Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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455 FXUS63 KMQT 181722 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 122 PM 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 122 PM EDT Wed Sep 18 2024 Another warm and dry day over Upper Michigan has developed. This, after morning temps in the 40s and 50s, and fog, some dense, across portions of central and eastern Upper Michigan. So far, temps have warmed into the 70s to low 80s, with the warmest spots being the southerly wind downsloping locations near Lake Superior. Effective mixing into a very dry airmass aloft has enabled dewpoints to fall into the upper 40s to 50s in the driest interior locations, which with the heat, is supporting RH values in the 30s and 40s in many locations. Thankfully, winds have been mostly light, which is limiting fire weather potential. As we progress through the remainder of the afternoon and tonight, expecting some additional warming before the heat wanes. Still expecting widespread low to mid 80s everywhere away from Lake Michigan`s influence where 70s will dominate. RH will respond as well and will support continued near and/or isolated elevated fire weather concerns into the evening. Overnight lows will again dip into the 40s and 50s. Also expecting another round of raditional fog to develop in interior locations of Upper Michigan`s south-central and eastern locations. Upstream, vertically stacked low spining over North Dakota will lift northeast into Canada. An associated cold front will march east into western Minnesota overnight. Ahead of the front, theta-e ridge with a plume of robust instability will support showers and thunderstorms overnight. Its possible that some of these showers/storms may continue into western Lake Superior by morning. && .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 /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 122 PM EDT Wed Sep 18 2024 VFR conditions will prevail 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...JTP MARINE...TAP