


Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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657 FXUS63 KMQT 231107 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 707 AM EDT Mon Jun 23 2025 .KEY MESSAGES... - A hot and humid airmass is expected over mainly central Upper Michigan today ahead of the cold front moving in. Those sensitive to heat, especially those without effective cooling and/or hydration, may be impacted. - A Slight Risk (category 2 out of 5) of damaging severe winds and hail exists across the area for today as a cold front pushes through, though temperatures return to normal following the front. && .SHORT TERM /THROUGH TUESDAY/... Issued at 312 AM EDT Mon Jun 23 2025 GOES water vapor imagery shows dry air in the lower levels keeping convection at bay and skies mostly clear across our area early this morning as a cold front is moving through Minnesota. With the warm, moist air still overhead this morning, temperatures have struggled to lower even despite the mostly clear skies; as of 240 AM EDT this morning, several spots in the interior western half of the U.P. have failed to get below 80 degrees. While we can expect temperatures to drop a few more degrees before the sun rises today, lows are still expected to only get down into the mid 70s across much of the interior west and central this morning. As the cold front begins to push into the far west late this morning, we could see a few scattered showers and storms develop and continue eastward throughout the day. However, confidence in unbroken/unceasing convection along the cold front today has greatly diminished, as the latest HRRR runs (which have handled the lack of convection over our region the best this morning) has much less convective coverage across our area late this morning through this evening in comparison to previous runs of itself and other model guidance. With bulk shear and hodographs being not all that impressive (0-6 km bulk shear around 30 knots), the large amount of sfc-based CAPE is going to have to compensate in order to severe weather to occur; that being said, different model guidances do show CAPE in the 1 to 2 thousand J/kg range, so there is plenty of energy in the atmosphere to work with, and the cold front will be a suitable forcing mechanism for air parcel uplift; as of the time of this writing, SPC still has a Slight (2 out of 5) risk for severe weather over us today, mainly for severe winds followed by severe hail. Thus, we still could see a couple of strong to potentially even severe storms today, particularly over the central and east where/when instability will be better (front expected to move through the central and east this afternoon to early evening). Again, though, confidence in the convection occurring over us today is actually decreasing as the latest runs, particularly of the HRRR, are now showing the area being mostly dry now as the cold front moves through. While we may see some post-frontal redevelopment of showers and a thunderstorm or two over the south central and east this evening, expect the rest of the area to remain dry for tonight, with the far east and south central looking to finally become rain- free by Tuesday morning. While we can expect temperatures to soar once again ahead of the cold front today, expect much cooler and more normal temperatures behind the front as we cool into the 70s over the west by late this afternoon. The south central looks to hold onto the hot and humid conditions the longest, with Heat Indexes over 95 degrees possible over a few interior spots this afternoon. As for highs, expect temperatures to get to around 90 over the central U.P. this afternoon before the cold front begins to cool things down late this afternoon. While we can expect gusty southwesterly winds at the sfc today ahead of and along the front, by tonight expect the winds to become quite calm as zonal flow aloft and sfc ridging build into the region. Expect the much needed relief from the heat to hit Upper Michigan tonight, with lows finally dropping down into the 50s across the area, except the lower 60s over the south central. On Tuesday, with synoptic forcing being very weak, expect the lake breezes to be the main driver in regards to high temperatures and winds; high temperatures are expected to be around to maybe even slightly below normal on Tuesday, with the 60s expected near Lake Superior and the 70s seen in the interior areas. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Issued at 312 AM EDT Mon Jun 23 2025 Expansive 500mb ridging will remain over the US Southeast by midday Tuesday, but some hints of a shifting pattern will begin to emerge, first in that the flow over the Rockies becomes split, with ridging over the Canadian Rockies and deep troughing remaining over the US Rockies. Throughout Wednesday into Thursday, a 500mb cutoff low moving into Florida, helping erode the blocking ridge over the eastern CONUS. With the split flow over the Rockies also moving east and deamplifying, flow goes quasi-zonal, allowing for the former Rockies troughing feature to shift through the Great Lakes, bringing with it disturbed weather. While the global deterministic and ensemble suites diverge significantly for the end of the week into next week, there are some early indications of a prominent trough moving into the region sometime in the late Sunday to early Tuesday timeframe which could bring yet another round of disturbed weather. In the wake of today`s cold front, the temperatures for the midweek period are forecast to be close to normal (perhaps a few degrees cooler) with a warming trend late in the week into the weekend. Chances of rain begin to creep up Wednesday as a subtle impulse riding the upper ridge forces precipitation over the area. The Gulf connection persists with flow aloft arcing from the Texas/Louisiana coastline to the Great Lakes, so moisture will be plentiful, though somewhat nebulous forcing and cooler surface temperatures limiting instability will keep most thunderstorm chances at bay. Current LREF mean QPF for the Wednesday and Wednesday night period is a widespread one to two tenths of an inch, with a "worst case scenario" 90th percentile of around a half inch. Thursday is when the more pronounced troughing that used to be over the Rockies arrives in the Great Lakes. Instability is still fairly limited, but with more robust forcing, expect a few thunderstorms (30 percent chance, highest in the south). Stronger forcing with PWATs pushing 1.5 inches will result in higher QPF, with the LREF showing chances of 2 inches of rain at about 10 percent by the end of the day Thursday. Everyone is likely to get at least a soaking, as chances of a half inch of rain is 40-60 percent (highest south, lowest Keweenaw). The WPC is watching the UP for flash flooding potential, giving a Slight Risk of Excessive Rainfall (category 2 of 4, or around 15 percent). Heading into the weekend, some slight chance PoPs (15-25%) linger in the forecast due to the increasing spread in solutions, but generally drier conditions are expected as ridging in the wake of the trough moves over the UP. Attention then turns upstream to the next trough dropping down from Canada sometime in the Sunday-Tuesday range, which could bring with it showers and thunderstorms. In the meantime, a warmup is expected for the weekend, with the NBM deterministic forecasting 980 degree highs for most by Sunday. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 706 AM EDT Mon Jun 23 2025 Gusty SW winds will be seen ahead of a cold front moving through late this morning through this afternoon across the TAF sites. While gusty W winds will be seen along and immediately behind the cold front, winds are expected to calm down tonight as high pressure builds in at the sfc and zonal flow sets up in the mid levels. Expect generally VFR conditions to dominate. However, showers and storms associated with the cold front`s passage could drop down conditions to MVFR or lower; confidence on the exact timing of the convection is only moderate at this time as some models have the area getting largely skunked (a.k.a. no rainfall). That being said, with convection currently over western Lake Superior and northern WI this morning, moderately (40-60%) confident on the timing of potential showers and storms moving through today. && .MARINE... Issued at 312 AM EDT Mon Jun 23 2025 Southerly winds of 20 to 30 knots over the eastern lake early this morning develop off of the southern shoreline near the western U.P. before dawn as a cold front (currently over Minnesota) continues eastwards over the lake today. As the front pushes through, expect the winds to veer more westerly today to 20 to 30 knots; while not widely expected, a rogue westerly gust or two up to 35 knots cannot be completely ruled out (the latest HREF shows up to a 30% chance along the northern shore of the Keweenaw Peninsula this afternoon). In addition, a few showers and storms could be seen along the front, but the chances for convection have decreased over the past several hours (see the latest Short Term discussion for additional details). As more zonal flow aloft and sfc ridging build over the region tonight into Tuesday, expect the winds to lighten to 20 knots or less by this evening, with thunderstorm chances ending over Lake Superior as well. Winds appear to remain light the rest of the week, although chances for thunderstorms do look to return around Thursday. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement through this evening for MIZ014. Lake Superior... Dense Fog Advisory until 11 AM EDT /10 AM CDT/ this morning for LSZ162-263. Lake Michigan... None. && $$ SHORT TERM...TAP LONG TERM...GS/TAP AVIATION...TAP MARINE...TAP