Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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732 FXUS63 KGRB 300343 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1043 PM CDT Wed May 29 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Frost is likely across northern Wisconsin late tonight. A Frost Advisory has been issued for locations generally north of a Merrill to Antigo to Wausaukee line. - Due to recent rainfall, a few rivers are expected to remain at bankfull but below minor flood stage through late this week. - A more unsettled pattern is forecast to return this weekend through at least the middle of next week. Currently, Sunday night through Monday has the best chance for thunderstorms and heavier rainfall. && .DISCUSSION... Issued at 224 PM CDT Wed May 29 2024 Short Term...Tonight and Thursday Fair weather cumulus developed this morning and continued this afternoon across central and portions of north-central Wisconsin. Temperatures warmed into the 60s to around 70 away from the bay and Lake Michigan, where readings were in the 50s. For tonight, the fair weather cumulus will erode fairly quickly around sunset across central and portions of north-central Wisconsin. After midnight, frost is likely across the northwoods as low temperatures should fall into the 33 to 37 range. A Frost Advisory has been posted for locations generally north of a Merrill to Antigo to Wausaukee line. Low temperatures elsewhere will be in the upper 30s and lower 40s. Mostly sunny skies will prevail on Thursday with some fair weather cumulus clouds developing in the late morning and afternoon. High temperatures will climb into the lower to middle 70s away from the bay and Lake Michigan. Afternoon relative humidity values will drop into the 25 to 40 percent range. Long Term...Thursday Night Through Wednesday Dry start to the extended period Thursday night through much of Friday as a ridge of high pressure moves over the region. A return to a more unsettled pattern is expected beginning Friday night as a series of disturbances are forecast to impact the area. Thursday night through Friday...Light southeasterly flow driven by the passing upper ridge and surface high should keep low temperatures Thursday night warmer compared to Wednesday night, especially across northern WI. This will also help boost Friday`s temperatures a few degrees with most locations expected to reach the 70s, except along the immediate lakeshore. While most of the region will stay dry Friday, a cold front stalling out over western WI along with an eastward push of increasing moisture (PWATS approaching 1") could produce a few scattered showers in central and north-central WI beginning Friday afternoon. Friday night through Sunday...As the ridge starts to depart the region Friday night the eastward push of warm moist air will continue, increasing the chance for scattered showers across the region Friday night through Saturday afternoon. A confluent upper- level pattern will provide additional support for these showers. Instability currently looks weak during the period limiting the potential for any thunderstorms to form, but can`t rule out a few rumbles of thunder, mainly Saturday morning. A brief period of ridging Saturday night through most of Sunday will return dry conditions to the region. The weak ridge also supports temperatures nearing or surpassing 80 degrees Sunday afternoon for locations away from the lakeshore. Sunday night through the rest of the extended period...A more widespread chance for showers and storms is forecast to arrive Sunday night into Monday morning with a surge of warm moist air out ahead of a mid-level shortwave. PWATs look more impressive during this period with values of 1.5-1.7" which is 1.25 to 1.5 standard deviations above normal. The severe weather potential during this period is still unclear, but with increasing instability during the day Monday and the increase in available moisture this period at least bears monitoring, especially for those with outdoor plans Monday. Looking ahead models are showing broad signs of another disturbance tracking across the western Great Lakes toward the middle of next week. && .AVIATION...for 06Z TAF Issuance Issued at 1039 PM CDT Wed May 29 2024 Clear skies will occur through the overnight period. Though patchy ground fog may occur in a few locations, confidence is not high enough to include at the TAF sites. A few high-based cumulus clouds may reform across the western part of the forecast area Thursday afternoon. Light and variable winds are anticipated overnight, with a gradual increase in SE-S winds by late morning Thursday. && .GRB WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 9 AM CDT Thursday for WIZ005-010>013-018- 019-021. && $$ DISCUSSION.....Eckberg/GK AVIATION.......Kieckbusch