Mainly dry and cool through the weekend

11 AM MST, Wednesday, November 25, 2020

Except for a small chance of some spotty light snow Thanksgiving evening, the 4-day weekend should be dry and cool. A weak storm moving through on Thanksgiving may produce a few patches of light snow in the early evening, but most of the Front Range region will have little or no accumulation. Where it does accumulate, it will likely be less than an inch.

Saturday will probably be the only day of the weekend with afternoon temperatures a little bit above average. The other days will likely be a little below average (staying below 50 in the urban corridor). So overall, there is not too much to report for the long weekend’s weather.

Snow by Tuesday morning

11:15 AM MST, Sunday, November 22, 2020

Today through Tuesday

A relatively fast moving but organized storm system is likely to bring some light to moderate snow accumulation Monday night and early Tuesday, mainly in the Denver-Boulder metro area south to the Palmer Divide region.

First we will see a warm-up on Monday with afternoon temperatures in the lower elevations reaching the 50s to around 60. As the storm first begins to impact the Front Range region Monday night, there is a good chance it will be rain below 6000 feet, but snow at all elevations by morning. Snow is likely to end during the day Tuesday.

Potential accumulation:

For areas north of a DIA-to-Lyons line the accumulations are probably going to be very minor if any (trace to 1 inch).

South of the DIA-to-Lyons line (including Boulder, Broomfield, Lakewood, Denver, Castle Rock) there is likely to be 1-3 inches, and because the storm’s organization is increasing with time, I think there is about a 1-in-3 chance for 3-6 inches. South of the Palmer Divide in Colorado Springs the chance for 3-6 inches is less.

Above 6000 feet a 6-inch storm appears likely, especially in Boulder, Jefferson, and Douglas counties.

Wednesday-Friday

After a seasonably cool and dry Wednesday and Thanksgiving Day, the next chance for snow (probably light amounts) will probably occur sometime between Thanksgiving evening and early Friday. Dry weather is likely to be with us for the remainder of the long weekend.

Strong winds this weekend; warm next week

6 AM MST, Friday, November 13, 2020

A Pacific cold front on Saturday is likely to bring some very strong west and northwest winds to the Front Range region, along with some snow near and west of the continental divide.

Today should be the mild day of the next three days. Snow is likely at the high passes tonight and Saturday (maybe 3-6 inches). Some brief rain or snow showers may move east over the lower foothills and plains on Saturday, but the weather east of the continental divide should be mainly dry.

The strong winds (gusts over 60 mph) could be affecting some local areas in the higher elevations and near the foothills by Saturday morning. The chance for high winds will probably increase and spread out onto the plains by Saturday night. I would not be surprised to see some local reports of 75 mph winds.

Temperatures should be seasonable to a little below average Saturday afternoon and Sunday. But it looks like an unseasonably warm period will begin Monday afternoon and continue through much of next week.

Cooler Sunday, maybe snow Monday

Noon, Friday, November 6, 2020

Our unseasonably warm weather is forecast to be replaced by colder, but not bitter cold weather, Sunday and early next week. No major precipitation episodes are expected, but some mountain snow/valley rain is likely in mountain areas Sunday, and on Monday the chance for some snow exists for the Front Range region (including the urban corridor).

A Pacific cold front on Sunday will start the cooling trend. Although most precipitation with it will be in mountain areas and west of the continental divide, there may be a brief period with showery precipitation (mainly rain) and gusty winds along the Front Range early Sunday. Monday should be colder still, with some areas of low clouds and mainly light snow for parts of the Front Range region.

Snow and record cold coming Sunday

9:30 AM MDT, Saturday, October 24, 2020

But first, the fires. Gusty and dry west winds are already occurring above 7500 feet and will continue through today creating conditions for spreading wildfire. Those winds make break through the denser cold air in some places below 7500 feet as well. Then, a record cold air mass and snow should quiet the fires tonight and Sunday.

The cold front will likely be through the Cheyenne area in the late afternoon, the Boulder-Denver area early this evening, and Colorado Springs a couple hours after nightfall. We are not likely to see temperature rise above freezing again until Tuesday afternoon. Snow is likely to begin during the late night in Cheyenne and spread southward during Sunday morning. Sunday and Sunday evening are expected to see the most snow, but some areas of snow could linger into Monday morning.

The upslope (northeasterly winds into the mountains) will favor areas in and along the foothills and the north side of the Palmer Divide for the heaviest amounts. But there will be another important element with this storm. Bands of heavy snow oriented southwest-to-northeast about 10-20 miles wide will probably develop and extend 100 miles or so out onto the plains. Snowfall rates in these bands could exceed an inch per hour. Some areas might only see those heavier rates for about an hour, while other areas could experience one or more multi-hour periods of moderate or heavy snowfall rates.

Most likely accumulation:

3-7 inches: northeast plains (DIA, east side of Denver metro, Weld County, Longmont), with the heaviest amounts where those heavy bands occur.

6-10 inches: in and near the foothills (west and south sides of Denver metro, Castle Rock, Boulder, Nederland, Estes Park, Cheyenne)

12 inches: in some locations where the heavy bands are more persistent (probably about 10% of the area)

Records:

Snowfall records are not expected since the storm is occurring on the same dates as the October blizzard of 1997 that left 15-50″ throughout the region (including 29.8″ in Boulder).

Record cold is very likely. Sunday and Monday high temperatures should remain below freezing, and possibly in the teens on Sunday. Monday and Tuesday mornings will probably range from the single digits to low teens.

Fire weather to winter weather

1:00 PM MDT, Thursday, October 22, 2020

The first of two strong cold fronts is impacting the lower foothills and eastern plains of Colorado but not resulting in much change for the higher terrain and west of the continental divide. The next cold front Saturday evening is expected to bring more widespread cold as well as snow to the whole area during the second half of the weekend.

Fire weather

The lower elevation fires east of the divide are being tamed by the colder and damper weather in the eastern foothills. There may be a brief period of warmer and drier westerly winds that develop on Saturday ahead of the next cold front, but then very cold weather and snow should really help control those fires Sunday and Monday.

The high elevation and west slope fires (like East Troublesome Gulch) are still in the relatively dry and warm air above this shallow cold air mass. By Saturday it is likely that strong westerly winds will develop ahead of the next cold front. Then snow and cold on Sunday and Monday should help quiet those fires as well.

Cold and Snow

Today’s cold air and clouds are shallow (the higher mountains are above it) and not likely to produce any significant precipitation. But there will probably be some areas of drizzle or freezing drizzle and maybe some tiny snowflakes (called snow grains) through Friday morning, mainly in localized areas in and along the foothills.

After the cold front late Saturday we are likely to see widespread snow and cold, with record cold possible early next week. At least a couple inches of snow appears likely, and this type of storm may exhibit some southwest to northeast bands of snow with heavier amounts. I will update on Saturday.

More fire weather, then colder Thursday, snow this weekend

11:30 AM MDT, Tuesday, October 20, 2020

Dry and mild weather with some gusty west winds Wednesday will keep the fire danger high for the next 36 hours. Then a cold front on Thursday will turn it colder and less windy (after an initial surge of north and northeast wind), and a colder front late Saturday will likely bring some snow with it.

Today through Friday morning

There is already a weak front moving through today. Wind should calm down later today and overnight. Gusty west winds may develop again in and near the foothills Wednesday afternoon and night ahead of the next cold front that should push through on Thursday (probably morning or early afternoon). There may be some areas of low clouds and light freezing drizzle Friday morning, but most areas will stay dry as the temperature falls below freezing.

The Weekend

The cold front this weekend is looking quite cold and accompanied by a storm system. It may not warm up too much ahead of the weekend cold front. Friday afternoon and possibly part of Saturday should be the relatively mild part of the weekend, but still cool. Right now it appears that the cold front will push through sometime Saturday afternoon and snow should develop Saturday evening or very early Sunday. It looks likely that at least several inches will occur across the Front Range region, but that part of the forecast will need updating later this week.

More wind and smoke

2:45 PM MDT, Friday, October 16, 2020

The next cold front for the Front Range region is due to move through late Saturday afternoon or evening. Gusty winds may develop tonight and continue Saturday ahead of the cold front, with warm and dry conditions. Areas east and southeast of the major fires will have the highest chance of smoke.

Gusty winds from the north or northwest are likely behind the cold front late Saturday, and then decrease in strength as they will swing around to the east and southeast by Sunday. Sunday will be the cooler day of the weekend, and there is a chance for some areas of clouds by Sunday morning. But overall, dry conditions are forecast to continue for the foreseeable future.

The impact of the cold front will be much smaller in western Colorado where dry and relatively warm weather is expected this weekend. Watch for gusty winds above treeline and at the passes on Saturday.

Widespread frost tonight

10:30 Am MDT, Wednesday, October 14, 2020

For many parts of the Front Range region there has already been frosts and freezes going back to the first snow on September 8th. But some areas have escaped anything too damaging. A cold front approaching Cheyenne late this morning should sweep down the Front Range this afternoon. With a good possibility of clear skies and lighter winds late tonight, there is a good chance for widespread temperatures in the upper 20s to low 30s by Thursday morning, and maybe again on Friday morning.

Until then expect warm and windy weather to give way to cooler and windy weather this afternoon and evening. The winds should ease up during the night. Thursday should be a cool day but mainly sunny, then warming up again by Friday afternoon.

Cold front on Sunday, Windy

6 AM MDT, Saturday, October 10, 2020

A cold front should return temperatures to more average autumn levels on Sunday afternoon. For the eastern foothills and plains, Sunday morning will probably still be relatively warm. Windy conditions across the state later today and Sunday are likely to enhance the already serious fire danger and create large areas of smoke downwind of fires.

Precipitation with the cold front on Sunday will probably be limited to mountain areas, especially west-facing slopes. That will probably help tame some of the fires. But significant and widespread precipitation is not expected, and a dry week ahead may very well see more fire issues.