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LMZ522 Expires:202312060900;;970146 Fzus53 Kgrb 060029 Nshgrb
nearshore marine forecast national weather service green bay wi 628 pm cst Tue dec 5 2023
for waters within five nautical miles of the shore on lake michigan
lmz521-522-060900- 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- 628 pm cst Tue dec 5 2023
Tonight..NW wind 5 to 10 kts. Mostly cloudy in the evening then becoming partly cloudy. Waves 2 ft or less.
Wednesday..W wind 5 to 10 kts backing sw 10 to 20 kts in the afternoon. A chance of sprinkles and flurries in the afternoon. Waves 1 to 3 ft.
Wednesday night..SW wind 10 to 20 kts with gusts to around 25 kts. A chance of sprinkles and flurries in the evening. Waves 3 to 5 ft subsiding to 1 to 3 ft early in the morning. A small craft advisory may be needed.
Thursday..SW wind 5 to 10 kts backing S in the afternoon. Partly cloudy in the morning then clearing. Waves 2 ft or less.

LMZ500
No data

FXUS63 KGRB 060004 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 604 PM CST Tue Dec 5 2023

Updated aviation portion for 00Z TAF issuance

DISCUSSION
Issued at 148 PM CST Tue Dec 5 2023

SHORT TERM...Tonight and Wednesday

Main forecast challenge to mainly be on temperatures over the next 24 hours, although increasing isentropic lift may produce some sprinkles/flurries Wednesday afternoon.

The 19Z MSAS surface analysis showed the weak clipper low pressure area over central IN with its main impact to northeast WI being a wind shift to the northwest. Surface observations have picked up on some lake effect sprinkles or flurries at times over far northern WI. A ridge of high pressure was situated over the central and northern Plains. Visible satellite imagery indicated a plethora of clouds over pretty much all of WI.

Any lake effect sprinkles or flurries over northern WI will come to an end this evening as the ridge of high pressure moves into the Upper MS Valley and winds begin to back to the west. Only a dusting at best would be expected. Otherwise, the extent of the clouds remains the main forecast issue for tonight. Initial clearing over eastern WI had already filled in and it may take most of the night before any clearing from the high pressure reaches the forecast area. Therefore, have gone with mostly cloudy skies for tonight and potential for some patches of fog to develop late tonight. Temperatures are a little tricky as any clearing would allow temperatures to easily plummet. For now, have readings ranging from around 20 degrees north-central WI, to the middle 20s east-central WI.

As the surface ridge slides across WI on Wednesday, winds will back to the southwest and help to push a warm front through WI.
These southwest winds could become gusty in the afternoon behind the warm front, but any warming will have to wait a day as clouds increase/thicken through the day due to increasing isentropic lift. While models have backed off on potential precipitation, enough saturation may occur to allow for a chance of sprinkles or flurries in the afternoon. Max temperatures for Wednesday to range from the lower to middle 30s north, middle to upper 30s south.

LONG TERM...Wednesday Night Through Tuesday

Wednesday night through Friday night...Quiet weather will be in place across the region for the beginning of the extended period.
Shallow upper ridging will pass over the area Wednesday into Thursday, tailed by an upper cyclone that will cross Canada at the end of the work week. Strong warm air advection associated with the return flow behind the ridge and the passing low pressure system to our north will bring above normal temperatures to the region. Expect highs in the 40s Thursday and possible low 50s on Friday. The highs on Friday will largely be dependent on how quickly the cold front arrives on Friday, which may bring back cloud cover and a few sprinkles but will be too dry to produce much in the way or precipitation, especially as the better forcing will accompany the low pressure system to our north.

Saturday through Monday...Attention then turns to our next potentially impactful system over the weekend, as shortwave energy crosses the Rockies ahead of the next upper trough. Model spread remains fairly wide with this system still keeping storm track uncertain. The 10% best case scenario impact-wise, would be more in line with the latest Canadian, which brings the developing low more eastwards and largely misses our area entirely. On the 10% worst case, the latest GFS retains a more northerly track which would embed eastern WI well into the cold sector, provide for a mainly snow forecast, with potentially heavy snowfall and wind to the area. A more blended consensus brings in some precipitation over the weekend, with the highest wind gusts more concentrated over Lake Michigan. Split flow patterns such as this are highly variable 5 days out, so additional details and confidence will slowly grow over the next few days. All together, the main area to watch the forecast for will be eastern WI, which will have the largest potential for wintry precipitation and potential lake enhanced snow on the backside of the low.

In the wake of this storm system, temps will be trend colder with signs of clipper energy traversing the region next week.

AVIATION
for 00Z TAF Issuance Issued at 604 PM CST Tue Dec 5 2023

Low-level clouds with MVFR and low-end VFR cigs prevailed across the TAF sites this evening. The MVFR cigs were focused in central and north-central WI, with the VFR cigs elsewhere. Despite clearing occurring upstream in eastern MN, anticipate the low clouds, with MVFR cigs, sticking around at the central and north- central WI TAF sites through Wednesday morning. The VFR conditions will continue at the east-central WI TAF sites overnight, with some breaks in the clouds occurring at times.

The remainder of Wednesday will continue to have clouds but with VFR cigs as high pressure gradually shifts eastward. This will result in the light west winds turning southwest and increasing in the afternoon, with gusts of 15 to 20 kts.

GRB WATCHES/WARNINGS/ADVISORIES
None.

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