FTB 09-09-2017: Mid-Level Energy and Moisture Increase Shower Coverage

Issue Date: Saturday, September 9, 2017
Issue Time: 09:50AM MDT

— Flooding is NOT expected today

More westerly flow across the state should give us a break from the haze excluding the Northeast Plains, which is expected to have more northwesterly flow. Mostly clear across the state this morning with exception of a few high clouds over the SW corner. A small amount of low-level moisture was able to make its way into the western portion of the state, especially the Four Corner region. Precipitable Water (PW) values over Grand Junction this morning were at 0.85 inches, while in Denver they were measured at 0.66 inches. With the eastward shift of the ridge, the upper-level trough over the southern CA coast will begin to pull moisture northward into the SW corner of the state today. This flow will also help usher in mid-level energy from the CA trough. Between the increase in moisture and mid-level vorticity, shower activity is expected to be more numerous across the mountains and valleys with rain totals increasing as well.

Showers will begin to initiate over the higher terrains around 1PM. In western Colorado, storm movement will be more northerly, while east, storm movement will be to the E/SE. PW values will be under 1 inch for the majority of the state with mid-level drying expected as well. This should produce high-based showers and thunderstorms with limited rainfall and gusty winds with the stronger storms. Showers may linger overnight with the increased moisture and mid-level energy, but most will dissipate by 11PM. There is no flooding expected 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, scroll below the map.

Zone-Specific Forecasts:

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

Sunny this morning becoming partly cloudy this afternoon with thunderstorm and shower coverage increasing over the higher terrains. These showers could drift into the adjacent plains with 1-hr max rain rates up to 0.8 inches further south. Over the mountains, max 1-hr rain rates could be up to 0.6 inches. Reduction in smoke is expected statewide with the exception of the NE Plains. Flooding is not forecasted today.

Primetime: 1PM to 11PM

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

Partly cloudy over the SW corner this morning with increasing clouds over the higher terrains this afternoon. Scattered showers and thunderstorms likely this afternoon over the higher elevations, which are expected to drift north into the valleys. Max 1-hr rain rates up to 0.5 inches (north) and 0.7 inches (south). Some showers may linger overnight. Flooding is not expected today.

Primetime: 1PM to 11PM