FTB 09-01-2017: More Showers and Storms, Mainly For Southeast Colorado

Issue Date: Friday, September 1, 2017
Issue Time: 10:15AM MDT

LOW flood threat for Junkins, Beulah Hill and Hayden Pass fire scars
LOW flood threat for Raton Ridge

Unsettled weather will continue on this first day of September, though mainly limited to southeast Colorado. As shown in the water vapor image, below, a strong disturbance is noted across northwest Colorado. Mid-level upward motion to its east is causing extensive mid and high clouds over central and eastern parts of the state. Isolated showers are already showing up on the Pueblo NWS radar. As the disturbance slowly moves east-southeast, expect enough sunshine to cause an increase in shower and storm activity mainly across the southern High Country. Moisture has increased sharply over the past 24 hours with Precipitable Water at 0.94 inches at Denver and 0.76 inches at Grand Junction this morning. Notable drying will occur in the wake of the disturbance, but moisture will continue to stay elevated in the southeast and south-central parts of the state. At the surface, a weak low-pressure was noted in east-central Colorado. This is expected to intensify modestly with the lee side trough development this afternoon. This will act to focus the strongest storms on its southeast side.

Putting it all together now, we expect scattered/numerous showers and storms in the southern High Country including the Southeast Mountains and adjacent foothills. Rainfall rates will be below flood threat levels for most locations. However, the fire scars in the Southeast Mountains will continue to be under a Low flood threat for mud flows and flash flooding due to the high probability of moderate rainfall rates. Additionally, a Low flood threat has been posted for the Raton Ridge where the best instability and upslope flow could cause an isolated storm or two capable of producing heavy rainfall and flash flooding or small stream flooding.

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, scroll below the map.

 Flood Threat Legend

Zone-Specific Forecasts:

Southeast Mountains, Raton Ridge, Southeast Plains:

Partly cloudy this morning numerous showers and thunderstorms developing by early afternoon. Highest coverage will be over the higher terrain as well as the adjacent foothills. Max 1-hour rain rates up to 1.1 inch closer to the foothills and 1.4 inches across the eastern plains. A Low flood threat has been issued for the Junkins, Beulah Hill and Hayden Pass scars for mud flows and flash flooding. A Low flood threat has also been posted for the Raton Ridge for isolated flash flooding and small stream flooding.

Primetime: 1PM to 9PM

Front Range, Urban Corridor, Palmer Ridge, Northeast Plains:

Partly cloudy this morning isolated to scattered showers and thunderstorms possible this afternoon. Highest coverage will be over the higher terrain east of the Continental Divide as well as the Cheyenne and Palmer Ridges. Farther east, coverage will be isolated. Max 1-hour rain rates up to 0.7 inches. Flooding is not expected today.