Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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785 FXUS63 KMQT 180725 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 325 AM EDT Wed Sep 18 2024 .KEY MESSAGES... - Extended stretch of well above normal temperatures continues through at least Saturday with highs mainly in the upper 70s and 80s. - A cold front brings scattered showers and a few thunderstorms late Thursday into Friday. && .SHORT TERM /THROUGH TODAY/... Issued at 121 PM EDT Tue Sep 17 2024 Dry and warm airmass continued to sit over the Upper Great Lakes today. Outside of some mid-high clouds here and there, and some recently developing diurnal cumulus in the west, the forecast area has been mostly clear which enabled many to easily break into the 70s before noon. In fact, many locations were beating hard on the 80 degree door at that point. As of publishing this discussion, most surface observations were in the upper 70s to low 80s, which is approximately 10 to 15 degrees above normal for mid-September. Under mostly light southerly flow, daytime mixing has supported dewpoints in the mid 50s to low 60s. This is yielding RH values mostly in 50s and 40s in areas removed from Lake Michigan`s influence. Some drier locations have fallen into the 30s as well. As we progress through the remainder of the afternoon, I expect temps to climb a little more and RH values in the 40s to be more widespread with some 30s here and there before recovering with the waning heat. Expecting clear skies to continue through tonight, which will yield overnight lows in the 50s and 60s, save the interior portions of south-central and east, which could slip into the 40s. Patchy overnight fog will be possible as well, particularly in the interior spots of central and eastern Upper Michigan. && .LONG TERM /TONIGHT THROUGH TUESDAY/... Issued at 325 AM EDT Wed Sep 18 2024 We get one more mostly dry, late summer-like day on Thursday before the high pressure ridging over us gives way to a cool front moving in from the west late Thursday through Friday. Afterwards, expect temperatures to decrease closer to normal, with a low pressure over the Canadian Prairies lifting towards Hudson Bay and another low lifting from the Desert Southwest/Southern Rockies into the Upper Midwest possibly bringing back rainfall over us as well next week. Another mostly clear night is in store tonight as the ridging persists but slowly weakens over us with time. As temperatures cool during the overnight hours, we could see some patchy fog develop in the south central and near Lake Michigan late as the temperatures reach the dewpoint. Overall, thinking low temperatures tonight will get into the 50s, with a few spots in the interior central possibly getting into the upper 40s via the help of the radiational cooling. Moving into Thursday, expect another very warm day and mostly sunny skies. While we won`t be as warm as the past few days, we can still expect high temperatures to get into the low to possibly mid 80s in the interior areas. Fire weather concerns should be lessened Thursday too, as min RHs aren`t looking to get below the upper 30 percents. In addition, rainfall looks to finally make its way into our area come Thursday as troughing from the Plains begins to push into our far west. As this happens, we could see some isolated showers and maybe a stray storm or two during the morning hours near Ironwood, in addition to partly cloudy skies over the rest of the western U.P. throughout a significant portion of the day. While CAMs are generally showing the showers and storms dying out and avoiding the Upper Peninsula by the early afternoon hours, there looks to be another line of convection that develops over Minnesota late in the day that makes its way into the U.P. after sunset. This line of convection looks to follow a cool front moving from west to east across the area late Thursday into Friday as the parent low lifts from the Canadian Prairies towards western Hudson Bay. While not much rainfall is expected with this cool front, we could see some heavier downpours in the stronger showers and storms that produce some locally soaking rainfall over the U.P. as guidance shows PWATs around 1.50 inches along the frontal boundary. While the European ensemble shows us that we do have enough instability to get thunderstorms and showers going, with bulk shear remaining fairly modest (25 knots or less) across the area, no severe weather is expected at this time along the cool front. With the thicker cloud cover overhead, we could see some record high minimum temperature records broken Thursday night (and possibly Friday night too across the eastern U.P.). The cool front looks to leave our area by Friday night as weak ridging fills in behind it. Model guidance begins to significantly diverge past this Saturday as each medium range suite has different strengths and locations for two vertically-stacked lows over the CONUS that could impact our weather. The first of which is one over the Canadian Prairies Saturday that lifts towards Hudson Bay for the latter half of the weekend. This low looks to bring another cold front over us Saturday night into Sunday. This front may bring us some additional showers and thunderstorms across our area during that time period, but with the lifting mechanisms weakening as it moves over us, some guidance looks to keep us dry but cloudy through the latter half of the weekend. However, once this front passes, expect to see temperatures closer to normal with highs only getting into the lower 70s post cold front on Sunday to the mid to maybe (?) upper 60s come Monday. A second vertically-stacked low looks to lift from the Desert Southwest and the Southern Rockies towards the Upper Midwest early next week. Depending on how the cold front of the first low phases with the developing warm front of the second low, as well as where the second low tracks, we may or may not receive rainfall during the first half of next week; while the GFS and Canadian suites are generous with the rainfall over us early into mid next week, the Euro is suggesting that we will remain dry through the remainder of the period. Hopefully, the former two will occur, as we really need some meaningful rainfall across our area. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 239 AM EDT Wed Sep 18 2024 Dry airmass over the region will continue VFR conditions in this TAF period. && .MARINE... Issued at 325 AM EDT Wed Sep 18 2024 Light winds of generally 20 knots or less continue today into Thursday before southeast to southerly winds pick up to 20 to 25 knots over the north central lake late Thursday ahead of an approaching cool front from the west. As the front weakens while traveling eastward across Lake Superior Thursday night into Friday, expect the winds to die down to 20 knots or less again by Friday morning. The light winds continue through Saturday as weak ridging moves through the Upper Great Lakes, before possibly another cold front from the west increases winds to greater than 20 knots Saturday night/Sunday. As for thunderstorm chances over Lake Superior the next several days, outside of a stray thunderstorm or two near Isle Royale early this morning, expect the lake to remain storm-free until the cool front reaches the far western lake near Duluth Thursday morning. Shower and storm chances continue over the far western lake Thursday before a line of convection moves from west to east across the lake along the cool front late Thursday through Friday. There is a marginal risk (2+% chance) for some strong, erratic winds and damaging hail over the far western lake Thursday. As the showers and storms move eastward into a less favorable environment, the severe weather threat diminishes. The last of the showers and storms looks to leave eastern lake Superior by Friday night. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...TAP AVIATION...07 MARINE...TAP