Sunrise 6:25 AM   Sunset 8:39 PM Moonrise 2:21 AM   Moonset 11:39 AM

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LHZ421 Outer Saginaw Bay Sw Of Alabaster To Port Austin Mi To Inner Saginaw Bay- 945 Am Edt Wed May 1 2024
.small craft advisory in effect until 9 pm edt this evening - .
Rest of today - South winds 10 to 15 knots becoming southwest 15 to 20 knots in the afternoon. Mostly cloudy late in the morning becoming mostly Sunny. A chance of showers. Waves 1 to 3 feet building to 2 to 4 feet late in the afternoon. Tonight - West winds 15 to 20 knots diminishing to 5 to 10 knots. Mostly clear. Waves 1 to 3 feet. Thursday - Northwest winds 5 to 10 knots veering to the northeast in the late morning and early afternoon, then becoming east 10 to 15 knots early in the afternoon. Partly cloudy. Waves 2 feet or less. Thursday night - East winds 15 to 20 knots diminishing to 10 to 15 knots after midnight. Partly cloudy in the evening, then mostly cloudy with a chance of showers after midnight. Waves 1 to 3 feet.
see lake huron open lake forecast for days 3 through 5.

LHZ400
No data

FXUS63 KDTX 011110 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 710 AM EDT Wed May 1 2024

KEY MESSAGES

- Mainly dry and slightly warmer today with afternoon gusts of 25-35 mph.

- Above normal temperatures continue through the rest of the week and into the weekend.

- Daily precipitation chances exists, but the main shower/storm threat arrives Friday.

AVIATION

VFR conditions will prevail through this TAF period as mid to high clouds spread over the region this morning with a decaying area of showers. KMBS will have the best chance to catch a very brief VFR rain shower at the start of this TAF period. South-southwest flow will be increasing by around 14Z and beyond in the wake of a warm front. Gusts are expected to increase into the 25-30 knot range by early afternoon. An influx of lower level moisture will arrive behind the warm front that should support a diurnal lower VFR cumulus field during the afternoon. Gusts and the lower cu field will diminish this evening with sustained westerly winds of 5 to 10 knots during the evening and overnight.

For DTW/D21 Convection...Thunderstorms are not expected through the TAF period. There will be minor concern for crosswind thresholds being met at DTW if daytime gusts come in closer to 30 knots.
Confidence is low at this time in gusts achieving these thresholds.

DTW THRESHOLD PROBABILITIES...

* Low for crosswinds late this afternoon.

* Low for ceilings at or below 5kft midday.

PREV DISCUSSION
Issued at 402 AM EDT Wed May 1 2024

DISCUSSION...

A negatively tilted shortwave trough quickly closes off through the mid-levels over western Lake Superior this morning. This feature sustains more robust convective activity in the vicinity of the wave feature while longwave ridge amplification ensues further upstream.
Because of the ridge builds northward while tracking toward the east, the aforementioned trough should remain displaced to the north throughout the day. This generally keeps Southeast Michigan dry today as the system's warm sector spreads northeastward across Lower Michigan. 01.00Z KILX (Lincoln, IL) RAOB sampled an H8 temp of +13C, and although low-level southwest flow lessens toward the north, still expect local values of +11C to +12C by this afternoon. A rather dry and well-mixed boundary-layer favors highs peaking in the mid to upper 70s. Additional boost possible should low clouds clear ahead of schedule with Metro Detroit and a few other spots across the far east potentially breaking 80F (see ECMWF MOS for DTW/DET/TTF). Latest temperatures reflect slight upward adjustments.
Winds also become gusty once profiles mix as enhanced LLJ winds push gusts into the 25-35 mph range. Could see some peak winds pop to around 40 mph along the front.

Main question with this system is whether or not the warm advection sufficiently moistens the column by the time its attendant cold front crosses through. Surface progs show the boundary working west to east across the forecast area from 15-21Z today with preceding FGEN convective activity. An analysis of representative forecast soundings show winds from 950-700 mb backing from NW to SW as the ThetaE plume tracks east, but mid-level drying due to approaching anticyclonic flow greatly inhibits convective depths. Any rainfall that manages to arise from the decaying line should be brief with lowering confidence east of US-23. Areas along/north of M-46 align with the nose of the moisture arc, thus Slight Chance PoPs were included. Also added a low-end Chance PoP for the Tri-Cities while areas further south and west now have mentions for Sprinkles as the line moves through. Dry and increasingly sunny skies arrive after 21Z with winds decreasing quickly after sunset. Clear skies early tonight, becoming more opaque after midnight as mid and high clouds spill in slowing nocturnal cooling. Should still see most areas drop below 50F for overnight lows.

Surface high pressure encompassing the Great Lakes Thursday morning eventually gets displaced by low pressure lifting northeast from The Plains. Uncertainty exists regarding the extent and timing of renewed the warm/moist conveyor as it pertains to southern Lower Michigan. Isentropic ascent along the next warm front offers potential for a leading band of clouds while some clearing may occur later in the day. 00Z model spread is unusually high regarding local shower activity, therefore decided to maintain dry PoPs for most areas until the evening timeframe. Main push of CVA holds further west until the inflection point in the longwave pattern arrives.
Thermal ridge still in place Friday morning before competing boundaries interact with the main low pressure system located well off to the north. A large swath of convection can be expected upstream with coverage from central Ontario down the Mississippi while a secondary low develops over the Ohio Valley, south of the triple point. NAM and GFS differ greatly in lapse rates and instability characterization, but with 0-6 km bulk shear near 35 knots, thunderstorm potential increases as the day progresses, especially if diurnal timing aligns with the FROPA. Most of the showers/storms should exit by midnight, but some signal exists for a deformation response.

A bit cooler, but still warmer than normal for the weekend with decreasing precipitation chances Saturday as subsidence arrives with surface high pressure. Moist low-levels and perturbed mid-level flow could provide some isolate showers Sunday with northeast flow component. Low amplitude shortwave crosses the Ohio Valley Monday clipping southern Lower with shower potential while an amplified pattern lingers across Central CONUS. The next broad-form low tracks into the High Plains Tuesday and Wednesday lending downstream rain/storm chances for Michigan.

MARINE...

Increasing south-southwest winds today as low pressure tracks through Lake Superior. Wind gusts this afternoon do look to reach 20- 25 knots over the nearshore waters, especially over Saginaw Bay and along the shoreline areas of the Thumb region. Banking on the warm air (925 mb temps up to 17 C) ahead of the cold front to provide just enough stability to keep gusts mostly around 25 knots. Despite the offshore winds and waves remaining aob 4 feet, will err on the side of caution and carry a small craft advisory for Saginaw Bay and the northern tip of the Thumb region. Winds veering to the west over Saginaw Bay by early evening should also help to keep wind speeds in check, vs the more favorable southwest wind.

Steady stream of cold advection behind the front Wednesday night into Thursday, and outside of the north half of Lake Huron, expecting wind speeds look to remain light, under 20 knots. Even over northern Lake Huron, wind speeds look to peak at 25 knots to perhaps up to 30 knots, centered around midnight per local probabilistic guidance.

A return to light and variable winds for Thursday as surface high builds over Lake Huron.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Small Craft Advisory from noon today to 9 PM EDT this evening for LHZ421-422-441.

Lake St Clair...None.
Michigan waters of Lake Erie...None.

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