Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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480 FXUS63 KGRB 230335 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1035 PM CDT Sun Sep 22 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Gusty north winds and building waves into Monday morning will result in hazardous conditions for small craft. Dangerous swimming conditions are also expected at Lake Michigan beaches, mainly south of Sturgeon Bay. A Small Craft Advisory and Beach Hazard Statement remains in effect. - Patchy to areas of frost are expected to develop across north- central WI early Monday morning and possibly again on Tuesday morning. A Frost Advisory has been issued for portions of northern Wisconsin tonight. - Temperatures closer to normal are expected through the middle of the week before trending well above normal late this week, where high temperatures could run as much as 10 to 15 degrees above normal. && .DISCUSSION... Issued at 354 PM CDT Sun Sep 22 2024 Short Term...Tonight and Monday Main forecast concerns in the short-term are cloud trends through this evening and frost potential overnight. This afternoon`s satellite and radar imagery indicated the cold front that moved through the forecast area earlier today was located in southeastern WI/northeastern IL. In the wake of this front, clouds were slowly departing the forecast area to the southeast with light drizzle observed in east-central WI. Otherwise, skies were mostly sunny in central WI and across the Northwoods. CAA in this area also aided in breezy northerly winds to mix to the surface this afternoon, with gusts up to 25 mph. This evening and tonight...As dry air continues to filter into the area with the arrival of a high pressure system, clouds will clear and winds will become calm. Much cooler air will also spread over the area with lows ranging from the low to middle 30s in north- central WI to the low to middle 40s elsewhere. Given the clear skies, light winds, colder temps, and a low-level temperature inversion, anticipate frost to develop across north-central WI. Decided to issue a Frost Advisory for locations in north-central WI given the favorable elements and probabilities for temperatures less than 37 degrees increased from the previous forecast from up to 50% to up to 75%. Patchy fog may also develop in these areas given it will be a decent radiative cooling night. The Frost Advisory is in effect from 2am to 8am Monday. Monday...Any frost development will end and any fog will burn off as the sun rises. With the high pressure overhead, dry and mostly sunny conditions with light winds are expected for the rest of Monday. The cooler air mass sticks around for Monday, but highs will be near normal with values ranging from the middle 60s to low 70s. Long Term...Monday Night Through Sunday Chilly again on Monday night over the north. Min temps in the middle 30s at typical cold spots. Similar to tonight with light winds and mostly clear skies, could see patchy fog and patchy frost. Only chance of rain for the workweek is on Tuesday as H5 trough shifts across the central Great Lakes. Appears areas from Fox Valley east to the lakeshore and to Door County could see some light showers (chances around 20%) though most rain stays over central Great Lakes. Signal that once that system shifts east Tuesday night, lingering dry air and light winds may lead to another chilly night over northern WI with potential for fog and frost. Rest of the week looks quiet as ridging sfc and aloft builds across the western Great Lakes. Given warming H85 temps and plenty of sunshine expected, high temps may make another run at 80 Thursday and/or Friday. Easterly low-level winds will keep temps cooler near Lake Michigan. By late week, attention will likely be on the Gulf Coast as another tropical system may be impacting that part of the county. What becomes of that system (how far northwest will it drift and how strong will it be by that time) dictate whether any chances of rain materialize here next weekend. Model spread is all over the place though and run-to-run model consistency is poor as well. Will not make many changes to blended grids at this point which feature broadbrushed low-end chances Saturday and Sunday. Highs next weekend will remain at least in the lower 70s, which remains above normal (normal highs for the last full weekend of September are in the low to mid 60s). Beyond the forecast period, the 8-14 day outlook from the Climate Prediction Center is calling for a greater chance of above normal temperatures and a greater chance of below normal precipitation and looking even farther ahead into mid October, the experimental week 3-4 outlook from CPC indicates there really is no change in this overall pattern. Guess that makes sense as looking at past La Nina winters, which is expected this winter, there was a strong signal for the fall to be warmer than normal at Green Bay. && .AVIATION...for 06Z TAF Issuance Issued at 1035 PM CDT Sun Sep 22 2024 Mostly clear skies are expected overnight as high pressure builds in across the western Great Lakes region. Some patchy ground fog may develop across north-central Wisconsin late tonight into early Monday morning, which may lower conditions to MVFR/IFR at times. Any fog will lift Monday morning, with mostly sunny skies and VFR conditions expected Monday into Monday evening. Light winds below 10 knots are expected during the TAF period. && .MARINE... Issued at 354 PM CDT Sun Sep 22 2024 Gusty northerly winds developed behind a cold front this afternoon, leading to hazardous conditions for small craft. Anticipate the northerly winds, with gusts of 25-30 kts, to continue through at least late tonight. The gusts may continue into Monday morning, however, there is some uncertainty of how long the gusty winds will prevail. In addition to the winds, waves up to 3 ft are expected on the bay and up to 6 ft on Lake Michigan, highest south of Sturgeon Bay. For now, kept the same timing of the Small Craft Advisory, which expires Monday morning, but could see it expiring early. Although winds will mainly be out of the north, there will be just enough of an easterly component to bring 3+ waves to the shores of Lake Michigan beaches. This will create dangerous swimming conditions, mainly south of Sturgeon Bay. A Beach Hazards Statement remains in effect. && .GRB WATCHES/WARNINGS/ADVISORIES... Frost Advisory from 2 AM to 8 AM CDT Monday for WIZ005-010>012- 018-019. Beach Hazards Statement until 7 AM CDT Monday for WIZ022. Beach Hazards Statement through Monday afternoon for WIZ040-050. && $$ DISCUSSION.....Kruk/JLA AVIATION.......Kurimski MARINE.........Kruk