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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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788 FXUS63 KDTX 072219 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 619 PM EDT Sun Jul 7 2024 .KEY MESSAGES... - The holiday weekend closes out with dry weather today under partly sunny skies. - Warming up into Monday with highs in the mid to upper 80s. Shower and thunderstorm chances return Monday and Tuesday. - Remnants of Beryl may begin to impact parts of the area by Tuesday night and Wednesday. && .AVIATION... A dry low level environment maintained under lingering high pressure ensures VFR conditions hold tonight and early Monday. Some pockets of convective showers evident on radar lifting across lake Michigan and farther upstream may offer a period of thicker mid cloud overnight, with a low probability for showers to near MBS toward daybreak. Some increasing convective potential Monday afternoon and evening as moisture improves along a slowly advancing frontal boundary, mainly at FNT/MBS. Conditions from PTK southward into the Detroit metro corridor marked simply by a standard high based VFR diurnal cu through the daylight period. Modest winds generally from a south to southwest direction through Monday. For DTW/D21 Convection...Thunderstorms are not expected across the airspace through the daylight hours Monday. Very low potential exists Monday night. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms Monday night. && .PREV DISCUSSION... Issued at 302 PM EDT Sun Jul 7 2024 DISCUSSION... Shortwave ridge overtop the Great Lakes has kept dry conditions in place with some spotty cumulus clouds and temperatures currently in the lower 80s. Dew points in the upper 50s will increase into the low to mid 60s tonight, with overnight temperatures dropping to the mid to upper 60s across the CWA. Winds remain light and variable through the rest of the day today before turning southerly overnight. Temperatures slightly warmer tomorrow barring any overachieving cloud cover, reaching the mid 80s across the CWA and the upper 80s in urban areas. Chances for showers and storms return ahead of a frontal boundary moving into the area Monday. The front will progress very slowly over the Great Lakes, leading to multiple chances for convective showers and storms on both Monday and Tuesday. Storms hold off until 20Z Monday evening, where SBCAPE up to 1000 J/kg in the Thumb and Tri-cities will be in place to help initialize the showers. Shear of 30-40 knots alongside the frontal forcing will help sustain the updrafts as they develop through the evening. A severe storm cannot be ruled out at this time. Only a few hundreths of an inch are expected, but given the scattered nature of the showers, locally higher amounts are easily possible. Tuesday`s chances to see showers and storms are in part dependent on how far the front is able to progress before stalling. Convection ahead of the front may also be stifled by slightly warmer upper- level air mixing in and creating just enough of a cap to limit the upward potential of the developing updrafts. Profiles on Tuesday will have lapse rates near the moist adiabatic lapse rate throughout the column, adding another obstacle for developing updrafts to overcome. The remnants of Beryl and how the system impacts southeast Michigan will be the main focus for the middle of the week. Trough will be slow to move eastward as it picks up the tropical system early Tuesday morning over Texas, allowing the low pressure center to interact with the trough`s left exit region. Upper level wave will progress northeastward on Tuesday afternoon, bringing the remnants of Beryl to the Great Lakes. Excessive rainfall is the primary threat with these storms at this time range. While yesterday deterministic models struggled to resolve the path of the storm, today shows more convergence, specifically in line with yesterday`s ECMWF solution. Under the assumption that the ECMWF has the best handle on the storm, today`s solution now highlights rain arriving Wednesday morning, the heaviest rainfall occuring Wednesday night, and placing the track/passage of the low over western Lake Erie Thursday morning. Too much faith cannot be placed in any one model however, and a range of possibilities still exist. Ensemble guidance gives mean storm total QPF amounts near an inch but there is a large variance among the members, reinforcing that much will depend on the exact track of the storm. At this time, a broad 1-2 inches of rain is likely, but locally higher amounts will be possible. Further model convergence over the next few model cycles on storm track and timing is needed to more effectively highlight the risks the remnants of Beryl will bring to southeast Michigan, although it is clear that a Wednesday arrival is most likely and that there is a threat of significant rainfall across the area. MARINE... Benign marine conditions prevail through tonight as high pressure maintains control of the area. A weak frontal boundary is forecasted to reach the western Great Lakes overnight and slowly track eastward across the central Lakes Monday night into Tuesday. Winds on Monday will orient out of the south ahead of this system at around 10 to 15 knots. Scattered showers and storms will accompany the system as well from Monday into early Tuesday. Drier light westerly flow follows on Tuesday before more active weather arrives Wednesday into Thursday as the remnants of Tropical System Beryl move into the vicinity. The forecast remains sensitive to the eventual track and strength of the system, but current information suggests gusty northeast winds and heavy rain will be possible. HYDROLOGY... The remnants of Beryl will move along an upper level wave and begin to impact the Great Lakes area Tuesday night into Wednesday. The remnant low pressure center will track overhead Wednesday night into Thursday morning. At this time, details on the track of this system are difficult to determine. An increased risk of heavy rainfall will exist as the system encroaches on the area. Most of southeast Michigan is set to receive at least an inch of rain, and if impacted directly, rainfall will most likely reach or exceed 2 inches in some areas. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....MR DISCUSSION...BC MARINE.......TF HYDROLOGY....BC You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.