Sunrise 6:05 AM   Sunset 8:52 PM Moonrise 3:08 PM   Moonset 2:50 AM

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LCZ423 320 Am Edt Fri Apr 19 2024
.strong Thunderstorms approaching the waters - .
the areas affected include - . Detroit river - . Michigan waters of lake erie from detroit river to north cape mi - .
at 320 am edt, doppler radar indicated strong Thunderstorms, capable of producing winds up to 30 knots. These Thunderstorms were located along a line extending from 6 nm northwest of bolles harbor of refuge to 9 nm south of north cape, moving northeast at 40 knots.
strong Thunderstorms will be near - . Monroe harbor, bolles harbor of refuge, north cape, luna pier, and detroit beach around 325 am edt. Stony point and woodland beach around 330 am edt. Estral beach and gibraltar around 340 am edt. Lake erie metropark harbor and detroit river light around 345 am edt. Elizabeth park marina around 350 am edt.
other locations impacted by strong Thunderstorms include woodland beach, stony point, gibraltar, estral beach, and detroit beach.
precautionary/preparedness actions - .
mariners can expect gusty winds up to 30 knots, locally higher waves, and lightning strikes. Boaters should seek safe harbor immediately until these storms pass.
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lat - .lon 4173 8345 4173 8350 4180 8350 4195 8337 4197 8328 4217 8321 4219 8319 4218 8313 4212 8312 4203 8315 4196 8311 4180 8333 4172 8341 4172 8347

LCZ400
No data

FXUS63 KDTX 182023 CCA AFDDTX

Area Forecast Discussion...CORRECTED National Weather Service Detroit/Pontiac MI 423 PM EDT Sat May 18 2024

KEY MESSAGES

- Patchy fog, locally dense at times, will be possible tonight.

- An Air Quality Advisory is in effect for portions of Southeast Michigan, including Metro Detroit through this evening.

- Warm and muggy conditions continue through early next week with daytime highs in the 80s.

- Chance for showers and thunderstorms tomorrow afternoon and evening favored toward the lakeshores. Locally heavy rainfall, hail, and strong thunderstorm winds will be possible.

DISCUSSION

Lower clouds supported by lake moisture under the strong inversion this morning has mixed out this afternoon bringing mostly clear skies. Warm and muggy airmass in place today. The 12Z DTX RAOB came in with 925mb temperatures in the mid teens (C). This is supporting the temperatures into the 80s this afternoon. Daytime heating and low level moisture has brought a scattered field cumulus, but high pressure and ridging should largely limit any shower activity with instability lacking and very weak forcing. Higher dewpoints, southeast flow off Lake Erie, and mostly clear skies will bring potential for patchy fog development again tonight.

An unstable airmass residing across Michigan tomorrow will set the stage for scattered shower and thunderstorm potential. The RAP offers 1000-1500 J/kg of MLCAPE developing by 18Z tomorrow across much of southeast Michigan with increased mid level lapse rates of 6.5-7.0 C/km and low level lapse rates to around 9 C/km. A northern stream shortwave will drive a weakening cold front into southeast Michigan tomorrow. Shear over much of the area will be weak though with best flow off to the north. Bulk shear from 0-6 km is mostly below 20 knots with the exception across portions of the Tri-Cities and Thumb. The northern stream shortwave will push a weakening cold front into southeast Michigan during the late morning/early afternoon while stronger surface heating will likely lead to the development of multiple lake breezes during the afternoon. This brings several opportunities for surface convergence to force convection initiation, especially if the front tracks further into southeast Michigan and meets up with any lake breeze. The weaker flow leads to mainly a pulse type thunderstorm mode that form initially on either of the aforementioned boundaries with thunderstorm outflow also driving additional updrafts. Current Hi- res model suite wants to place greater probability for initiation across Port Huron to the Detroit Metro area and down to Monroe County along the lake breezes. Though, some capping in the forecast soundings could also put a damper on some thunderstorm development.
Will maintain the chance PoPs in the forecast here. Main threats with activity will be strong downburst winds, hail, and brief heavy rainfall with the PWATs of 1.25" to 1.35". Heavy rainfall and slow storm motions bring some potential for localized flooding of prone spots, especially in the urban footprint in and around Detroit for any areas that experience a longer duration of thunderstorm activity. Shower and thunderstorm activity will weaken and eventually come to an end in the evening with the loss of instability.

The next shortwave lifts out of the central plains and through the southwest flow between the Canadian troughing and the ridging through the Appalachian Mountains. A weak surface reflection is forecast to travel across WI and northern Lake Michigan. A plume of theta-e will support scattered showers and thunderstorms with a boost in larger scale ascent from the shortwave. Greater forcing and placement of the higher moisture axis puts higher PoPs towards the Tri-Cities. Active stretch of weather remains as the above normal temperatures and moist airmass remain over Michigan into the middle of the week helping field additional showers and thunderstorms. Long range models are mostly in agreement with a Tuesday night into Wednesday system as shortwave energy originating off the Baja Coast shoots northeast within the flow of the southern and northern stream jets. Frontal timing will ultimately decide severe weather potential mid-week. The well above normal temperatures with daytime highs in the 80s will carry continue Sunday through Tuesday with overnight lows in the upper 50s to mid 60s. Cooler temperatures will arrive behind frontal system mid-week bringing highs back down into the 70 degree range for the late week period.

MARINE

High pressure dominates local conditions this weekend with light southeasterly winds generally 10 knots or below through the rest of today, veering south tonight. Very warm and humid air in place keeps areas of fog across marine areas, with potential for dense fog to redevelop tonight. Will continue to monitor observations and reissue a marine Dense Fog Advisory if/where conditions warrant. Models do show a slightly stronger gradient picking up overnight which may disperse any more dense fog before sunrise Sunday. A weak cold front moves into the region on Sunday with a few showers and storms possible, mainly in the nearshore waters. An area of low pressure then tracks in from the Midwest late Monday into Tuesday, bringing the next likelihood for showers and storms. Winds and waves are expected to remain below Small Craft Advisory criteria outside of any localized higher winds within any thunderstorms.

HYDROLOGY

Scattered to numerous showers and thunderstorms are possible, mainly tomorrow afternoon and evening with favored areas along the lake breezes across Port Huron through Metro Detroit to Monroe County.
Locally intense rainfall rates are possible with any thunderstorms that can develop with the high moisture environment. Forecast average rainfall amounts are a quarter to half inch with locally higher amounts of 1 inch or more possible. Several areas may remain dry, but the slow moving nature of the scattered thunderstorms will bring potential for these localized higher rainfall totals. Main concern would be for localized flooding of prone urban areas across the Detroit Metro if any of these thunderstorms develop and linger over parts of the metro region.

PREV DISCUSSION
Issued at 1251 PM EDT Sat May 18 2024

AVIATION...

Morning fog and LIFR/IFR low clouds have dissipated (outside of DET), and looking at just a bit of diurnal CU development this afternoon, mainly in the 5000-6000 foot level. The rest of the mid levels look very dry, and not anticipating convective development.
Enough low level drying during the day and a subtle southerly wind tonight to help limit fog potential compared to this morning.
However, leaning toward fog/moisture from Lake Erie to make inroads into the southern TAFS late tonight, and have put tempo LIFR cigs in for DTW/YIP/DET. A weak surface cold front should allow for light winds to flip to southwest, helping to accelerate the mixing out of the low clouds and fog with diurnal CU (around 5000 feet) likely in the afternoon. Lake breeze convergence and instability will bring the potential for scattered thunderstorms during the late afternoon.

For DTW/D21 Convection...Potential for FEW-SCT clouds flirting with the 5000 foot level much of the period. Fog/LIFR low cloud concerns late tonight as light southeast flow off Lake Erie exists.

Thunderstorms are not expected this afternoon, but there is a chance of thunderstorms Sunday afternoon, with lake breezes serving as the focus.

DTW THRESHOLD PROBABILITIES...

* Low for ceilings aob 5kft.

* Low for ceilings and visibilities to drop below 200ft or 1/2SM 8-14Z Sunday.

* Low for thunderstorms Sunday afternoon.



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

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