesday activity collectively could lead to a brief response in the level of streams and rivers across the area. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....TF DISCUSSION...BT MARINE.......DRK HYDROLOGY....BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.