


Area Forecast Discussion
Issued by NWS Rapid City, SD
Issued by NWS Rapid City, SD
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
013 FXUS63 KUNR 290519 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1119 PM MDT Sat Jun 28 2025 .KEY MESSAGES... - Isolated to scattered storms (some severe) this afternoon, mainly along and south of I-90. Primary hazards will be damaging wind gusts and large hail. - Thunderstorms continue through tonight into Sunday, with locally heavy rainfall possible - Drier on Monday. Chances for isolated thunderstorms return Tuesday and Wednesday. && .DISCUSSION...(This Evening Through Saturday) Issued at 211 PM MDT Sat Jun 28 2025 Visible satellite imagery shows CU field developing across northeastern WY and along a sfc boundary over the Black Hills. Sfc obs show dewpoints in the 50s to 60s across much of western SD into northeastern WY with drier air over southwestern SD and nosing into the Black Hills. Corridor of 2000+ J/kg CAPE has developed across much of the western SD plains and northeastern WY with mostly clear skies allowing plenty of sfc heating. 18z UNR RAOB does show a modest capping inversion from 850-775 mb which has limited convection thus far. Isolated storms may develop over the Black Hills and higher terrain in WY where terrain driven convergence and upslope flow should be sufficient to overcome the cap. Any updrafts that form this afternoon will encounter 40kt bulk shear which will be sufficient for rotating updrafts. With the relatively fat CAPE profile, dry boundary layer, and modest low to mid level lapse rates of ~7-8 C/km, main concerns with any stronger convection will be large hail and damaging winds. Later tonight, converging outflow boundaries from this afternoons storms may contribute to a predominately linear mode with a damaging wind threat becoming the main concern. Additionally, PWAT values approaching 150-175% of normal will support heavy rainfall with storms tonight. Upper level trough deepens and moves to the east through Sunday with baroclinic zone sagging southward through the area. This frontal boundary could support more convection Sunday afternoon. In terms of severe potential, widespread severe weather isn`t expected with afternoon CAPE values approaching 1000-1500 J/kg, however 30-40kt 0- 6 km shear could support a few stronger updrafts. Ridge builds into the region Sunday night into Monday with large scale subsidence and drier air supporting a warm and dry day Monday. The ridge will also facilitate the return of warmer temperatures to the region through the next week. Northwest flow will set up over the CWA as the ridge remains to our west. This will support chances for at least daily chances for isolated convection from Tuesday through the mid week as weak disturbances move along the upper level flow and low level southerly flow continues to advect warm and moist air into the region. && .AVIATION...(For the 06Z TAFS Through 06Z Sunday Night) Issued At 1119 PM MDT Sat Jun 28 2025 ISO/SCT TSRA and associated localized MVFR/IFR conditions will continue to move from west to east across the area thru the night, but impacts are not expected at TAF sites. Areas of MVFR/IFR in low stratus and SHRA may develop around or after 09z, mainly along northern/northeastern slopes of the Black Hills. Additional rounds of SHRA/TSRA are anticipated thru the remainder of the period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Wong AVIATION...Sherburn