674 FXUS65 KCYS 251727 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1027 AM MST Sat Jan 25 2020 .UPDATE... Issued at 903 AM MST Sat Jan 25 2020 Latest 12Z guidance showing winds increasing across WY106 and 116 later this afternoon with 700mb winds up to 45kts across the south Laramie Range and 800mb winds near Bordeaux at 45kts. Leeside trough currently over the east slopes of the Laramie Range shifts east late afternoon and evening...allowing stronger surface gradient to shift east behind the surface trough. Have therefore...upgraded the watch for the south Laramie Range and added WY106 (Bordeaux) to the High Wind Warning. Timing wise...made a little later than Arlington...but do feel confident we will see these stronger winds after 00Z. Updates have been sent. && .SHORT TERM...(Today through Sunday) Issued at 400 AM MST Sat Jan 25 2020 Overnight WV/IR imagery showed a upper low poised over the western OH Valley, shortwave upper ridge across the Northern Plains, and upper trough entering northwest MT. A weak surface front extended from eastern MT to northeast CO, and a trough over central/southwest WY. Mid-level moisture covered most of the Cowboy State, with some snow showers developing over higher elevations of Albany and Carbon counties. prevailing winds were westerly 5-15 mph, with occasional gusts to around 30 mph over parts of southeast WY. Temperatures ranged from the upper teens to middle 30s. Snow showers will continue this morning west of the Laramie Range, decreasing this afternoon. As the trough tracks east across MT this afternoon, 850 mb CAG-CPR height gradients increase to 50-60 mtrs. 700 mb winds increase to 45-50 kt 21Z to 03Z between Rawlins and Bordeaux, and 40-45 kt over the I-80 Summit 03Z to 06Z. Upgraded the High Wind Watch to a Warning for the North Snowy Range Foothills including Arlington/Elk Mountain for gusts near 60 mph. Not as confident for the South Laramie Range/I-80 Summit, where gusts of 55 to 60 mph will be possible. Winds will diminish Sunday as the upper trough approaches the Upper Midwest and the low-level height gradients relax. Above normal high temperatures in the 30s and 40s are forecast. .LONG TERM...(Sunday night through Friday) Issued at 400 AM MST Sat Jan 25 2020 Transitory upper ridge along the Front Range Sunday gives way to the next Pacific upper trough Sunday night and Monday. Most of the energy with this system will affect the southern Rockies and Plains. Colder air aloft in the wake of the trough passage will enhance snow shower development, with more widespread coverage Monday. Snow amounts will be light for lower elevations, with 2 to 4 inches over the Snowy, Sierra Madre and North Laramie Ranges. Transitory ridging aloft will be short-lived Tuesday, with another Pacific upper trough digging southeast across the Intermountain West and Rocky Mountains Wednesday. Shortwave energy with this trough is further south per the GFS, while the ECMWF forms a closed low over southeast CO late Wednesday. Snow shower coverage will increase from west to east, with light amounts lower elevations and 3 to 5 inches for the Snowies/Sierra Madres. Snow showers will linger over the south central WY mountains Thursday through Friday, while the remainder of the CWA remains dry. It will be windy across much of southeast WY, with the strongest winds possible early and late in the week. Temperatures will average near seasonal normals. && .AVIATION...(For the 18Z TAFS through 18Z Sunday morning) Issued at 1027 AM MST Sat Jan 25 2020 VFR expected to prevail at the terminals through the period though some patchy MVFR cigs may occur around KRWL this evening. Some gusty winds this afternoon with gusts near 30 kts at the se Wy terminals. && .FIRE WEATHER... Issued at 250 AM MST Sat Jan 25 2020 Fire weather concerns will be negligible through next week. A low pressure trough will track east across Montana and the Dakotas this afternoon and tonight, and increase the low-level gradient flow over southeast Wyoming resulting in strong and gusty west winds. Snow showers will continue this morning west of the Laramie Range, and taper off this afternoon. A more significant low pressure trough will move into the region late Sunday and Monday with accumulating snow. Much of next week will be cooler than normal with chances for snow showers, mainly over the higher terrain. Minimum relative humidities will range from 30 to 40 percent, with excellent nighttime recoveries. Also, it will be windy early and late next week across much of southeast Wyoming. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning from 5 PM this afternoon to 8 AM MST Sunday for WYZ106-116. High Wind Warning from 2 PM this afternoon to 8 AM MST Sunday for WYZ110. NE...None. && $$ UPDATE...GCC SHORT TERM...MAJ LONG TERM...MAJ AVIATION...RE FIRE WEATHER...MAJ