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Strong storm Sun evening – Tue morning: rain, thunder, hail, snow, and even a dry sector.

1 PM MDT, Sunday, May 19, 2019

A powerful storm will move from the 4-corners region, across southeastern Colorado, and into Kansas on Sunday evening through Tuesday. The headlines from the storm Monday and Tuesday could be from a severe weather outbreak with tornadoes in West Texas, Oklahoma, and Kansas. Closer to home we will see a variety of weather in the Front Range region, with some thunder here too. Much cooler than average temperatures will continue into midweek.

 

The dry slot

With these kinds of storms there is often a dry sector that moves up from the south on the east side of the storm and is known as the dry slot. That will likely affect south central parts of Colorado Monday and Tuesday, so areas along the Front Range from Colorado Springs southward have a lower chance of persistent clouds and wet weather.

Rain and thunderstorms

Showers and a few thunderstorms are likely to develop in some areas this afternoon and evening despite the low clouds and cold temperatures. Tomorrow and early Tuesday will likely see some intervals of rain or drizzle, with thunderstorms developing in some areas in the afternoon. The most intense thunderstorms are likely near the Kansas or Oklahoma borders, but a few strong thunderstorms (with hail) may occur along the Front Range.

Snow, again?

Heavy snow (over a foot) is likely above treeline and mainly north of the Pikes Peak region. The snowline is likely to work its way to lower elevations Monday night and early Tuesday. Some snow accumulation appears likely in most areas above 7000 feet (and mainly north of I-70). A couple inches appears likely for Nederland and Estes, with a small chance of more than 6.

Some mesoscale models bring the snow all the way down to the urban corridor late Monday night with a bit of slushy accumulation by Tuesday morning. It appears these models don’t really have temperatures cold enough, but it’s close, and nighttime is the right time if it’s going to happen. I’d say that snow in Boulder, Denver, and Fort Collins is unlikely but not out of the question (about a 20% chance).

 

Low elevations freezes

A widespread hard freeze is unlikely, but areas of local frosts are possible, especially if there is some clearing on Monday, or Tuesday nights (Tue or Wed morning). It’s probably good to protect sensitive plants just in case.

 

Whew, and I didn’t even get into the latter part of the week yet…

 

 

 

 

The warm spell is over

5:30 AM MDT, Friday, May 17, 2019

The 80 degree days are over for at least 5-7 days. Two major storm systems will move through the Colorado/Wyoming region, one later today and tonight, and another early next week.

Today and tonight

It will still be near or a little above average in temperature today, but with a better chance for thunderstorms this afternoon and evening. The best chance for strong or severe thunderstorms will be on the far northeastern plains of Colorado, southeastern Wyoming, and in Nebraska. The lowest chance for thunderstorms is south of Denver.

 

Saturday and Sunday

Cooler weather with some showery periods possible, but for the foothills and plains it should be dry most of the time. In the mountains, the chance for showery periods is a little greater, and there may be some snow above treeline. The potential for clouds and precipitation increases a little late Sunday as the next storm approaches.

 

Monday-Tuesday

This could end up being a very cool and occasionally wet period, with substantial snow above 8000 feet and cold rain in the lower elevations. I’ll have to update on this later in the weekend. There is a small chance for damaging nighttime temperatures for tender plants, but it’s too early to tell yet.

Rain, snow, and cold into Thursday

6:00 AM MDT, Tuesday, May 7, 2019

We are in for several days of generally cloudy, damp weather with some freezing temperatures in the lower elevations possible Thursday and Friday mornings.

 

The clouds may thin a bit at times today, but even if that happens, expect some more showers or even some thunderstorms this afternoon, and cool temperatures. The coldest stretch of this pattern will move in on Wednesday. Several intervals of steady rain (snow in the higher elevations) are likely Wednesday afternoon into Thursday, It is now looking more likely the rain will mix with or change to snow in parts of the urban corridor Wednesday night or Thursday morning. I would not be surprised to see a couple inches, mainly in grassy areas. The amount of snow will be greater as you go up in elevation, with 5-12″ above 7500 feet.

 

Temperatures are likely to be within a few degrees of freezing on Thursday and Friday mornings, so prepare to protect tender annuals that are outside.

Another multi-day cold & damp spell is coming this week

11:30 AM MDT, Sunday, May 5, 2019

This coming week is likely to bring a multi-day stretch of below-average temperatures and a good chance of rain (snow in the mountains).

Although Monday may be a little cooler than today, it will likely still be a mild day with only a slight chance of afternoon showers or a thunderstorm. Tuesday might be a bit cooler with another chance for afternoon showers or a thunderstorm.

The peak of the cold snap appears to be on track for Wednesday and Thursday. During that time there may be long cloudy stretches and a period or two of steady rain (snow in the mountains). Although this spell is not likely to be quite as cold as last week’s cold snap, I can’t completely rule out the chance for some wet snow in the lower elevations, but the chance appears to be small. Gardeners even in the low elevations should prepare for the risk of damaging frosts (for tender annuals) on one or more mornings from Wednesday to Friday.

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.