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
543 FXUS65 KRIW 292303 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 503 PM MDT Wed May 29 2024 .KEY MESSAGES... - Scattered thunderstorms are capable of producing 35-45kt outflow wind gusts through early Wednesday evening. The best chance for these winds will be east of a line from Cody to Ft. Washakie to Green River, with the main threat until 5 PM Wednesday. - Showers and storms end late Wednesday evening over central Wyoming. A push of cooler, moist air brings low clouds to Natrona County between 2 AM and 8 AM Thursday. - High temperatures ranging from 5-10F above normal are in store Saturday through Monday. Breezy southwest wind Saturday and again Monday could heighten rangeland fire conditions on those two days. && .DISCUSSION... Issued at 220 PM MDT Wed May 29 2024 Satellite imagery clearly shows shortwave energy tracking east through central Idaho early Wednesday afternoon. Following passage of a weak morning shortwave, clearing skies allowed for destabilization across central and southwest Wyoming. Scattered showers and thunderstorms have erupted within this airmass of negative lifted indices and lapse rates of 8-9C/km. These showers and storms track east through 5 PM with most of the strong convection confined to Johnson and Natrona Counties between 5 PM and sunset. Temperature-dew point spreads indicate the potential for 35-45kt gusts across the central and southwest. The chance for small hail is better over the north where dew points are a bit higher. Convection begins to fade from west-to-east during the evening, and most should come to an end by 9 PM. Wrap-around moisture on the backside of the shortwave in combination with 80kt jet-level winds should aid lingering isolated showers over the far north much of the night. Northeasterly moist upslope along the I-25 corridor generates low clouds late tonight and Thursday morning in that region. Otherwise, the overnight trend will be toward decreasing clouds. Cyclonic west-northwest flow aloft keeps an isolated chance (10-20 percent) of showers over the north Thursday; however, for the most part Thursday is dry with a breezy westerly wind. The passage of the shortwave leads to cooler temperatures in the upper 50s and 60s Thursday, with the far north and far west valleys seeing the coolest temperatures. Temperatures rebound Friday as the trough and cyclonic flow move east away from the state. A dry day is in store Friday, and breezy westerly wind prevails across southwest Wyoming. Saturday and beyond will be largely characterized by zonal flow, and shortwave ridges and troughs progressing across the region. Saturday finds warmer temperatures and breezy conditions in southwest flow aloft. This may lead to elevated fire weather conditions across southwest and central Wyoming. Early indications are that a shortwave trough tracks through Montana Sunday and provides a better chance of convection, particularly across the north. Next week dawns with above normal temperatures persisting. A deepening trough off the Pacific Northwest Coast may pump warmer southwest flow aloft into the forecast area Monday. Current temperature projections indicate widespread 80s for Monday highs. These temperatures in combination with a dry southwest wind could again lead to elevated rangeland fire conditions. Any shower chances early next week would largely be confined to far west and northern Wyoming. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 500 PM MDT Wed May 29 2024 Shower and thunderstorms, which are associated with the weak shortwave trough passing through the area this evening, will continue to shift east. KWRL and KCPR are the only remaining terminals with >10% of thunderstorms. After 06Z, showers and thunderstorms are no longer expected, with VFR prevailing at all terminals. East of the Divide terminals will see a light northerly wind push behind the showers and thunderstorms overnight, which will decrease and become light by around 06Z. Winds generally become light and variable overnight for most other terminals. Models are hinting at low clouds as a result of moist, weak northerly surface flow at KCPR overnight. Have left VFR for now, but there is a 50% chance of MVFR cigs and a 30% chance of IFR cigs developing between 06Z and 09Z at KCPR. These cigs will scatter out Thursday morning, between 13Z and 16Z. By late morning to early afternoon, winds become predominantly westerly, and will increase through the afternoon. Gusts will generally be less than 30kts, but favored locations may see gusts of 25 to 35kts for a portion of the late afternoon. 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