Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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
557 FXUS65 KRIW 301901 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 101 PM MDT Thu May 30 2024 .KEY MESSAGES... - Daytime high temperatures 5-10F above normal Saturday through Monday initiate another period of active snow melt in the mountains. Foothill creeks and streams will see daily diurnal water rises. - Breezy west to southwest wind on Monday and Tuesday could heighten rangeland fire conditions over central and southern Wyoming. - Ensemble forecasts are in agreement with a ridge of high pressure developing over the western United States by the middle of next week. Temperatures will be well-above normal. && .DISCUSSION... Issued at 101 PM MDT Thu May 30 2024 Mid-level moisture within cyclonic flow draped over the northern half of the forecast area has allowed for isolated showers and cloud cover over the northern mountains today. Otherwise, plenty of sunshine and more seasonable temperatures across the the remainder of the forecast area Thursday afternoon. The cyclonic flow persists across the north overnight enabling a few showers to linger over the northern mountains into Friday morning. The parent trough over the Canadian Prairie Provinces lifts northeast by midday Friday. This leaves the forecast area with a mostly clear sky Friday afternoon and night. There will be a breezy west wind across southern Wyoming, but nothing out of the ordinary. Temperatures warm to at or just above seasonal normals regionwide. Zonal flow is found across the region through the weekend. Temperatures will be running 5-10F above normal both days, which allows for a period of active mountain snowmelt. Much of the snowpack is now confined to elevations above 9K feet. Foothill creeks and streams will see daily diurnal rises, but available channel capacity and the fact this will be higher elevation melt should limit flooding concerns. The exceptions would be the Salt and Snake drainages where lower snow has yet to melt, and those drainages fed by the northern Bighorn Mountains. Mid-level moisture sneaks into southwest Wyoming Saturday and ignites isolated afternoon and early evening showers and storms in that region. A better plume of mid-level moisture arrives from the west Saturday night and Sunday, leading to better coverage over the northwest-quarter of the state during that time period. A deepening trough off the Pacific Northwest coast generates southwest flow aloft Monday leading to even warmer temperatures. The above normal temperatures combined with a breezy southwest wind and a drier airmass elevates rangeland fire weather concerns Monday. However, many areas are still in greenup. The flow flattens Tuesday as shortwave energy rolls through the Northern Rockies with little noticeable impacts to sensible weather. It may be a bit breezier Tuesday as the pressure gradient tightens. Attention then turns to a building ridge across the western United States. Much above normal temperatures in the 80s and even lower 90s look increasingly likely. Current projections have daily highs the latter half of next week falling short of record highs that run in the lower to mid 90s. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1126 AM MDT Thu May 30 2024 VFR conditions will prevail through the period at all terminals. Skies will remain mostly clear across the region through the period as well, with only FEW to SCT high clouds. Breezy west-northwest winds will develop early in the period at most terminals. Gusts 20 to 25kts will be common through the afternoon. Winds then decrease to light and variable drainage flows toward sunset and light and variable winds will prevail through much of the rest of the period. A weak boundary will bring mid-level cigs into KCOD and KWRL this afternoon. A few isolated rain showers may be possible with this boundary at these terminals (20% chance at KCOD and 10% chance at KWRL), but due to low confidence in these showers, have left mentions out of the TAFs. The BKN mid-level decks will likely (80% chance) persist through much of the rest of the period for the aforementioned terminals. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...CNJ AVIATION...Hensley