413 FXUS65 KCYS 161104 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 504 AM MDT Thu May 16 2024 .KEY MESSAGES... - Warm & dry conditions prevail through Saturday. Daytime highs on Friday may reach the lower to middle 80s for areas along and east of I-25. - Windy on Friday as a strong disturbance tracks across the northern high plains. Wind gusts 45-55 MPH are expected for Arlington and Bordeaux. A couple brief gusts in excess of 60 MPH cannot be ruled out. && .SHORT TERM /THROUGH SATURDAY/... Issued at 410 AM MDT Thu May 16 2024 A generally quiet forecast period ahead for southeast WY and the western NE Panhandle as split upper-level flow prevails w/ short wave energy remaining well to the north and south of the CWA. As a result, any chances for precipitation are likely to remain low to almost nil through Saturday. 700-mb temperatures are expected to climb to +6 to +8 deg C across the CWA today, and continue to rise to +10 to +12 deg C by 00z Saturday. As such, expect to see a substantial warming trend over the next couple of days w/ high temperatures likely reaching the lower 80s over areas along/east of I-25 on Friday afternoon. Strong winds are possible from late Thursday night through Saturday morning across the southeast Wyo wind corridors as height falls spread across the western Dakotas ahead of a vigorous mid-level short wave, resulting in 850 & 700 mb CAG-CPR gradients of 45 to 55 meters. Modest 700-800 hpa flow only peaking around 45 knots should preclude any widespread wind gusts over 60 MPH, but in-house RF models do suggest appreciable probabilities of 45+ MPH wind gusts at both ARL and BRX. At this time, do not anticipate the need for wind headlines. However, we will need to pay close attention to model trends during the next few cycles as a marginal warning-level wind event is certainly a possibility. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Issued at 410 AM MDT Thu May 16 2024 A longwave, upper-level trough will begin to develop over the Pacific Northwest on Saturday evening into Sunday. Several 500mb vorticity maxima will eject out ahead of the incoming trough, promoting scattered shower potential across southeast Wyoming and western Nebraska. Widespread precipitation does not look likely at this time for the end of the weekend. By Monday, the upper-level trough will be over Idaho, with two separate jet branches overhead. The northern jet branch will stretch from southwest Wyoming to the northeast towards southwest North Dakota, while the southern branch will stretch from Baja California northeast through western Nebraska. The positioning of these two jets will support synoptic life across the region Monday ahead of the advancing cold front. 700mb temperatures will drop from the 6-9C range to the -1 to 3C range leading to temperatures on Monday dropping approximately 10 to 15F. With the rather strong cold front, showers and likely thunderstorms will develop out ahead of the front, leading to area wide PoPs in the 40-60% range. At this time, CAPE values do not look to be impressive at all, so while some thunderstorms may develop they will likely not be long lived or overly strong. However, winds will be rather gusty behind the cold front, though should remain below high wind criteria. The upper-level trough will continue to push across the region Tuesday into early Wednesday morning before a brief ridge develops over the western CONUS. On Tuesday, PoPs will remain across the region as the residual forcing associated with the upper-level trough continues to push out of the region. 700mb temperatures will remain cool, in the -2 to 3C range, leading to another cooler day on Tuesday. Highs in the upper-50s to mid-60s are likely for Tuesday. Once the upper-level trough clears the region and the shortwave ridge moves overhead for Wednesday, temperatures warm once more. Warm air advection will be present at 700mb as the ridge moves towards the region, favoring lift across the region for Wednesday. The GFS is much quicker will the development and progression of the ridge, while the ECMWF does not show ridging until Thursday and instead favors zonal flow. Given some of the disagreement, but both models showing WAA at 700mb, kept PoPs around 20-30% across the region. Temperatures will increase with this WAA into the mid-60s to mid-70s for Wednesday. Thursday morning, the next upper-level trough is progged to continue its progression from the Pacific Northwest. The GFS and ECMWF are in relatively good agreement on the development of this trough and its movement across the CONUS, but the ECMWF suggests a more negatively tilted trough while the GFS keeps the trough neutral. Ahead of the incoming trough, 700mb temperatures on Thursday surge into the 6-8C range, favoring surface temperatures in the mid-60s and mid- to upper-70s across the region. As the trough pushes towards the region, several 500mb vorticity maxima will eject out ahead and favor precipitation chances again Thursday afternoon into the evening. Kept PoPs in the 20-30% range at this time. Cold air advection at 700mb late in the day Thursday will favor cooler temperatures once more for Friday. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 503 AM MDT Thu May 16 2024 A pleasant day in store for southeast Wyoming and western Nebraska. Partly cloudy skies expected throughout the day with light winds. Could see a stray shower or two, but confidence is low that any showers would impact the terminals. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CLH LONG TERM...AM AVIATION...AM