Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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415 FXUS63 KGRB 162021 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 321 PM CDT Tue Jul 16 2024 Forecast discussion for routine afternoon forecast issuance .KEY MESSAGES... - Below normal temperatures expected tonight through Wednesday night, then temperatures return closer to normal by the weekend. - Mainly dry weather is expected through Saturday morning. The next chance of showers and storms is on Saturday afternoon, and then again early next week. The risk of severe weather is low over the weekend, and uncertain next Monday and Tuesday. && .DISCUSSION... Issued at 320 PM CDT Tue Jul 16 2024 Short Term...Tonight and Wednesday Minimal impacts are anticipated through this forecast period with only slight chances for precip and below normal temperatures. This evening and tonight...This afternoon`s water vapor imagery indicated a vort max/shortwave dropping south into northern WI, which has triggered isolated showers to develop across the Northwoods. Meanwhile, the rest of the forecast area saw dry conditions under an agitated cu field. The isolated showers will continue to drop south with the vort max/shortwave and gradually dissipate by early this evening with a loss of daytime heating. Cannot rule out the low chance (10-15%) for some rumbles of thunder given a couple hundred J/kg of CAPE around. Clearing is expected for the first part of the night following these precip chances before the main trough begins to move overhead and bring the return of clouds. In addition to the clouds, a few showers may also develop. Overnight lows will be slightly below normal with values mainly in the 50s. Wednesday...With the trough gradually shifting eastward into Wednesday morning, low-level winds will turn north/northwest and combine with delta Ts around 13C to generate lake-enhanced rain showers across far northern WI throughout the day. Isolated showers may also develop in far eastern WI as the trough exits during the afternoon. This pattern will bring cooler temperatures to the region with highs about 5 to 15 degrees below normal, ranging from the middle 60s to middle 70s. Long Term...Wednesday Night Through Tuesday 500mb ridge across the Rockies with downstream troughing across the western Great Lakes will bring cooler than normal temperatures Wednesday night into Thursday. The 500mb ridge will shift westward and while the upper trough shifts eastward leaving the area with a weak trough on Saturday which shifts southward on Sunday. Below normal temperatures are expected Wednesday night with lows in the 40s to lower 50s. Readings could be close to 40 at a few of the colder spots like Land O` Lakes and Tomahawk. Temperatures will rebound back into the 70s on Thursday. Another cool night is in store Thursday night, but should be a few degrees warmer than the previous night. Dry conditions will prevail Friday through Saturday morning. The first chance of showers and thunderstorms will arrive Saturday afternoon as a weak frontal boundary sinks southward across the area. The risk of severe weather is low. Any lingering showers or storms should end early Saturday evening. Dry conditions will then prevail late Saturday evening through Sunday morning. Another a small chance of instability showers and storms are expected Sunday afternoon. For Monday and Tuesday, the models are in fairly good agreement for diurnally driven chances of showers and thunderstorms with the highest chances during the afternoon and evening. It is too early to determine if any of these storms would become severe. Temperatures over the weekend will be fairly close to normal. Normal high/low temperatures are at the peak for the year and will start the slow decline by the end of the month. && .AVIATION...for 18Z TAF Issuance Issued at 1258 PM CDT Tue Jul 16 2024 VFR conditions are expected in most places through at least Wednesday night. There will be Cumulus clouds with bases between 4000 ft and 7000 ft this afternoon and early evening, along with isolated showers. These clouds should dissipate late this evening. Cool air flowing across Lake Superior could produce lake effect clouds across northcentral Wisconsin late tonight through Wednesday morning, mainly north of a RRL to IMT line. These clouds will likely have bases between 2500 and 3500 ft, lowest near the Michigan border. VFR ceilings are expected Wednesday, but those clouds should dissipate Wednesday evening, with clear skies Wednesday night. .OSH...VFR conditions are expected for the next few days. Cumulus clouds with bases between 4500 and 8000 feet are likely this afternoon. They should dissipate this evening, with clear skies overnight through Wednesday morning. Scattered to broken Stratocumulus clouds are expected Wednesday afternoon with bases above 4000 feet. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Kruk/Eckberg AVIATION.......RDM