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LCZ423 851 Pm Edt Wed Sep 6 2023
.strong Thunderstorms approaching the waters...
the areas affected include...
detroit river... Michigan waters of lake erie...
at 848 pm edt, doppler radar indicated strong Thunderstorms, capable of producing winds to up 30 knots. These Thunderstorms were located along a line extending from 16 nm west of lake erie metropark harbor to 8 nm northwest of Monroe harbor to near luna pier, moving northeast at 20 knots.
strong Thunderstorms will be near, Monroe harbor, bolles harbor of refuge, north cape, luna pier, woodland beach, and detroit beach around 855 pm edt. Stony point around 900 pm edt. Lake erie metropark harbor, estral beach, and gibraltar around 910 pm edt. Detroit river light around 915 pm edt. Elizabeth park marina and wyandotte around 920 pm edt. Grosse ile around 925 pm 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.
these strong Thunderstorms will likely produce winds up to 30 knots, and could pose a serious hazard for boaters. A special marine warning may eventually be required when these storms reach the nearshore waters. Boaters should consider heading for shore before these storms arrive.
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lat...lon 4173 8350 4180 8350 4195 8337 4197 8328 4226 8317 4233 8311 4238 8294 4235 8293 4232 8307 4224 8313 4212 8312 4203 8315 4196 8311 4180 8333 4172 8341

LCZ400
No data

FXUS63 KDTX 010226 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 926 PM EST Thu Nov 30 2023

UPDATE

Temps have now dropped into the mid 30s north of a weak cold front located over the Saginaw region this evening. Boundary layer temps south of this front have held up quite nicely post sunset. The 00Z DTX sounding even showed sub 2k ft level temps to be much warmer than several model solutions suggested. An forecast update was issued to nudge nighttime temps up several degrees generally south of Flint- Port Huron. While the timing of precip in the current forecast looks reasonable, current temps suggest most of the morning precip south of I-69 will be rain. As elevated frontogenetical forcing strengthens during the day Friday, there is still expected to be some cooling of the column across the northern half of the forecast area. So at this time, no major adjustments will be made to forecast precip types/snow amounts Fri afternoon evening.

PREV DISCUSSION
Issued at 615 PM EST Thu Nov 30 2023

AVIATION...

A cold front now over central Michigan will slowly settle southward tonight, reaching FNT or PTK before weakening/stalling. There is enough low level moisture pooling along this front to support some MVFR and/or low end VFR ceilings at mbS and FNT from late evening onward. An upper level short wave and associated sfc low will then lift toward Se Mi late tonight through the day Friday. The system will drive ample moisture into the frontal boundary draped overhead.
It will bring widespread precipitation into the area late tonight and through the day Friday. Latest model guidance suggests the rain/snow line will be from FNT northward. Low level moisture advection and pooling along the frontal system will support IFR ceilings (with occasional LIFR) through the day Friday.

For DTW...Lower clouds associated with the frontal system to the north will remain well north of metro through the evening. Moisture advection in advance of the approaching system will drive MVFR based clouds into the area overnight. Ceilings should actually quickly drop to IFR by 12Z. Model soundings are quite warm across metro Detroit. This will support precip type as all rain on Friday.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet overnight and Friday.

* High in ptype remaining as all rain late tonight through Friday.

PREV DISCUSSION...
Issued at 349 PM EST Thu Nov 30 2023

DISCUSSION...

Increasing mid-level clouds mark the presence of an elevated moisture stream settling in ahead of a cold front just upstream this afternoon. Milder southwest wind ahead of this front has brought highs to the upper 40s/lower 50s this afternoon, up from the 20s/30s earlier this morning. Continued quiet and mild conditions carry through tonight even as the front eases its way in before stalling across SE MI. A system organizing along the front in the southern Plains will track northeast and move into the Great Lakes on Friday, bringing widespread precipitation.

The mid-level wave lifting out of the southern Plains tonight opens up/dampens slightly as it reaches the Ohio Valley early tomorrow morning. The anticyclonically arcing jet streak preceding this wave lifts in overnight, placing lower MI in the right entrance region by Friday morning with an area of light precip filling in from south to north. This leads into a brief period featuring a coupled jet structure as the left exit region of the southern stream jet streak noses in around the wave in the Ohio Valley during the same period.
Initial shallow isentropic ascent deepens through the course of Friday morning as this setup sharpens the frontal slope overhead and induces a more robust ageostrophic response. Moisture progs with 700- 850mb mixing ratios of 3 to 4 g/kg will be sufficient for widespread precip.

Ascent maximizes between 8am and 2pm with model cross sections showing favorable intersection of lift with a layer of neutral static stability, so moderate to heavy precip rates may occur in this window with some potential for mesoscale banding. The swath of moisture and ascent then begin to lift north and out of the area by mid afternoon. Run-to-run consistency for QPF has been fairly stable, so relatively high confidence exists for liquid equivalent amounts ranging from one to three tenths of an inch north of I-69 to higher totals near three quarters of an inch along/south of I-94.

Thermal profiles show a high DGZ positioned roughly between 500 and 600mb with surface temps initially residing in the upper 20s/lower 30s north of I-69 and mid 30s/lower 40s from M-59 south. The diurnal temp response will be muted by the clouds and incoming precip, but should still see afternoon highs in the mid 30s (north) to lower 40s (south). Latest forecast trends have limited the best snow probabilities along/north of I-69 with all rain favored along/south of M-59. In between will be a mix of rain and melting snow. With the mild skin temps, snow to the north will be a melting/wet variety with latest data supporting an inch or two of slushy accumulation.
Given the favorable dynamics there remains potential for localized/transient banding of precip, which would lead to dynamic cooling and higher snowfall amounts than in the going forecast. This remains a low confidence outcome based on the 12z/18z guidance, and do not currently anticipate Advisory criteria snowfall. Local ensemble moving 12-hr snowfall accum probabilities advertise about a 15 to 20 percent chance for 3+ inches at Owosso/Saginaw/Caro with negligible chances elsewhere.

A brief lull in precip occurs late Friday before the surface low itself tracks northeast toward western Lake Erie early Saturday morning, causing scattered/numerous lighter rain showers to move back in. This rain looks to move out by midday Saturday but leads into a grungy/drizzly afternoon as abundant low-level moisture sticks around with the stalled surface troughing. Mild conditions hold into Sunday as the next wave lifts in, bringing another low pressure system on a similar track as the Friday night system. This system favors rain as the predominant ptype on Sunday afternoon with some potential for snow to mix in north. Cooler air fills in behind this wave with a downward temperature trend ensuing for the early work week - back to the 30s for highs.

MARINE...

Southwest winds will remain elevated this afternoon as a cold front currently moves into northern Lower Michigan. Winds have been gusting to around 20-25 knots thus far. Expect a few more hours of these winds as the front rolls through before winds gradually decrease into tonight. Small Craft Advisory conditions are expected to come to an end this evening for Saginaw Bay and Thumb nearshores.
As winds veer to the west and eventually to the north-northeast by tomorrow morning winds, higher wave activity will move toward the eastern Lake Huron shorelines allowing for a period of quiet marine conditions. A low pressure system will track north of the Ohio Valley and into the southern Great Lakes Friday into Saturday morning. This system will bring rain and snow showers to the region from central Lake Huron to Lake Erie. A favorable north east wind across Lake Huron will build waves into Saginaw Bay Friday night into Saturday morning possibly resulting in another around of small craft conditions. Most of the area will be dry on Saturday afternoon with the exiting low pressure system before another low pressure system develops and takes a similar track. Rain and snow showers return for Sunday with this system and wind gusts are forecast to increase to around 20 knots.

HYDROLOGY...

Widespread precipitation will spread across SE MI from south to north early tomorrow morning into the afternoon. The rain/snow line has trended north into the M-59/I-69 corridors with wet/melting snow favored to the north of I-69. For locations south that receive all rain, accumulation totals between a half inch and three quarters of an inch are likely through Friday night. An secondary period of lighter rain then follows late Friday night into Saturday morning, capable of producing an additional one to two-tenths of liquid accumulation. No flooding concerns are expected at this time.

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

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