FTB 05-28-2020: Scattered Storms Return to the Mountains

Issue Date: Thursday, May 28th, 2020
Issue Time: 9:15AM MDT

— Flooding is NOT expected today

Similar set up to yesterday with northerly flow aloft over the state as seen in the 500mb RAP analysis below. The main difference is that there is no distinct shortwave that will move through the flow to help enhance lift and increase moisture. Still expecting storms to pop over the mountains with upslope flow and residual moisture this afternoon. The northerly storm motion should keep storms mostly over the mountains, although they may move into the adjacent eastern plains favoring the higher elevations of the Palmer and Raton Ridges for accumulations later this afternoon and evening. With PW measured at 0.63 inches in Grand Junction and 0.74 inches in Denver, storms will have better coverage east of the Continental Divide and favor the Front Range, Southeast Mountains and eastern San Juans for development. Although dew points in the mid-40Fs will produce high-based storms, slow steering winds under the ridge will allow totals to increase more than they typically would. However, rain rates will not reach flood threat criteria.

Today’s Flood Threat Map

For more information on today’s flood threat, see the map below. If there is a threat, hover over the threat areas for more details, and click on burn areas to learn more about them. For Zone-Specific forecasts, scroll below the threat map.

Zone-Specific Forecasts:

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

Afternoon upslope flow will increase storm activity over the mountains by early afternoon. Storms are anticipated favor areas along and east of the Continental Divide for accumulations. Max 1-hour rain rates up to 0.50 inches will be possible over the mountains with gusty outflow winds and small hail being the main threats under the stronger storms. As storms spill into the adjacent plains, totals over a 1 to 2-hour period could increase to 0.75 inches over the Palmer Ridge and just east of the Denver Metro with small hail possible under the stronger storms. With spotty coverage and lower rain rates, flooding is not forecast. Some late-night rainfall may be possible over the adjacent eastern plains tonight as well.

Primetime: 1PM to 1:30AM

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

Bit drier than yesterday over these regions, which means a downtick in afternoon storm activity. Scattered storms are still anticipated to develop over the mountains, and the storms will favor areas along and near the Divide. Expecting some gusty outflow winds, as seen yesterday with totals up to 0.15 inches possible. With southerly storm motion, the San Luis Valley may get some more light rainfall. Totals are not expected to exceed 0.10 inches. Storm activity should decrease around sundown.

Primetime: 1PM to 8PM