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LCZ460 Lake St Clair- 355 Am Est Thu Dec 7 2023
Today..Southwest winds 15 to 20 knots diminishing to 10 to 15 knots in the afternoon. Partly Sunny. Waves 1 to 3 feet.
Tonight..South winds 10 to 15 knots increasing to 15 to 20 knots early in the morning. Partly cloudy. Waves 2 feet or less.
Friday..South winds 15 to 20 knots diminishing to 10 to 15 knots early in the afternoon. Partly Sunny. Waves 1 to 3 feet.
Friday night..South winds 15 to 20 knots. Mostly cloudy. A chance of light showers after midnight. Waves 1 to 3 feet.
Saturday..South winds 15 to 20 knots with gusts to 30 knots veering to the southwest in the evening. Mostly cloudy with light showers likely. Waves 2 to 4 feet. A small craft advisory may be needed.
Sunday..Northwest winds 10 to 15 knots. Mostly cloudy with a chance of light rain and snow showers. Waves 1 to 3 feet.
Monday..Southwest winds 10 to 15 knots. Partly cloudy. Waves 2 feet or less.

LCZ400
No data

FXUS63 KDTX 071907 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 207 PM EST Thu Dec 7 2023

AVIATION

Longwave ridging approaching the western Great Lakes promotes column stabilization and VFR conditions through the afternoon and overnight hours with south-southwesterly flow. The next wave lifts out of the Mid-Mississippi Valley Friday morning promoting low-level moisture advection bringing potential for MVFR cloud and -RA or -DZ as the preceding warm front lifts into Southeast Michigan.

DTW THRESHOLD PROBABILITIES

* Medium for ceiling at or below 5000 feet Friday afternoon.

PREV DISCUSSION
Issued at 350 AM EST Thu Dec 7 2023

DISCUSSION...

The last of the mid level shortwave tracking across Lake Huron is beginning to push east out of the area. Though the radar showed returns at times Wednesday evening and into the overnight, it appears to be nearly all virga with surface obs (rain or snow) hard to come by over lower MI. We'll drop POPs down to a 20% slight chance just to usher the rest of the low level moisture out of the Thumb before drier air and warm advection kicks in stronger, ending precip chances for the day.

Attention then turns to the much warmer temperatures heading into the weekend and the large, dynamic trough that will progress across the region bringing the next chance of precipitation, possible strong wind gusts, and then some lake effect showers.

Troughing has begun to take shape over the west coast helping to amplify the ridge over the Plains and into the Great Lakes. Warm air advection in the mid levels has already started with temps above 0C up through about 8kft already. We'll only see a modest boot in temps today with highs into the 40s with the added sun and warm air aloft but being on the northwest flow side of the ridge with lack of deep mixing will hold off on mixing the warmest air down. Bigger boost in temps comes Friday as a warm front lifts across lower MI with longwave ridge axis passing east early in the day with deep layer southwesterly flow then kicking in. This should help highs just into the low 50s. Though some models are trying to kick out light precip with the frontal passage, the moisture depth is shallow up around 4- 6kft with dry air above and below it so with lack of better forcing and better moisture, think we'll just see some clouds as a result.

By Friday night, the original vort max will curl north into Ontario with an additional 130 knot jet digging into the trough, helping to carve it deeper into the southern Plains. This will sharpen the baroclinic zone extending from the western Great Lakes down to east Texas. A surface low has been projected to develop along the front and lift through the region Saturday bringing the next shot of precip to the area. The trend in the models has been a westward shift, now taking the low northeast through WI. This brings the warm front up through southern MI with a strong 50 knot low level jet surging north behind it. This will enhance the warm air advection into the state for Saturday and will help temperatures rise into the mid/upper 50s. More on temps in a moment. As for precipitation and weather Saturday, expectations are for warm frontal showers early in the day with the cold front possible bringing addition showers in the afternoon. Soundings show that the mixed layer, though only extending up to around 9kft, would tap into the strong low level jet which could produce strong winds gusts through the afternoon. The other noted trend in the long wave pattern is a more positive/neutral orientation to the trough, leaning away from the fast pivot to a negative tilt. This keeps driving the bulk of the moisture axis to the east which should largely miss SE MI. It also allows the surface low to keep tracking northeast instead of curling and stalling over the northern Great Lakes. So a more progressive system and less precipitation for our area.

As for high temperatures Saturday, Detroit's forecast high of 58 is tied with the record for December 9th. Interestingly, every record high from the 1st through the 16th is in the 60s...except for the 9th at 58. Flint and Saginaw records are in the 60s so likely won't flirt with those records.

Moving on to Sunday, cold front will pass early allowing northwest flow cold advection to begin. 850mb temps will fall from 7C Saturday afternoon down to -7C by Sunday afternoon. Typical concerns with lake effect processes kicking in with snow the primary ptype with activity reaching the east side of the state later in the afternoon. With the low racing off to the northeast, we shouldn't have to worry about the lingering deformation axis or trough enhancing the forcing over the area but models have yet to show run to run consistency so changes are likely to the forecast.

Quieter weather to start the week possibly as we reside on the north side of a large surface high with a ridge building in. Longwave pattern looks much less energetic across the conus, with the next trough holding over northern Ontario.

MARINE...

Weak low pressure currently contributing to snow showers across Lake Huron will exit into Ontario by mid-day, making way for ridging and drier weather to briefly build in. A relaxing gradient eases southwest flow to around 10 knots this afternoon, with subsiding wave heights to follow. Ongoing Small Craft Advisories on track to expire late morning-early afternoon as a result. First indications of the next system arrive tonight as warm and stable air surges in owing to a deep and expansive low pivoting over the Dakotas.
Interaction of this low with several additional disturbances creates an energetic wind field beginning Friday, with southerly flow ramping up once again to around 20 knots. Not out of the question to see a stray shower Friday as the first wave of moisture moves in, but the more impressive system arrives Saturday which brings a more widespread rain shield to the Great Lakes. Magnitude of the low level jet will touch 50 knots, but the seasonably warm airmass (temperatures near 50 degrees) limits these gusts from reaching the surface for most of the day Saturday. The current forecast low track drives a cold front through the Great Lakes late Saturday-Sunday, which will be a window to watch for enhanced gusts and possible gales, but duration of gale potential may be too short for long- fused headlines.

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

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