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Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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972 FXUS63 KMQT 171156 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 756 AM EDT Sat Aug 17 2024 .KEY MESSAGES... - Patchy fog this morning, becoming locally dense across portions of the UP. - Showers this morning with increasing thunderstorm activity by this afternoon. Main threats will be brief, heavy downpours and small hail. Below normal highs in the upper 60s to low 70s today. - Isolated showers are possible tonight through Sunday morning. - Mostly dry forecast through mid next week. Cooler temperatures continue through early next week, becoming more seasonable late in the week. - Chances for showers/storms develop late next week. && .SHORT TERM /TODAY/... Issued at 449 AM EDT Sat Aug 17 2024 As low pressure continues to rotate over northern Lake Michigan early this morning per water vapor imagery/surface analysis, there has been an uptick in scattered showers over the last few hours. Rain showers on current radar mosaics are concentrated over central portions of the U.P. in the wraparound flow around the aforementioned low. Meanwhile, with plenty of lingering low level moisture and light winds, ground-based obs across the forecast area have been reporting widespread patchy fog. And, pockets of 1/4-3/4 mile visibilities have been more prevalent over areas that received the heaviest rainfall yesterday. And, with the blanket of cloud cover, temperatures early this morning have been holding steady in the 60s. With limited instability this morning, there has been little thunderstorm activity. As diurnal instability increases throughout the day, however, look for more embedded thunder in these rain showers. Again, severe weather is not anticipated. But, PWAT values continue to trend toward 1.50 inches again today, so brief, heavy downpours accompanied by small hail cannot be ruled out until the trough exits the area. As far as temps, daytime highs will be below normal, only topping off in the upper 60s to mid 70s. && .LONG TERM /TONIGHT THROUGH FRIDAY/... Issued at 447 AM EDT Sat Aug 17 2024 Once this low pressure system`s rain diminishes, a generally drier pattern is expected for the extended forecast as the pattern often consists of ridging and high pressure. That said, there are two main chances for showers during the period: Wednesday into Wednesday night and Friday/Saturday. Otherwise, temperatures hold near to just below normal through Tuesday night with a warming trend toward the following weekend. Starting tonight, the mid level closed low will have opened up into a deep trough, centered over lower MI with the sfc low situated just out ahead of it over Lake Huron. These two features shift east with ridging and high pressure building in behind it resulting in gradual drying. Isolated showers supported by upslope flow will continue through Sunday morning. Lows slowly settle into the mid 50s to low 60s, coldest interior west where the least cloud cover is expected. While the deep moist profile diminishes on Sunday as high pressure continues to build in, low level cloud cover may be stubborn to clear out over the east half where 850 mb temps drop to 8-10C over an area of water temps ~14-17C. With that in mind, cooler than normal temps are expected in the upper 60s to mid 70s, coolest near Lake Superior over the north central and east where the cloud cover lingers. With mixing, north winds gusting to 20-25 mph are expected, strongest over the east. Lows Sunday night fall into the upper 40s to upper 50s, coldest interior west. Monday and Tuesday stay dry with plenty of sunshine as high pressure extending south from Hudson Bay into the Midwest shifts east- southeast toward the Atlantic. Also during this period, mid level ridging builds in from the west. Cooler to near normal temps continue with highs in the upper 60s to mid 70s. The drier airmass descending south into the region will also help radiative cooling bring cool temps overnight with 40s in the interior and upper 40s to mid 50s by the lakeshores. Some places may even dip into the 30s! The next chances for showers return with a shortwave riding atop the mid level ridging on Wednesday; this is already a delayed onset from the guidance 12 hours ago. Late next week, guidance begins to spread, but the best chances for more showers and storms accompany a shortwave on Friday that brings a cold front across the region. With uncertainty in following shortwaves into the weekend, left NBM PoPs mainly as is, but limited it to slight chance only (15-24%). && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 755 AM EDT Sat Aug 17 2024 LIFR conditions to persist at IWD and SAW into this afternoon before slight improvement to IFR and eventually MVFR late in the afternoon. Elsewhere, CMX could see IFR/MVFR conditions by late morning/early afternoon, but low level moisture is abundant over the area. And, it will take awhile for drier air to filter in behind the departing trough. In addition, scattered showers with possible embedded thunder are expected through this evening. && .MARINE... Issued at 447 AM EDT Sat Aug 17 2024 North winds of 20 kts or less continue through tonight as the low pressure system meanders east to southern Ontario. Winds over the east half of the lake increase to around 15-25 kts on Sunday before diminishing below 20 kts across the entire lake Sunday evening. With high pressure building in over the lake Sunday night, maintaining overhead into Wednesday, winds are generally expected to remain below 20 kts on Monday. East winds on Tuesday veer southerly by Wednesday morning, mainly holding below 15 kts. The next chances for winds to exceed 20 kts hold off until late next week/the following weekend. Otherwise, thunderstorm chances continue into tonight and some patchy fog is expected through this morning. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...Jablonski AVIATION...TDUD MARINE...Jablonski