Sunrise 6:09 AM   Sunset 9:01 PM Moonrise 2:15 PM   Moonset 2:44 AM

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LMZ323 Grand Traverse Bay South Of A Line Grand Traverse Light To Norwood Mi- 401 Pm Edt Fri May 17 2024
Through early evening - North wind 5 to 10 knots. Sunny. Waves 2 feet or less. Tonight - Light winds. Patchy fog. Waves 2 feet or less. Saturday - North wind 5 to 10 knots. Sunny. Waves 2 feet or less. Saturday night - Light winds. Scattered showers and Thunderstorms. Waves 2 feet or less. Sunday - Light winds. Sunny. Waves 2 feet or less.
winds and waves higher in the vicinity of Thunderstorms.
see the open lakes forecast for days 3 through 5.

LMZ300
No data

FXUS63 KAPX 172301 AFDAPX

Area Forecast Discussion National Weather Service Gaylord MI 701 PM EDT Fri May 17 2024

KEY MESSAGES

- Warm Saturday.

- Weakening cold front arrives Saturday night...dwindling rain threat along it.

- Sunday afternoon lake breeze convection near Lake Huron? (Definitely a non-zero probability)

- Weather more unsettled starting Monday...strong storms maybe Tuesday night?

SHORT TERM /THROUGH SATURDAY/
Issued at 351 PM EDT Fri May 17 2024

Pattern/Synopsis: Decaying surface front has progressed into ne lower MI. After that washes out, broader and warm southerly flow gets established tonight and especially Saturday, well ahead of low pressure in s central Canada.

Forecast: With stronger surface heating finally being realized, convection has sprouted in ne lower MI, where moisture is pooled near the decaying front. SPC mesoanalysis has a skinny axis of circa 1k j/kg of MlCape extending into ne lower MI. First couple cells of the day had no problem getting strong, with one become marginally severe. Now outflow air covers a good portion of this area, though there is time for recharging. Additional cells should also cook off along the westward-moving outflow boundary, though instability is weaker with westward extent (BL moisture is less...59f dew point at APN now, vs 50 at GLR and 48 at TVC). Convection will continue to be extremely averse to moving out over chilly Lk Huron.

Spotty convection should continue in ne and perhaps n central lower MI, well into evening. Have stretched out those pops a little longer. A n-s convergence line is also progged to form down the spine of central lower MI over the next few hours, thanks to continued heating. A number of HRRR runs generate convection here by early evening, then propagate it east with some marginal upscale growth. Another reason to stretch out pops a hair longer.

Otherwise, diurnal cu will diminish. Light surface winds will allow for good radiational cooling. Low-level moisture will be less than this morning (except potentially for where it rains). Do have plenty of low clouds (and fog) returning to eastern upper and ne lower MI by morning. Fog/stratus should be more localized in nw lower MI.

Min temps upper 40s to lower 50s.

Fog/stratus should be somewhat faster to erode Saturday. Ne lower MI coastal counties, and eastern Chip/Mack Cos, could see clouds until almost lunchtime. Otherwise, mostly sunny skies, and with warm advection beginning, it'll be toasty (away from the big lakes).
Highs were boosted into the lower 80s across much of northern lower MI, with 70s along the coasts and in eastern upper MI.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/
Issued at 351 PM EDT Fri May 17 2024

Pattern Forecast: Several pieces of short wave energy lined up in the northern branch wave train extending across the Pacific. First feature of interest is over the Pacific Northwest this afternoon that will swing across the upper Midwest and into northern Ontario Saturday...with another wave on its heels Sunday but this trough will dig/amplify over the western U.S. to start next week. Southwest flow aloft will predominate across the Great Lakes...with a spell of warmer and potentially more unsettled weather by midweek as a result.

Lead short wave moving into Ontario will push a cold front into Michigan Sunday though it will likely tend to wash out. After that evolution of western trough and its impact on the surface pressure pattern starting Monday as an intial lee cyclone that develops as it tracks into the upper Midwest and (perhaps) the upper Lakes Tuesday but there is spread in the ideas of system evolution which will dictate timing of cooler air back into Michigan (roughly Wednesday vs. Thursday).

Primary Forecast Concerns:

Weakening cold front arrives Saturday night...dwindling rain threat along it: Expect a line of convection to develop along the front over western Upper/Wisconsin Saturday afternoon/evening...with the remnants moving toward northern Michigan Saturday night along a narrow low level theta-e axis coincident with the front. Better rain probabilities are indicated across eastern Upper but can't really rule out some rogue showers popping anywhere overnight into Sunday morning (northeast Lower).

Sunday afternoon lake breeze convection near Lake Huron? (Definitely a non-zero probability): Cold front looks to fall apart across Lower Michigan Sunday but a weak gradient expected to allow for lake breeze development with strongest convergence near Lake Huron.
Coincidentally looks like a west-east moisture gradient is going to set up (boundary layer mean mixing ratios ranging from around 4g/kg eastern Upper to 11g/kg near Saginaw Bay. As a result dew points will likely remain in the 55-60F range roughly east of an HTL-APN line
This should generate several hundred J/kg MLCAPE values
enough to justify at least some PoPs over parts of northeast Lower (same area mentioned above). NBM probabilities are hinting at this but have blended in higher SREF PoPs to better get the idea in the forecast.

Weather more unsettled starting Monday...stronger storms maybe Tuesday night?: Surge of deep moisture into the Great Lakes ahead of the digging upper trough (precipitable water values 1.25+ inch) will begin to increase rain chances on Monday (evolution of this may revolve around upstream convection which always complicates things).
But arrival of the surface low and attendant warm sector into the upper Lakes on Tuesday certainly portends the potential for more significant weather...especially on the other side of Lake Michigan as usual but a nice nocturnal squall line passage could be in the offing Tuesday night
At least the setup is good for it
the devil is in the details of course. SPC Day 5 15% severe probability knocking on western Lower's door...along with the Day 5 marginal risk the WPC Excessive Rainfall Outlook which is not unreasonable given the potential magnitude of moisture advecting northward.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
Issued at 700 PM EDT Fri May 17 2024

Weak high pressure centered over Eastern Upper and Lower Michigan will slowly push eastward tonight into Saturday
Meanwhile
an upstream cold front will slide into the Western Great Lakes region Saturday afternoon and night. Dry wx is expected across our area tonight thru Saturday evening...before chances of showers and storms begin to increase late Saturday night. In the meantime
VFR conditions will persist thru this evening
before areas of low stratus/fog/IFR conditions develop late tonight into early Saturday across Eastern Upper and far Northern/NE Lower Michigan. VFR conditions will return to this area later Saturday morning and afternoon as daytime mixing helps to lift/dissipate the low status and fog. Light/variable winds tonight will become SE under 10 kts on Saturday...lending to lake breeze development along our shoreline areas.

APX WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...None.

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