Sunrise 5:44 AM   Sunset 7:54 PM Moonrise 12:24 AM   Moonset 8:20 AM

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LMZ522 Expires:202404282000;;526503 Fzus53 Kgrb 281401 Nshgrb
nearshore marine forecast national weather service green bay wi 901 am cdt Sun apr 28 2024
for waters within five nautical miles of the shore on lake michigan
lmz521-522-282000- 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- 901 am cdt Sun apr 28 2024
.small craft advisory in effect through Monday morning - .
Today - NE wind 15 to 25 kts. A chance of rain showers in the morning, then rain showers and a slight chance of Thunderstorms in the afternoon. Patchy fog in the afternoon. Waves 2 to 4 ft. Tonight - E wind 10 to 20 kts with gusts to around 30 kts. Patchy fog. Rain showers and a slight chance of Thunderstorms. Waves 3 to 5 ft. Monday - SE wind 10 to 20 kts veering S 10 to 15 kts in the afternoon. Gusts to around 25 kts. Patchy fog in the morning. Rain showers likely. Waves 2 to 4 ft subsiding to 2 ft or less in the late morning and afternoon. Monday night - SW wind 10 to 20 kts. Mostly cloudy. Waves 1 to 3 ft.

LMZ500
No data

FXUS63 KGRB 281144 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 644 AM CDT Sun Apr 28 2024

Updated aviation portion for 12Z TAF issuance

KEY MESSAGES

- Better chances for rain returns this morning and continues through Monday. Periods of moderate to heavy rain tonight into Monday morning, could result in isolated flash flooding in urban and low lying areas. Rivers will be on the rise through the middle of next week, with a few of them reaching bankfull stage.

- Conditions hazardous to small craft are expected into Monday on the Bay and Lake. Patchy dense fog is possible on the waters as well.

- There is a chance of showers and a few thunderstorms Tuesday night and at times late Wednesday night into next weekend.

DISCUSSION
Issued at 324 AM CDT Sun Apr 28 2024

Short Term
Today
Tonight...and Monday

Leading shortwave trough is heading east this morning while primary active frontal boundary has sunk into far southern WI. A few showers are occurring over northeast WI, but next main area of showers will not arrive until later this morning into early afternoon from south to north as yet another sharp shortwave trough ejects out of the central plains. By late afternoon main sfc low will be over western Iowa with sfc warm front still stuck over southern Wisconsin. Sfc high near James Bay and the low to the southwest will result in increasing NE winds across all but southern Wisconsin. The showers driven by mid-upper diffluence and warm, moist advection aloft ahead of H85 low along with the NE winds off chilly Lake Michigan and the bay will keep temps *much* cooler than what occurred over most of the area on Saturday as readings this afternoon will commonly be in the 40s. Elevated instability limited today, but will support some rumbles of thunder into the south half of the area this afternoon. Rainfall amounts late this morning through the afternoon should top out over 0.50 inch in many areas, but be hard pressed to reach over 0.75 inch. Still a soaking rainfall is on tap.

Tonight, wave of showers will lift to northern areas early this evening and there may be a brief break for part of the evening.
However, another round of showers and some thunderstorms will impact all the cwa from south to north as the warm front lifts farther north. There are some differences in where axis of heaviest rain streams northward. At this point, the NAM along with WRF-ARW and FV3 shows more of a direct hit with the second round of showers while the GFS, Canadian and ECMWF favor areas just to our east. Showers will still occur, but this will impact if our area sees heavy rain that could possibly cause minor flooding issues in low-lying and poor drainage areas. Diving into HRRR probabilities, certainly a decent chance most areas over eastern and northeast cwa see another 0.25 to 0.50 from the rain later tonight, but probabilities drop off to around 30 percent when looking at seeing amounts over an inch, which is what the NAM, WRF-ARW and FV3 are advertising. Have added fog as well as there are hints that we'll see some fog either due to the advection of marine fog onto land with persistent E/NE winds or just with enhanced low-levels to the north advancing warm front.
Lows will be similar to what temps will be late this afternoon.
Temps will rise more into the 50s late over far south as the warm front moves in.

On Monday, shortwave trough pivots northeast while sfc low lifts into northwest WI. Parts of the area will break into the warm sector of the low, but dry air will quickly be shifting eastward across WI. Still, after the morning showers, could see a brief window of sfc based development of showers and storms where Td surge up into the 50s in the warm sector. MLCAPEs nothing too notable at this point (maybe up to 300j/kg) but with effective shear 35+ knots, can't rule out an isolated stronger storm early to mid afternoon. SPC Day2 only shows general thunder for our area. Highs in the warm sector will reach well into the 60s over east-central WI with a 70 over far southern cwa not out of the question.

Long Term...Monday Night Through Saturday

A zonal flow at 500mb is expected at the start of the period, with a system moving through the mean flow that would bring a chance of showers and a few thunderstorms Tuesday night. A deeper 500mb trough will approach the area Thursday then across the area Friday into Friday night, bringing a better chances for showers and some thunderstorm activity.

For Tuesday night, the models have been consistent in bringing rain into the area during the evening hours over much of the area, thus the small chances of rain Tuesday afternoon were removed. The better forcing with the shortwave energy will be focus across north-central and far northeast Wisconsin which will coincide with the highest QPF totals. The GFS bufkit sounding indicated a few hundred J/KG of CAPE, so a few thunderstorms will be possible with the passage of the system. Dry conditions are expected to prevail on Wednesday before the next system approaches from the west late Wednesday night and Thursday.

Building 500 ridge over the eastern seaboard with 500mb trough eventually evolving into a negatively tilted system Thursday into Friday should bring a few rounds of showers and thunderstorms.
At the surface, at 12z Thursday a surface low is forecast to be across the central plains into Iowa with a warm front extending to near (south) of the Wisconsin/Illinois border. An MCS is forecast to develop north of the warm front which is expected to clip the southern half of Wisconsin. Based on the models tonight, we will be on the northern edge of the MCS which should keep most if all severe weather south of the area. On Thursday, the surface low will push slowly northward which should keep the surface warm front along our southern counties or to the south which will bring a continued chance of showers and thunderstorms. By the time you get to Friday, there are significant difference in the track of the main surface low. It is too early to determine if any of the storms would become severe. Confidence is low on the next system bringing chances for rain on Saturday, thus no changes made to this period. High temperatures will need to be watched Thursday and Friday.
Rain, clouds and easterly flow could keep temperatures in check on one or both days depending on the final storm track.

AVIATION
for 12Z TAF Issuance Issued at 641 AM CDT Sun Apr 28 2024

A low pressure system moving from the central Plains to western Great Lakes will bring periods of showers and isolated thunderstorms, most widespread this afternoon through tonight.

Ceilings will become MVFR this morning, with some IFR ceilings possible north of a Rhinelander to Iron Mountain line. IFR ceilings will spread over most of the region this afternoon though MVFR may persist over far north-central Wisconsin. Plan on widespread IFR or LIFR ceilings everywhere tonight. IFR visibility is likely as well due to the rain and also some fog.

GRB WATCHES/WARNINGS/ADVISORIES
None.

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