Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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162 FXUS63 KTOP 052051 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 251 PM CST Fri Dec 5 2025 .KEY MESSAGES... - Fog possible overnight into the morning, although confidence is low on how much of it or exactly where. - Temperatures go up and down through the next week: seasonal through Saturday, cooler Sunday, then warming back up into mid-week. - Low chance for a brief rain shower in northern KS Saturday afternoon, otherwise looking dry through the next week. && .DISCUSSION... Issued at 250 PM CST Fri Dec 5 2025 Water vapor imagery continues to show broad mid-level troughing across most of the CONUS with moisture streaming along the Gulf states into the southern Atlantic states, all just south of the upper jet. Within the broad troughing pattern, a couple of shortwaves are noted: one moving through the Central Plains and another in central Canada. The combination of these has led to a weak sfc troughing pattern across the state as we sit in between the sfc lows that have developed in response to these shortwaves. Another shortwave aloft is noted near the Pacific Northwest, and this will set the stage for Saturday`s weather. In the meantime, our only impact from the wave near us is high cloud cover, which will slowly push south into tonight. The clearing skies plus light winds from the weak sfc pattern may result in enough radiational cooling for fog to develop overnight into early Saturday morning. That said, there is a wide range in the guidance as a few models suggest widespread fog development while others produce little to no fog. The higher resolution models are on the warmer side of temperature guidance for Saturday morning, so that could be the reason for the discrepancy. Forecast soundings seem to suggest shallow fog as we get closer to sunrise. So will need to monitor this potential as well as how widespread or dense it might get. The rest of Saturday sees the Pacific shortwave strengthening a bit as it moves through the northwest flow across the Missouri River Valley. There is still some variation in how far south the sfc low will track even with CAM guidance, as some solutions bring it as far south as the KS/NE border while others keep it north into Nebraska. Overall the best PVA is north of the area with most precip north of the sfc low, but there does look to be enough isentropic lift ahead of the sfc cold front to produce some light precip in northern KS Saturday afternoon. CAMs support this as well with some light reflectivity shown mainly north of I-70. Forecast soundings show only a brief time window (1-2 hours) where precip could reach the ground. Temperatures are warm enough to support rain, and forcing for ascent weakens by the time colder air arrives. So have added slight chance PoPs north of I-70 to account for the possibility of a brief rain shower. Colder air advects into the area behind the front, bringing temperatures back down for Sunday as highs reach the mid 20s to mid 30s. From there, northwest flow aloft remains persistent into the middle of next week with the track of additional systems currently favored to keep precip northeast of the area. The low-level winds take on a downsloping component by Tuesday, favoring a warm-up with highs reaching the 50s. Confidence decreases in the temperature forecast by the end of the week as models diverge on the evolution of the upper trough to the east as well as embedded waves within the flow aloft. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1133 AM CST Fri Dec 5 2025 VFR conditions are forecast with wind changes being the main driver of this forecast, although there is some uncertainty with fog potential overnight into early Saturday morning. Would like to see more consistency among models before inserting fog mention in TAFs, so have left it out for now, but later shifts may want to consider adding if confidence grows. Otherwise, winds around 5-10 kts will persist this afternoon from the WSW to west, then become light and variable overnight. They should pick up from the SSE late in the period. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Picha AVIATION...Picha