Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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944 FXUS63 KMQT 181843 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 243 PM EDT Tue Jun 18 2024 .KEY MESSAGES... -Showers and thunderstorms possible tonight, particularly over the far west. Some severe weather is possible over the far west. -Potential heavy rain event this weekend. && .SHORT TERM /THROUGH TONIGHT/... Issued at 242 PM EDT Tue Jun 18 2024 A scattered cu deck has formed over the western half this afternoon whereas the eastern half is mostly cloud free as strong southerly winds off of Lake Michigan are helping to stabilize the air a little. Observations have already shown temperatures reaching the 80s across much of the area, with some spots such as Ontonagon and L`Anse already getting to 90+F. Meanwhile, a shortwave low moving through MN is continuing to lift along a cold front boundary over the area. As the cold front continues to move eastwards into our area tonight, expect showers and thunderstorms to move into the far west before midnight local time. We could see some severe hail and winds come this evening as the convection moves into our western area, as models show MUCAPEs in the 1k-3kJ/kg range and shearing very high in the lowest levels of the atmosphere as a low-level jet screams across our area. In addition, the hodograph and LCL levels are supportive of a very small chance (<5%) for an isolated tornado late tonight. However, with CAMs showing a lot more of the convection dying than previously anticipated, the severe weather potential looks to be relegated to the far western U.P. as the cells die and collapse (similar to how we saw the severe winds over the eastern U.P. yesterday afternoon). Given the sharp drop in precip chances as the cold front moves eastwards tonight, I`ve reduced the chances across the central and eastern U.P. to chance wording (30- 40%). However, this may need to be lowered further as the most recent CAMs seem to amplify the lack of rainfall late tonight. && .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 /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 109 PM EDT Tue Jun 18 2024 VFR conditions are expected to continue at the TAF sites this afternoon into very early this evening, although with a high-end MVFR cu deck having already formed over the western half of the U.P., we could see some BKN MVFR cigs from time to time across the TAF sites for the afternoon hours. As the showers and storms over Minnesota move eastwards across our area tonight, expect the conditions at the terminals to likewise worsen from west to east tonight to MVFR/IFR. In addition, LLWS is expected across all the TAF sites when the gusty winds aloft from a low-level jet overhead fail to mix to the surface. However, when those gusty winds reach the surface from time-to-time tonight into Wednesday morning, the LLWS will not be as much of a problem. Conditions improve Wednesday morning behind the cold front, with the terminals eventually becoming VFR from west to east near the end of the TAF period (save for maybe KSAW, which could hold onto high-end MVFR cigs until after 18z). && .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 until 10 PM EDT this evening for MIZ014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TAP LONG TERM...LC AVIATION...TAP MARINE...LC