Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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758 FXUS63 KDTX 141802 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 202 PM EDT Tue May 14 2024 .KEY MESSAGES... - There is a chance of showers across all of southeast Michigan this morning shifting toward the Ohio border this afternoon and tonight. An isolated weak thunderstorm is possible. - Notably cooler temperatures settle into the area today with highs in the upper 50s to lower 60s after highs yesterday in the lower 80s. - High pressure brings dry weather and a gradual temperature rebound Wednesday and Thursday. - The next low pressure system arrives with a chance of showers Thursday night and Friday. && .AVIATION... Frontal boundary across Lower Michigan just south of the terminals bring east-northeast winds this afternoon of 6-10 knots. Pocket of clearing across the metro terminals has brought mostly clear skies prior to 18Z with lower VFR ceilings present across central Michigan and KMBS. Some diurnal cu are starting to develop in the clearing, which will also be where the best chances for scattered rain showers will be this afternoon. Have left any prevailing or TEMPO for rain showers out of the TAFs for now as latest guidance and observational data point toward activity possibly holding to the south/west. Any lower clouds should clear out later this evening with mid/high clouds remaining. Some lower clouds may return tonight, but have moderate confidence ceilings remain VFR. For DTW/D21 Convection...Little to no chance for thunderstorms with any showers developing near the I-94 corridor this afternoon given instability holding further to the south. May see scattered sub 5kft clouds both this afternoon and again early tomorrow morning. DTW THRESHOLD PROBABILITIES... * Low confidence in cigs aob 5000 feet this afternoon and early tomorrow morning. && .PREV DISCUSSION... Issued at 357 AM EDT Tue May 14 2024 DISCUSSION... Early morning observational trends and model analysis fields indicate the cold front overhead and settling very slowly toward the Ohio border leading up to sunrise. Slightly stronger high pressure reaching down from northern Ontario combined with a slower/farther south pace of mid MS valley low pressure is keeping the front slowly on the move rather than completely stalled across southern Lower Mi. Clusters of showers in progress are embedded in the west to east mid level moisture axis extending north of the surface front up through the Tri Cities and Thumb, and this is expected to continue during the morning. The temperature contrast will become the notable aspect of conditions this afternoon as readings stall in the upper 50s to lower 60s compared to highs in the lower 80s across all of SE Mi yesterday. A shift toward surface based convective potential is confined to along and near the cold front that will be very near the Ohio border by mid afternoon, if not to the south when factoring in the influence of Lake Erie. This will limit the chance of surface based convection to Lenawee and Monroe counties during feeble peak instability from mid afternoon to mid evening. HREF mean surface based CAPE is only a few hundred J/kg after 18Z and almost non- existent by 00Z this evening to go along with an impressively weak wind profile featuring about 10 knots of flow at 500 mb. Scattered afternoon and evening showers is the best way to describe the result, with a rumble of thunder possible. A stray shower then remains possible after midnight off the northern fringe of the low pressure system as it moves slowly along the Ohio valley. Clouds decrease north to south across Lower Mi during Wednesday as surface high pressure builds down farther from northern Ontario. Lingering NE boundary layer cold advection is balanced by breaks of afternoon sunshine across interior locations making guidance highs around 70 within reach. Given the NE wind, locations closer to the shorelines will have much more of a temperature struggle where readings end up stuck in the 50s near Lake Huron. Temperatures then take a step upward Thursday as high pressure retreats into Quebec. The Lake Huron shoreline remains the exception as easterly/onshore wind continues, although on a weaker gradient compared to Wednesday. For the late week and next weekend, extended/global model solutions depict a less amplified long wave upper air pattern compared to recent days/weeks. The relatively zonal flow carries the next short wave system into central Canada during mid week with improved agreement among solutions on Thursday night/Friday arrival timing in the Great Lakes. The quick moving system brings our next chance of showers and thunderstorms until exiting eastward Friday night. Model consensus for the weekend maintains a progressive/zonal configuration favoring mostly dry and mild weather this weekend. MARINE... The chance for showers will continue along a stationary front which is currently positioned west-southwest to east-northeast, extending from the basin of southern Lake Michigan into southern Lake Huron. Some rumbles of thunder cannot be ruled out, but with limited instability, mainly rain showers are expected. Shower chances remain possible leading into the early afternoon, but will decrease as high pressure builds into the northern Great Lakes, pushing the frontal boundary south of the state line. Some renewed rain and some thunder chances will build back in mainly across Lake Erie late tonight into Wednesday as a low pressure fills in across the Ohio Valley. This low pressure system will reinforce northeast flow across all of the Great Lakes, building wave heights into Saginaw Bay and across the Lake Huron shoreline. Small Craft Advisories will likely be needed across the Bay and portions of the shorelines given wave heights building to or slightly above the four feet. High pressure will continue to settle in over the Great Lakes on Thursday, relaxing wind speeds and subsequently wave heights. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....AA DISCUSSION...BT MARINE.......AM You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.