Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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148 FXUS63 KDTX 170948 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 548 AM EDT Tue Sep 17 2024 .KEY MESSAGES... - The lengthy stretch of warm and dry weather is projected to hold today through Friday. - The Mid Atlantic tropical system is only able bring a modest increase in cloud cover tonight and Wednesday. - A weak cold front from the Plains states has a low chance of reaching Lower Mi with spotty light rain later Friday into Saturday. && .AVIATION... Stable conditions and just enough near surface moisture is resulting in another round of patchy morning fog. This is expected to stay mainly in the MVFR range but may dip below for brief periods before fog mixes out around 13z. Prevailing SKC conditions again today as high pressure continues to dominate the region. Cirrus shield associated with a broad low over the southern Appalachians may reach the Metro Detroit terminals but is likely to stall to the southeast of the local area. Wind will remain predominantly out of the east to east-southeast below 10 knots. Model signal and persistence forecast points to another chance for patchy fog development in the pre-dawn hours Wednesday. For DTW/D21 Convection... Thunderstorms are not in the forecast for the foreseeable future. DTW THRESHOLD PROBABILITIES... * None. && .PREV DISCUSSION... Issued at 353 AM EDT Tue Sep 17 2024 DISCUSSION... Today marks day 11 in the string of consecutive dry weather days for the bulk of SE Mi to go along with 16 out of 17 for September. Today is also day 8 in a string of above normal temperatures after a cooler start during the first week of the month. This remarkable stretch of warm and dry conditions is driven once again today by a larger scale blocked 500 mb ridge and associated surface high pressure locked in from the Great Lakes eastward across the NE States. To the south is the Mid Atlantic tropical system drifting inland far enough to graze SE Mi with high clouds during the day which might be just enough to hold temperatures down slightly compared to recent days when combined with persistent easterly flow off Huron and Erie. Temperature guidance offering highs around 80 looks good while readings warm more firmly in the lower to mid 80s toward the Tri Cities and interior Lower Mi. High clouds are about the only concern associated with the Mid Atlantic system as it drifts to the SC/TN border and stalls during mid week. The last few model runs have converged on a 500 mb low position that is nearly stationary through 12Z Wednesday. This occurs partially due to reinforcement of the rex ridge over Ontario and the Great Lakes downstream of the strong central Rockies low as it lifts into the northern Plains. The system then spends the late week period filling and opening up toward the Atlantic coast while high pressure is reestablished in the Great Lakes to ensure dry weather through Friday. Extended range/global models show the powerful Pacific jet finally bringing a larger scale pattern change during the weekend, or perhaps better described as a northward reorientation of high amplitude mid level flow that still exhibits blocking tendencies. The Pacific cold front associated with the late week northern Plains system has a chance to reach Lower Mi Friday into Saturday. It has a weak and moisture-starved character but represents our next chance to see a few raindrops heading into next weekend. MARINE... Sprawling high pressure continues to govern conditions for the central Great Lakes through the forecast period offering mainly dry weather and light southeast winds (AOB 15 knots). A subtropical cyclone tracking west across The Carolinas remains positioned downstream of more meaningful steering dynamics over western CONUS. Latest guidance shows the system turning toward the southwest by late morning which precedes a rather rapid collapse over SC/GA. This effectively keeps the resident ridge of high pressure in control of the waterways featuring persistent light easterly composed flow which yields favorable marine conditions into the weekend. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....TF DISCUSSION...BT MARINE.......KGK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.