FTB 06-22-2019: Cool and Wet, High Elevation Snow

Issue Date: 6/22/2019
Issue Time: 8:20 AM

A LOW FLOOD THREAT IS FORECAST TODAY FOR THE FOLLOWING AREAS:

Portions of the Front Range, Southeast Mountains, Urban Corridor, Northeast Plains, Southeast Plains, and Raton Ridge regions.

Saguache Creek, the headwaters of the and along the Rio Grande in Mineral and west Rio Grande Counties, and for the San Antonio and Conejos Rivers in south central Colorado.

NOTE: Elevated snow melt runoff continues across the High Country, with various flood advisories issued across the Northern Mountains, Northwest slope, Central Mountains, Southwest Slope, and Grand Valley. Please visit the website of your local National Weather Service Office for more details.

No one told Mother Nature that it is the second day of summer, and the image below depicts a weather pattern more reminiscent of late-September/October than late-June. An upper-level low is currently centered over southern Saskatchewan, with the trough axis extending southwest towards the California Baja. Associated with this system is plenty of upper-level support for showers and embedded thunderstorms, which has kept rainfall (and high elevation snow) ongoing this morning across the Front Range, Central Mountains, Urban Corridor, Palmer Ridge, and Northeast Plains. The unsettled weather will expand in coverage and intensity this afternoon and evening as temperatures warm a bit and increase instability. Ample shear will also be in place thanks to strong southwest flow aloft, so there will be a few embedded strong-to-severe thunderstorms. The greatest severe threat will be east of the mountains, where the combination of shear/instability will be best. These stronger storms will also hold the potential for heavy rainfall, thus the issuance of the low flood threat.

Over the High Country and Western Slope, widespread showers and thunderstorms are expected, with the main impacts being light-to-moderate precipitation, gusty winds, and small hail. A couple stronger thunderstorms cannot be ruled out, which may produce hail up to 1 inch in diameter and strong winds up to 65 mph. Accumulating snow is expected above 9,000-10,000 feet in the Grand Valley, Northwest Slope, Northern Mountains, Central Mountains, and Front Range regions, with higher peaks picking up 6-10 inches of snowfall through tomorrow morning.

For more details on timing and rain rates, please see the zone-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.

Flood Threat Legend

Zone-Specific Forecasts

Front Range, Southeast Mountains, Urban Corridor, Northeast Plains, Southeast Plains, Palmer Ridge, and Raton Ridge:

Scattered-to-widespread showers and thunderstorms expected today/tonight, with lingering showers into the morning hours tomorrow. A few of the storms will be strong/severe, with the potential to produce hail up to 2 inches in diameter, strong winds up to 75 mph, and a brief tornado or two. Rain rates will generally be below flash flood thresholds, but stronger storms could produce the following maximum rain rates:

Front Range and Southeast Mountains: 0.5-1.0 inches/hour
Urban Corridor: 1.0-1.5 inches/hour
Palmer Ridge, Northeast Plains, and Southeast Plains: 2.0-2.5 inches/hour
Raton Ridge: 1.5-2.0 inches/hour

Storm motions will be at a decent clip towards the east, so only a low flood threat is warranted. The Junkins, Beulah Hill, Spring Creek, and Hayden Pass burn scars may need a watchful eye.

Timing: 10 AM – Midnight for the Front Range and Southeast Mountains (a few lingering showers into tomorrow morning), 1 PM – 1 AM for the Urban Corridor, Raton Ridge, and Palmer Ridge, 2 PM – 2 AM for the Northeast Plains and Southeast Plains (a few thunderstorms lingering until sunrise tomorrow)

Northern Mountains, Northwest Slope, San Luis Valley, Central Mountains, San Juan Mountains, Grand Valley, and Southwest Slope:

Scattered-to-widespread showers and thunderstorms expected throughout today and tonight. The bulk of the activity will end by 9-10 PM, but a few isolated showers/thunderstorms will continue into the morning hours tomorrow, mainly north of I-70. Snow accumulation is expected above 9,000-10,000 feet. Most rain rates will be less than 0.2 inches/hour, but a stronger thunderstorm may produce rainfall at 0.2-0.4 inches/hour.