FTB 07-07-2019: Rain Returns to the High Country, Low Flood Threat Issued Over Burn Areas

Issue Date: Sunday, July, 7th, 2019
Issue Time: 10:15AM MDT

A LOW flood threat is forecast today over the 416, Spring Creek, and Hayden Pass burn areas

The weak high pressure ridge aloft that influenced our weather yesterday has not moved at all and remains a major feature across the central United States.  Southwesterly flow aloft (yellow line) will bring in mid and upper level moisture from the Pacific and Southerly flow in the low levels will bring in warm temperatures and moisture from the Gulf.  Embedded within the flow is a shortwave (marked with an “X” below) that will aid moderate to high moisture levels in producing afternoon and early evening thunderstorms over the high country and eastern plains.  Westerly flow aloft over the northern half of the state will limit rainfall totals over the northern areas of the high county.  Cloud cover and fog over the eastern plains is expected to burn off this morning, which will increase instability over the area throughout the morning and into the early afternoon.  PW measured in Denver this morning is 0.83 inches, providing chances for moderate rainfall.

A surface low is forecast to form in central Colorado midday.  This feature will create convergence over the southern Urban Corridor and Palmer Ridge, which will aid thunderstorm generation over the area.  Downslope flow on the backside of the low will limit chances for thunderstorms over the Southeast Plains and areas adjacent to the foothills.  Storm motion west of the continental divide will be quick enough to limit chances of heavy precipitation over the area.  Over the eastern plains storm motion will be much slower, allowing for moderate rainfall near the Kansas border.

Riverine: There are currently no flood warnings this morning (as of 10AM), although rivers and streams remain elevated in the high country and Arkansas River valley.  There is a possibility of more dam releases, which will increase the chances of flooding of low laying areas.  There are currently flood advisories in effect for: the Roaring Fork River near Aspen, and the Blue River below Dillon.  Please use caution near swift moving waters.   Additionally, we have had reports of high flows within the SLV along the Conejos and Rio Grande River with Platoro and Terrace Reservoirs looking very full as well.  Along the Arkansas River gages at Avondale and La Junta are at Action stage.  Unless there is a dam release from the Pueblo Reservoir today, these areas should remain below minor flood stage.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. For Zone-Specific forecasts, scroll below the map.

Flood Threat Legend

 

Zone-Specific Forecasts:

Southwest Slope, San Juan Mountains, Southeast Mountains, Raton Ridge, Central Mountains, San Luis Valley

Passage of a shortwave and upslope flow of moist air from the south will provide chances for moderate thunderstorms this afternoon and into the early evening.  A Low flood threat is issued for the 416, Spring Creek, and Hayden Pass burn areas.  Max 1-hour rain rates of 0.4 inches and max 3-hour rain rates of 1 inch could cause issues over the burn areas.  Threats over these areas include flash flooding, mud flows and debris slides.  Steering winds up to 25 mph will limit heavy, long duration rainfall over the area.  Thunderstorms are expected to be confined over upper elevations, but brief rainfall over the valleys is possible.

Primetime: 2PM to 12 AM

Grand Valley, Northwest Slope, Northern Mountains, Front Range, San Luis Valley

Westerly upper level flows have limited moisture advection into the area.  Brief, isolated thunderstorms are possible, with max 1-hour accumulation of 0.25 inches.  Wind gusts up to 30 mph can be expected within the storm vicinity.  Flooding is not expected today.

Primetime: 2PM to 1AM

Urban Corridor, Northeast Plains, Palmer Ridge, Southeast Plains

Surface moisture remains high today, with dewpoints measuring in the 50°Fs and low 60°Fs this morning.  Convergence along the Palmer Ridge is forecast to produce moderate to severe thunderstorms this afternoon and into the evening.  As storms move into the far eastern plains, increased moisture and slow steering winds will produce moderate rainfall.  Max 1-hour rain rates of 1 inch are possible over the Palmer Divide.  Max 3-hour rain rates up to 2 inches are possible, but drying of the soil yesterday should prevent flooding.  No flooding is forecast over the area today.

Primetime: 3PM to 4AM