Issue Date: 5/8/2016
Issue Time: 9:10 AM
LOW FLOOD THREAT ISSUED FOR PORTIONS OF THE FRONT RANGE, URBAN CORRIDOR, SOUTHEAST PLAINS, NORTHEAST PLAINS, AND PALMER RIDGE.
Unsettled weather is expected across much of the state today as the upper-level low shifts overhead. Thanks to the low being cutoff between the split streams in the atmospheric flow pattern (two yellow lines), its movement to the northeast has been slow. The core of the upper low will move overhead today, and the associated cold air aloft will steepen lapse rates and allow for another day of showers/thunderstorms across much of Colorado.
In general, most areas will be less unstable than yesterday, especially over much of the High Country. As a result, storm coverage will be less and maximum rain rates will be lower. Areas from the Continental Divide and to the east will be the exception as instability will be higher, allowing stronger storms to produce moderate-to-heavy rainfall.
Far eastern Colorado will be the area to watch for a few strong-to-marginally severe storms. Instability will be higher here than any other locations across Colorado. The main threats from any severe storms will be hail (up to 1.5 inches in diameter), gusty winds (greater than 60 mph), and brief heavy rain. For more details, please see the region-specific forecast discussions below.
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
Urban Corridor, Palmer Ridge, Northeast Plains, Raton Ridge and Southeast Plains:
Scattered showers and thunderstorms expected this afternoon and evening, perhaps as early as 11 AM for western extents of the area. Most activity will be responsible for gusty winds, light-to-moderate rainfall, and lightning, while the stronger storms will be capable of brief heavy rain, small hail, and wind gusts over 40 mph. A few severe storms are expected, mainly near the CO/KS border. The main impacts from severe storms will be hail (up to 1.5 inches in diameter), damaging wind gusts (greater than 60 mph), lightning, and brief heavy rainfall.
Storm coverage will be highest over the Northeast Plains, with the least coverage expected over the Raton Ridge and far Southeast Plains.
Rain rates will generally be 0.3-0.7 inches/hour, with maximum rain rates of 1.2-1.8 inches/hour possible. A low flood threat has been issued.
Timing: 11 AM – 9 PM
Front Range, Northwest Slope, Northern Mountains, and Central Mountains:
Scattered showers and thunderstorms expected to begin late this morning, increasing in coverage through the afternoon, and continuing through the evening hours. A few showers will linger into the early morning hours.
Generally speaking, rain rates will be 0.2-0.4 inches/hour. Over the Front Range, thunderstorms will have enough moisture/instability to work with to produce rain rates up to 0.8-1.0 inches/hour. After yesterday’s moderate rainfall across northern portions of the Front Range, a low-end, low flood threat is warranted.
Timing: 11 AM – 9 PM, with a few showers lingering into tomorrow morning
Grand Valley, San Juan Mountains, Southwest Slope, San Luis Valley and Southeast Mountains:
Scattered showers are ongoing this morning across portions of the area, and will increase in coverage later this morning. A few weak thunderstorms will join the scattered showers this afternoon and evening, before much of the activity diminishing with sunset. A couple showers will linger into the early morning hours tomorrow across the higher terrain.
Rain rates will generally be light at 0.15-0.25 inches/hour, with thunderstorms maxing out rain rates at 0.2-0.4 inches/hour.
Timing: Ongoing – 9 PM, with lingering showers overnight and into tomorrow morning
