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LHZ464 Expires:202407030945;;342813 Fzus63 Kdtx 030134 Glflh
open lake forecast for lake huron national weather service detroit/pontiac mi 934 pm edt Tue jul 2 2024
for waters beyond five nautical miles off shore on lake huron
waves are the significant wave height - the average of the highest 1/3 of the wave spectrum. Occasional wave height is the average of the highest 1/10 of the wave spectrum.
Synopsis - A cold front, 29.80 inches, will move across the great lakes tomorrow morning and afternoon. Showers and Thunderstorms will be possible ahead and along the front, mainly across lake huron. Wind direction will veer from the southeast to southwest as the front approaches. A weak area of high pressure, 29.90 inches, will fill in behind the front on Thursday.
lhz462>464-030945- lake huron from port austin to harbor beach beyond 5nm off shore- lake huron from harbor beach to port sanilac beyond 5nm off shore- lake huron from port sanilac to port huron beyond 5nm off shore- 934 pm edt Tue jul 2 2024
Rest of tonight - Southeast winds 10 to 15 knots becoming south 15 to 20 knots early in the morning. Waves 2 to 4 feet. Wednesday - South winds 15 to 20 knots becoming southwest 10 to 15 knots in the afternoon. A chance of showers. Waves 3 to 5 feet. Wednesday night - Southwest winds 5 to 10 knots. Waves 1 to 3 feet. Thursday - Southwest winds 5 to 10 knots early in the morning becoming light and variable. Waves 2 feet or less. Thursday night - Northeast winds 5 to 10 knots early in the evening becoming light and variable - .then becoming northeast 5 to 10 knots after midnight. Waves 2 feet or less. Friday - East winds 5 to 10 knots. A chance of showers. A chance of Thunderstorms late in the afternoon. Waves 2 feet or less. Saturday - South winds 10 to 15 knots veering to the southwest in the late morning and early afternoon - .then becoming west 5 to 10 knots until early morning. Waves 1 to 3 feet. Sunday - West winds 5 to 10 knots backing to the southeast until early morning. Waves 2 feet or less.

LHZ400
No data

FXUS63 KDTX 030432 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1232 AM EDT Wed Jul 3 2024

KEY MESSAGES

- Chance of light showers tonight, mainly across the Saginaw Valley and Thumb region. An isolated non-severe thunderstorm is also possible early Wednesday morning.

- Warm and humid on Wednesday with a continued chance of showers and thunderstorms. An isolated strong to severe storm will be possible during the afternoon, capable of producing strong wind gusts and heavy downpours.

- Typical heat and humidity for the 4th of July holiday. Isolated showers and thunderstorms will be possible late in the day south of M-59.

AVIATION

Extensive mid level cloud will mark the overnight period, as Southeast Michigan maintains position downstream of an area of convection migrating through the lake Michigan corridor. Expectation remains for this activity to outpace the trailing frontal boundary, leaving simply pockets of light showers with a gradual decline in cloud base heading into the late morning period. Potential for a chaotic coverage of showers to emerge with daytime heating as a weak frontal passage attempts to engage a gradually moistening and destabilizing environment. This occurs within some reduction in cloud base, potential resulting a brief period of MVFR to lower VFR.
An isolated thunderstorm occurrence remains plausible in this environment, but unworthy of a defined mention at this stage. There remains the low likelihood that a deeper shower or storm may develop during the early afternoon hours across the Detroit airspace - especially if any prolonged breaks in the cloud cover arise. A strengthening wind off the surface maintains a period of low level wind shear through mid morning. Increasing boundary layer depth with time then turns this higher wind magnitude into gusty southwest conditions through the remainder of the day.

For DTW/D21 Convection...There is a low chance for a thunderstorm as a front washes through this afternoon.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less this morning, moderate this afternoon.

* Low for thunderstorms this afternoon.

PREV DISCUSSION
Issued at 331 PM EDT Tue Jul 2 2024

DISCUSSION...

A mid-level trough and associated surface low moving from Manitoba into northwestern Ontario will have increasing influence over local conditions tonight into Wednesday. The system is currently directing a shortwave and plume of 700-500mb moisture advection over west and mid MI, producing pockets of light to moderate showers. The SW upper jet will steer most of this moist flow north of the forecast area, but trends in radar presentation and surface obs bring at least a chance for a few late afternoon sprinkles mainly north of I-69.
Otherwise, we continue to be governed by dry SSE flow below 700mb which should hold overall dry conditions through tonight. Another shortwave follows a similar track into northern Lower MI overnight into early Wednesday morning, bringing a renewed chance for showers and an isolated elevated thunderstorm mainly for the Tri-Cities and Thumb. Instability will be minimal and severe weather is not anticipated.

Low pressure developing today along the trailing cold front over the Midwest tracks northeast across northern Lower MI Wednesday morning, sending a surge of higher low-level theta-e across the state to start the day. Much warmer and muggier conditions will be in store with HRRR mean dew points rising to around 70 degrees. This will be paired with highs in the mid to upper 80s. With mean flow parallel to the SW-NE oriented cold front and neutral PV advection and height fields providing little organized forcing, expectation is for just widely scattered showers through the day as the front eases eastward across the state.

A window emerges late in the day southeast of a line from Jackson to Sandusky where daytime heating and resultant instability (MLCAPE near 1000 J/kg) may be enough to induce better convective development as the front moves through. Should this play out, a conditional marginal severe threat exists as bulk 0-6km shear of 30 kt may support an isolated stronger cell with damaging wind gusts and heavy downpours the most likely threats. There remains a sizable camp of hi-res guidance that pushes the front through before convection gains much traction, with 30 to 50% of 12z HRRR membership showing <500 J/kg of SBCAPE by 6pm. This faction of solutions suggests little to no severe threat. The front then departs to our south and east Wednesday night with slightly lower dew points settling in and dry conditions likely thereafter.

Weak cool advection behind the front keeps a seasonably warm and humid air mass around for the 4th of July holiday. Highs again will be in the mid to upper 80s with dew points in the upper 60s and weak winds keeping a muggy feel to the air. Model soundings show a respectable cap in place much of the day, but weak height falls associated with a low amplitude shortwave arriving during the evening may be sufficient to allow for isolated convection late in the day. Given the relatively warm mid-levels, any instability would be lean and do not expect an organized severe threat at this time.

Friday presents a higher probability for showers and thunderstorms as a higher amplitude upper low tracks in from the Midwest, bringing a corridor of more focused height falls and associated ascent during the latter half of the day. Blended guidance advertises a 60-70% PoP peaking during the mid afternoon to early evening. Wind shear will be favorable for organized severe weather with a 50 kt jet streak passing overhead, but instability progs remain modest with only 15% of LREF members showing >1000 J/kg SBCAPE. The most likely outcome at this stage looks to be numerous showers with scattered thunderstorms.

Slightly cooler weather for Saturday as the upper trough sinks across the Great Lakes. At least scattered light shower activity appears likely as moist cyclonic flow wraps around the low across the state. Medium range progs show a strong ridge developing over the SW CONUS this weekend and persisting into the early part of next week. This favors a troughy, active summertime pattern over the local area with periodic chances for showers and thunderstorms.

MARINE...

Return flow from the departing high pressure that is now centered over New England has reinforced southeast flow over the Great Lakes, which will hold through tomorrow morning. A weak surface low will move across Lake Michigan later this evening, strengthening the pressure gradient across the lakes which will support gusts on the order of 20 to 25 knots across Lake Huron today. Rain showers with possible embedded thunderstorms will continue mainly across Lake Huron through tonight as low pressure approaches.

A cold front is then expected to move over the Great Lakes tomorrow morning and afternoon which will veer wind direction to the west- southwest. There will be a window between 4AM-4PM tomorrow where gust potential will near 25 knots across the Saginaw Bay with the southwest flow, but will preclude the issuance of a Small Craft Advisory as model soundings exhibit a stable profile, lowering confidence of 25 knot gust potential for any 3+ hour window. There will be a low chance for a shower or storm along the front tomorrow.
Otherwise, high pressure fills back in Thursday, relaxing wind speeds and gust potential.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.

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