Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, 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
45
430 FXUS65 KCYS 010551 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1151 PM MDT Tue Apr 30 2024 .KEY MESSAGES... - Strong winds likely with and behind the front across the Laramie Range Tuesday morning. Gusts up to 60 mph possible. - A series of weather disturbances will move across the forecast area Thursday and Friday, producing a chance of showers and thunderstorms mainly during the afternoons and evenings. - Drier and warmer conditions are anticipated for the weekend. && .UPDATE... Issued at 539 PM MDT Tue Apr 30 2024 Latest surface analysis was showing the surface low continuing to push east across the northern Plains with weakening pressure gradients starting to take place across the forecast area. Wind speeds are still hanging around 50 mph around Bordeaux and Bear Creek, but these wind speeds will continue to diminish fairly quickly after sunset. As a result, we are going to let the High Wind Warnings expire at 6pm. && .SHORT TERM /THROUGH WEDNESDAY NIGHT/... Issued at 232 PM MDT Tue Apr 30 2024 Gusty afternoon winds have reached over 50 knots in several locations across southeast Wyoming as well as even a few isolated gusts over 50 knots in western Nebraska. As surface gradients relax this evening, expect wind speeds to quickly drop back around 0z. After sunset, most locations should be back below 30 mph save for perhaps the elevated wind corridors along the Snowy Range Foothills. Forecast guidance remains in tight agreement showing fast flow aloft with relatively dry soundings in the lowest few km. Will favor a partly to mostly cloudy overnight with seasonably mild temperatures as our next system approaches from the west. On Wednesday, a shortwave trough will dive through the northern Rockies. This will turn flow aloft southwesterly through the day and usher in elevated PWAT values in the form of mid and upper-level moisture from the Pacific. A favorable zone of lift develops over the northern Front Range and southern mountains by around 18z and short-term forecast guidance has consistently depicted a period of moderate snowfall in the Snowy and Sierra Madre ranges on Wednesday afternoon. The period of snow should be fairly brief however, coming to an end around 0z as the energy with this shortwave trough heads east into the high plains. East of the I-25 corridor, surface flow will turn to easterly upslope during the afternoon hours, especially in the Nebraska Panhandle. Although moisture return with this easterly flow looks rather paltry, some CAM guidance does support surface dewpoints near or just above 40 degrees from Sidney to Alliance after 21z. If sufficient low-level moisture can advect northeastward in this return surface flow, there may be just enough instability out there for a few thunderstorms in the Cheyenne County through Morrill County corridor capable of producing some sub-severe hail. Any activity that does develop should quickly move east of the CWA by around 1-2z. Have increased PoPs in the Nebraska Panhandle as well as the probability of thunder to cover this threat. Overall, expect a drying and clearing trend overnight on Wednesday night with temperatures running much colder than on Tuesday night in the wake of the front. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 232 PM MDT Tue Apr 30 2024 Shortwave city in the long term as an active synoptic pattern leads to mostly unsettled weather into next week. Shortwave one of the long term arrives Thursday, bringing with it cooler temperatures. 700 mb temperatures will be on the chilly side, falling below 0C behind the FROPA. This will lead to high temperatures below average for the beginning of May! Highs will be in the 40s west of the Laramie Range and predominately 50s for the eastern plains. Luckily, post-frontal, conditions look relatively dry with minimal chances for precipitation during the day Thursday. Shortwave two arrives Friday, bringing continued cold air and a better chance for precipitation. Similar high temperatures are expected Friday. This shortwave originates over the Pacific, so there will be more moisture associated with it. Some jet energy associated with this system will likely bring widespread light precipitation to the CWA. Temperatures may be cold enough out west to see snow, while the eastern plains should remain rain. Non-zero CAPE values exist across the area so a brief thunderstorm and/or a few rumbles of thunder will be possible. A brief break from the shortwaves arrives just in time for the weekend. A progressive upper-level ridge will move across the Rockies and into the plains over the weekend. As a result, drier and warmer weather is expected. Temperatures will warm on Saturday to near-average, while temperatures on Sunday will further warm to above average! Highs by Sunday could be in the 70s to low 80s in the eastern plains! The warmer and drier weather will be short-lived as another potential system moves in during the beginning of the next work week. However, models diverge on solutions, so will not go into too much detail. But, it does look like it will at least be cooler. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1146 PM MDT Tue Apr 30 2024 Southwest flow aloft will prevail, with a weather disturbance moving across the terminals today producing some showers. Wyoming TAFS...Ceilings will range from 5000 to 10000 feet with showers in the vicinity of Laramie and Cheyenne from 08Z to 02Z. Winds will gust to 25 knots at all terminals after 14Z. Nebraska TAFS...Ceilings will vary from 4000 to 10000 feet with occasional showers this morning through early evening reducing visibilities to 5 miles at times. Winds will gust to 35 knots. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...REC SHORT TERM...MAC LONG TERM...SF AVIATION...RUBIN