Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 240750 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 350 AM EDT Sat Jun 24 2017 .DISCUSSION...
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Broad mid level troughing will grip the Great Lakes region throughout the upcoming weekend. The subsequent suppression of the mean thickness field under prevailing deep layer west-northwest flow will maintain a cooler and less humid resident environment during this time. The combination of cooler mid level temperatures and near surface diabatic heating will establish a steep lapse rate environment for substantial diurnal cu growth today. This ascent will be augmented this afternoon by the arrival of a shortwave and cold pool, as energetic northwest flow directs a series of perturbations into the base of the mean trough over the next several days. Recent model guidance remains supportive of an increase in shower coverage as weak instability emerges beneath the inbound cold pool and with the small scale increase in cyclonic flow. Higher probability of development with northward extent given favorable positioning, which should translate into a scattered coverage of showers with isolated thunderstorms largely impacting the tri- cities/thumb down through the I-69 corridor. MLCAPE reaches upwards of 800 J/KG, perhaps sufficient to generate a deep enough updraft to support small hail given the lower freezing levels. Paltry deep layer wind fields will preclude a greater risk of organized development. A stronger wave will lift across central lower MI late tonight into early Sunday. This will yield a period of greater forced ascent, potentially capitalizing on sufficient moisture and steep lapse rates at the mid levels to produce another round of scattered showers/isolated thunderstorms. Should the timing prove a touch slower allowing for greater diurnally driven low level destabilization, then a localized region of higher coverage will be plausible. This wave will lead in a secondary period of cold air advection for Sunday, as 850 mb temperatures dip into the 5-6C range. This will place highs in vicinity of 70 degrees all locations, or a good 10 degrees below normal. Timing of any subsequent shortwaves remains too ill-defined to provide greater detail, but it generally appears SE Michigan will remain susceptible to additional bouts of heightened cva and cold pool intrusions through Monday. A scattered shower/isolated thunder mention remains highlighted for the Monday period. Neutral temperature advection under this relatively static pattern will again ensure temperatures remain well below normal to begin the work week. Airmass modification commences beginning Tuesday as the upper trough axis eases eastward and upper heights begin to recover. Warm air advection then ramps up Wednesday, with temperatures returning to around average for midweek.
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&& .MARINE...
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West to northwest flow will be maintained through the weekend between low pressure over eastern Canada and high pressure building through the Plains and into Tennessee Valley. The highest speeds will be over western Lake Erie where the gradient will be a little tighter, resulting in gusts that will just top 20 knots both this afternoon and Sunday afternoon. Scattered showers, and possibly a thunderstorm, are also expected each afternoon. Weak low pressure tracking through the area will bring scattered to numerous showers and a few thunderstorms Monday.
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&& .PREV DISCUSSION...
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Issued at 1205 AM EDT Sat Jun 24 2017 AVIATION... Cooler and much drier air has filtered into southeastern Michigan this evening. Impressive shortwave feature with some linkage to upper level jet entrance region has resulted in aggressive altostratus and a tiny amount of virga over southern Lower Michigan this evening. Cold advection and stability just too tough to overcome. A ribbon of midlevel moisture will linger back over the central Great Lakes late tonight keeping altostratus around. This ribbon of moisture will then result in boundary layer cumulus development late Saturday morning along with some shower and isolated thunderstorm potential over the northern cwa Saturday afternoon. //DTW THRESHOLD PROBABILITIES... * Medium confidence in ceilings aob 5kft Saturday afternoon.
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&& .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ DISCUSSION...MR MARINE.......HLO AVIATION.....HLO You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.

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