Issue Date: Wednesday, August 22nd, 2018
Issue Time: 09:25AM MDT
— A LOW flood threat has been issued for portions of the Front Range, Urban Corridor, Palmer Ridge, Southeast Plains, Southeast Mountains and Raton Ridge
— A LOW flood threat has been issued for the 416/Burro and Spring Creek burn areas
This morning is a reminder that fall is just around the corner. A nice cool start to Wednesday morning after near statewide rainfall yesterday. Temperatures are currently in the upper 50Fs to low 60Fs over the lower terrains with some snow being reported over the higher peaks. The monsoon moisture surge is still well under way with the 500mb high positioned over eastern TX. The trough to northwest will start its eastward migration today, which should provide a little extra lift to keep light to moderate showers going over northern Colorado throughout the day. By early afternoon, some breaks in the clouds over southeast Colorado will allow a bit of instability to build. This is expected to lead to some thunderstorm development over this area, whereas elsewhere, convection will be more moderate and stratiform in nature.
Soundings this morning show PW was over an inch for both Grand Junction and Denver. This is very high for this time of year, but it will help provide another round of some much needed rainfall to the state. This afternoon, dew points are forecast to remain in the low 60Fs over the Southeast Plains. This means that the isolated thunderstorms that form over this area will have the potential to produce some heavy rainfall again. Extra mid-level energy will also continue to rotate clockwise around the high, which will provide some extra lift. Decent storm motion should keep in check widespread flooding, but storms that track over the same areas as the last 24-hours could produce increased runoff. A Low flood threat has been issued with the mains threat being field ponding, flooding of low-lying roads and local stream flooding. While rainfall over the San Juan Mountains is not expected to be overly convective today, max 1-hour rain rates up to 0.8 inches, due to the high low-level moisture, could be problematic for the 416 and Burro burn scars. A Low flood threat has been issued for these burn scars as well.
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.
Zone-Specific Forecasts:
Grand Valley, Central Mountains, San Juan Mountains, San Luis Valley, Southwest Slope, Northern Mountains, Northwest Slope, Northeast Plains:
Showers are expected to pick up in intensity throughout the day, though rain rates are expected to be light to moderate. This will bring some beneficial rain to all the regions once again. Burn scars will continue be susceptible to flash flooding today as rain rates greater than 0.5 inches/hour are possible, so a Low flood threat has been issued for the 416/Burro burn area. Max 1-hr rain rates up to 0.8 inches are possible though most 1-hour totals will be in the 0.25-0.5 inch range under the stronger cores. Threats for storms that track over burn scars include mud flows, debris slides and local stream flooding.
Primetime: 12PM – 8PM
Southeast Plains, Raton Ridge, Southeast Mountains, Front Range, Palmer Ridge, Urban Corridor:
Thunderstorm development is likely again over the Southeast Plains today as well as over the Palmer Ridge. The more severe threat will be over the far Southeast Plains, though storms are expected to meet only minimal severe threat criteria. The convection should be somewhat isolated in nature as there will be limited instability over the adjacent plains where there are breaks in the clouds by early afternoon. The exact location of the cloud breaks are difficult to forecast, thus all areas in the adjacent plains have been included in the Low threat. Threats include heavy rainfall, hail, strong winds and local stream flooding due to increased runoff. Unlike yesterday, storm activity should decrease a couple of hours after sundown as the low-level jet sets up east of Colorado. It will still be possible for a few light showers over the Southeast Plains overnight. Max 1-hr rain rates up to 1.1 inch (west) and 1.75 inches (east) are possible today. A Low flood threat has been issued that includes the Spring Creek burn scar.
Primetime: 1:30PM – 10PM
