Extended wintry period tonight through Thursday

Noon MDT, Saturday, April 11, 2020

Easter Sunday will be wintry this year. In fact, looking back over the last few months, Christmas Day, New Years Day, Martin Luther King Jr Day, and St Patricks Day all had dry weather with daytime temperatures in the 50s. Easter will be different.

A multi-day spell of unseasonably cold weather will begin tonight and extend through at least Thursday. Record lows might be set early in the week and there will probably be more than one snowy period, with the first beginning early Easter morning.

Snow

The ground will probably be whitened Easter morning by 1-4″ in and near the foothills (Boulder, Broomfield west side of metro Denver, Castle Rock, and Cheyenne), but perhaps and inch or less farther northeast (DIA, Longmont, Fort Collins) and down in Colorado Springs.

There is a good chance lull periods Sunday, but it appears a few more inches are likely after Sunday morning, especially Sunday night into Monday. Some areas, especially foothills locations, will probably top 6 inches. Very cold temperatures Sunday night might cause widespread icy road conditions.

The cold unsettled weather will continue through midweek, with some indication of another period of accumulating snow late Wednesday or Thursday.

 

Cold

If skies clear or partially clear, there is a good chance for record lows Monday morning, and a chance Tuesday morning too. The record low for Monday is 14 in Boulder (1959) and 17 in Denver (1933). The Tuesday morning record lows are 14 in Boulder (2014) and 15 in Denver (1933). Temperatures on Sunday are likely to remain below freezing all day, and only get up to around freezing on Monday. The strength of the April sun (even when it’s overcast) should be able to keep the main roads just wet during the day, or dry them during lull periods.

Unseasonably Cold Sunday-Thursday, Snow on Easter

5:15 AM MDT, Friday, April 10, 2020

A stretch of unseasonably cold weather is set to begin Saturday evening and continue until Thursday of next week.

April Snow

There is a possibility of a couple periods of snowfall at all elevations, the first such period Saturday night and Sunday. The potential exists for a 6 inch snowfall for Easter, although at this point it appears the lower elevations probably won’t have that much.

Record cold

Temperatures on Easter Sunday might stay below freezing during the day even in the low elevations. If there is clearing Sunday night we might see record lows (the records for Monday morning are 15 in Boulder and 17 in Denver).

Colder Thursday, some wet snow

5:45 AM MDT, Wednesday, April 1, 2020

After a mild Wednesday a cold front will push south through the Front Range region tonight. Thursday is forecast to be a colder and cloudier, with cold and mainly cloudy conditions lingering into Friday. After a cold start on Saturday, the weekend should see the return of milder spring weather by Sunday.

 

Precipitation: After a chance for some intermittent mix of rain, drizzle, or snow Thursday morning (snow above 7500 feet), there will likely be a period from late afternoon through Thursday night when wet snow is more likely. This storm appears to be about the same magnitude as last week’s. So the most likely accumulation by Friday morning is 2-5″ above 7500 feet, 1-4″ lower foothills, and 0-2″ in the urban corridor.

Colder Friday, some clouds and precipitation around

5:45 AM MDT, Thursday, March 26, 2020

Today will be the last day with above-average temperatures for a while. Although very cold weather is not expected, Friday will trend colder with clouds around and some showery precipitation. This is not expected to be a very wet storm like last week. Saturday to Monday are forecast to be generally dry (maybe a few showers around Monday). Sunday will probably see the mildest temperatures of the weekend, with afternoon temperatures close to average (which is upper 50s for Denver-Boulder).

 

Will it snow Friday? The precipitation that is around Friday morning is expected to be intermittent and mainly rain below 7500 feet. Later Friday there is a chance for a change to snow in lower elevations, mainly in southeastern Wyoming and in the Palmer Divide region of Colorado. Accumulations in Cheyenne and the Palmer Divide region are likely to be in the 2-5 inch range.  For Denver-Boulder-Fort Collins and Colorado Springs, 0-2 inches. The chance for accumulation goes up with elevation, and there is a good chance for a 6-inch snowfall above 7500 feet.

Spring storm Thursday

2:40 PM MDT, Wednesday, March 18, 2020

Spring officially begins tomorrow at 9:49 PM. A strong storm should move fairly quickly through the region in the morning to afternoon hours with rain, snow and wind. There may be a few showers scattered around this evening. Toward morning rain below 6000 is likely, and snow above 6000 feet (probably starting as rain between 6000 and 7000 feet). The heaviest precipitation is likely Thursday morning when it will transition to snow at all elevations, probably organized into some intense north-south bands. If those bands occur before the changeover in  lower elevations, most precipitation will fall as rain. For low elevation areas that experience the heavier bands after the change to snow, there could be 6 inches in a few hours.

 

One of the better performing high-resolution models, the HRRR, forecasts little or no snow for parts of the region below 6000 feet (including Boulder and northwest Denver). Although I can’t dismiss that, I think a more likely scenario is widespread accumulation below 6000 feet, with some locally heavy areas.

Mountains, foothills, Palmer Divide above 6500 feet: 10-18 inches.

Below 6500 feet: widespread 3-6 inches mainly in grassy areas, with a subset of the area (not necessarily near the foothills) getting 6-10 inches in a short period of time and experiencing travel disruptions. Colorado Springs will probably get less than 3″.

Gusty north-northeast winds will probably cause blowing snow, especially along and east of I-25.

Storm still expected to move through Wednesday night and Thursday

4:10 PM MDT, Tuesday, March 17, 2020

A strong storm system is still expected to move through the Front Range region Wednesday night and Thursday.  We will likely see a mild Wednesday ending with a small chance for showers and thunderstorms late in the day. Wednesday night will bring a good chance for rain below 6000 feet, snow above 8000 feet, and rain changing to snow in between. Thursday morning is when we will likely see a changeover to snow at all elevations, then tapering off late in the day.

 

Thursday morning is the most uncertain part of the forecast. Although the storm is farther south that it appeared it would be in yesterday’s forecasts, it is moving rather quickly and may do most of its intensification as it gets to the east of the Front Range. For now the Front Range urban corridor should expect that there could be a period of heavy snow and wind early Thursday with amounts around 6 inches in a short period of time (lesser chances in Colorado Springs). Foothills and mountains could see locally 12-18″, mainly north of I-70. Will update tomorrow.

Strong storm Thursday; maybe a near miss for Denver-Boulder

12:30 PM MDT, Monday, March 16, 2020

This afternoon through Wednesday

There is a cold front moving southwestward across northeastern Colorado at noon today. The temperatures at noon are about as warm as they are likely to get, and it may start trending cooler this afternoon. It’s not a cold air mass moving in, so tonight and Tuesday are likely to be cool, but not cold, with some clouds around through Tuesday morning. Wednesday is likely to see warmer temperatures.

Wednesday night and Thursday

A strong storm should move through the central Rockies Wednesday evening and Thursday with some rain or thunderstorms in its warm sector, and the potential for blizzard conditions on the north side of the storm track as it moves into the Great Plains. With the center of the surface storm likely to be in northeastern or east-central Colorado, it may strengthen too late and be too far north for major snowfalls in metro Denver-Boulder. But we can’t write it off yet.

 

Here’s a roundup of what it is currently looking like for different parts of the area:

Far northeastern plains of Colorado , western Nebraska, southeastern Wyoming (including the Cheyenne area): Good chance for a period of heavy snow and wind Thursday and Thursday night with travel disruptions.

Fort Collins and Greeley: lesser chances of heavy snow here, but certainly it’s still a real possibility.

Denver-Boulder metro: Chances are smaller here, but even here just a small shift in storm track (to the south and west) could result in a significant storm.

Colorado Springs: there would have to be a major error in the current models for a big snowstorm in Colorado Springs.

For most areas there will probably be some rain or thundershowers around on Wednesday evening as the storm approaches, and blustery north winds as the storm pulls away late Thursday.

Spring Equinox

Spring officially begins at 9:49 PM MDT on Thursday.