FTB 09-25-2018: Scattered Storms Expected over the Southeast Mountains and Raton Ridge with Cooler Temperatures Forecast Statewide

Issue Date: Tuesday, September 25th, 2018
Issue Time: 09:05AM MDT

— Flooding is NOT expected today

A secondary cold front dropped through the state early this morning and is currently over the Texas panhandle. Breezy northerly winds are being experienced behind the front over the eastern plains this morning with temperatures in the mid 40Fs to 50Fs. A Frost Advisory has been issued for the northern Front Range and Urban Corridor tonight as temperatures today will only reach the mid-60Fs and drop to 28-32F overnight due to the cold air mass remaining in place and light winds. Increased low-level moisture behind the front has created some light upper-level clouds over the Front Range and along the front, but the shallow moisture is mixing out quickly with the sunrise. Despite the cold front passage, the northern 2/3 of Colorado already has dry air filling in behind the front. This can be noticed by the shades of yellow over the majority of the state. The exception is over southern Colorado where a little better moisture is able to hold on with more westerly flow aloft rather than northwesterly flow aloft. Upslope flow is expected to initiate showers and weak thunderstorms this afternoon with surface winds turning from more northerly to northeasterly over eastern Colorado. While some spotty, light showers may form over the high terrains, the best chance for afternoon rainfall is expected over the southern Southeast Mountains and Raton Ridge due to the better moisture over the region. Storms are expected to be high-based with dew points in the 30Fs, so that should limit totals with brief gusty winds possible. A few showers may linger eastward overnight into the Southeast Plains as there are some upper-level dynamics at play. Over western Colorado, skies will be mostly clear with some cloud cover likely over the San Juan Mountains this afternoon. Flooding is not forecast today.

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:

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

Temperatures today will be a 10-20F degrees cooler than yesterday with highs in the 60Fs for most of the lower elevations. Light winds tonight with the cold air mass over the region will drop overnight lows near freezing. A Frost Advisory has been issued for the northern Front Range and northern Urban Corridor due to temperatures dropping between 28 and 32F. Some upslope showers are expected this afternoon over the higher terrains. Showers to the north will be rather spotty in coverage with totals under 0.1 inches. Further south over the southern Southeast Mountains and Raton Ridge, shower and weak thunderstorm coverage will be the greatest. Storms are expected to be high-based, so some brief windy conditions are possible with max 1-hr rain rates up to 0.2 inches. A few storms may linger eastward overnight into the Southeast Plains, but totals will remain under 0.15 inches. Flooding is not expected today.

Primetime: 2:30PM to 9PM

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

Cooler temperatures are also expected over the northern half of these regions this afternoon with higher temperatures over the Grand Valley and Southwest Slope. Without much moisture, rainfall is not anticipated this afternoon. Expecting mostly clear skies with some scattered cloud cover over the San Juan Mountains. Today, there will also be a break from enhanced and critical fire weather. Hopefully crews are able to make some progress with the ongoing wildfires across the state.