Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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598 FXUS63 KGRB 102306 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 606 PM CDT Mon Jun 10 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Chilly again for northern Wisconsin with another frost advisory issued for late tonight into early Tuesday. - Light showers spreading west to east on Tuesday afternoon through Tuesday evening. Rain amounts less than 0.25 inch and minimal chance of thunder. - There is a risk of strong thunderstorms Wednesday night as one or more complexes of storms impact the region, but confidence is low in exact tracks of these complexes. Threat for severe weather needs to be monitored. - Warm up begins Wednesday with well above normal highs late this weekend into early next week. && .DISCUSSION... Issued at 301 PM CDT Mon Jun 10 2024 Sunsplashed day this afternoon with high pressure overhead. This will transition to another quiet and chilly night. High clouds thin and fleeting do increase late but this will not impact temps much. PWAT still well below normal and light winds will result in good radiational cooling. Continued to favor MOS guidance which has another round of low to mid 30s for northern WI toward the Upper Michigan border. Issued another Frost Advisory. Only difference tonight is northern Marinette County is included. Temps elsewhere will bottom out in the low to mid 40s. No big changes to the forecast for Tuesday and Tuesday night. Narrow ribbon of deeper moisture and lift within that higher RH ahead of an cold front and mid-level trough will be efficient in squeezing out some pretty light rainfall as instability over central and eastern WI is less compared to what builds up by late in the day MN/IA to western WI. Initial showers will be ahead of that instability axis but eventually diminishing instability working east could support some rumbles of thunder over much of the area. Showers and any rumbles will end around midnight over east-central WI. Warmer ahead of the front across the board with readings in the low to mid 50s. Wednesday and Wednesday night are in focus for the potential for strong to severe storms. Ahead of this, cold front washes out it is lifts east/northeast of our area. This results in decent surge of warm air aloft working in from the west/southwest. H85 temps by late day are 18-19c over the area which supports highs into the low if not mid 80s. A touch humid too as dewpoints near 60 Fox Valley to the southeast. Late Wednesday heading into this airmass will be strong mid-level jet across the Dakotas with increasing low-level jet aimed into the upper Mississippi River valley. This forcing will be interacting on MLCAPES over 2000J/kg banked from central MN into southwest WI. Decent agreement from models of more sfc based complex of storms developing late afternoon over MN and shifting southeast, mainly staying south of our area. However, there is also a signal that additional storms will develop farther north, closer to the nose of the H5 jet from northern MN into northwest WI and western Upper Michigan. Strong effective shear (50+ kts) and sufficient instability (500-1000J/kg CAPE) that if these storms develop they would swing southeast across much of our forecast area. Main issue by time they reach central, north- central and northeast WI would be strong to damaging winds. SPC has the Day3 slight risk just clipping far west with marginal risk elsewhere. That idea fits the forcing/instability pattern forecasted, but there is still a LOT of uncertainty with the details that result in lower confidence at this point for the Wednesday night forecast. In wake of whatever occurs on Wednesday night, seems the primary axis of instability and what generally will be the effective frontal boundary will be shoved to the south of most of our cwa. Thus, pops have trended down on Thursday/Thursday night which is very reasonable. Other thing to watch Thursday is there is still decent warm air around aloft and stronger winds aloft and really not a lot of low clouds shown in wake of the convection. Thus, could end up being a warm and breezy day. Friday appears quiet with temps a bit cooler (mid to upper 70s) with high pressure briefly settling across. Plan on increasingly unsettled, warmer and humid conditions next weekend into early next week. A warm front lifting across will focus multiple chances of showers and thunderstorms. Temps probably remain only upper 70s/near 80 on Saturday, but by Sunday and Monday will be heading upward with good chance of at least low to mid 80s and even a chance of seeing readings near 90 by early next week. Currently NBM shows just over a 50 percent chance of the high reaching 90 over at least southern half of the area next Monday (upward trend from previous run). However, one thing to note is NBM temp spread is pretty high by then with warmer guidance suggesting lower or even mid 90s while cooler tail of guidance is mainly lower 80s. Plenty of time to sort out the details as we get later into this week. && .AVIATION...for 00Z TAF Issuance Issued at 605 PM CDT Mon Jun 10 2024 Mostly clear skies and VFR conditions will prevail over the TAF sites tonight as high pressure tracks through the western Great Lakes region. A cold front will bring increasing clouds and shift winds to the south-southwest on Tuesday. Showers will then track through the TAF sites Tuesday afternoon from west to east as conditions fall to MVFR and even IFR at times, especially across central and north-central Wisconsin. There will be a small chance for a few thunderstorms, but not high enough to include in the TAFs. && .GRB WATCHES/WARNINGS/ADVISORIES... Frost Advisory from 1 AM to 7 AM CDT Tuesday for WIZ005-010>013- 018. && $$ DISCUSSION.....JLA AVIATION.......Kurimski