457 FXUS63 KGRB 190948 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 448 AM CDT Sun May 19 2019 Forecast discussion for routine morning forecast issuance .SHORT TERM...Today...Tonight...and Monday Issued at 448 AM CDT Sun May 19 2019 Forecast issues include precipitation trends, thunderstorm potential, flooding potential, gusty northeast winds in the Fox Valley, and marine fog trends. MSAS analysis showed low pressure over northeast IA early this morning, with a warm front extending eastward into northern IL. Widespread low stratus covered the GRB forecast area. A deformation band of steady rain was situated across north central and far northeast WI, while another band associated with a short- wave trof was pivoting into east central WI. Web cams and observations near Lake Michigan indicated that marine fog had diminished, so the marine dense fog advisory has been cancelled. The surface low is forecast to track from southwest WI through east-central WI today, with the warm front perhaps reaching our far southeast counties during the early to mid afternoon. The upper deformation zone will remain over the northwest half of the forecast area through the day, so the steadier precipitation and highest precipitation amounts are anticipated there. Farther southeast, the showers will be more periodic. Expect a break for several hours this morning before showers and scattered thunderstorms redevelop with the arrival of a powerful negatively- tilted upper trof during the late morning through mid- afternoon. Have attempted to work these trends into the pop grids, though the actual timing may differ a bit. Still see a small window of opportunity for a marginal severe risk over our far southeast counties in the early to mid afternoon, which will be conditional on the warm sector reaching the area. Gusty northeast winds in the Fox Valley and lakeshore areas should taper off by early afternoon. Highs will be in the 40s and lower 50s, except possibly mid to upper 50s far southeast. Showers will taper off from southwest to northeast tonight. It may get just cold enough for a mix of rain snow over far north central WI, but any accumulations would minimal (a few tenths of an inch or less, and mainly over Vilas county). Lows should range from the middle 30s northwest to the lower 40s southeast. High pressure will bring clearing skies and a dry day on Monday, with high temperatures "warming" into the middle 50s to lower 60s. .LONG TERM...Monday Night Through Saturday Issued at 448 AM CDT Sun May 19 2019 The weather pattern during the period will be dominated by a building 500mb ridge across the southeastern United States with a trough across the western United States, resulting in an active southwest flow pattern across the western Great Lakes. For Monday night, high pressure will move slide east of the area with the next system approaching from the west. On Tuesday, will trend toward the slightly slower Canadian/ECMWF model for the arrival of the rain during the day. A band of rain and a few thunderstorms are expected to move across the area Tuesday night into Wednesday morning. The main band of rain will shift north and east of the area on Wednesday, although some scattered shower activity may still linger across the region Wednesday afternoon. A more active pattern is expected Thursday into next weekend as a a surface boundary lingers across the region. This feature could bring an active period of weather with showers and thunderstorms that could bring locally heavy rainfall. It is way too early to determine the severe potential as well. It is possible that the surface boundary could shift southward during this period of time which could impact the severity of the storms, rainfall amounts and high temperatures. Will have plenty of time to adjust to the model trends. Only minor adjustments made to the max/min temperatures during the period. && .AVIATION...for 06Z TAF Issuance Issued at 1032 PM CDT Sat May 18 2019 IFR/LIFR ceilings continued to be widespread across the area during the evening. Little change in conditions is expected through tomorrow morning as the area will remain north of a strong frontal boundary across southern Wisconsin. It is possible some periods of heavier rain will result in mixing and briefly higher ceilings. A gradual but significant improvement in conditions will begin late tomorrow afternoon as a frontal wave passes through the region, allowing the front to begin to sag to the south. && .HYDROLOGY... Issued at 448 AM CDT Sun May 19 2019 A low pressure system and abundant gulf moisture will bring showers and scattered thunderstorms to the region today. The rain will taper off from southwest to northeast tonight. Additional rainfall amounts of around a half inch are anticipated over central and east-central WI, with 0.75 to 1.25 inches over northern WI. The additional rainfall should cause some rivers to reach bankfull or flood stage next week. Areal flood warnings have been issued for parts of northern Brown county, where water has backed up due to persistent strong northeast winds off the bay of Green Bay. A road closure has been reported near the Suamico River, and there was flooding along the Fox River Trail yesterday evening. The northeast winds are expected to continue through at least midday, and there will be runoff from several periods of rain, so flooding concerns should continue into this afternoon. As winds turn northwest later in the day, water should be able to flow back into the bay. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....Kieckbusch LONG TERM......Eckberg AVIATION.......Skowronski HYDROLOGY......Kieckbusch