Issue Date: 5/20/2016
Issue Time: 10:02 AM
NO FLOOD THREAT IS FORECAST.
The water vapor image below provides a nice overview of the big players aloft in our forecast today. The strong upper-level low (red “L”) will continue digging along the West Coast, dipping down into the Desert Southwest by tonight. Meanwhile, the upper-level ridge that move into Colorado yesterday will continue to shift eastward, with the ridge axis sitting overtop western Kansas by later tonight. The ridging will allow the warming trend to continue across Colorado, while suppressing most thunderstorm activity.
Even though the upper-level ridge will try its best to suppress activity, it will not be entirely successful. Orographic effects will work with daytime heating to produce isolated showers/thunderstorms over the mountains, mainly along the Continental Divide and San Juan Mountains. A few will develop over the Front Range and Southeast Mountains, moving over adjacent lower elevations of the Urban Corridor, Palmer Ridge, and Southeast Plains.
Further east, the storm threat is more conditional. Due to warming aloft, much of the environment will remain capped off across the Northeast Plains, Palmer Ridge, and Southeast Plains regions. A couple isolated thunderstorms will likely break the cap, but will remain high-based due to fairly dry lower-levels. The greatest threat from these storms will be gusty winds and lightning. For more information regarding timing and rain rates, please see the zone-specific 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, Northeast Plains, Southeast Plains, Palmer Ridge, and Raton Ridge:
Isolated showers/thunderstorms are expected, mainly along and near the higher terrain. A couple of isolated thunderstorms are possible further east, dependent on whether or not they can break through the cap. The main threats with any thunderstorms will be gusty winds and lightning. Maximum rain rates vary:
Urban Corridor: 0.25-0.5 inches/hour
Northeast Plains and Palmer Ridge: 0.3-0.6 inches/hour
Southeast Plains: 0.25-0.5 inches/hour
Raton Ridge: 0.15-0.25 inches/hour
Timing: Noon – 10 PM
Front Range, Southeast Mountains, Northern Mountains, Northwest Slope, Central Mountains, Grand Valley, Southwest Slope, San Juan Mountains, and San Luis Valley:
Isolated showers and thunderstorms are expected to develop this afternoon and evening, with the best chances (relatively speaking) over the Continental Divide and San Juan Mountains. The main threats from any thunderstorm activity will be gusty winds and lightning. Maximum rain rates vary:
Front Range and Northern Mountains: 0.2-0.4 inches/hour
Central Mountains, Southeast Mountains, and San Juan Mountains: 0.1-0.3 inches/hour
Northwest Slope, Grand Valley, Southwest Slope, and San Luis Valley: 0.05-0.2 inches/hour
Timing: Noon – 9 PM, with a couple isolated showers/weak thunderstorms lingering until midnight.
