Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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937 FXUS63 KGRB 291700 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1200 PM CDT Wed May 29 2024 Updated aviation portion for 18Z TAF issuance .KEY MESSAGES... - Areas of frost are possible late tonight into early Thursday morning across far northern WI. - Due to recent rainfall, a few rivers are expected to remain at bankfull but below minor flood stage through late this week. && .DISCUSSION... Issued at 333 AM CDT Wed May 29 2024 Short Term...Today...Tonight...and Thursday Frost potential is main concern with return to dry weather in the offing. Last vestiges of the heavier showers and thunder that brought heavy rain to parts of east-central Wisconsin Tuesday afternoon and evening has shifted to south of the area early this morning. Widespread clouds and a few sprinkles still remain in the wake of the system that brought the showers. These clouds extend from central Upper Michigan across northeast and east- central Wisconsin and will gradually diminish this morning. The only other blemish on a mostly sunny late morning and afternoon will be scattered fair weather high based cu developing over central Wisconsin. Gradient winds will be from north- northeast, so it will stay cooler lakeside today with highs around 60 into the lower 60s. Elsewhere mixing to H8 supports highs in the upper 60s to near 70 over parts of central Wisconsin. Frost still possible for northern Wisconsin tonight. No significant changes to continuity with lows in the lower to middle 30s which is also agreed upon by latest MOS guidance. High pressure overhead with light winds leads to prime cooling potential with low PWATs helping the cause. Ensemble data not near as bullish on the potential with NBM probabilities of min temps less than 36F along the Michigan border barely up to 30 percent with most of the area less than 10 percent. HREF probabilities check in at 20-30 percent for same thresholds. Given the synoptic setup and what MOS guidance is showing (as low as 33 at LNL), thinking these ensembles are underdone. Per coordination with DLH and MQT, will let dayshift take final crack at location of the frost advisory headline. Seems at the least Vilas, northern Forest and Florence counties would be good starting point for an advisory but could see additional counties as well. Elsewhere, readings will drop into the upper 30s to lower 40s, warmest near Lake Michigan. Plenty of sunshine on Thursday as high pressure slowly shifts east. That high off to the east will result in lake breeze off Lake Michigan extending as far west as the Fox Valley in the afternoon. Highs will follow that gradient with readings again in the low to mid 60s near Lake Michigan, but pushing into the 73-75F range farther inland where deeper mixing occurs with minimal lake cooling influence. Long Term...Thursday Night Through Tuesday Dry weather will be in place at the beginning of the extended before more active weather returns again over the weekend into early next week. Thursday night through Friday... Upper riding and surface high pressure will move eastwards Thursday night, bringing back weak southerly flow by Friday morning. The warmer air will make for a warmer night than Wednesday night and will also add a couple degrees to the high temps, with most of the area likely to get into the middle to upper 70s. The influx of warmer, more moist air will also bring some showers with them into western WI. A few of these showers may yet clip portions of central or north- central WI late in the day, but most of Friday should remain dry. Rest of the forecast...As the ridge continues to slide eastwards, the axis of warmer and more moist air will shift into our neck of the woods, bringing in a window for scattered light showers sometime late Friday night through Saturday afternoon. Instability will be lacking during this period so little to no thunder is expected, but the early rain and clouds will keep high temperatures from reaching into the 80s. Sunday has trended drier, but a few of the long term models still hang on to a couple showers as a weak shortwave crosses in the afternoon, so kept the slight pops in place for the afternoon. The drier forecast does support the warmer temperatures getting into the upper 70s to lower 80s however. Finally, the next period to watch will be late Sunday night through Monday morning, which is when models bring the next clipper like low pressure system through the region, with the trailing cold front likely to be our next round of widespread rainfall for early next week. && .AVIATION...for 18Z TAF Issuance Issued at 1155 AM CDT Wed May 29 2024 Fair weather cumulus clouds from five to seven thousand feet will continue this afternoon, mainly west of the Fox Valley. Drier air and winds off the bay and lake should limit cloud cover formation from KMTW to KGRB on northward to KIMT to KLNL. Northeast to northeast winds of 5 to 10 knots are expected with a few gusts up to 15 knots possible. The fair weather cumulus will dissipate around sunset with clear skies expected overnight. Frost is expected north of a Merrill to Antigo to Wausaukee line. On Thursday, fair weather cumulus clouds will develop again during the late morning and afternoon while winds turn to the south or southeast around 10 knots. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....JLA/Uhlmann AVIATION.......Eckberg