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LMZ522 Expires:202404201300;;058887 Fzus53 Kgrb 200756 Nshgrb
nearshore marine forecast national weather service green bay wi 256 am cdt Sat apr 20 2024
for waters within five nautical miles of the shore on lake michigan
lmz521-522-201300- green bay south of line from cedar river to rock island passage and north of a line from oconto wi to little sturgeon bay wi- green bay south of line from oconto wi to little sturgeon bay wi- 256 am cdt Sat apr 20 2024
Overnight - W wind 10 to 20 kts with a few gusts to around 25 kts. Mostly cloudy. Waves 1 to 3 ft. Today - W wind 10 to 20 kts. A chance of sprinkles in the afternoon. Waves 1 to 3 ft. Tonight - W wind 10 to 15 kts. Partly cloudy in the evening then clearing. Waves 2 ft or less. Sunday - W wind 10 to 20 kts veering nw 10 to 15 kts in the afternoon. Sunny in the morning then becoming partly cloudy. Waves 2 ft or less.

LMZ500
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FXUS63 KGRB 200315 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 1015 PM CDT Fri Apr 19 2024

Updated aviation portion for 06Z TAF issuance

KEY MESSAGES

- Scattered snow showers could result in briefly reduced visibilities tonight over north-central Wisconsin. Any snow accumulation will be minimal.

- Elevated fire weather conditions are possible on Sunday and Monday afternoons due to low relative humidities ranging from 25 to 30 percent and sustained winds of 10 to 20 mph.

- Next chance for precip returns late Monday through late Tuesday.
Rain will be the main precipitation type, but some snow may mix in across the far north on Tuesday.

DISCUSSION
Issued at 200 PM CDT Fri Apr 19 2024

Short Term...Tonight and Saturday

Breezy day across much of the area. Peak gusts have reached around 40 mph at times, especially central to east-central Wisconsin.
Clouds have steadily built from northwest to southeast as vigorgous shortwave within broad upper trough works toward the area. Thus far, snow showers over north-central WI have been very isolated and light. Given steep low-level lapse rates (9-10c/km in lowest 1.5km) and the approaching sharp PV anamoly/shortwave, expect snow showers to increase especially over north-central WI along and north of the track of the wave. Not much for snow accumulations, but brief lower visibility could occur as has occurred upstream today at times in northeast MN. These diurnally enhanced snow showers will fade away early this evening.

Then, later this evening and overnight, more snow showers or flurries could occur again mainly northern areas as another embedded shortwave within the larger scale trough rotates across. This wave along with deeper moisture (to H6) and NW winds flowing across western Lake Superior with H85 temps down to -9c to -11c (water temps of 3-4c) should result in at least scattered snow showers due to weak lake enhancement and upslope lifting into north-central WI. Snow accumulations will be minor, generally under an inch over Vilas County. Chilly night no matter where you are at with readings in the mid 20s northern Wisconsin, to only the lower 30s from the Fox Valley to the lakeshore.

On Saturday, we'll be in wake of the shortwave moving through tonight so there will probably be subsidence to start the day.
Even so, we'll also be on the edge of the thermal trough and there will be sufficient low-level moisture. Liked and retained previous shifts idea of adding some small chancy pops for light snow showers/sprinkles with coverage maxing out late morning into the early afternoon. NW winds will be breezy, though not as strong as we have seen today. High temperatures will range from the lower 40s north-central WI, to the mid to upper 40s elsewhere.

Long Term...Saturday Night Through Friday

Precipitation...Quiet weather remains expected for the second half of the weekend as an upper trough slowly lifts to the northeast.
Then a shortwave energy and an associated surface low will bring precipitation to the region during the late Monday afternoon through Tuesday time frame.

The shortwave is looking more disjointed in the latest forecast cycle and the large spread with the timing/strength of the impulse makes it difficult to add high resolution to the forecast.
Regardless, guidance generally points to around 0.15 to 0.30 inches of precipitation, which is trending down compared to the forecast yesterday.

Still think that dynamics are relatively robust given the 40+ kt low level jet and mid-level lapse rates of 7 C/km will accompany the shortwave. That could lead to a few thunderstorms, but probability looks low at this time.

Probabilities remain low (less than 20%) for snow on the backside of the system across northern WI on Tuesday. If snow were to occur, warm temperatures during the daylight hours would lead to near zero impacts.

Another chance of precipitation will occur late next week from a southern stream system.

Temperatures: Will be on a roller coaster ride over the next week, but no anomalous cold or heat is expected.

AVIATION
for 06Z TAF Issuance Issued at 1006 PM CDT Fri Apr 19 2024

Another round of scattered snow showers is expected to impact NC WI overnight, with possible MVFR/IFR vsbys at the RHI TAF site during the early part of the TAF period. A few snow showers or flurries may linger into Saturday morning before ending. Ceilings should prevail in the 4000-6000 ft AGL range for much of the TAF period, though MVFR ceilings may accompany any snow showers, and may also move into NC WI late tonight into Saturday morning.
Gusty WNW winds will decrease slightly overnight, increase again late Saturday morning, then diminish Saturday evening. Clearing skies are anticipated by sunset.

FIRE WEATHER
Issued at 200 PM CDT Fri Apr 19 2024

Moderating temperatures and a dry airmass will lead to elevated fire weather days on Sunday and Monday. Winds will be a little stronger on Sunday compared to Monday with sustained values of 15-20 mph and gusts up to 30 mph (sustained winds 10-15 mph with gusts to 25 mph on Monday). While elevated fire weather conditions will be present each day, concern is a little higher on Sunday due to slightly stronger winds.

Another period of elevated fire weather conditions is possible next Wednesday and Thursday as a Hudson Bay high pressure system moves into the region. PWATs are forecast to be 20% of normal according to the GFS ensemble. Because of the proximity of the high, winds will likely be below critical criteria.

GRB WATCHES/WARNINGS/ADVISORIES
None.

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