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LMZ847 Grand Haven To Whitehall Mi- 1105 Am Est Wed Dec 6 2023
.small craft advisory in effect from 7 pm est this evening through Friday morning...
Rest of today..West winds 15 to 25 knots. Mostly cloudy. Waves 2 to 4 feet.
Tonight..Southwest gales to 35 knots. Partly cloudy. Waves 6 to 9 feet.
Thursday..West winds 10 to 20 knots backing south 15 to 25 knots. Mostly Sunny. Waves 5 to 7 feet subsiding to 3 to 5 feet.
Thursday night..South winds to 30 knots. Partly cloudy. Waves 3 to 5 feet building to 5 to 7 feet toward daybreak.
Friday..South winds to 30 knots. Partly Sunny. Waves 6 to 9 feet.
Saturday..South winds 15 to 20 knots backing northeast late in the day. Rain. Waves 2 to 3 feet building to 3 to 5 feet.
Sunday..Northwest winds around 25 knots. Cloudy with a chance of rain and snow. Waves 4 to 6 feet.

LMZ800
No data

FXUS63 KGRR 061740 AFDGRR

Area Forecast Discussion National Weather Service Grand Rapids MI 1240 PM EST Wed Dec 6 2023

LATEST UPDATE...
Aviation

SHORT TERM
(Today through Thursday)
Issued at 324 AM EST Wed Dec 6 2023

A few light snow showers and flurries will continue to develop through the morning with h8 temps down around -8 C yielding delta t/s in the middle teens. Precipitation will taper off toward midday as deeper moisture decreases and h8 temps begin to moderate.

Dry wx is expected for most of our area tonight. A mid to upper level disturbance passing by well to the north to ne of our area may bring just a few light mixed light rain/light snow showers to our ne fcst area. Milder and dry wx is forecast for Thursday. A fair amount of sun in conjunction with increasing sw flow waa will help to boost max temps well into the 40s.

LONG TERM
(Thursday night through Tuesday)
Issued at 324 AM EST Wed Dec 6 2023

The latest 00Z deterministic runs of the ECMWF/GFS/Canadian have all changed their tune quite a bit as far as the late weekend weather goes. The longwave trough which digs over the center of the nation is now shown to be a bit more progressive and less amplified so the sfc frontal zone just drifts east through Michigan with no notable sfc low developing along it.

This scenario would mean a round of rain showers Friday night through Saturday night ahead/along of the front, followed by some light lake effect snow showers in the cold advection behind the front Sunday into Monday. Ensemble 50th percentile QPF amounts have lowered, as well as the threat of stronger winds.

That said there are still a few (minority) ensembles members which support the idea of a decent sfc low developing along the baroclinic zone although that number is shrinking in the new 00Z data. A few members are also still putting down a stripe of synoptic snow through the area but it should be noted that the EC ENS 90th percentile snow amounts have lowered considerably and the prob of >6" is now less than 10 percent.

So while overall fcst confidence still remains relatively low for later in the weekend, the risk of any higher impact weather is definitely decreasing in the new 00Z 12/6 data.

Otherwise confidence is high regarding the unseasonable warmth preceding the frontal passage, with temps Friday expected to be in the 50s and even a decent potential for sunshine. Similar highs are possible on Saturday as well, especially over ern sections, depending on frontal timing and shower coverage.

AVIATION
(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1233 PM EST Wed Dec 6 2023

Generally VFR conditions ongoing at present with an area of high end MVFR intermixed with VFR moving through this afternoon into the evening. Skies become completely VFR this evening and cigs are forecast to scatter out tomorrow morning. Southwest winds of 10-15 knots are expected tonight with gusts to 25 knots at MKG. A few hours of LLWS are possible for BTL and JXN as a 40-45 knot low level jet moves overhead early Thursdat morning.

MARINE
Issued at 324 AM EST Wed Dec 6 2023

We will issue a small craft advisory for tonight through early Friday morning as winds and wave heights will ramp up considerably beginning this evening. Conditions could briefly flirt with gale force but an overall guidance consensus favors winds to stay under gale force. The small craft will likely eventually need to be extended through Friday.



GRR WATCHES/WARNINGS/ADVISORIES
MI...None.
LM...Small Craft Advisory from 7 PM this evening to 7 AM EST Friday for LMZ844>849.

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