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
498 FXUS63 KUNR 010455 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1055 PM MDT Sun Jun 30 2024 .KEY MESSAGES... - Chance for isolated storms this afternoon with the possibility of a strong to severe storm or two in northeastern WY. There are elevated fire weather concerns for northeastern Wyoming as well. - Chance for storms on Monday with strong to severe storms possible, especially towards central SD. - Unsettled weather will continue through the week with near daily chances for showers/storms. && .DISCUSSION...(This Evening Through Sunday) Issued at 155 PM MDT Sun Jun 30 2024 Current wv imagery depicts upper ridge over the Rockies/northern plains. A plume of very dry air extends from southern Cal northeastward into Wyoming. The dry air at the low to mid levels is contributing to a strong cap which will inhibit convection this afternoon across much of the area. Despite this dry air, isolated high based storms have managed to develop along the dryline in WY. These storms are currently moving eastward into Campbell County. 30-45kts of effective shear over northeastern WY will lend to a marginal severe threat with these storms. Inverted-V profiles indicate that these storms will be capable of putting out strong wind gusts. With the the deep layer of dry air, it`s questionable if precip will be able to reach the ground. Dry conditions (RHs have dropped to 15 to 30% across portions of northeastern WY), hot temperatures of 80 to 90 degrees, and breezy winds have contributed to some elevated fire weather conditions across northeastern WY. Convection will make its way into far western SD by the evening hours, though strength and coverage will be limited due to the strong cap in place over western SD. The main trough with attendant front will cross the region Monday, bringing chances for storms to the region once more. Strong southerly low level flow will advect ample GOMEX moisture into the northern plains with sfc Tds expected to reach into the mid-50s to upper-60s. Fcst soundings indicate deep layer moisture which will lend to the severe threat as storms won`t struggle as much as they will today. Short term models depict corridor of 1500-2500 J/kg MUCAPE across the eastern half of our CWA, towards central SD. MUCAPE across western SD into northeastern WY will be less but still a decent amount with values of 500-1500 J/kg. 50-60 kt of 0-6km shear will be sufficient for rotating updrafts. Large hail and damaging winds will be the main hazards though there is also a low tornado threat. Upper trough will move east by Tuesday with quasi-zonal and unsettled flow setting up over the region by Wednesday. Temperatures through the mid week will be warm but not overly hot with highs in the 70s to 80s. Disturbances along the flow will contribute to daily chances for showers/storms. Another wave/developing upper low swings through the area Thursday bringing cooler temps and stormy weather for the 4th of July. && .AVIATION...(For the 06Z TAFS Through 06Z Monday Night) Issued At 1055 PM MDT Sun Jun 30 2024 Isolated showers and thunderstorms are again expected Monday afternoon and evening. Gusty, erratic winds, and MVFR conditions can be expected near any stronger storms. Otherwise, VFR conditions will prevail. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Wong AVIATION...13