Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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599 FXUS63 KGRB 150337 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1037 PM CDT Sat Sep 14 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - There is 20% chance of showers or thunderstorms in central and north-central WI Sunday. Severe weather is not expected. - Summer-like temperatures are expected through next week with highs ranging from the upper 70s to middle 80s. && .DISCUSSION... Issued at 302 PM CDT Sat Sep 14 2024 Short Term...Tonight and Sunday Focus in the short-term is on small precip chances and temperatures. Radar imagery at 1930Z showed a broken light of very weak returns stretching from southwest into north-central WI. Some light rain may be reaching the ground in spots, but suspect this is isolated due to the high cloud bases and lack of any rain at ob sites. This precip is being generated by a weak piece of energy which broke off from the remnants of Francine and tracked north, along with a very weak upper jet and RRQ placement. As this energy continues to track north this evening kept low end (15-20%) PoPs in central and north-central Wisconsin through the afternoon and overnight. Cannot rule out isolated thunder within any shower due to MUCAPE ~200-600 J/kg in this region, but confidence in any thunder is decreasing as there has yet to be any detected. Precip changes on Sunday are even lower, but with MUCAPE as high as 1000 J/kg across northern WI, kept low-end precip and thunder chances here through Sunday afternoon. Otherwise, cloud cover will be widespread to start the day, with some thinning throughout the afternoon. Temperatures at 1930Z were in the upper 70s and low 80s, a degree or two cooler than forecast in some spots, but overall guidance had a low mean error. Given there will not be a significant airmass change, will stick close to the best performing guidance for temperatures going forward, which yields lows tonight around 60 degrees, and highs Sunday in the low to mid-80s, a few degrees cooler near Lake Michigan. Long Term...Sunday Night Through Saturday Generally dry weather and well above normal temperatures are expected across the western Great Lakes region through the upcoming week. An upper level ridge across the Great Lakes will keep low pressure systems approaching from the west mainly stalled across the upper Mississippi Valley during the early part of the week and keep our area dry. Meanwhile, an interesting upper level pattern appears to be developing across the region during the middle to late part of the week. A trough of low pressure was already in place well to the west; however, a developing low pressure system off the Carolinas will retrograde westward and deepen as it settles in across the middle Atlantic states. This will set up an Omega pattern across the CONUS with the western Great Lakes firmly in the ridging portion of this pattern to end the week. There are signs this pattern could push off to the east next weekend, which would allow the trough to the west to approach the western Great Lakes and bring rain to the area. That being said, this far out it is difficult to determine when Omega patterns break down or slide off to the east so precipitation next weekend isn`t a given by any means. Regardless of what happens with the pattern it looks like the region is in for continued well above normal temperatures into next weekend. && .AVIATION...for 06Z TAF Issuance Issued at 1036 PM CDT Sat Sep 14 2024 Middle and high clouds will cover most of the area west of a IMT to STE line overnight. There could be a few light rain showers west of MDZ to EGV. Skies will be mostly clear across eastern Wisconsin, which may permit the formation of ground fog just inland from the bay and Lake Michigan. MTW, SUE, OCQ and MNM are airports that could see the fog. It will probably not reach GRB but not certain. Any fog should dissipate by 13z Sunday. VFR conditions are expected Sunday, with middle and high clouds across central and north central Wisconsin and mostly clear skies across the east. Isolated showers or thunderstorms are possible west of a IMT to ISW line. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....KLJ/Kurimski AVIATION.......RDM