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
548 FXUS63 KUNR 082321 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 521 PM MDT Sat Jun 8 2024 .KEY MESSAGES... - A storm or two could develop over northeastern WY/southwestern SD this evening, with a non-zero chance of becoming severe - There is a marginal risk of severe storms Sunday, especially across northeastern WY - Best chance for severe weather arrives Monday as a stronger wave moves through. && .DISCUSSION...(This Evening Through Saturday) Issued at 205 PM MDT Sat Jun 8 2024 Upper flow over the northern plains is nearly zonal, between a low across Alberta/Saskatchewan and weak ridging over the west coast. Water vapor shows a weak shortwave trough pushing through Idaho. Morning showers have dissipated, and skies are becoming less cloudy. Surface high pressure sits over SD, resulting in fairly light southeasterly winds across the CWA. Temperatures are warming into the 60s and lower 70s. Today`s southeasterly winds over northeastern WY/southwestern SD will result in some weak buoyancy development this afternoon, although the best CAPE will be to our south. As the ID shortwave pushes through WY into NE, thunderstorms are expected to develop. Shear could support a few strong to severe storms, but expecting most of the activity to stay to our south. Lingering moisture and light upslope winds could produce some patchy fog over parts of northeastern WY, the Black Hills, and SW SD late tonight into Sunday morning. Upper ridging will build over the Rockies on Sunday. Slightly stronger southeasterly surface winds will contribute to warmer temps and better buoyancy over northeastern WY and the Black Hills. Another weak shortwave moving over the ridge is expected to approach our area Sunday evening, which could spark another round of storms across northeastern WY. Before then, storms could develop over the Black Hills Sunday afternoon. With 0-6 km shear around 40 kts, strong to severe storms cannot be ruled out. SPC has recently placed northeastern WY in a marginal risk. The Canadian low will push the ridge to our east Sunday night into Monday, and the trough will slide through the northern plains. Ahead of the trough, breezy southerly winds will allow temps to warm to the upper 70s/lower 80s Monday, with dew points near 60, and MLCAPE 1000-1500 J/kg. Shear will be supportive of severe thunderstorms, especially as the surface trough moves through. And with PWATs 175- 200% of normal, heavy rain is expected. Somewhat zonal flow develops after the trough shifts east. Occasional shortwaves and typical June warm/moist conditions will produce storms at times through the end of next week. && .AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening) Issued At 517 PM MDT Sat Jun 8 2024 Areas of patchy fog and MVFR Cigs/vsbys are possible across the Black Hills and southwest SD and sections of NE Wyoming aft 06z through roughly 14z Sunday. The low clouds are expected to linger in the KGCC terminal area through early afternoon before lifting. VFR conds are expected through the valid fcst period for the KRAP terminal location. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Pojorlie AVIATION...Hintz