FTB 05-04-2021: More Sunshine & Isolated PM Storms

Issue Date: Tuesday, May 4th, 2021
Issue Time: 9:05AM MDT

— Flooding is NOT expected today

A shift in the weather pattern will take place today, which means more sunshine and warmer temperatures. The trough that brought a nice round rainfall and snow to the state the last couple of days is currently to our southeast, and more dry, northwesterly flow aloft has begun to fill in over the state. Both the Grand Junction and Denver sounding’s this morning show this much drier air mass in the mid to upper levels of the atmosphere. Nonetheless, the visible satellite image below (from 8AM this morning) still shows plenty of cloud cover and some fog, which means there will be enough residual moisture for a round of scattered storms this afternoon.

A shortwave (orange X) is expected to travel through this northwesterly flow, which will help create lift out in front of it. As this shortwave progresses through the northern and northeast portion of the state, it will help produce scattered storms across the Northern, Central and Front Range Mountains during the early afternoon. Storms will push into the adjacent plains (Urban Corridor, Palmer Ridge and Northeast Plains), but fast northwest steering flows and high cloud bases indicate rainfall accumulation will be limited. Flooding is not expected, and the main threat from the thunderstorms that develop today will be brief outflow winds and lightning.

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:

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

Another round of scattered storms is expected this afternoon. Snow showers are likely over the highest elevations, but precipitation should mostly fall as rain. A couple scattered thunderstorms are not out of the question over the mountains, but heavy rainfall is not expected. Isolated max 1-hour rain rates up to 0.20 inches will be possible. Additionally, forecasting westerly and northwesterly surface winds to pick up over the high terrains as the jet moves overhead. As storms move swiftly off the mountains into the adjacent plains with southeast movement, they will likely produce a little more lightning, brief wind gusts and light to moderate rainfall. Isolated storm totals may come close to 0.30 inches. Light showers look to develop over the Palmer Ridge tonight and move into the Southeast Plains by the early morning hours with favorable lift from the jet overhead. Flooding is not forecast.

Primetime: 12:30PM to 11PM

Southeast Mountains, Southeast Plains & Raton Ridge:

Moisture and lift won’t be quite as strong over these regions today and downsloping winds will help dry out the lower levels even more. The isolated storms that are able to develop likely won’t produce much (if any) accumulation. Best chance for accumulation will be if storms can stay intact from the northwest and make it to the eastern Southeast Plains or eastern Raton Ridge. Totals up to 0.25 inches will be possible. Light showers may be possible in the early morning hours over the Southeast Plains. Flooding is not forecast.

Primetime: 3PM to 11PM

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

Broken cloud cover is forecast over the high terrains with sunny conditions for the San Luis Valley and Southwest Slope. With dew points in the teens and 20s, rainfall is not forecast for these regions. Northwesterly surface winds are forecast to pick up over the Grand Valley, San Luis Valley and San Juan Mountains with the windiest conditions over the San Juan Mountains as the jet moves in. High temperatures should be around normal for early May.