602 FXUS63 KUNR 160405 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1005 PM MDT Sat Oct 15 2022 .DISCUSSION...(This Evening Through Saturday) Issued at 235 PM MDT Sat Oct 15 2022 Regional satellite imagery this aftn shows a broad area of stratus/altostratus across the nrn Plains, transitioning to stratocu/cu with swd extent. This cloud cover is associated with a E- W oriented midlevel shortwave trof, trailing a broader trof over sern CN/the nern CONUS. Within the stratocu/cu field over nern WY and wrn SD, some showers are producing enough precip to reach the sfc, but dry boundary layers are limiting any precip to sprinkles in most locations. Sfc troughing over the Great Lakes region coupled with ridging east of the Rockies continues to support breezy NW winds this aftn. Competing effects of modest CAA and a downslope wind component have kept temps rather stable today, with mid 60s over far s cntrl SD decreasing to the upper 40s across our far W/NW. As aforementioned midlevel trof digs SE of the area tonight into early tomorrow, low-level CAA will increase, particularly across the ern half of our area. Though thermal trof will be along/east of the Red River Valley by midday/aftn tomorrow, cooler temps should extend far enough west to bring 5-15 F lower highs over the wrn/cntrl SD plains tomorrow. Sfc pressure gradient will also weaken tonight into tomorrow, allowing winds to decrease somewhat. Gradient slacks further tomorrow night into Monday AM, which--coupled with mostly clear skies--should bring a chilly night. Upper-level pattern Monday through Thursday will be dominated by a building ridge over the Rockies/Intermountain West and a deepening trof transitioning to a closed low over the Great Lakes region. This will promote generally northerly flow aloft across the nrn Plains and a low-level thermal ridge expanding nwd and ewd from the Great Basin. A shortwave trof progged to cross the region on Wednesday may bring increased mid- to upper-level cloud cover and breezy winds, but given a relative lack of deep moisture, not anticipating any associated precip at this time. In fact, probs of measurable precip are <10% across all global ensembles for our entire area thru Friday. Other sensible weather impact for our area will be gradually warming temperatures from west to east over the next several days. Fire weather concerns may return late next week as predominant low- to-midlevel flow transitions to westerly/southwesterly and thermal ridging continues to reside over the region. && .AVIATION...(For the 06Z TAFS Through 06Z Sunday Night) Issued At 1003 PM MDT Sat Oct 15 2022 MVFR clouds will trend VFR overnight. Some fog is possible over northeast WY Sunday morning, mainly around the Black Hills. Otherwise, VFR conds expected the rest of the period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION...Sherburn AVIATION...JC