FTB 05-09-2021: Cooler, Rain Turning To Snow For Many, And No Flood Threat

Issue Date: Sunday, May 9th, 2021
Issue Time: 9:00AM MDT

— Flooding is NOT expected today

Happy Mother’s Day!

This morning’s visible satellite imagery, below, shows a developing surface cyclone over the Four Corners with a thick mid/low level cloud deck along with some showers and a weak storm or two in southern Colorado. While the dynamics with this system will certainly be impressive, the main missing piece preventing heavy rain potential is the moisture content. This morning’s PW at Grand Junction was only 0.18 inches, with 0.40 inches measured at Denver. However, even western KS and NE had PW below 0.5 inches, a noticeable drop since yesterday. Overall, this system has trended a bit drier since we first began watching it five days ago. In turn, this implies less instability and more stratiform, versus convective rainfall (and yes, snowfall). Maximum atmospheric instability today will be below 500 J/kg in southern and southeastern Colorado. This is far too low for anything besides a local, short-pulsed heavy downpour so flooding is NOT expected today. However, isolated severe weather, mainly in the form of strong winds and perhaps large hail, will be possible in southeast Colorado.

West of the Continental Divide, gusty winds and low relative humidity will continue to support conditions favorable for wildfires. Fortunately, the cooler temperatures will mitigate the threat somewhat, compared to Saturday. Stay tuned to National Weather Service forecasts for updates on this.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts:

Raton Ridge and Southeast Plains:

Mostly cloudy and much cooler with scattered to widespread showers and a few thunderstorms through the day and into the evening. Maximum 1-hour rainfall up to 0.5 inches possible for most areas below 6,000 feet, but up to 0.9 inches in far southeast CO along the OK and KS borders. A severe storm, with large hail and gusty winds to 55mph cannot be ruled out in these areas. The snow level will drop from 8,000 feet this morning down to 6,000 feet later this evening and into the overnight hours.

The Spring Creek burn scar is not expected to have flooding concerns because precipitation will be transitioning to snow later today, if it hasn’t done so already.

Flooding is NOT expected today.

Primetime: Now through 6AM, with highest rainfall intensity between 1PM and 7PM

Northern Mountains, Front Range, Urban Corridor, Central Mountains, Palmer Ridge, Northeast Plains:

Increasing clouds and much cooler with isolated to scattered rain and snow showers developing later this afternoon and increasing in coverage overnight. A rumble of thunder cannot be ruled out. Max 1-hour rainfall up to 0.4 inches earlier in the afternoon. The snow level will drop from 7,500 feet this afternoon to 5,000 feet overnight.

Fire burn scars are not anticipated to experience flooding issues because of the combination of light rainfall intensity and transition of precipitation into snowfall.

Flooding is NOT expected today.

Primetime: 1PM through the overnight hours

Grand Valley, San Juan Mountains, Southwest Slope & San Luis Valley, Northwest Slope:

Mostly sunny to partly cloudy and cooler this afternoon. Rain and snow showers will increase in coverage this afternoon mainly for elevations above 7,500 feet. Below this level, it will be too dry for any significant precipitation. Max 1-hour rainfall up to 0.2 inches. A Red Flag warning is currently in effect for the San Luis Valley, so please stay tuned to your local NWS office for updates on fire conditions.

Flooding is NOT expected today.