Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000 FXUS65 KBOU 210254 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 854 PM MDT Tue Apr 20 2021 .UPDATE... Issued at 849 PM MDT Tue Apr 20 2021 Low to mid level cloudiness is increasing across the area and mostly cloudy skies are still expected overnight. This should keep lows a few degrees warmer than last night, which was accounted for in the forecast. The next shortwaves are advancing east over the Great Basin and south over the Rockies, and mid to upper level moisture will increase ahead of them tomorrow. There still looks to be enough lift and moisture to support scattered, light showers across northeast Colorado tomorrow afternoon and evening. The forecast is on track with only minor updates this evening. && .SHORT TERM...(This evening through Wednesday) Issued at 238 PM MDT Tue Apr 20 2021 A weak wave embedded in the northwest flow aloft is passing east of Colorado. This is bringing gusty winds and clouds to the northeast plains. Some of this cloudiness will creep westward through the late afternoon and evening bringing mostly cloudy skies for tonight. It will be another cold night, but the cloud cover will help keep temperatures from reaching record lows. Most locations are expected to bottom out in the 20s. For Wednesday, two systems will affect the region, one dropping out of the Northern Rockies and the other moving east across the Great Basin. Both of these systems will be weakening as they track across the Central Rockies. The piece from the north will help reinforce the cooler air in place. Lift will be weak Wednesday, but expect enough lift and moisture to be in place for light snow. An easterly low level flow will provide weak upslope lift as well. Snowfall amounts through Wednesday afternoon are expected to be light with a few inches possible over the mountains and foothills. Don`t expect any accumulation across the lower elevations. Cold air will remain in place with highs only in the 30s across much of northeast Colorado. .LONG TERM...(Wednesday night through Tuesday) Issued at 238 PM MDT Tue Apr 20 2021 Light snow showers will continue across the mountains during the overnight hours Wednesday under a weak deformation zone, ahead of a relatively weak shortwave trough axis. The forecast trend has been towards a drier solution over the past few model cycles, especially over the plains. Still, there is enough lift around for a couple inches of snow across the Front Range mountains and Foothills. Snow showers will mix with rain over the plains, with most locations seeing a half inch of snow or less. The better forcing departs the area by Thursday morning and should lead to a drier day over most of the plains. Temperatures should also warm a bit as a warm air advection regime develops. Despite the warmer temperatures, cloud cover should be fairly widespread with mid-level moisture around. Across the mountains, a few convective showers are possible with instability increasing during the day. A few of these showers could spread east into the urban corridor during the afternoon hours, but otherwise expect a relatively quiet day. Another trough passes across the area late Thursday into Friday, with a separate round of showers likely across the higher terrain. The strongest QG ascent is well to our south and the surface cold front is pretty weak. There is enough moisture and instability left in the mountains to continue some likely PoPs with lower chances across the plains. Warm weather finally makes a full return this weekend as ridging builds into the region and warm/dry southwest flow increases. Temperatures should make it into the 60s on Saturday and will likely reach the 70s Sunday. Warm weather looks like it will try to continue into Monday as guidance has pushed back the arrival of the next storm system. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 849 PM MDT Tue Apr 20 2021 Expect VFR conditions to persist until visibility decreases with precipitation Wednesday afternoon as some weak weather systems move over the central Rockies. Expect light showers in the vicinity of the terminals by the early afternoon and MVFR conditions with showers over the terminals by the late afternoon. ILS conditions are also expected to persist through the TAF period with broken to overcast skies and cloud bases at 4000 to 6000 feet. Light and variable winds this evening should turn southeasterly overnight and remain southeasterly Wednesday, with speeds generally under 15 knots. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Direnzo SHORT TERM...Meier LONG TERM...Hiris AVIATION...Direnzo

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