Plaincast — the National Weather Service forecast, decoded into plain English

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Above normal temperatures and dry conditions will prevail today, followed by more seasonable temperatures this weekend into next week.

Chances for rain and snow showers across the high country Saturday, with a few showers possible over the eastern plains.

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Current satellite shows a clear night for much of the state with only a few thin high clouds over western CO. To our east, a much cooler airmass and its accompanying cold front have pushed over the Great Lakes and across the central Great Plains, up against our eastern counties. Given the clear skies in place, light easterly winds, and a somewhat of a surge in dewpoints (low to mid 30s), at least some patchy fog is likely over the eastern CO plains and along the South Platte River valley in the early morning hours. Areas of fog can already be seen slowly creeping over the CO-NE border. The fog should clear by mid morning as temperatures rise.

High clouds will continue to increase over the region Friday as the upper level ridge axis moves off to our east and a shortwave trough drifts over the desert Southwest. The ascent and vorticity enhancement with this disturbance will remain well to our south, and no precipitation is expected. However, cloud cover should keep temperatures a few degrees cooler, in the low to mid 60s at low elevations and 40s-50s for the mountains.

Temperatures finally cool down to near-average values for the time of year this weekend as a broad upper level trough (remnants of what was once a potent mid-latitude cyclone) slides southeast over our area. Areas of fog are likely to develop as far west as the I-25 corridor in the early morning hours Saturday as temperatures drop into the mid 30s and southerly winds, as well as a lee surface cyclone, advect higher dewpoints. The weakening upper level trough will also bring a plume of Pacific moisture that should promote light mountain snow and scattered rain showers over the plains Saturday afternoon. In terms of snow, 1 to 3 inches of total accumulation for this event seems reasonable at elevations above 10kft, with locally higher amounts above 12kft. For the low elevations, rain showers should remain quite light in intensity, with only a trace up to a few hundredths expected mainly over the east CO plains. A few snowflakes or a rain/snow mix cannot be ruled out over the Palmer Divide late Saturday evening as the system exits the region and temperatures begin to drop into the mid 30s.

Sunday is shaping up to be a mostly sunny autumn day with temperatures in the low to mid 50s for the Denver metro and east CO plains, which is near-average for the time of year. An upper level ridge will begin to build over our region on Sunday into Monday, with temperatures expected to warm back up into the 60s once again for much of the plains and foothills Monday-Tuesday. A pattern change is expected to arrive by Wednesday as a shortwave trough slides over northwest CO. This is also where uncertainty enters the picture, with ensemble guidance showing increasing spread in temperature and moisture through next weekend. At this time, our northern mountains look to be favored for mountain snow with the first wave on Wednesday. We are fairly confident in temperatures dropping to seasonable values by the end of next week. Long-range ensemble members and deterministic runs have continued to hint at another system bringing more mountain snow chances, and potentially some snow for the low elevations as well. However, it is far too early to come to any conclusions about snow amounts or even precipitation type. At this time, global model ensembles show a 15- degree spread in temperature between the 25th and 75th percentiles alone. Nevertheless, more active weather and cooler temperatures seem to be in store starting mid next week, likely continuing through Thanksgiving week.