Monthly Archives: April 2019

Multi-day cold spell, and some snow too

11 AM MDT, Sunday, April 28, 2019

At 11 AM Sunday a cold front resulted in a 15-20 degree drop in temperature at Casper, WY. That cold front should move through Cheyenne in the midday hours and then through the Colorado Front Range urban corridor by late afternoon.

Rain and snow is likely to come in several intervals. The first this evening. After a lull, the period with the best chance for snow at all elevations will probably be late Monday afternoon and night. There may be one more round of precipitation Tuesday evening too.

 

This afternoon/evening

Some showers and thunderstorms are likely to develop behind the front this afternoon/evening followed by some areas of drizzle during the night. Snow above 9000 feet is likely to move to lower elevations by late night, but accumulation, if any, should be mainly above 7500 feet and mainly in the 1-5 inch range (highest above 9000 feet).

Monday and Monday night

The second round of precipitation likely from about midday Monday until late Monday night will occur with the highest amount of atmospheric moisture during the next few days, and the lowest temperatures. Therefore, this period may bring the best chance for heavy snow in the mountains and rain changing to wet snow with some accumulations in the lower elevations. During the period 5-9 inches could occur above 7500 feet, with 3-6″ in the 6500-7500 elevation range, and 1-4″ below 6500 feet.

Tuesday night and Wednesday morning

There may be one more round of rain and snow Tuesday evening through Wednesday morning. It looks like the atmosphere  may be a little warmer for this period (than on Monday night) so the chance for additional snow in the lower elevations is small.

 

With this kind of wet period over several days, the total amount of snow accumulated will probably be higher than the maximum on the ground at any one time due to melting during lull periods.

Colder and maybe some snow early next week

9 AM MDT, Friday, April 26, 2019

Many parts of the Front Range urban corridor have had 10-11 days without a frost or freeze and gardens are coming to life. But don’t be fooled. Not only does climatology suggest that the last freeze in Denver-Boulder-Fort Collins is typically in early May, but today’s weather maps strongly suggest a cold period beginning Sunday evening and continuing until midweek. We will probably see widespread freezing temperatures during at least one morning in that stretch. There is also a chance for one of more periods of cold rain giving way to wet snow even in the lower elevations (possible heavy amounts in the mountains) in the Sunday night through Tuesday time period.

 

Until then the weekend should be relatively mild and dry. But be prepared for some afternoon/evening showers or thundershowers scattered around today and again on Saturday.

Some rain on Easter, but probably late in the day

Noon, Saturday, April 20, 2019

Showers and thunderstorms are likely to develop in the Front Range region on Easter Sunday, but probably not until mid afternoon or later. So odds are that morning Easter egg hunts will be okay.

 

After some showers and thunderstorms late Sunday, there may be a period of steady rain or drizzle in the evening or overnight. The snow level will start to lower, but probably not enough to result in accumulating snow below 6500 feet. Even higher up snow accumulation will likely be minor. Cooler weather arriving late Sunday will continue into Tuesday.

Changeover to snow a little ahead of schedule

12:25 PM MDT, Wednesday, April 10, 2019

The changeover to snow is occurring a couple hours ahead of schedule compared to yesterday’s forecast. For the urban corridor (north of Colorado Springs) we are still looking at 2-5 inches widespread. But, it is likely that a band of intense snow, roughly in a north-south direction, will develop on and off between now and early evening. This could make some heavy snowfall rates of 1-2 inches per hour and maybe thundersnow. In areas that end up under the band for a couple hours there may be some local reports of 5-8″, but that is likely to be a subset or the region between Denver and Cheyenne. Be prepared for rapidly changing conditions over distances less than 10 miles.

 

Thursday morning’s commute should be fine.

Strong storm develops in eastern Colorado and moves east on Wednesday and Wednesday night

2:15 PM MDT, Tuesday, April 9, 2019

The impacts of the storm will be greatest out in the northern Great Plains states, but there will also be big changes tomorrow here along the Front Range. The storm will feature rain, some localized thunderstorms (possibly with small hail), snow of varying intensity, and strong north winds. The cold front will likely move through in the morning, and the best chance for snow beginning in the urban corridor is in the early to mid afternoon after some rain. Snow will likely begin affecting the high elevations and Cheyenne in the late morning to early afternoon. Wind and precipitation should let up during the night (before Thursday morning).

 

Snow Accumulations:

Above 7000 feet:

5-15 inches, heaviest above 8500 feet and north of I-70.

Lower foothills and urban corridor:

Most likely: 2-6 inches, perhaps in bursts with strong north winds, metro Denver to Fort Collins (probably less in Colorado Springs and at least 5 in Cheyenne)

~10% chance of 6-10 inches (this small chance is based on the storm being a little farther southwest resulting in more northeasterly flow and snow lasting well into the night)

~10% chance of little or nothing

High Plains:

Most likely 3-8 inches on the plains east of Denver with blowing snow Wednesday evening.

Impacts:

Flight disruptions at DIA Wednesday and some winter travel conditions on the roads, especially in the mountains north of I-70, east of Denver on I-76 and I-70, and I-25 from Fort Collins to Cheyenne.

Getting around should be fine Thursday morning unless you are in the far northeastern plains of Colorado, Nebraska, South Dakota, or Minnesota.

Thursday to Saturday

This change to cold won’t move on very quickly.  A relatively cool period will continue, with some more chances for light precipitation Friday or Saturday before mild weather returns Sunday.

 

 

 

Winter is not gone yet…

12:15 PM MDT, Monday, April 8, 2019

Despite the warm weather today and tomorrow (maybe even near record warm tomorrow), anyone who has lived along the Front Range for a while knows that winter often makes a few encore performances during the Spring season. A shift to colder and wetter weather is on track for Wednesday and Wednesday night. The shift will likely be accompanied by a strong surface cyclone Wednesday afternoon and evening that should cause strong north winds on the plains.

Thunder, rain, and snow

This could be a situation with a foot of snow in the mountains, especially north of I-70, with lesser amounts as a go below 8000 feet due to more rain at the start.

For plains the snow potential is highly uncertain. Right now it appears the location of the storm will result in mainly north winds, rather than northeastly. In those situations the areas right along the foothills (eastern Larimer and Boulder counties and the west side of Denver) will often see the precipitation shift east soon after the changeover to snow resulting in only minor accumulation. But a slight error in the storm track forecast can make a difference.

 

So here is the synopsis for now:

Showers and thunderstorms develop Wednesday and change to snow in the late afternoon. Strong north winds develop during the afternoon, especially east of I-25. Accumulation potential in the lower elevation ranges from 2-8 inches. Travel may be difficult east of Denver Wednesday night (I-70 and I-76), and if you are travelling through DIA bring a good book.

 

 

 

April showers

6:00 AM MDT, Tuesday, April 2, 2019

A weak Pacific storm system approaching and moving through the central Rockies today and tomorrow will increase the chance for a few showery periods over the next two days. This is not a wash-out type of pattern. We are likely to have long dry intervals and temperatures near average today and Wednesday. The best chance for showers (mainly rain below 7500 feet) and maybe a thundershower will be in the afternoon/early evening today and tomorrow. Warmer weather is expected on Thursday .