


Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
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049 FXUS63 KUNR 152009 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 209 PM MDT Sun Jun 15 2025 .KEY MESSAGES... -Daily chances for thunderstorms, some possibly severe, through Tuesday. -Wet and cooler mid-week -Mostly dry and much warmer weather for the second half of the week && .DISCUSSION...(This Evening Through Sunday) Issued at 122 PM MDT Sun Jun 15 2025 .Severe Risk Today... Satellite and water vapor analysis shows the main forcing continuing to move westward through central Montana. The most active area for convective activity has been to our southwest across the higher terrain over eastern Wyoming along the heating differential boundary. Across the Black Hills we had some agitated CU (Cumulus) develop this afternoon but this turned into failed initiation as the main updraft tower encountered some stronger shear and got sheared apart with only the orphan anvil remaining. In the wake the CU field along the Black Hills looks meager at best. We could continue to see the CU field expand but it looks like our show will be dependent on the arrival of the upper level forcing as it approaches northeastern Wyoming. Atmospheric parameters again show large instability but as evident with yesterdays limited convective activity, this afternoon`s sounding continues to show a drier boundary layer, which should limit convective activity prior to the upper level forcing progged to be over our area by the early evening. CAM models continue to show two small liner/bowing segments one skirting across the South Dakota/Nebraska border while the other and stronger of the two, pushes out of southeastern Montana and scrapes across the South Dakota/North Dakota border. These segments will pose a damaging wind threat as these clusters move east through the overnight hours. Severe weather remains a threat on Monday as a cold front pushes through the region. Timing of this front will shift where the greatest magnitude threat as the prefrontal environment will continue to yield ~3000 J/kg of CAPE and have an environment for severe storms. Environment post-frontal may still yield ~1500 J/kg of CAPE but high 0-6km shear may again shred weaker convection that tries develop during the afternoon hours. The severe threat in the post-frontal sector will occur when main shortwave trough approaches eastern Wyoming. This aforementioned trough continues to progress through our region on Tuesday which will lead to scattered to widespread showers and thunderstorms across much of western South Dakota along with some cooler temperatures. By mid-week increasing heights return as a ridge axis moves into the Intermountain West which should bring drier conditions and warm to hot temperatures to the region. && .AVIATION...(For the 18Z TAFS Through 18Z Monday) Issued At 1113 AM MDT Sun Jun 15 2025 Low clouds and fog continue to dissipate across NW SD, with MVFR/IFR conditions transitioning to VFR after 18z. Otherwise VFR conditions are generally expected through the forecast period. The next round of strong thunderstorms will develop this afternoon across NE WY and spread north/east across western SD this evening. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Woodward AVIATION...SE