325 FXUS63 KDMX 182326 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 626 PM CDT Fri Sep 18 2020 ...Updated for 00z Aviation... .DISCUSSION.../Tonight through Friday/ Issued at 247 PM CDT Fri Sep 18 2020 General Summary... A quiet, generally comfortable forecast is on tap. Cool conditions will prevail today, slowly giving way to warmer temperatures through the weekend and early next week, back into the low to mid 80s. Breezy southerly winds will prevail over the weekend, especially Sunday when gusts could push 30 to 35+ mph over portions of wester/northwest Iowa. Precipitation chances will be very hard to come by as well, with only very low end chances in the forecast over far northern Iowa into Minnesota Sunday and Wednesday nights. Smoke from western wild fires also likely to linger overhead form now through early to middle of next week. A Bit More Detail... The seven day forecast is devoid of major concerns with regards to temperatures, winds, and precipitation. Instead, there are a few lower-end areas of concern. To begin with, upper level pattern across the western and central CONUS will continue to be conducive for smoke advection across the area. Currently, a closed upper low just entering the western Oregon coast will continue southerly mid and upper level flow over the main fire region, allowing smoke to ride overtop the ridge and down the northwest flow into the upper Mississippi Valley region. HRRR Smoke has shown a consistent trend for higher concentrations of smoke to pass overhead this weekend, resulting in continued and increased filtering of sunlight. Fortunately, the smoke should remain aloft, limiting any surface/near-surface issues. Synoptic guidance suggests relief from smoke aloft may not come until mid-late week when the upper level flow may keep some smoke west, but with fires ongoing in Oregon and Washington as well, we may be hard pressed to see truly clear skies. Main consequences revolve around reduced insolation and potential affects on temperatures including cooler highs, possibly slightly warmer lows. Have adjusted Saturday a degree or two in accordance with that line of thought. Away from smoke, the aforementioned upper level low entering the PNW will force amplified ridging in to the Plains, resulting in warming temperatures into the weekend and new work week. While smoke may temper highs a bit, high confidence in low to mid 80s returning as early as Sunday in western forecast areas and area wide during the early portions of the week. As this transition occurs, current surface high will slide off and surface low will build into the central and northern Rockies front range areas causing surface pressure gradient and winds to increase. Winds over the weekend may yield sustained 20+ mph and gusts pushing 35+ over the area, especially across the west on Sunday. As the parent upper level system slides across southern/central Canada late in the weekend, very low end precipitation chances may be seen in far northern Iowa along a weakening boundary. The trend in reducing POPs has continued and for the time being the Sunday night period is now dry. Broad upper level ridging/zonal flow will dominate early-mid week, keeping the region dry and pleasant. Flagship synoptic guidance remains in fair agreement on a shortwave trough moving through in the Wednesday evening/overnight time frame, bringing with it another chance for a few showers and a slight cool down. With the surface low anticipated to be along/near the Canadian border, the frontal passage, along with large surface dew point depressions, appears to be hard pressed to provide enough of a kick for much precipitation potential with best chances as you move northward into Minnesota. At this point cannot rule out an elevated shower or two though. Main discernible change more likely to be a brief one day switch from southerly winds to northerly winds and nominal few degree cool down. && .AVIATION.../For the 00Z TAFS through 00Z Saturday evening/ Issued at 626 PM CDT Fri Sep 18 2020 VFR conditions will persist through the TAF period. Winds will become southerly on Saturday and increase, gusting over 20 kts mainly over the western half of the state. Upper-level smoke will increase across portions of the state again on Saturday. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Curtis AVIATION...Hagenhoff