Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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908 FXUS63 KGRB 020904 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 404 AM CDT Tue Jul 2 2024 Forecast discussion for routine morning forecast issuance .KEY MESSAGES... - Periods of rain may be heavy at times through late tonight. In general, 0.5 to 1.5 inches of rain is expected across the entire area, highest in central Wisconsin, which could lead to minor river and stream flooding, along with urban flooding. - Conditions will be hazardous to mariners and beachgoers on the bay and Lake Michigan through tonight due to gusty winds and high waves. - The next round of widespread rain arrives late on the 4th of July and will last through Friday. && .DISCUSSION... Issued at 358 AM CDT Tue Jul 2 2024 Rounds of showers and some thunderstorms expected through tonight. Moderate to heavy rainfall is likely, especially over central WI. It then turns mainly dry Wednesday and Wednesday night, before more showers return later on the 4th, continuing through Friday. First full weekend of July will be unsettled with chances for showers and thunder both days. Today...Showers with moderate to heavy rain ahead of a shortwave trough and well to the north of main warm front are shifting across the state early this morning. Decaying area of lightning strikes is present over southwest cwa on edge of MUCAPE of 1-2k/kg well to the west and southwest over IA. As shortwave and low- level jet translate east this morning, expect widespread showers early to be followed by additional showers through midday. Maybe a brief lull after that over parts of the area, but there will already be another sharp H7 shortwave (generating showers and storms over west central IA at current) and resurgent low-level jet taking aim into central WI as early as early to mid afternoon. This should keep at least scattered showers going. As has been highlighted, PWATS nearing 2 inches are well above the 90th percentile and closer to max values for early July. Thus the threat for heavy rain will be across the region all day. With multiple rounds of showers at the worst and patchy drizzle and cloud cover at the best, went lower for high temps today. 70 will be a stretch for any spot in the cwa today and northwoods will have tough time reaching mid 60s. Tonight into Wednesday...Another round of moderate to heavy rain likely as primary shortwave trough edges closer and stronger shortwave within the trough rotates through. Right entrance jet forcing will only enhance lift as warm front approaches. Sfc based instability (and associated severe threat) will be maximized along and south of the warm front and approaching low pressure wave, but sufficient MUCAPE just upstream of our area along with PWATs still around 2 inches suggest moderate to heavy rain showers especially during the evening into the early overnight hours scntral to east-central WI along increasing low- level jet. To the west of the LLJ axis, appears showers shut down quickly after midnight especially after weak cold front/drier air moves through. All areas should be in the process of drying out by daybreak as the boundary shifts east of WI. Most areas will be dry rest of Wednesday, but a few isolated showers out of some high based stratocu may fall across northern WI. Rebound day for temps with readings pushing into the 80s. Soundings and MOS guidance point to it turning breezy from the west (gusts 25-30 mph) midday into the afternoon. 4th of July and Friday...Signals in models and ensemble guidance remain persistent that as shortwave trough digs across the northern Plains and sfc low spins up over the upper mississippi river valley by Friday morning, showers will spread west to east across WI late Thursday afternoon into Thursday night. Heavier rain likely holds off til late Thursday night into Friday, but sufficient forcing ahead of the trough and some elevated MUCAPE justify pops increasing to likely for central WI Thursday evening while there is still a bit of uncertainty on whether the more widespread showers reach the Fox Valley and lakeshore areas by late evening or more so overnight. Looking like widespread showers are in store for Friday (possible heavy rain again) and with sfc low tracking across or south of our area, it likely will be another cooler early July day with highs probably ending up below normal. Sat-Mon...Pattern remains active with multiple shortwave troughs and frontal boundaries dropping across the region. There will be a lot of dry time, but the forecast carries chances of showers throughout. At this time, Sunday looks like the day with better chance of more widespread showers. Temps will be at or slightly below normal. && .AVIATION...for 06Z TAF Issuance Issued at 1024 PM CDT Mon Jul 1 2024 Rain is expected to arrive at the western TAF sites around 07z-08z/Tue and eastern TAF sites 10z-11z/Tue. The steadier/heavier rain is expected to taper off from west to east during the late morning and early afternoon on Tuesday, but patchy drizzle or light showers may continue during the afternoon. Another round of more significant rain is expected to arrive during the late afternoon and evening hours as a short-wave trough and resurgent low-level jet impact the region. There may be a small chance of thunderstorms during the late afternoon and evening, but confidence is not high enough to mention any storms in the TAFs. Flight conditions will deteriorate to MVFR/IFR at RHI/AUW/CWA late tonight into early Tuesday, and to MVFR at GRB/ATW/MTW in the late morning and afternoon. Have continued the mention of LLWS at RHI/AUW/CWA late tonight into Tuesday morning, but current models suggest the threat will remain northwest of GRB/ATW/MTW. SE-S surface winds will prevail through the TAF period, with winds becoming quite gusty during the day on Tuesday. && .GRB WATCHES/WARNINGS/ADVISORIES... Beach Hazards Statement from 7 AM CDT this morning through Wednesday morning for WIZ022-040-050. && $$ DISCUSSION.....JLA AVIATION.......Kieckbusch