FTB 06-12-2018: Overnight Heavy Rainfall Threat for the Eastern Plains

Issue Date: Tuesday, June 12, 2018
Issue Time: 09:45AM MDT

LOW flood threat for portions of the Southeast Plains, Palmer Ridge and Northeast Plains

Once again today, Colorado will be under westerly flow aloft, which should keep dry air in place over the majority of the state. There is a bit more moisture than the last couple of days to the west of Colorado (blue streaks below), so cloud coverage this afternoon over the higher terrains should be more plentiful when compared to the last few days. In the water vapor imagery below you can also see the start of the first northward push of the subtropical moisture at the southern AZ border. The 5880 meter ridge marked in the image will build north to the CO/WY border through this afternoon. Under the ridge and over the eastern plains, decent moisture will return this afternoon as winds shift from north to easterly and support upslope flow.

The best coverage for afternoon thunderstorms initiation will be over the southern Front Range, Southeast Mountains and Palmer Ridge. An isolated storm may also form over the Raton Ridge area. With dew point values in the 30Fs (west), storms are not expected to drop much rainfall. However, as storms move off of the mountains to the east this evening, they will encounter favorable moisture and dynamics for overnight convection over the plains. Threats include gusty winds, large hail and local heavy rainfall, which will could lead to street flooding and field ponding. The thunderstorms are expected to continue into tomorrow morning before crossing east over the Kansas border. With dew points in the mid-50Fs and slow steering winds, a Low flood threat has been issued for the Southeast Plains and portions of the Palmer Ridge and Northeast Plains through tomorrow morning.

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:

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

Upslope flow will return to the region, which should initiate thunderstorms over the higher terrains later this afternoon. Max 1-hour rain rates up to 0.7 inches/hour are possible this afternoon near the Palmer Ridge/Front Range intersect. Over the Southeast Mountains, mostly gusty winds and dangerous lightning are likely with precipitation totals under 0.1 inches. As convection spreads to the eastern plains this evening, thunderstorm and rainfall coverage will increase and continue into the morning hours. Max 1-hour rain rates up to 1.75 inches/hour are possible with local totals up to 2.1 inches over the Southeast Plains near the KS/CO border.

Primetime: 4PM – 8:30AM

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

Dense Smoke Advisory continues for the San Juan Mountains through noon today. Some smoke from the fire in Utah may also sneak into west, central Colorado. Rainfall is not expected today, but cloud cover will increase over the higher terrains this afternoon when compared to the last couple of days. This should help provide some shade from another day of above normal heat.