Near record highs Sunday across the region, snow and cold return to the forecast on Monday

Denver is set to challenge its record high for the date (74°F, 1934) today as temperatures warm across Eastern Colorado ahead of a dramatic change to our weather on Monday.

The outlook for Denver is below, WARM today... to perhaps sub-zero temperatures by Wednesday morning –– along with that chance of snow:

As is often the case, the arrival of the cold air and snow looks a bit faster than it did in our update on Friday. Northern Colorado is likely to start seeing freezing drizzle and snow Monday morning, with the latest guidance showing snow showers on the increase across the Denver area by late morning to the early afternoon after an initial chance of freezing drizzle in the morning. The latest GFS is painting a very tough commute across the northern urban corridor Monday evening, with temperatures in the low to mid-20s and pockets of heavy snow up and down the Front Range. Tuesday morning's commute won't be much fun either.

The National Weather Service in Boulder has issued a Winter Storm Watch for the foothills. Should things stay on track today, it's likely the advisories eventually grow to include the urban corridor. Several inches will be possible when all is said and done, with the heaviest snow expected to fall along and west of I-25.

Snowfall forecast
We will go with 3 - 7" from Denver north along the I-25 urban corridor. Locations to the west and south as you go up in elevation a bit will fall into the 5 - 10" range. A few foothill locations could do a foot of snow we think. Colorado Springs will be on the edge of the heavier snow (the trend has been for less snow for COS), but the north side especially could still do okay.

This morning's gamblers are bullish, to say the least. At 15:1 snow to liquid ratio (we'll likely average a bit lower than this overall) we see odds of Denver hitting the high-end of our forecast for Denver (7 inches) seeing at about 65%, with Boulder seeing a greater than 50% odds for 9 inches or more. Totals should be lesser south of the Palmer Divide, but even Colorado Springs could manage a few inches by Tuesday:

Probabilities from the European ensemble look much like they did on Friday. For the Colorado Springs area again –– much lower odds you'll break the 3-inch mark. For the Denver metro area and points north and west the odds are looking pretty good:

Temperatures!
A big part of the story will be the dramatic drop in temperatures over the coming days (hours really). MOS guidance has highs in the low to mid-70s today, but only in the teens for highs by Tuesday. MOS guidance has the coldest air of the year in place by Tuesday night, dropping most of Northeast Colorado to near zero, or perhaps below by early Wednesday morning.

The European model (and several other operational models) are even colder with their 2-meter temperatures. Most NWP show lows from 5 to 10 degrees below zero Wednesday morning. We'll stick closer to MOS guidance, with a low around -2 for Denver at this time.

Impacts, timing, etc
Sunday will just beautiful across the region, however windy in many spots.

Monday that all changes as the wind will bring in a sharply colder airmass.

Snow will increase from north to south through the day Monday, and become heavy at times from Monday afternoon through Monday night. Travel will not be advised (especially west of I-25) Monday evening and night, with conditions gradually improving Tuesday.

The worst commutes at this time look to be Monday evening and Tuesday morning, though if freezing drizzle does materialize Monday morning some slick spots to start your day across Northeast Colorado will be possible too. For those north of Denver, it could be both your commutes on Monday have snow, so please plan accordingly.

Still, a few more rounds of data to work through today, so we'll see if any major changes to our thinking develop and if so offer an update to say as much either tonight or Monday. For now, plan on some accumulating snow Monday PM through Tuesday AM, with COLD air to boot!

Brendan Heberton

Brendan is founder of Weather5280. He is co-founder of FreshyMap, and develops software for geospatial data analysis and visualization.

Denver, Colorado
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