Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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704 FXUS63 KGRB 231140 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 640 AM CDT Sun Jun 23 2024 Updated aviation portion for 12Z TAF issuance .KEY MESSAGES... - Scattered thunderstorms are possible this afternoon. A few could produce wind gusts to 40 mph and small hail. - Runoff from recent rains will cause many rivers and streams to rise into the middle of the week. Minor flooding is possible. - Strong to severe thunderstorms capable of producing large hail and damaging winds are possible Monday night and Tuesday, mainly across northern and central WI. && .DISCUSSION... Issued at 352 AM CDT Sun Jun 23 2024 Short Term...Today...Tonight...and Monday Scattered light rain will end early this morning as a weak shortwave exits northeast Wisconsin. Some clearing is expected by midday, as drier air moves in on northwest winds. A stronger upper level disturbance will move through during the afternoon, and produce steeping lapse rates and scattered showers and low top thunderstorms. An inverted V sounding wit colder air aloft suggests that a few storms with gusty winds and small hail are possible. Highs today will be near normal. Any scattered showers will end during the evening hours, with clearing skies overnight. Clear skies and dry air will allow for low temperatures near or a couple degrees cooler than usual. Monday will start out sunny, but middle and high clouds will increase during the afternoon in warm advection ahead of a frontal system approaching from Minnesota. Highs will be a couple degrees above normal. Many rivers and streams will continue to rise today from recent rains. Minor flooding is possible at a few locations. Long Term...Monday Night Through Saturday Chance for strong to potentially severe storms, mainly across northern WI, late Monday night into Tuesday morning is the main focus of the extended forecast. Otherwise, mostly dry conditions through the middle part of the up coming week before the next weather makes arrives toward the end of the week. Monday night through Tuesday...As a low-level jet intensifies Monday nigh the chance for strong thunderstorms will increase in an area of convergence along the noise of the LLJ. A strong cap created by an elevated mixed layer will allow for increasing low- level moisture and elevated instability (MUCAPE over 2000 J/kg).Strong effective layer shear (40-60kts) along the noise of the LLJ should allow for storm organization and sustained updrafts capable of producing large hail. As the night progresses there is the potential for upscale growth that may result in an MCS moving southeast across northeast WI and the UP early Tuesday morning. In this case the threat for severe wind gusts would increase. There are hindrances to the severe threat during this time which are import to note. First the strongest large scale ascent associated with the driving short-wave appears to be well north of the region limiting the forcing available to break the cap. Additionally, will have to monitor how upstream convection earlier in the day over MN effects the low-level storm environment. Should be able to get a better handle on the expected environment over the next day as CAMs come into range. It does look like once the trailing cold front is through the region Tuesday morning the remainder of the day will be dry. Temperatures do look warm on Tuesday with highs forecast to reach the 80s across the region and a few locations in the fox Valley possibly getting into the low 90s. Wednesday through Thursday...A second shortwave propagating across northern Wednesday may create scatter cloud cover, but with forecast soundings showing a robust warm layer in the 800- 700 mb layer went with a dry forecast for Wednesday. A ridge of high pressure is progged to take over the region for Thursday keeping the conditions in place. Temperatures trend near or just slightly below normal each day with highs in the upper 60s to upper 70s. Rest of the extended...Long range ensembles are showing early indications the next chance for widespread moderate to heavy rain may come Friday with a surge warm moist air out ahead of a low pressure system progged to move east across the northern Plains. It`s too early to get a handle on the severe potentially, but this will be a time period to watch, especially if you have outdoor plans next Friday. && .AVIATION...for 12Z TAF Issuance Issued at 639 AM CDT Sun Jun 23 2024 IFR/MVFR ceilings will quickly rise this morning, and clouds should scattered out by afternoon. There could be scattered showers or thunderstorms in the late afternoon or early evening as an upper level disturbance moves across the region. Skies should clear by late evening. Some ground fog is possible a few hours before daybreak Monday morning. VFR conditions are likely Monday, with increasing middle and high clouds in the afternoon. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....RDM/GK AVIATION.......RDM