textproduct: Topeka

KEY MESSAGES

- Red Flag Warning remains in effect until 8pm this evening for counties along the Hwy 81 corridor.

- Dry and warm until Thursday, when the next chance for thunderstorms arrives, including the potential for severe weather.

- Cooler late this week into next week with off and on rain chances.

DISCUSSION

Issued at 239 PM CDT Mon Apr 20 2026

Northwest flow aloft holds this afternoon while the next large upper low can be seen circulating off the Pacific coast via water vapor imagery. At the surface, high pressure dominates much of the eastern CONUS while lee troughing has developed, leaving a tightening pressure gradient over our area. Southerly winds have turned gusty in response and will likely remain breezy into Tuesday, with the pressure gradient relaxing slightly that night. In the meantime, the BL looks to stay fairly well-mixed tonight, which could keep temperatures warmer than forecast overnight into Tuesday morning.

Upper-level ridging continues to favor warm and dry weather into Wednesday, all while the low moves across the western US. The main part of this low looks to eject across the Northern Plains into Thursday, bringing the best lift associated with that feature to the north of this area. Still, it's a large enough system that the base of the trough as well as an associated speed max should help to generate some lift along with a dryline and cold front moving across the region. An early look at instability, shear, and sounding data in the environment just ahead of these boundaries indicates the potential for all severe hazards to be in play IF all the ingredients come together just right. It's still several days out, and cluster analysis shows some differences in the strength of the main upper low, which could impact the timing and placement of the aforementioned surface features. Additionally, guidance is showing cloud cover in the morning and afternoon, so if this prevents the atmosphere from destabilizing as much as currently indicated, this could temper the severe threat as well. All this to say, plenty of uncertainty exists as is typical in this time frame.

A cooler air mass arrives behind the front for Friday, and sticks around into early next week. The large upper low stalls out and may even retrograde in the northern US and southern Canada during the weekend. Embedded perturbations within the flow aloft over us keep precipitation chances around through much of this time period, but shouldn't be a washout as rain does not look continuous.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 536 PM CDT Mon Apr 20 2026

Models continue to show a strong pressure gradient across the terminals tonight with forecast soundings keeping some mixing in the boundary layer. This is forecast to mitigate wind shear potential with sfc gusts through the overnight hours. So will keep wind shear out of the forecast and monitor for the boundary layer decoupling. Otherwise VFR conditions should prevail. The low level mixing should also limit potential for low clouds with the expected increase in dewpoints tonight.

FIRE WEATHER

Issued at 150 AM CDT Mon Apr 20 2026

Winds increase from the south through the day today; expect sustained winds of 10-20 MPH with gusts of 25-30 MPH this afternoon. Given how low relative humidity values were yesterday, have trended dewpoints towards drier guidance which creates relative humidity values of 15- 20 percent across north- central Kansas this afternoon. A lack of green-up for areas along the Highway 81 corridor keeps fuels receptive to rapid fire spread and erratic fire behavior, so have issued a Red Flag Warning for this area from 1-8 PM today.

Increasing moisture Tuesday and Wednesday should keep relative humidity values above 30 percent and limit fire weather concerns, even with gusty south winds.

TOP WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 8 PM CDT this evening for KSZ008-KSZ020- KSZ034.