RED FLAG WARNING FOR MUCH OF THE WESTERN SD PLAINS THROUGH TUESDAY EVENING. . RED FLAG WARNING FOR MUCH OF THE NORTHEASTERN WY PLAINS THROUGH THIS EVENING. .Critical fire weather conditions are expected today through tomorrow for much of the area. Today, critical fire weather conditions are ongoing over portions of northeastern Wyoming and much of western South Dakota. Temperatures in the 90s, relative humidity values in the single digits to lower teens, and sustained south to southwest winds of 15 to 25 mph with gusts as high as 35 mph have been observed over the last few hours. This includes portions of the northeastern Wyoming plains not previously in a Red Flag Warning. Winds are still expected to decrease in some of these locations this afternoon, particularly western Crook County; however, critical fire weather conditions will likely continue in the near term, especially in the vicinity of any virga or showers that may lead to locally enhanced wind gusts. Tonight, winds will decrease from west to east, with winds expected to fall below criteria across northeastern Wyoming. Over western and central South Dakota, a developing low-level jet should allow breezy and gusty winds to continue, along with limiting relative humidity recovery. Although critical fire weather conditions may briefly subside, very dry and gusty conditions should persist, particularly from southwestern to south central South Dakota. As such, the Red Flag Warning for western South Dakota continues through tomorrow evening. The National Weather Service in Rapid City has issued a Red Flag Warning for gusty winds and low relative humidity, which is in effect until 8 PM MDT this evening. * AFFECTED AREA. Fire Weather Zones 315 Southern Campbell, 316 Crook County Plains and 317 Weston County Plains. * WINDS. West to southwest 10 to 20 mph with gusts to 30 mph. * RELATIVE HUMIDITY. As low as 9 percent. * IMPACTS. The combination of gusty winds and low relative humidity will produce critical fire weather conditions.