Sunrise 5:33 AM   Sunset 8:00 PM Moonrise 4:16 AM   Moonset 5:14 PM

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LMZ543 Expires:202405060800;;690512 Fzus53 Kgrb 052301 Nshgrb
nearshore marine forecast national weather service green bay wi 601 pm cdt Sun may 5 2024
for waters within five nautical miles of the shore on lake michigan
lmz542-543-060800- sturgeon bay to two rivers wi-two rivers to sheboygan wi- 601 pm cdt Sun may 5 2024
Tonight - S wind around 5 kts backing E after midnight. Clear. Waves 2 ft or less. Monday - E wind 5 to 10 kts. Sunny. Waves 2 ft or less. Monday night - E wind 10 to 15 kts. Partly cloudy. Waves 1 to 3 ft building to 2 to 4 ft early in the morning. Tuesday - SE wind 10 to 20 kts with gusts to around 25 kts. Rain showers. Waves 3 to 5 ft. A small craft advisory may be needed.

LMZ500
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FXUS63 KGRB 052257 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 557 PM CDT Sun May 5 2024

Updated aviation portion for 00Z TAF issuance

KEY MESSAGES

- Patchy fog is possible late tonight until an hour or two after sunrise on Monday.

- Relative humidity values are expected to drop into the middle 20s and 30s Monday afternoon. Recent rain, lack of strong gusty winds and continued green-up will limit fire weather concerns.

- Next round of showers and storms arrives Tuesday morning. Best chance for thunderstorms will be Tuesday afternoon and evening.
There is a small risk for a stronger storm especially for our western areas.

DISCUSSION
Issued at 253 PM CDT Sun May 5 2024

Short Term...Tonight and Monday

Fair weather cumulus clouds developed late this morning and continued this afternoon away from the bay and Lake Michigan.
Temperatures climbed into the 60s, except only around 50 near the Lake Michigan shoreline. The lake breeze was beginning to move westward towards Green Bay and the Fox Cities.

For the rest of the afternoon, the lake breeze should move into Green Bay and the Fox Cities late this afternoon. The passage of the lake breeze front will bring a wind shift to the southeast along with temperatures falling several degrees.

For tonight, the fair weather cumulus clouds should dissipate around sunset. With clear skies and light winds overnight, some patchy fog is expected to develop toward sunrise on Monday. The fog is expected to be patchy and not dense with the amount of drying taking place today.

On Monday, a sunny and mild day is anticipated with highs in the middle 60s to lower 70s away from the bay and Lake Michigan.
Afternoon relative humidity values should drop into 25 to 30 percent range across the far north with 30-40 percent away from the bay and Lake Michigan. Southeast winds will increase Monday afternoon with gusts of 15 to 20 mph expected at most spots.

Long Term...Monday Night Through Sunday

Several opportunities for rain this week as a general unsettled pattern dominates. No great signal for anything too significant in terms of storms or rainfall, though we'll have to keep eye on late Tuesday if destabilization can occur.

The Monday night through Tuesday evening time frame will likely be when the most rainfall occurs this week. Deep low sub 985mb will be lifting northward across the northern plains. Occluded front well ahead of the low will be interacting with PWATs up to 1.25 inch approximately the 90th percentile for this time of year.
SE flow ahead of this front will also be drawing in dry air tied to departing high pressure. Slower trend for rain shower arrival that started showing up 24hr ago remains today, if not even slower yet. Expect most cwa to remain dry on Monday night, except maybe the very far western fringe. Eventually though band of moderate showers (lasting 3-6 hrs at any one location) will swing across the area beginning mid to late morning on Tuesday. Lingering dry air could keep parts of east-central and northeast WI from not seeing rain arrive until at least early Tuesday afternoon.
Current forecast temperatures show decent range with expected showers and SE winds keeping central to north-central/northeast WI cooler while earlier ending of steady showers and winds shifting to the SW could allow temps to reach near 70 south of Wisconsin Rapids to Oshkosh.

Best chance for thunderstorms comes Tuesday afternoon and evening as models show a thin band of instability (MLCAPE now increasing to 500 to as much as 1000 J/kg) building from western to central WI. Additionally mid-level lapse rates approach 7.5-8.0 C/km during this period owing to cooler air aloft as H5 temps drop below -20c beneath elongated trough from Montana to the western Great Lakes. Seems another embedded shortwave arrives over west- central WI late afternoon to kick off the additional convection chances. Forecast soundings show relatively low wet-bulb zero heights (6-8kft) with inverted-V look. Effective shear is 30-40 kts. Timing will be key as if initial wave of showers moves through quicker, then there would be more time to destabilize in the afternoon. SREF thunder/severe probs point to far southern WI for better severe potential, but think there is at least a small risk into our southwest areas. In terms of rainfall amounts the consensus of the ensembles point to likely (60-80%) of seeing at least 0.50 inch of rain but tail off to less 30 percent for seeing over 1".

Wednesday through Thursday...Ensembles have come into decent agreement with a period of dry weather Wednesday morning as dry air behind an occluding front filters over the region. Dry conditions may not last long as the weakening cyclone moving east out of the northern Plains merges with a developing southern stream system returning rainfall to the region late Wednesday into Thursday. Possible some convection may occur late Wednesday mostly over central and western WI away from more easterly flow developing off Lake Michigan. These east winds may get a bit gusty on Thursday as they turn northeast once primary low pressure system begins to shift more to the central Great Lakes and Ohio Valley.

Rest of the extended...Seems Thursday night into Friday will dry out. If clearing occurs earlier, some risk for fog or frost over north-central WI early Friday morning. Rather vigorous trough is on track to drop across the western Great Lakes by Saturday. Due to this, the risk for showers has increased for Friday night into Saturday but the chances for chilly min temps and some frost Friday night over the north has lessened. Will just have to see if the trend holds. Unsettled weather continues for the weekend as low pressure slowly drifts away and a reinforcing cold front drops across.

AVIATION
for 00Z TAF Issuance Issued at 557 PM CDT Sun May 5 2024

VFR conditions will prevail through the TAF period. The only exception could be for some MVFR visibilities across far north- central Wisconsin, especially Vilas County, towards sunrise on Monday morning. Fair weather cumulus between four and six thousand feet will clear around or shortly after sunset. Fair weather cumulus clouds will redevelop, generally around the same height, late Monday morning and afternoon. The next chance of rain will be on Tuesday morning.

GRB WATCHES/WARNINGS/ADVISORIES
None.

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