Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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501 FXUS63 KGRB 280344 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1044 PM CDT Sat Apr 27 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - There is a good chance for rain Sunday through Monday. Periods of moderate to heavy rain Sunday afternoon into Monday morning, could result in isolated flooding in urban and low lying areas. Rivers will be on the rise through the middle of next week, with a few of them reaching bankfull stage. - Conditions hazardous to small craft are expected this weekend on the Bay and Lake. && .DISCUSSION... Issued at 319 PM CDT Sat Apr 27 2024 Short Term...Tonight and Sunday Gusty southwest winds will continue ahead of an approaching cold front slated to track through the region late this afternoon into early this evening. Despite the passage of this cold front, precipitation chances will remain low for east-central Wisconsin as model soundings show a substantial mid-level capping inversion in place around 750 mb with abundant dry air. Although some showers and thunderstorms could develop in the far southeast corner of the cwa in Manitowoc or Calumet counties, hi-res models keep most of the activity to the southeast or only in these counties for a brief period of time. Therefore, will only keep a small chance for convection late this afternoon and early this evening (20-30 percent) before the cold front tracks through the area. Any convection that can develop will have the potential to be severe given the SBCAPE values of 1000-1400 J/kg and bulk shear values of 40 to 45 knots; however, hodographs show that despite decent veering of direction and speed in the lowest 3 km, there is backing between 3 to 6 km, which would act to inhibit updraft development as dry air gets entrained within the storm. Therefore, confidence in seeing severe weather even across the southeastern portion of the cwa is rather low despite the decent parameters. A low pressure system lifting north towards Iowa on Sunday will bring a swath of rain showers and embedded elevated thunderstorms late tonight from the southwest and spread across the rest of the area during the day on Sunday. Cool northeast winds on Sunday will make for a fairly cool day when combined with the persistent rain showers expected. Long Term...Sunday Night Through Saturday Precipitation...Rain showers and a few embedded thunderstorms will be ongoing at the start of this forecast period for Sunday night as a warm front gradually lifts north across the state, paired with an increasing low-level jet. Although there are timing differences in the placement and timing of the warm front (some guidance delays the front lifting north till Monday morning), there is still decent agreement with the forecast area seeing an increase in rainfall between Sunday night and Monday morning. PWATs during this time will be between 1 and 1.40 inches, leaving the potential for localized heavy rainfall, leading to possible flash flooding, especially in urban areas. A few elevated thunderstorms are possible throughout Sunday night into Monday morning, however, the potential for severe storms looks low given the uncertainty in the timing and placement of the warm front. Precip will decrease in intensity for the remainder of Monday, as the warm front`s surface low tracks northeast across the state. The precip should come to an end Monday evening/night. Surface ridging will build over the area for Tuesday, resulting in dry conditions. A quick-moving shortwave and surface cold front will bring the next chance for precip Tuesday night, and exit by Wednesday afternoon. A few elevated thunderstorms are possible, but given the timing of the precip, the potential for severe storms is low at this time. Details for the remainder of the forecast period are unclear, but there appears to be some agreement with a prolonged period of precip chances to end the week and continue for a portion of the weekend. Temperatures...With a warm front expected to lift over the region on Monday, normal or above normal highs are anticipated ranging from the mid to upper 50s in north-central WI to the mid to upper 60s in east-central WI. The warm air will stick around for Tuesday, allowing all locations to warm above normal with readings ranging from the mid 60s to low 70s. Due to the timing of the cold front occurring Tuesday night, temperatures should be able to rebound quickly enough on Wednesday to remain above normal. With potential for rainfall for the remainder of the extended, temperatures will take a dip back to closer to normal. && .AVIATION...for 06Z TAF Issuance Issued at 1043 PM CDT Sat Apr 27 2024 A low pressure system will move north from the central Plains to Western Great Lakes and bring periods of showers and isolated thunderstorms tonight through Sunday night. Ceilings will become MVFR across most of the area by daybreak Sunday, with IFR ceilings north of a Merrill to Iron Mountain line. IFR ceilings are likely over most of the region Sunday and Sunday night. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Kurimski/Kruk AVIATION.......RDM