Sunrise 5:54 AM   Sunset 9:13 PM Moonrise 6:35 PM   Moonset 3:48 AM

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LMZ342 Norwood Mi To 5nm West Of Mackinac Bridge Including Little Traverse Bay- 1128 Am Edt Tue May 21 2024
.small craft advisory in effect from 10 pm edt this evening through Wednesday evening - .
Today - North wind 5 to 10 knots becoming northeast 10 to 15 knots early in the evening. Chance of showers and slight chance of Thunderstorms in the afternoon. Waves 2 feet or less. Tonight - Southeast wind 15 to 20 knots. Rain showers and numerous Thunderstorms. Waves 2 to 3 feet. Wednesday - Southwest wind 15 to 25 knots with gusts to around 35 knots. Mostly Sunny. Waves 4 to 6 feet. Wednesday night - Southwest wind 15 to 20 knots. Mostly clear. Waves 3 to 5 feet.
winds and waves higher in the vicinity of Thunderstorms.
see the open lakes forecast for days 3 through 5.

LMZ300
No data

FXUS63 KAPX 211902 AFDAPX

Area Forecast Discussion National Weather Service Gaylord MI 302 PM EDT Tue May 21 2024

KEY MESSAGES

- A strong to severe line of storms is expected late this evening/tonight. The primary hazard will be damaging winds, with large hail and a tornado or two also possible.

- Pleasant temperatures but with occasional rain chances for Memorial Day weekend.

SHORT TERM /THROUGH TONIGHT/
Issued at 414 AM EDT Tue May 21 2024

Pattern Synopsis:

The weak shortwave and associated cyclone that supported strong thunderstorms this past evening will continue to work east of the Great Lakes today as subtle ridging temporarily slides overhead. A second weak shortwave over the Midwest will progress over the northern Great Lakes this afternoon and evening ahead of the main wave ejecting from the Great Plains over the Midwest at that time.
This much stronger wave with coupled upper-level jet dynamics will punch overhead tonight, providing impressive forcing aloft to support a sub-990mb cyclone that looks to trek across the Upper Midwest into Wednesday morning. The attendant warm front draped east of the cyclone is expected to lift into northern Michigan later this afternoon/evening as the cold front swings across the state late tonight/early Wednesday morning.

Forecast Details:

Strong/severe storms this evening/tonight -- Lingering showers will exit the area this morning, leaving rain-free conditions and clearing skies for most of northern Michigan into this afternoon.
The primary focus will be the anticipated line of strong to severe storms set to impact northern Michigan late this evening and tonight. This line looks to begin as storms forming back across the Midwest near the Nebraska/Iowa state border this afternoon, eventually congealing into a line and racing northeast towards the Great Lakes. A few main points on severe potential:

1.) Uncertain instability -- One main uncertainty later this evening/tonight will be how much instability will be in place for expected storms to work with. This will likely be the main "limiting" factor for storms later today. As storms track northeast across the Midwest and into the Great Lakes, they'll encounter an environment characterized by decreasing instability with eastward extent and time into tonight -- especially surface-based instability. Storms will likely have elevated instability to work with (~500-1,000 J/kg MUCAPE) as they reach the Lake Michigan shoreline, but will move into an increasingly unfavorable environment and become further displaced from support aloft as they work east across the area. While confidence is relatively high in strong/severe storms across our western counties, confidence decreases with eastward extent. Most high-res/CAM guidance resolves considerable weakening of storms as they arrive in the forecast area, but said guidance notoriously struggles handling these forecast situations and current confidence is that strong/severe storms will at least maintain themselves as they move into the CWA Future guidance later today should bring higher confidence in how far east strong/severe storms may be supported.

2.) Expected hazards -- The primary threat with the aforementioned line of storms today will be damaging wind gusts. Forecast soundings display impressive wind profiles with 50+ kt winds just off the surface. Strong low-level shear (35-45 kts 0-1km shear, 40-50 kts 0- 3km shear) combined with relatively steep low-level lapse rates and dry air near the surface will fuel the damaging wind threat, especially near the Lake Michigan shoreline. Latest Day 1 SPC Convective Outlook noses the Enhanced Risk (3/5) into Manistee county, with a Slight Risk (2/5) outlined for most of northern lower Michigan to highlight this threat. With aforementioned strong wind shear, a tornado or two cannot be ruled out for western portions of the area where surface-based instability may linger into the evening hours as the line moves onshore, supporting this threat for a short window of time. However, near-surface stability/dry low-level airmass is expected to limit a higher threat for tornadoes at this time. Large hail will also be possible, but comes as a secondary threat to damaging winds. Most likely timing of severe storms will be between 11 PM and 4 AM tonight. Be sure to plan ahead and have multiple ways to receive warnings for severe weather, as this is especially important for severe weather threats after dark.

Low chances for storms this afternoon -- While confidence is low in this forecast scenario, there are slight chances for storms to form along the warm front lifting across the area this afternoon.
Forecast soundings display a favorable environment to support strong, even severe storms should this occur. Low confidence exists as forcing for initiation will be weak with the shortwave and main wave well to our west and relatively dry boundary layer in place.
However, a favorable enough environment supportive of low-end chances for all severe hazards will be in place to at least mention this potential at this time. Future forecast updates may remove mention of this potential, or highlight it further with addition of expanded severe threat timing in more public-facing products should afternoon storms become more likely.

LONG TERM /WEDNESDAY THROUGH MONDAY/
Issued at 414 AM EDT Tue May 21 2024

Pattern Synopsis / Forecast:

Cutoff 500mb low will slowly be forced eastward by a ridging response ahead of a Canadian prairie wave through the day on Wednesday. Dry slotting / strong subsidence within the surface cyclone associated with the 500mb cutoff should suffice in scouring out deeper moisture across the board through the day across northern lower, resulting in more of a partly to mostly sunny day filled with diurnal cumulus and temps in the 60s and 70s. West wind and downsloping could bump Lake Huron locales near 80. May be just enough moisture in the eastern Yoop coupled with closer proximity to forcing for some diurnally driven showers, though even up there, the day will be far drier than not. Trough axis pivoting around the low Wednesday night may be enough to generate a widely scattered shower, but overall confidence in this is quite low outside the eastern Yoop. Ridging and high pressure should bring about slowly moderating temperatures into the weekend, with highs holding more seasonable in the 60s and 70s for Memorial Day weekend as flow turns more zonal.
Long term guidance paints a quick moving wave passing through Friday night, which could bring the next appreciable shower chance to the region. On the heels of this wave, a much deeper shortwave ejecting into the Plains is set to be forced into the region later in the holiday weekend, bringing more shower chances to the region.

Primary Forecast Concerns:

Holiday Weekend: All important Memorial Day weekend outlook is within sight, and it looks like temperature wise, things should be quite pleasant with highs in the 60s and 70s for most, perhaps in the 80s across the far southern part of the CWA That all being said, there will be some rain chances at times through the weekend.
As of now, the best chances for showers and perhaps some thunder will be Friday night into Saturday as a quick moving wave passes through, and again Sunday night into Memorial Day as low pressure moves into the Great Lakes. Overall, the weekend does not look to be a washout at this juncture, with ample dry time expected to be had.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
Issued at 257 PM EDT Tue May 21 2024

Lingering fog and stratus has finally cleared out of the taf sites. Attention will turn to a possible strong to severe line of thunderstorms that may arrive before midnight into the overnight hours. This line will likely be weakening but still could contain strong damaging winds and possible hail, especially at mbL and TVC with a somewhat lesser threat at PLN.
The line may not even reach APN or CIU. Low clouds likely move in late tonight into Wednesday morning with clearing skies expected after that
In addition
LLWS is expected late tonight. Surface winds are also expected to become strong and gusty late tonight into Wednesday.

APX WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory from 10 PM this evening to 8 PM EDT Wednesday for LMZ323-341-342-344>346.
Small Craft Advisory from midnight tonight to 8 PM EDT Wednesday for LSZ321-322.

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