FTB 08-29-2017: Persistent Pattern: Hot Out West, Isolated T-Storms East

Issue Date: Tuesday, August 29, 2017
Issue Time: 9:40AM MDT

— Flooding is NOT expected today

This morning’s water vapor image, below, shows a very persistent atmospheric pattern across the central and western US. The remnants of Hurricane Harvey continue to be a very serious threat across the Gulf Coast states. However, drying is noted on the west side of the storm’s center, and Harvey’s moisture will never make it to Colorado. Instead, subsidence will continue to be the main player today, supporting mainly clear skies and hot weather west of the Continental Divide with isolated storms possible over the higher elevations and foothills to the east. Morning Precipitable Water (PW) values were 0.62 and 0.47 inches at Denver and Grand Junction, respectively. This is down 10-20% from yesterday. PW is expected to stay steady today. With plenty of morning sunshine, expect weak instability and upslope flow to generate isolated to scattered storms mainly over the higher elevations and foothills east of the Continental Divide. A few storms could make it farther eastward off the Cheyenne, Palmer and Raton ridges. However, only short-term moderate rainfall is expected. Flooding is not expected today.

The main headline today will continue to be above average temperatures statewide, but especially west of the Continental Divide where high temperatures of up to 15F above normal are expected.

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:

Mostly sunny this morning, then partly cloudy with isolated to scattered showers and weak thunderstorms possible. Highest coverage will be over the higher terrain east of the Continental Divide as well as the Cheyenne, Palmer and Raton ridges. Max 1-hour rain rates up to 0.75 inches (below 7,000 feet) and 0.5 inches (above 7,000 feet), though most everyone will stay dry. Gusty winds will accompany the strongest storms. Flooding is not expected today.

Primetime: 1PM to 8PM

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 0.4 inches is possible. Gusty winds will accompany the strongest cells. Flooding is not expected today.

Primetime: 12PM to 8PM