Sunrise 6:12 AM   Sunset 8:51 PM Moonrise 7:36 AM   Moonset 12:00 AM

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LHZ462 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- 335 Pm Edt Sat May 11 2024
Tonight - West winds 10 to 15 knots veering to the northwest after midnight. A chance of showers in the evening. Waves 1 to 3 feet. Sunday - Northwest winds 5 to 10 knots veering to the southeast late in the afternoon. Waves 1 to 3 feet. Sunday night - South winds 10 to 15 knots. A chance of showers in the evening - .then showers likely after midnight. Waves 1 to 3 feet building to 2 to 4 feet in the late evening and overnight.Monday - Southwest winds 10 to 15 knots decreasing to 5 to 10 knots in the late morning and early afternoon - .then veering to the southwest 5 to 10 knots early in the afternoon. A chance of showers in the morning - .then a chance of showers and Thunderstorms in the afternoon. Waves 2 to 4 feet subsiding to 1 to 3 feet in the late morning and afternoon. Monday night - North winds 5 to 10 knots. A chance of showers and Thunderstorms in the evening - .then a chance of showers after midnight. Waves 2 feet or less. Tuesday - North winds 5 to 10 knots increasing to 10 to 15 knots. A chance of showers in the morning. Waves 1 to 3 feet building to 2 to 4 feet late in the afternoon. Wednesday - North winds 10 to 15 knots decreasing to 5 to 10 knots in the late evening and early morning. Waves 2 to 4 feet. Thursday - Northeast winds 5 to 10 knots veering to the east in the late evening and early morning. A chance of showers in the late evening and early morning. Waves 1 to 3 feet.

LHZ400
No data

FXUS63 KDTX 111839 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 239 PM EDT Sat May 11 2024

KEY MESSAGES

- Above normal temperautures are expected Sunday into Monday.

- Showers and thunderstorms return late Sunday night and Monday as a cold front drops through the region. This front will then stall overhead leading to persistent rain chances into early Tuesday.

- The potential for heavy rainfall will exist for a portion of Southeast Michigan Monday and Tuesday.

- Cooler than average temperatures are expected Tuesday and Wednesday.

DISCUSSION

Cold core aloft has extensive cumulus/stratocumulus deck in place across Southeast Michigan this afternoon. Spokes of absolute vorticity and corresponding axes of convergence have provided for waves of ascent to result in loosely organized, scattered to numerous rain showers over Southeast Michigan. Satellite imagery and radar reflectivity trends support a very shallow convective response with a struggle to get much above 8.0-11.0 kft agl where dry air and a slightly stable environmental temperature lapse rate profile exists. Given the absolute vorticity center and support for cyclonic flow, expectations are for a persistence of rain showers for the remainder of the afternoon. There is a potential for the showers to wane for some areas while focusing more across the Thumb. There still remains a potential for some thunder particularly if a few breaks can develop due to increasing convective depths and convective scale subsidence. No strong or severe weather with CAPES of only 100-200 J/kg.

For tonight, the popular question again centers on whether or not the Aurora Borealis will be visible across Southeast Michigan with a G5 Severe Geomagnetic Storm Watch in effect from the NWS Space Weather Prediction Center. A difference scenario today with the extensive lower tropospheric cloud due to the vorticity maximum.
Will most likely see some thinning out of the cloud as the boundary layer cools, however, cannot not envision a total clearing out.
Therefore, sky coverage is expected to vary on a local basis, particularly earlier in the evening. It behooves one to err on a more pessimistic/cloudier outlook this evening/tonight for two reasons. The forecast area will be in a zone conducive for persistent weak stretching deformation and a lowering subsidence inversion could hold/trap saturation at its base. Possible for some clearing, but will be carrying a mostly cloudy forecast early.

Rising geopotential heights and confluence aloft will allow for another shortwave ridge feature for the Central Great Lakes on Sunday. A sharp, distinct absolute anticyclonic vorticity maximum is progged to to push directly through the cwa between 12-18Z. Forecast soundings depict active subsidence occuring in the midlevels by the mid morning hours, then lowering down in the column around midday.
Pleasant and comfortable conditions are anticipated for much of the day. By afternoon, its only natural Southeast Michigan will be influenced by differential cyclonic vorticity advection as the AVA moves eastward away from the region. Therefore, increasing clouds are expected as warm advection precipitation spreads across the U.P.
and northern Lower Michigan. Temperatures are expected to be near 70 Sunday afternoon, but have kept it lower by a degree or two.

Two PV anomalies are then forecasted to move eastward over portions of North America in tandem from Sunday night through Tuesday.
Locally, the first wave is expected to drop a cold front into Southeast Michigan on Monday while it stalls and becomes stationary.
Difficult to pinpoint duration of rain shower and/or thunderstorm activity. High confidence in an unsettled period with relatively higher certainty there will be showers and thunderstorms Monday afternoon. Will need to monitor model trends as very weak flow will bring the potential for slow moving convection and heavy rain.
Potential for severe weather is on the low side with 0-6km bulk shear of 20 knots and Mixed Layer Cape of less than 1000 J/kg. Wet weather to continue on Tuesday with Southeast Michigan possibly getting clipped by the northern periphery of the southern wave as it passes through. Concern there is if the same area could get heavy rainfall both days. Way too early to try and hammer out details on convection.

MARINE

Northwesterly gusts to 25 knots in the wake of cold frontal passage will subside late this evening into the overnight. Until then, will maintain current Small Craft Advisories for Saginaw Bay and Lake St Clair/Western Lake Erie. While an isolated thunderstorm cannot be ruled out into early evening, generally just expect rain showers (which will taper off quickly this evening). High pressure briefly builds into the area Sunday morning providing favorable marine conditions before a secondary low approaches later on Sunday. This second system offers potential for enhanced southwest flow over Saginaw Bay, and possibly Small Craft Advisory criteria gusts.
Showers and storms arrive late Sunday evening and overnight. A stationary front then settles over the Great Lake early next week offering additional opportunities for thunderstorms.

HYDROLOGY

A cold front will settle southward into Southeast Michigan Monday night before stalling across the area on Tuesday. Showers and thunderstorms will be possible along this boundary. Rainfall may exceed 0.50 inch for portions of Southeast Michigan. Forecast confidence is low at this time and impacts to rivers next week is unknown.

PREV DISCUSSION
Issued at 126 PM EDT Sat May 11 2024

AVIATION...

Widely scattered to numerous rain showers will continue through the afternoon and early evening hours in response to the departing low pressure system presently located over the Thumb. A rumble of thunder is possible but coverage and duration remains too limited for inclusion in the forecast. Cloud ceilings will attempt to lift towards low-end vfr through the afternoon, however periods of mvfr cigs are favored with the rain chances.

The cloud shield will gradually shift northeast tonight as low pressure continues to travel east. This persistent cloud shield will linger through the late evening to early morning hours over the Thumb, and it will be a close call if the western edge of the shield holds on across the terminals beyond Midnight. Most model guidance supports the cloud coverage shifting just northeast of all terminals, which is represented on the outgoing TAFS. Otherwise, breezy westerly flow with gusts around 25 knots are expected during daylight hours.

For DTW/D21 Convection... Another round of showers are expected with peak heating this afternoon into early evening. Thunderstorm chances remain very limited.

DTW THRESHOLD PROBABILITIES...

* Very low for an isolated thunderstorm this afternoon into the early evening.

* High for ceiling 5000 ft or less today and tonight.

* Medium confidence in reaching westerly crosswind threshold this afternoon.



DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422.

Lake St Clair...Small Craft Advisory until 8 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 8 PM EDT this evening for LEZ444.

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