FTB 08-25-2017: A Few Isolated Showers And Weak Storms Amidst General Drying

Issue Date: Friday, August 25, 2017
Issue Time: 10:40AM MDT

— Flooding is NOT expected today

The water vapor image, below, shows a weak ridge is currently positioned near the Four Corners. This ridge is expected to modestly strengthen today and support large-scale subsidence to its east. Morning Precipitable Water (PW) values at the Denver and Grand Junction radiosondes measured 0.73 and 0.61 inches, respectively. With the exception of far eastern parts of the state, PW is expected to drop into the 0.5 – 0.65 inch range by this afternoon.

With clear skies this morning and a still strong late-August sun, expect adequate instability for isolated to widely scattered showers and thunderstorms mainly east of the Continental Divide. A weak surface low pressure was noted in southeast Wyoming this morning and with the diurnal lee side trough development, we expect a weak convergence zone to setup just south of the South Platte River. This will be the focal point for the highest rainfall chances (in addition to favored higher elevation locations east of the Continental Divide). However, as already noted, coverage should be lower than Thursday. Short 15-30 minute bursts of heavy rainfall will be possible with the strongest storms especially towards the KS border. However, flooding is not expected today.

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.

Zone-Specific Forecasts:

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

Sunny this morning, then partly cloudy with isolated to widely scattered showers and weak thunderstorms possible. Highest coverage will be over the higher terrain as well as parts of the Northeast Plains. Max 1-hour rain rates up to 1.1 inches (east) and 0.5 inches (west). Flooding is not expected today.

Primetime: 12PM to 9PM

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

Sunny early with isolated showers and a weak thunderstorm possible this afternoon. Highest coverage will be over the San Juans. Max 1-hour rainfall up to 0.5 inches is possible. Flooding is not expected today.

Primetime: 12PM to 8PM