Sunrise 5:59 AM   Sunset 8:53 PM Moonrise 5:11 PM   Moonset 3:21 AM

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LHZ464 Expires:202405201600;;527651 Fzus63 Kdtx 200755 Glflh
open lake forecast for lake huron national weather service detroit/pontiac mi 355 am edt Mon may 20 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 warm front lifts north today as a low pressure system moves into the great lakes from the midwest. This system passes through northern lake huron tonight into Tuesday. A stronger low reaches western lake superior Wednesday morning with the associated cold front moving through the central lakes during the day. High pressure then builds in through Friday.
lhz363-462>464-201600- 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- 355 am edt Mon may 20 2024
Today - Light and variable winds becoming southeast 5 to 10 knots in the late morning and afternoon. Scattered showers and Thunderstorms in the afternoon. Waves 2 feet or less. Tonight - South winds 5 to 10 knots. Scattered showers and Thunderstorms. Waves 1 to 3 feet. Tuesday - South winds 5 to 10 knots veering to the north early in the afternoon. Scattered showers in the afternoon. Waves 1 to 3 feet. Tuesday night - East winds 5 to 10 knots becoming south 10 to 15 knots after midnight. Scattered showers and a chance of Thunderstorms. Waves 1 to 3 feet building to 2 to 4 feet after midnight. Wednesday - South winds 15 to 20 knots becoming southwest 10 to 15 knots late in the evening. A chance of showers and Thunderstorms in the morning - .then a chance of showers. Waves 4 to 6 feet. Waves occasionally around 8 feet. Thursday - Southwest winds 10 to 15 knots becoming northwest 5 to 10 knots in the late evening and early morning. Waves 2 to 4 feet. Friday - Northwest winds 5 to 10 knots veering to the northeast in the late evening and early morning. Waves 1 to 3 feet.

LHZ400
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FXUS63 KDTX 200929 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 529 AM EDT Mon May 20 2024

KEY MESSAGES

- Very warm and muggy conditions continue for the next several days.

- Showers and thunderstorms develop this afternoon with highest confidence for broader coverage north of I-69.

- Brief heavy downpours, gusty winds, and small hail are the main concerns today, although an isolated storm could approach severe wind or hail thresholds.

- Additional storms are possible Tuesday afternoon followed by a line of strong to severe storms late Tuesday night which poses the greatest threat for 50+ mph gusts.

- One more chance for showers/storms Wednesday before a cooler and less humid airmass arrives for the rest of the workweek.

AVIATION

VFR conditions continue into the afternoon, outside of a chance for patchy mvfr fog across the Metro terminals. Scattered to numerous showers and embedded thunderstorms will be possible from the afternoon hours into the evening as a warm front moves in, soon followed by an upper-level wave. The better coverage is expected across KFNT into KMBS, however, all locations will be susceptible to thunderstorm development.

There is high confidence that thunderstorms will develop across SE MI, however, exact timing and location of development remains very low. Storms will have the potential to become strong to severe, capable of highly localized gusts to 45-50 knots, hail, and heavy downpours. Additional showers with embedded thunderstorms will be possible overnight, but confidence in the timing and location also remains low.

For DTW/D21 Convection...Isolated to scattered thunderstorms will be possible Monday afternoon into Monday evening between 18Z-02Z. While confidence remains low regarding specific timing and coverage of thunderstorms today, any storms observed will be capable of gusty winds, hail and very heavy downpours. Storm motion will be west to east at 30 mph.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms between 18Z - 02Z Tues, with the most probable window for thunderstorms centered between 19Z - 23Z.

PREV DISCUSSION
Issued at 422 AM EDT Mon May 20 2024

DISCUSSION...

Shortwave trough shearing off the southern stream jet and coincident with an MCV over Missouri will continue to progress/decay northeastward this morning. The convectively augmented wave takes aim at northern Lake Michigan while another day of anomalous warmth bears down on Southeast Michigan. In the absence of airmass modification, expect the combination of afternoon dewpoints in the low-mid 60s and high temperatures the mid-upper 80s to result in SBCAPE values of 1750-2250 J/kg, mirroring the previous day's SPC mesoanalysis data. While the low-shear/high-CAPE setup drives the prevailing forecast narrative, some enhancement to shear profiles arrives later in the day north of I-69 with the approach of the aforementioned remnant wave. Although surface-based convective storms are possible across the entire forecast area this afternoon and evening, locations along/north of M-46 are favored for enhanced storms given proximity to improved shear profiles and positioning along the PWAT gradient. This offers the best chance for severe- adjacent cells. Localized outflow boundaries intersecting pockets of higher instability may suffice in the production of hail approaching 1 inch in diameter or gusts to 50 mph. Uncertainty exists regarding the persistence of nocturnal convective activity as elevated instability lingers until approximately midnight.

Interfacing of the polar and subtropical jets amplifies a speed max over the central Plains Tuesday. This drives a deepening surface low into southern Minnesota while the southerly flow within its broad cyclonic shield pushes the resident surface boundary northward across the MI/OH border. Dewpoints respond to the ThetaE plume with most locations crossing into the mid-60s, but forecast soundings indicate a slightly capped thermodynamic structure given the warm frontal boundary. Still expect some degree of afternoon convection as shear vectors improve with ample MUCAPE.

Main event looks to arrive late Tuesday night into Wednesday morning as the system's cold front races through Lower Michigan. Potential exists for an organized QLCS to accelerate through the area ahead of the front which poses a strong to severe wind threat. Latest SPC SWODY2 includes a combination of Marginal (1/5) to Slight (2/5) Risk for isolated to scattered severe events.

The upper level pattern undergoes major adjustments Wednesday as an energetic low drops into the Pacific Northwest triggering down stream ridge amplification. An orphaned upper low parked over Saskatchewan dampens the height rises, but it still unlocks the stalled eastern Plains jet axis. One more dose of CVA triggers a secondary convection response Wednesday before the more potent cold front clears through Wednesday night. Post-frontal conditions should be noticeably drier and cooler for the latter portion of the workweek as temperatures and dewpoints drop by roughly 10F and 15F, respectively.

MARINE...

Weak winds this morning organize predominantly out of the southeast today as a warm front lifts across the region in response to low pressure tracking in from the Midwest. This system brings an increasing coverage of showers and thunderstorms this evening into tonight, especially across northern/central Lake Huron closer to where the center of the low is forecast to track overnight.
Conditions are expected to remain below Small Craft Advisory criteria, though locally higher winds and waves will be possible within any thunderstorms. A stronger low develops over the Plains on Tuesday, lifting into western Lake Superior on Wednesday. Winds increase out of the south to 20 to 30 knots ahead of the associated cold front Wednesday, then veer to the west Wednesday night into Thursday while remaining gusty to around 25 knots. Less humid air settles in for the late week as high pressure builds in.

CLIMATE...

Here are the record high temperatures for May 20th through May 22nd:

May 20th: Detroit 91 (set in 1977)
Flint 92 (set in 1934)
Saginaw/Tri-Cities 93 (set in 1977)

May 21st: Detroit 92 (set in 1977)
Flint 93 (set in 1921)
Saginaw/Tri-Cities 94 (set in 1977)

May 22nd: Detroit 90 (set in 1994)
Flint 91 (set in 1934)
Saginaw/Tri-Cities 89 (set in 1992)

Here are the record high low temperatures for May 20th through May 22nd:

May 20th: Detroit 68 (set in 1934)
Flint 65 (set in 1939)
Saginaw/Tri-Cities 70 (set in 1975)

May 21st: Detroit 71 (set in 2013)
Flint 67 (set in 1934)
Saginaw/Tri-Cities 66 (set in 2021)

May 22nd: Detroit 67 (set in 1941)
Flint 65 (set in 1977)
Saginaw/Tri-Cities 68 (set in 1977)

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

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