Sunrise 6:25 AM   Sunset 8:18 PM Moonrise 7:23 PM   Moonset 5:14 AM

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LHZ463 Expires:202404232145;;239765 Fzus63 Kdtx 231343 Glflh
open lake forecast for lake huron national weather service detroit/pontiac mi 943 am edt Tue apr 23 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 - Low pressure, 29.40 inches, crosses central ontario and northern lake superior today producing a period of showers which may include some Thunderstorms later in the day, especially ahead of a cold front. Colder air filters in tonight leading a brisk morning Wednesday. Benign conditions expected Thursday with high pressure returning, at least through Friday morning.
lhz363-462>464-232145- lake huron from sturgeon point to alabaster mi beyond 5nm off shore- 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- 943 am edt Tue apr 23 2024
Rest of today - South winds 15 to 20 knots decreasing to 10 to 15 knots late in the afternoon. A chance of showers late in the morning. Waves 5 to 7 feet. Waves occasionally around 10 feet. Tonight - South winds 10 to 15 knots veering to the northwest 10 to 15 knots with gusts to around 30 knots after midnight - . Then becoming north 20 to 25 knots with gusts to around 30 knots early in the morning. Showers likely in the evening - .then a chance of showers after midnight. Waves 3 to 5 feet building to 6 to 9 feet after midnight. Waves occasionally around 12 feet. Wednesday - North winds 20 to 25 knots with gusts to around 30 knots decreasing to 15 to 20 knots early in the afternoon. Waves 8 to 12 feet. Waves occasionally around 15 feet. Wednesday night - North winds 10 to 15 knots decreasing to 5 to 10 knots in the late evening and early morning - .then becoming light and variable after midnight. Waves 4 to 6 feet subsiding to 2 to 4 feet after midnight. Waves occasionally around 8 feet. Thursday - Light and variable winds becoming east 5 to 10 knots. Waves 1 to 3 feet. Friday - Southeast winds 10 to 15 knots increasing to 15 to 20 knots with gusts to 35 knot gales in the late evening and early morning. Showers in the late evening and early morning. Waves 2 to 4 feet building to 5 to 7 feet in the late evening and early morning. Waves occasionally around 10 feet. Saturday - South winds 20 to 25 knots with gusts to 35 knot gales decreasing to 15 to 20 knots with gusts to around 30 knots until early morning. Showers until afternoon - .then a chance of showers until early morning. Waves 6 to 9 feet. Waves occasionally around 12 feet.

LHZ400
No data

FXUS63 KDTX 231715 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 115 PM EDT Tue Apr 23 2024

KEY MESSAGES

- Rain today with possible thunderstorms this afternoon and evening.
The potential for hail exists with any thunderstorm activity.

- Strong winds of 30 mph will be possible in the Thumb late tonight.

- Dry weather with below normal temperatures is expected Wednesday and Thursday

- Periodic rain and/or thunderstorm chances will impact the region late Friday through the upcoming weekend as a series of low pressure systems lift into the central part of the country. Low confidence exists in the timing of rain activity.

AVIATION

Light rain my work back into the I-94 corridor this afternoon, but trends suggest most of this will be a bit further south. Will adjust forecast to limit duration and increase cig/vsby restrictions. To the north of this, scattered showers will develop by early evening within pocket of marginal instability between light rain to the south and cold front to the north. A few thunderstorms will even be possible along front as it drops south through the area later in the evening. MVFR cigs should occur in the wake of the front. Southwest winds will gust to 25-30 kts this afternoon and then veer to north 06z-10z from north to south.

For DTW/D21 Convection...Confidence is low on occurrence of thunder this evening as a cold front encroaches on the region. Any activity would be isolated and likely weakening as it tracks into the more stable sector KPTK south after initially developing within an area of marginal instability from KFNT north.

DTW THRESHOLD PROBABILITIES...

* Medium confidence in ceilings aob 5 kft after 21z today, high late tonight into Wednesday morning.

* Low in thunderstorms impacting the terminal late this evening.

PREV DISCUSSION
Issued at 1026 AM EDT Tue Apr 23 2024

UPDATE...

12z KDTX RAOB this morning shows a prominent dry layer in the lowest 8.5 kft agl, which is supported by large T/Td spread of 15-20 F across southeast MI. Local scattered radar returns, likely just virga or light showers attm, are tied to a broader frontal slope/theta-e gradient that has contributed to expanding shower and thunderstorm coverage from northern Missouri to central Illinois.
Continued northeast expansion of the precipitation shield is expected through early afternoon toward southern portions of the cwa. No adjustments were made to the categorical PoPs south of M-59 for this afternoon, and thunder potential still looks low as mid level lapse rates decrease and equilibrium levels drop toward -10 C this afternoon.

Other component of the short-term forecast is the Marginal Risk for northern portions of the cwa this afternoon-evening. Mid-level WV loop shows the vort max currently ~120 miles northwest of Minneapolis, with the wave actively taking on a more neutral tilt.
Lapse rates invof this wave are in excess of 7 C/km, per morning RAOBs at INL and MPX. As the wave pivots toward SE MI, it will drive a ribbon of DPVA and steep lapse rates atop low level moisture advection (observed dewpoints upper 40s-low 50s upstream), with the interface of these two features to produce a narrow ribbon of enhanced instability between roughly I-94 and I-69. A band of broken, shallow convection forms in its wake after 4 PM or so followed by some trailing convection across the Tri Cities and Thumb along the front. 12z model suite so far is consistent with earlier guidance suggesting the environment will be favorable for a stronger updraft or two to produce hail up to an inch in diameter and/or wind gusts of 40-60 mph. A main limiting factor to this setup is a large imbalance between shear and instability, with forecast maximum MUCAPE of only ~500 J/kg invof a strong 65-75 mid level jet that produces 0-6km shear values of up to 80 knots in the more bullish solutions.

PREV DISCUSSION...
Issued at 352 AM EDT Tue Apr 23 2024

DISCUSSION...

A positively tilted upper level trough will deamplify with opening geopotential heights as it swings progressively from the Dakotas to the Eastern Great Lakes during the next 30 hours or so. The first of three phases is arriving now as arrival of 115 knot upper level jet will support warm advection across all of Lower Michigan. Regional radar mosaic supports a fairly thin band of light shower/sprinkles from Lake Superior clear down to the northern Illinois. Modeled RH fields pinpoint the better moisture/saturation north of I 69 between 09-12Z this morning. For the southern cwa including Metro Detroit, there are some serious reservations on how widespread/how much rainfall will occur early with a significant amount of dry air holding in the lowest 5000 ft agl. Given the trends, preference is to have PoPs at less than 50 percent early this morning. After 12Z, tail of midlevel moisture strings out overhead while system relative isentropic ascent becomes neutral. Lower column moisture remains subsaturated and the setup appears to support a period of dry weather over much, if not all of the forecast area.

The second phase of the event today will occur as a subtle right entrance region to an internal jet impulse slides overhead of Southeast Michigan. Models have been consistent in recent days of depicting an area frontogenesis lifting through the region as a frontal wave. The model trends over the past 24 hours have coalesced around the older ECMWF solution which does bring the best 1000-850mb fgen along and south of M59 and I 69 corridors between 17-01Z today.
Was very aggressive in trying to time/locate categorical PoPs for widespread precipitation during the afternoon period. There is some uncertainty with regards to the northern extent, whether or not the precipitation will fill in north of M59. Given the extensive cloud, and precipitation cooler high temps are expected across the southern CWA today.

The third phase of the event today will coincide with the arrival of the height falls/midlevel cold advection that will occur immediately in advance of the deep trough axis. Steepening lapse rates are progged after across western and northern Lower Michigan. Decent model UVV signal in convective shower/tstorm initiation upstream that will then track towards the northern cwa between 21-03Z. There is some question on what the coverage of activity will be here across Southeast Michigan as model soundings are holding onto a residual subsidence bubble between 1.3 and 5.0 kft agl. It is this dry air that will really impact the setup, limiting MUCAPES to 250 J/kg if/when it develops and ensuring that it will remain elevated. There is also the potential for some thunder late along the northern fringe of fgen that could sneak into northern portions of Metro Detroit. That will be dependent on how pervasive and opaque the low cloud will be during the afternoon. Marginal instability with very low freezing heights bring a potential for hail. The latest Swody1 has a Marginal designation for severe weather for the far northern portion of the cwa, and this is for any thunderstorm activity in the aforementioned 21-03Z time window.

The potential exists for a brief period of gusty north winds late tonight in the Thumb, along the Lake Huron shoreline as wind directions abruptly turn northerly. Latest model trends have backed off a bit on the strength of the winds as the low is depicted to be more of en elongated surface trough structure. Overall, the magnitude of the gradient flow is not expected to be as strong as previously expected, but surface wind gusts of 30 to 35 mph are expected.

Differential cold air advection in the lowest 5.0 kft of the atmosphere and rising geopotential heights will support a prototypical stable spring anticyclone over Southeast Michigan Wednesday through much of the daytime Friday. Wind trajectories will classically begin out of the north Wednesday then veer to the southeast for both Thursday and Friday. Very low to nil sky fraction anticipated through the middle of the day Friday. Favorable radiative cooling conditions are expected both Thursday and Friday mornings. Frost and Freeze warnings will likely be needed. The coldest will be Thursday morning with temperatures down into the middle to upper 20s areawide.

An anomalously deep upper level trough with a southern stream connection will remain very progressive as it pushes into the upper Midwest for the weekend. Model trends are holding that a double barrel low pressure system will plague the region from late Friday throughout the upcoming weekend. The first of the low centers is expected to be impacted by the stable blocking ridge here locally which should force the strong potential vorticity anomaly well to the west of Lower Michigan. As a result, there is a thought the initial precipitation activity to fall across Lower Michigan will remain elevated, forced by a strong low level jet primarily Friday night and early Saturday. There has been a consistent signal that flow trajectories will remain overwhelmingly anticyclonic Saturday and into Sunday as short wavelength ridging amplifies downstream of the main upper level trough energy.

MARINE...

Surface low pressure associated with an upper level disturbance crosses central Ontario and northern Lake Superior today driving an uptick in gradient flow. A Small Craft Advisory remains in effect until 4 pm today as 25+ knot gusts and 4+ feet waves spread from Saginaw Bay to the rest of the nearshore zones by sunrise. The system also provides some rounds of showers which include potential for a few thunderstorms later in the day, particularly ahead of an evening frontal boundary. Colder post-frontal air filters in tonight leading to brisk northerly flow. Some low-end potential for gusts to gales exists while lapse rates remain steep and forecast soundings are well-mixed while the stronger LLJ winds clip central Lake Huron.
More favorable marine conditions are expected Thursday with high pressure in control, at least until midday Friday.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-422- 441>443.

Lake St Clair...Small Craft Advisory until 4 PM EDT this afternoon for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 4 PM EDT this afternoon for LEZ444.

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