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
44
45
46
587 FXUS63 KUNR 160413 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 1013 PM MDT Sun Sep 15 2024 .KEY MESSAGES... - Very warm through Tuesday with near critical fire weather conditions - Strong thunderstorms with a marginal chance for a few severe storms possible very late this afternoon into the evening - Pattern change mid to late week with cooler weather likely, along with better chances for precip at times, especially Tuesday night && .DISCUSSION...(This Evening Through Sunday) Issued at 1227 PM MDT Sun Sep 15 2024 Water vapor shows upper trof digging on the west coast with ridge amplifying over the Northern Rockies/Northern Plains. Strong short wave is ejecting across western CO. At the surface, weak low is over the Black Hills with boundary extending eastward across western SD. Ejecting short wave will move into the area this evening, with showers/storms developing across far southwest SD by very late this afternoon then spreading north/east through western/central SD this evening/overnight. While there could be a few stronger to severe storms early on, the later arrival along with marginal bulk shear values should limit the overall severe threat. However, precipitable waters will be on the increase into the neighborhood of 150%+ of normal, so efficient rain can be expected with any stronger activity. Precip should end by morning in our eastern zones. Short wave ridge in wake of tonight`s short wave will bring warm and drier conditions for Monday. Gusty southerly winds will develop on the plains east of the Black Hills, especially towards south central SD. High temps will be well into the 80s, with 90s south/east of the Black Hills. Large upper trof will work slowly east across the western CONUS early to mid week. Ejecting upper low will lift through the Central Rockies Tuesday, with strong/broad forcing bringing a band of widespread showers/storms to the area Tuesday night. Models have been very consistent with this scenario for multiple days now, so confident is quite high. Cooler and somewhat drier conditions then expected for the last half of the work week as upper low lifts west and north of the area. Precip chances for very late in the week and weekend are questionable at this time as models are not very consistent with the details of the broad trof as it crosses the Plains. However, confidence is high that much cooler weather will accompany the trof. && .AVIATION...(For the 06Z TAFS Through 06Z Monday Night) Issued At 1011 PM MDT Sun Sep 15 2024 Thunderstorms with local MVFR/IFR conditions will move across NERN WY and WRN SD through about 10z -- from southwest to northeast. Some thunderstorms may produce small hail and gusty winds. Otherwise, VFR conditions will prevail through the TAF period. && .FIRE WEATHER... Issued At 1227 PM MDT Sun Sep 15 2024 Elevated to near critical fire weather conditions expected through at least Monday, especially over northeastern WY and far southwest SD where minimum relative humidities will dip to 10-20%. There is a small chance that southwest winds could mix deep enough to produce some areas of critical conditions over northeast WY and southwest SD Monday afternoon, but the stronger winds should remain east of the Black Hills where RH will be higher. A wetter and cooler pattern will develop mid to late next week. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION/KEY MESSAGES...Johnson AVIATION...Bunkers FIRE WEATHER...Johnson