Area Forecast Discussion

KEY MESSAGES

-Red Flag Warning has been issued for east central and far northeastern South Dakota as well as west central Minnesota due to gusty winds (up to 30-40 mph) and low relative humidity values. Fire weather concerns continue Wednesday as well.

- Rain chances return Wednesday night into Thursday, with a 40-75% chance along and after a cold front moves through.

- Strong sustained west-northwest winds 25 to 40 mph with gusts up to 50 mph are expected on Thursday.

DISCUSSION

Issued at 208 AM CDT Mon Apr 20 2026

A high pressure is moving east out of eastern SD this morning as another area of surface high pressure starts to develop in Canada. The south/southwesterly winds between these two highs will pick up early this morning over central SD and move east during the morning over north central SD and west central MN. These winds are forecast to gust up to 30-40mph. The winds taper off over central SD before noon and decrease during the afternoon over northeastern SD.

The southerly/southwesterly winds will be bringing warm, dry air into the area, which will lead to increased fire weather concerns today. Minimum relative humidity values are forecast to get below 25% over most of central and northeastern SD, with south central SD seeing values below 20%. A Red Flag Warning has been issued for parts of east central and far northeastern SD and west central MN as the lower RH values and stronger winds are forecast to overlap. If a fire were to ignite in these areas, it could become difficult to control or suppress. While areas to the west will see the lower RH values, these values will occur after the stronger winds move through. While these areas west of the James River will not meet Red Flag Warning criteria, there will still be some fire weather concerns due to the lower RH values.

Temperatures will warm today and Tuesday to be 10-20 degrees warmer than normal, into the mid 60s to low 80s, with the warmest temperatures over south central SD. The continuous warm air moving into central and northeastern SD will add up though the beginning of the week and cause temperatures to be 25-30 degrees warmer than normal Wednesday, getting up into the 90s for some areas. The dry air and occasional high pressure moving over the state will help to keep precipitation out of SD and mostly sunny skies around through the middle of the week. Wednesday continues to show some signs for fire weather concerns due to the warm and dry conditions and stronger winds (gusts of 30-40 mph) forecasted during the afternoon.

A surface low pressure starts developing to the northwest Tuesday night into Wednesday. This low and a cold front attached to it look to move east Wednesday night into Thursday. Rain is forecast to develop along the front as it passes through the area Wednesday night through Thursday (40-75 percent chance), with a chance for some thunderstorm development as well. The front will push cold air into central and northeastern SD, dropping temperatures below normal during the end of the work week into the weekend. This CAA will help the stronger winds aloft get down to the surface Wednesday afternoon through Friday, with the strongest winds forecast to occur Thursday. There is a 30-70% chance for winds to gust over 45 mph (wind advisory criteria) Thursday afternoon, with the highest chances over areas west of the Missouri River.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1235 AM CDT Mon Apr 20 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast to prevail through the TAF period. A period of low-level wind shear (LLWS) is expected across central SD early this morning, affecting KPIR/KMBG and inserted mention of this into the TAFs.

ABR WATCHES / WARNINGS / ADVISORIES

SD...Red Flag Warning from 11 AM this morning to 8 PM CDT this evening for SDZ008-019>023. MN...Red Flag Warning from 11 AM this morning to 8 PM CDT this evening for MNZ039-046.