Issue Date: 5/21/2016
Issue Time: 9:05 AM
NO FLOOD THREAT IS FORECAST.
Current analysis shows the upper-level trough/low continues to spin over the West Coast while an upper-level ridge continues to build over the High Plains. This set up will continue to develop/strengthen the leeside trough sitting across eastern Colorado. Meanwhile, a dryline will sharpen across the eastern Plains, effectively delineating the areas that could see isolated thunderstorms across the lower elevations. Over the mountains, a couple isolated, high-based showers/weak thunderstorms will develop mainly along and north of I-70 during the afternoon and evening hours. Not much rain is expected from them.
Now, we turn our attention back to eastern Colorado where the strongest thunderstorms are possible today. There will not be much coverage, and will probably only be a couple of thunderstorms. Warming in the mid-levels will effectively cap off the environment from any thunderstorm development west of the dryline. Along/east of the dryline, enough moisture/lift will be present to break the cap in a few places, resulting in isolated strong-to-severe thunderstorms. The main threats will be damaging wind gusts, hail, and lightning. An isolated tornado cannot be ruled out along/near the CO/KS border. Thunderstorm activity will come to an end/move out of the state by 6-8 PM. Please see the zone-specific forecast discussions below for more information regarding maximum rain rates and timing.
Today’s Flood Threat Map
For more information on today’s flood threat, see the map below (hover over threat areas for more details). For Zone-Specific forecasts, jump below the map.
Zone-Specific Forecasts
Palmer Ridge, Northeast Plains, Raton Ridge, and Southeast Plains:
Isolated strong-to-severe thunderstorms are possible for eastern extents of the regions today, for areas along and east of the dryline. The dryline will likely sit along a line from eastern Weld County, across central Morgan to central Washington County, arcing southward through eastern Lincoln, western Kiowa/Bent Counties and eastern Las Animas County. The main threats will be damaging wind gusts, hail, and lightning, but an isolated tornado cannot be ruled out near the CO/KS border. Brief moderate-to-heavy rainfall is also likely, but storm motions will mitigate the threat of any flash flooding issues. Maximum rain rates will be 1.2-2.0 inches/hour.
West of the dryline, it will be mostly sunny and dry today, with highs ranging from the upper 70s to low 90s.
Timing: 2 PM – 8 PM
Northern Mountains, Front Range and Urban Corridor:
Mostly sunny and warm, with only a couple isolated showers/weak thunderstorms developing over the higher terrain. One or two may drift over the Urban Corridor. The atmosphere will be too dry to produce rain rates capable of flash flooding, and the main impact from any thunderstorm will be gusty winds and lightning.
Timing: 1 PM – 8 PM
Central Mountains, Southeast Mountains, Northwest Slope, Grand Valley, Southwest Slope, San Juan Mountains, and San Luis Valley:
Mostly sunny and warm, with winds being the main weather impact today. Winds will be breezy today, especially across the Northwest Slope, Grand Valley, and Southwest Slope regions. Winds will be out of the southwest at 10-25 mph, gusting to 35-45 mph. A cool front will nudge closer to the area from the west overnight, perhaps producing an isolated shower or two over the Northwest Slope overnight tonight, resulting in very little rain.
