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
400 FXUS63 KUNR 011505 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 905 AM MDT Wed May 1 2024 .KEY MESSAGES... -Cool/unsettled weather continues through Friday -Warmer this weekend -Strong storm with wet/windy conditions early next week? && .UPDATE... Issued at 859 AM MDT Wed May 1 2024 A band of widespread showers is spreading northward across western SD due to strong jet streak overrunning the low level baroclinic zone, so have raised pops quite a bit for much of western SD. Activity will increase further into the afternoon as inverted surface trof, currently over southeast WY, lifts northeast. && .DISCUSSION...(Today Through Tuesday) Issued at 230 AM MDT Wed May 1 2024 Current surface map places low across northern Minnesota with high pressure across eastern Montana into western South Dakota. Mid/high clouds are spreading across the forecast area. A few radar echoes show up across northern Nebraska. Persistent upper low located across southern Alberta/Saskatchewan spins another vigorous impulse across the area later today/tonight. Shower activity across northern Nebraska spreads northward this morning as better isentropic lift shifts north. Showers/thunderstorms will increase in coverage this afternoon/evening as stronger mid level forcing arrives. A bit of buoyancy/marginal shear will support some stronger updrafts with sub-severe hail/wind threat. Secondary impulse swings through early Thursday with additional showers. Showers linger into Friday with cyclonic flow aloft and steep mid level lapse rates. Thermal profiles support the potential for some snow in the higher elevations of the Black Hills. LREF gives a 30-40% probability of 2" of accumulation through Friday afternoon...mainly for elevations above 5500ft agl. Canadian upper low shifts east this weekend as strong low digs across the western CONUS. Upper ridge builds across the Northern Plains with robust low level warm advection. Highs climb into the 70s Sunday/Monday. 00Z deterministic runs of GFS/ECMWF/GEM are in decent agreement with western CONUS swinging through the Rockies into the eastern Dakotas by Tuesday. That would result in wet and windy conditions across the forecast area. At this time, low confidence in overall forecast details that far out given the spread in ensemble guidance. && .AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning) Issued At 502 AM MDT Wed May 1 2024 VFR conditions expected through the 06z Thursday. MVFR CIGS will develop on the western SD plains after 06z Thursday, especially along/east of K2WX-KICR. Gusty southerly winds will develop this morning and persist through this afternoon on the SD plains with gusts around 30kts. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ UPDATE...Johnson DISCUSSION/KEY MESSAGES...7 AVIATION...Helgeson