Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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649 FXUS63 KMQT 181151 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 751 AM EDT Tue Jun 18 2024 .KEY MESSAGES... -Hot and humid today with southerly winds of 10-20 mph, gusting to 30+ mph. Showers/storms returning this evening from the west. - Multiple rounds of showers and thunderstorms expected this week. Strong to severe storms possible tonight into Wednesday. - Potential heavy rain event this weekend. && .SHORT TERM /TODAY/... Issued at 500 AM EDT Tue Jun 18 2024 Scattered showers with embedded thunder continue to drift across northern and southern portions of Upper Michigan early this morning due to frontal boundary. Current water vapor imagery/RAP analysis show a surface low situated over the spine of the Keweenaw with its occluded frontal boundary extending northeastward into Ontario and arcing southwestward into Minnesota. As that boundary pushes northward as a warm front this morning, any remaining showers and thunderstorms will exit Upper Michigan to the north after Tue 12Z. And, this will result in a short break from the active weather before another round by this evening and a mostly sunny day. The downside, though, will be the hot temperatures as the UP resides in the warm sector along with strong southerly surface winds under ample mixing. Temperatures will soar to near the 90 degree mark, combined with dew points in the 70s, pushing heat index values into the mid 90s. And, southerly winds will be sustained at 10 to 20 mph, gusting to 30 mph, especially across downslope areas near Lake Superior. && .LONG TERM /TONIGHT THROUGH MONDAY/... Issued at 407 AM EDT Tue Jun 18 2024 The overall consensus of both ensemble and deterministic guidance packages suggests the pattern across CONUS will continue to include a stout mid-upper level ridge over the eastern third of CONUS while deep and broad troughing holds fast over the western third. This places Upper Michigan in a predominate south to southwest flow regime and open to both Gulf of Mexico moisture and a warm/hot airmass, and on the path for any shortwave, impulse, or MCS developing across the Plains, at least until the weekend when a more zonal pattern begins to emerge. The low currently ejecting out of the central Plains early this morning will move into Ontario tonight, slowly dragging a cold front through Upper Michigan tonight through Wednesday. Showers and thunderstorms begin to move into the western UP as early as this evening, which will present another opportunity for some strong to severe storms given impressive CAPE and sufficient shear over the area. However, this risk remains limited and wanes further eastward as given an unfavorable timing of the frontal passage. Will note that most of the hi-res guidance indicates that convection will be able to make it even as far eastward as M-95 overnight. However, where storms can develop, heavy rain will yet again be a concern with near 2in PWATs. As the front continues to slowly track through during the day Wednesday, expect additional convection to develop along it with weak daytime instability. Otherwise, expect temperatures to come in cooler than Tuesday, with highs ranging in the 70s behind the front and the upper 70s to lower 80s ahead of it. Dewpoints in the 60s ahead of the front will keep things feeling rather muggy. The front largely clears the area Wednesday evening, with PoPs receding southward as high pressure builds in. Thursday looks to be mostly dry as the pattern begins to shift into something more zonal, but some showers cannot be totally ruled out with weak impulses rippling through. As another shortwave begins to eject out of the Rockies, another warm front will lift into the Upper Great Lakes Thursday night/Friday, potentially supporting showers/storms Thursday night into early Friday. The boundary appears to stall out Friday over the Upper Great Lakes as a surface low deepens and lifts out of the Central Plains. The low will press through the region Saturday night and Sunday while the shortwave aloft takes on a negative tilt. For a few days now, guidance has been suggesting this setup, which could lead to a potential heavy rain/flooding event in some areas in Upper Michigan as PWATs again increase to as high as 200% of normal. Of course, this will be dependent on preceding rain, but this system warrants monitoring. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 748 AM EDT Tue Jun 18 2024 LLWS to persist through this morning at IWD and CMX followed by strong southerly surface winds at all TAF sites by Tue 18Z. Widespread sustained speeds of 25-30 kts and gusts to 35 kts will prevail into tonight. Otherwise, expect VFR conditions except for some lingering flight restrictions at CMX this morning. VFR will then be the predominant flight category into tonight, but cannot rule out some deterioration to MVFR as showers and thunderstorms approach from the west again this evening. Some of these storms could become strong to severe at IWD this evening. && .MARINE... Issued at 407 AM EDT Tue Jun 18 2024 A warm front lifting northward early this morning is supporting additional showers and some thunder, but showers largely move north of the area shortly after sunrise. Meanwhile, light winds to start us off will keep in a potential for some patchy dense fog through the morning. South of the warm front, a strong low level jet will move over Lake Superior ahead of a cold front moving eastward through Minnesota. This low level jet will support southerly winds upwards of 30kts across eastern Lake Superior, possibly some low end gales for higher reporting platforms or where topography plays a local influence on winds near the lakeshores between Marquette and Whitefish Pt. Cold front will press through the lake tonight through Wednesday, potentially supporting another round of strong to severe storms across western Lake Superior and thunderstorms and showers lake- wide. Winds slowly fall back below 20 knots while turning mainly to the west behind the front Wednesday afternoon. High pressure appears to try to work in Thursday but will be dependent on upstream systems. Another front moves over the lake Friday/Saturday as a low pressure approaches from the west, bringing with it another round of showers/storms. Current thinking is for light winds in this system outside of thunderstorms. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement through this evening for MIZ014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...LC AVIATION...TDUD MARINE...LC