Issue Date: 9/5/2015
Issue Time: 9:00AM
—NO FLOOD THREAT TODAY
The atmosphere has only subtly changed form over the past 24 hours. An unseasonably strong trough has now entered the North American west coast, as shown in the water vapor image below. This large disturbance is continuing to direct strong moisture transport from the subtropics into the southwest United States. Morning precipitable water (PW) values have increased into the 0.8 to 1.2 inch range. This, by itself, would suggest the possibility of a heavy rainfall threat. However, a 100 mph jet stream is positioned over Colorado today, which will lead to storms motions of 35 to 45 mph. Further, instability will once again be very minimal. Altogether, there will once again be showers and a few weak thunderstorms today, but heavy rainfall will be very unlikely and flooding is not expected.
For today, we expect the ongoing rainfall over southwestern Colorado to intensify and grow in coverage. Once again, rainfall will have a difficult time moving into the eastern plains due to the downsloping flow, but a few showers and a weak thunderstorm will be possible over the Southeast Plains. Hourly rain rates up to 0.5 inches will be possible across the San Juans, Central Mountains, Southeast Mountains and Raton Ridge. Total 24-hour rainfall amounts of up to 0.7 inches will possible locally. As such, there is no flood threat 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, jump below the map.
Zone Specific Forecasts
Front Range, Urban Corridor, Northeast Plains, Southeast Plains, Palmer Ridge, Raton Ridge, Southeast Mountains:
Partly to mostly cloudy today and seasonably warm with highs in the 50s in the higher terrain to the lower 90s F in the lower elevations of the Arkansas River valley. Scattered thunderstorms will be possible closer to the mountains from the mid-afternoon through early evening hours. However, max 1-hour rainfall rates will be limited to 0.4 inches or less due to weak instability. Flooding is not expected today. Scattered showers may continue into the overnight hours.
Southwest Slope, San Juans, San Luis Valley, Central Mountains, Northern Mountains, Grand Valley, Northwest Slope, Southwest Slope:
Partly to mostly cloudy with scattered showers and weak thunderstorms developing, mostly across the south and central portions of the area. Max 1-hour rain rates up to 0.5 inches will be possible. Thunderstorms will weaken by early evening, but showers may continue overnight. Flooding is not expected today due to the lower rainfall intensities. Due to a strong jet stream overhead, gusty winds will be possible over the higher ridges.
