FTB 09-27-2018: Dry Statewide with a Big Chill on the way East of the Divide

Issue Date: Thursday, September 27th, 2018
Issue Time: 08:05AM MDT

— Flooding is NOT expected today

After some of the coldest morning temperatures of the season to start the day yesterday, most places warmed up considerably during the day as high pressure sliding off to the east ushered in warm southerly winds. With high pressure at the surface and very dry air throughout nearly the whole depth of the atmosphere, precipitation chances are essentially zero statewide today and temperatures are expected to be near or a bit above seasonal averages. There is, however, a strong cold front lurking to our north, and while it will be unable to break the dry pattern across Colorado, it will mean the coldest day of the season so far east of the divide come tomorrow. The front’s late-morning position today has been drawn on the map below, with moister areas on the water vapor imagery nicely highlighting the influence of the jet stream and cold front. Further south, desert air sits over much of the state with just isolated pockets of high-level cloudiness across the northern tier of the state.

As the jet stream once again dips a little further south over the northern plains, it will help to push the cold front further south today and tonight, but it should remain north of Colorado through this evening. By the early morning hours of Friday, it will have passed through most of northeastern Colorado, and should reach southern Colorado by mid-day tomorrow. The pool of cold air associated with this feature is quite shallow, so the dramatic drop in temperatures may not even be felt in the mountains and foothills above 8000-9000’ above sea level. Many locations in the northern plains and urban corridor may experience their high temperatures for tomorrow at midnight tonight, as temperatures may drop 20+ °F behind the front and only recover into the 50s °F during the day tomorrow. In short: little in the way of sensible weather across Colorado today, but big changes are on the way for the eastern half of the state overnight.

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:

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

Mostly sunny and seasonably warm today as predominantly southwesterly winds carry dry desert air into the region. Low relative humidities may enable some growth of active fires like the Silver Creek and Ryan fires, but wind gusts and temperatures should be low enough to prevent any errant behavior or rapid growth. A few clouds may drift overhead from time to time across the northern half the state. Tonight’s cold front will not affect these areas.

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

A mostly sunny and seasonably warm day is in store for the northeast 1/3rd of the state today, with temperatures running around 5-10°F above normal. Expect the cold front to reach the northeastern corner of the state after midnight tonight and be through the Palmer Ridge by sunrise Friday. Southeastern reaches of the state will not be affected by the front until tomorrow morning.