Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 261046 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 646 AM EDT FRI AUG 26 2016 .AVIATION...
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Drier air has settled over southeast Michigan this morning, with little if any low level CU development expected today. There will be some high clouds (20-30 kft) around with light (less than 10 knot) westerly winds, becoming light and variable/calm early this evening. //DTW Threshold Probabilities... * none.
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Issued at 310 AM EDT Fri AUG 26 2016 DISCUSSION... Sfc high pressure will expand from the upper midwest across the Great Lakes region today under building mid level heights. The low level anticyclone will affectively suppress the moisture and instability reservoir south across the Ohio Valley. Much drier low level air has been slowly filtering into the forecast area in the wake of last evenings fropa. Diurnal mixing will sustain this dry air in the boundary layer, making today much less humid than yesterday. While there is a decent moisture gradient along the front, the thermal gradient is quite weak. Afternoon mixing depths, especially within the drier boundary layer, will thus be able to push afternoon highs into the 80s. The forecast will carry just partly sunny skies today in light of recent satellite imagery which show a good deal of high clouds streaming into the area from the southwest. In fact, these clouds may be rather opaque at times today. Despite the dry air and sfc high overhead, these high clouds may limit the degree of nighttime radiational cooling enough to support min temps just in the 60s tonight. An influx of deep layer moisture and instability will be transported into the Upper Mississippi Valley/wrn Great Lakes tonight into Saturday as a result of strengthening southwest low level flow. This will precede a mid level trough traversing the northern plains. Low level convergence and moisture transport is then forecast to shift into the northern Great Lakes Sat afternoon and evening, likely driven by a convectively induced mid level short wave impulse. Southeast Michigan will see a little more influence from the mid level ridge parked over the Mid Atlantic, which will sustain low level dry air through much of the day and result in rather shallow mid level lapse rates. So just a low chance of some late day showers will be carried in the forecast. Moisture depth is forecast to increase Sat night as the low and mid level flow veers more westerly. Weak mid level frontal forcing and height falls associated with the aforementioned mid level trough as it rotates across the nrn Great Lakes, combined with the ample moisture and weak instability, will support better chances for showers/tstms Sat night. Mid level dry air advection and capping is shown by the 00z model suite to overspread srn Mi on Sunday, supporting a dry forecast past mid morning. Model soundings suggest decent mixing under westerly flow and lack of cooler air infiltrating srn Mi will support highs into the 80s again Sunday. Warm and dry conditions will persist to start the work week with a mid level ridge across the Ohio Valley. The medium range model suite are showing an amplification in the height field across noam next week. A sfc cold front is forecast to move from north to south across the area on Tuesday, associated with a northern stream mid level impulse tracking across nrn Ontario. Mid level trough amplification forecast across ern Canada late in the week suggests cooler air will overspread the Great Lakes during the end of the forecast period. MARINE... West-Northwest winds of 10 to 15 knots early this morning over lake huron will become light and variable this afternoon, continuing through tonight. A light southeast wind looks to develop on Saturday, along with a low chance of showers and thunderstorms as low pressure tracks through the Northern Great Lakes, allowing for winds to shift to the west-southwest over the second half of the weekend.
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&& .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....SF DISCUSSION...SC MARINE.......SF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.

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