Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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458 FXUS63 KGRB 100929 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 429 AM CDT Mon Jun 10 2024 Forecast discussion for routine morning forecast issuance .KEY MESSAGES... - Light showers are possible late Tuesday morning and afternoon, especially over northern WI. There is a chance for a few storms late Tuesday afternoon/evening as well, but the severe threat is very low. - A more widespread round/complex of storms will be possible Wednesday night into Thursday, but confidence is low it track. Threat for severe weather needs to be monitored. - Slightly below normal temperatures today and Tuesday with a warm-up expected mid to late week. && .DISCUSSION... Issued at 428 AM CDT Mon Jun 10 2024 Quiet weather on tap today then we enter a fairly active pattern for the rest of the week and possibly into the weekend. Main forecast challenges will be timing best chances for showers/storms, assessing the severe threat, and temps. Uncertainty regarding subtle/mesoscale features will make it hard to pin down details this far out. No changes planned for the Frost Advisory which expires at 7AM this morning. Shower/Storm/Severe Chances & Clouds: There will be lots of sun today as surface high pressure builds across the western Great Lakes. High clouds will increase overnight into early Tuesday, with clouds thickening Tuesday morning as a quick moving shortwave and front approach from the west. These features, along with a ribbon of moisture, will bring a broken area of showers to parts of the area late Tuesday morning and afternoon, highest chances over northern WI. Moisture is pretty meager and forcing is weak, so the rain will be on the light side. Zero instability through at least 5pm, so no thunder is expected during the day. A secondary area of showers and storms will be on the heels of the first one, with a ribbon of instability (500-1000 J/kg) and bulk shear of 25-35 kts pushing east across the state. This pool of instability will be waning late in the afternoon and evening as the isolated/scattered storms arrive, which will keep the the severe threat very low (a little higher to our west where SPC has the marginal risk), but some brief gusty winds are possible as the storms weaken as soundings showing 30-40 kt winds aloft (highest threat across central WI). Another chance for showers and storms arrives late Wednesday into Thursday morning as a fast moving shortwave within the zonal flow crosses the region. Models continue to show/hint at a complex of storms forming in association with this shortwave and weak frontal boundary, somewhere west of the area and spreading E/SE through the region. Still some timing, placement and strength differences, so it will remain difficult to pin down any details. That said, while severe parameters are better to our west, building instability and shear in our area and the possibly of an organized complex of storms making a run at our area, will bring a marginal/slight risk for severe weather. Will not hit the threat too hard just yet in messaging do to the uncertainty, but the threat will be monitored. As the upper flow turns to the southwest this weekend, additional chances for showers and storms look to arrive with a least one main shortwave crossing the region, but still uncertainty on strength/timing this far out. Temps / Humidity: After a chilly start to the day, especially across north-central WI where temps fell into the 30s, nearly full sunshine will allow temps to climb quickly in the morning hours. 925mb temps climb to between 12-16C this afternoon which will support highs topping out in the upper 60s to lower 70s (with the warm spots touching the mid 70s) which is slightly below normal. It will not be as cold tonight with lows dropping into the upper 30s over far northeast WI and into the 40s elsewhere. Could get some patchy frost near the MI border. Slightly warmer temps are expected on Tuesday, but should remain a touch below normal. Return flow sets up across the region on Wednesday as the high departs to our east, allowing temps to climb mid- week. Warmest days of the week will be Wednesday or Thursday with above normal temps expected. Humidity levels will be on the rise mid- week as well, with dewpoints climb into the 60s. Still some question to just how much we warm up as any complex of storms could keep more clouds in the region, along with keeping the front further south. But latest guidance has 925mb temps getting to at least 20C, which should allow highs to get into the upper 70s and lower 80s. Some guidance has 925mb temps closer to 23C which would support highs further into the 80s. Another surge of warmer/hot? air will arrive this weekend, with highs in the 80s likely, with a 90 even possible if the warmer guidance comes to fruition. && .AVIATION...for 06Z TAF Issuance Issued at 1044 PM CDT Sun Jun 9 2024 Lingering clouds should clear out across eastern Wisconsin early in the overnight hours, with mostly clear skies and VFR conditions expected for the rest of the TAF period as high pressure builds in across the western Great Lakes region. && .GRB WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 7 AM CDT this morning for WIZ005-010>012- 018. && $$ DISCUSSION.....Bersch AVIATION.......Kurimski