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Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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813 FXUS63 KUNR 300712 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 112 AM MDT Sun Jun 30 2024 .KEY MESSAGES... -Moisture and warmer temps return today with slight chances for thunderstorms -Stronger system will bring increased chances for storms Monday, some of which may be severe -Unsettled pattern will bring near daily chances for storms the remainder of the week with temps around normal or slightly below && .DISCUSSION...(Today Through Saturday) Issued at 107 AM MDT Sun Jun 30 2024 Fairly active northern stream will prevail this week with near daily chances for showers and storms as a frontal boundary wavers over the region. Warmest day this week will be today as temps surge into the 90s over the western third (approaching 100 at some locations on the WY plains), much cooler in the east. LLJ with pos theta-e adv may support a few showers/storms this morning across scentral SD where some accas are in place. LL moisture will increase through the day per gusty SE winds with winds approaching adv levels over NW SD. Strong capping inversion will be place today per sfc based convection. However, warm temps and deep mixing will erode the cap in WY where isold TS are expected in the afternoon as a shortwave approaches the region. TS may be able to carry into far western SD this evening, but will likely dissipate given lack of strong forcing and a strong cap in place. Closer to the upper impulse, storms may adv into far NW SD overnight, per outflow of an expected MCS to the north. Sfc cool front will settle into the region Monday morning. However, the next strong impulse will take aim at the region, supporting a trend to LL easterly flow, allowing LL moisture to hold steady across western SD. This impulse will support a good deal of LSA and strong forcing, allowing TS to develop in the afternoon over NE WY and far western SD. Storms should grow upscale into isolated supercells and convective line segments, supporting large hail and damaging winds given bulk shear of 50-60 knots. CAPE will be somewhat limited in western SD topping out AOA 1000 J/kg, however dynamic forcing should make up for the lack of sig CAPE there. Deeper moisture will reside over central SD where storms will likely intensify in the evening. Unsettled flow will persist the remainder of the week with near daily chances for storms as some monsoon moisture and GOMEX moisture interacts with passing impulses and a sfc front wavers over the region. There will be a few drier days mixed in and rain chances will at best be scattered with the stronger impulses. Temps will reside around seasonal norms with highs in the 70s/80s through the period. && .AVIATION...(For the 06Z TAFS Through 06Z Sunday Night) Issued At 1040 PM MDT Sat Jun 29 2024 Gusty southeasterly winds expand from northeastern WY overnight to northwestern SD Sunday. Isolated/scattered showers/thunderstorms will occur east of the Black Hills 09z-18z Sunday and then over northeastern WY/Black Hills Sunday afternoon/early evening. Local MVFR conditions will occur with the strongest storms. Otherwise, VFR conditions will prevail through the period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...JC AVIATION...Helgeson