Castle Rock Weekend Weather Outlook for Feb 26-28


Friday February 26, 2016

Friday is a day that will feature light winds and clear skies. Temperatures will be pleasant near 60 for the Castle Rock area and in the low 60’s for Denver and nearby areas. Overnight temperatures will be in the mid to upper 30’s.

Saturday February 27, 2016

Mostly clear skies for Saturday with temperatures generally in the upper 60’s to low 70’s. Castle Rock is currently projected to be just shy of 70, but if we get a little help from some down-sloping winds (possible in the afternoon) we could see the 70’s for many areas South of Denver. Nighttime temperatures will be in the upper 30’s to lower 40’s for most areas.

Sunday February 28, 2016

Sunday will be slightly cooler but still feature well above average temperatures. Many areas will be in the lower 60’s during the day and mid to upper 30’s overnight under mostly clear skies and a bit of breezy conditions here and there.


Severe Weather Outbreak Likely in Southeastern U.S.

Severe Weather Outbreak Likely for Southeastern U.S. Please Warn Your Friends and Family in the Area. The possibility of violent, long track tornadoes is high.



As the storm system responsible for our snow in Colorado moves off the Southeast it will spawn some pretty nasty weather on the front end of the system. The Storm Prediction Center has a moderate risk over portions of Southeastern Louisiana, South Alabaman and Mississippi. This is not entirely unusual for this time of year for these areas, we have seen several early seasons severe weather outbreaks in this area in the last few years.

I know this page is mainly dedicated to Colorado weather, however many of us have friends and family all across the country. This will be a serious situation as we head into the afternoon and overnight hours on Tuesday. If you have friends or loved ones in the area, please tell them to be very alert.


Here’s a closer look at the affected areas:


Technical Synopsis

For those interested in more of the technical aspects of this severe weather setup, I will briefly go over a bit of that information right now. **Note all times I discuss are mountain so add 2 hours for Eastern… i.e. 8am is 10am and 8pm is 10pm.

Currently the storm system that moved through Colorado is intensifying over the Texas panhandle. A look at upper and lower level wind maps shows the upper low and closed surface low clearly:

Upper level jet

Upper level jet

Mid-Low level winds

Mid-Low level winds










The two above images show the storm system as it was at 8am this morning.

The next two show the storm this afternoon as it has intensified and moved Eastward:

8pm storm position

8pm storm position

Low-mid level position as of 8pm

Low-mid level position as of 8pm










So as you can see, a strong upper level jet (100 kt winds) and strong wind motion at the mid levels (60kt winds) should create ample wind shear in the atmosphere. This is usually called vertical shear or speed shear. Winds travelling at different speeds in the same direction in the atmosphere create a rolling motion:


This is important as it is a critical component of creating and sustaining severe thunderstorms.

Illustration of the formation of a tornado. (1) A wind shear forms; surface winds roll air into a horizontal tube. (2) Updraft; Sun warmed air lifts a section of the vortex vertically. (3) A storm forms; one side of the vortex becomes stronger and forms into a thunderstorm, while the other side dies. (4) Supercell; A mesocyclone pulls more warm air up into the storm, allowing it to grow. The spin then intensifies and a rotating column of air will break through the wall cloud and hit the ground.

Image Credit:

I’ll describe this setup briefly:

  1. Just like the image above, vertical wind shear create a rolling motion in the atmosphere
  2. As daytime heating increases and destabilizes the atmosphere you begin to get lift in the atmosphere
  3. Once a thunderstorm forms or moves along this rotating column of air it lifts and stretches this tube of rotating air
  4. As the storm becomes a super cell it uses the rotating air to pull warmer air into the storm, causing it to intensify

There are a few other factors that will allow these storms to be very strong across the South today. There is a ton of moisture and instability along the front edge of this storm system. That coupled with strong low level winds means Tornadoes will be likely.

I don’t want to get too much into the mechanics of severe weather in general yet, that’s another longer post for another day. When we get towards severe weather season in Colorado I will have a much longer post with more detail on how severe weather and tornadoes form.

In the meantime, if anyone wants to discuss any of this or has any questions, I can always be reached in the comments below or my facebook page.


Monday Winter Storm Update

A quick update on our winter storm set to affect the area tonight and into Tuesday morning; we will be backing off on snow totals slightly with the new data that has come in overnight. The biggest concern will be the lack of strong up slope and the warmer temperatures. As I have mentioned previously, this is not set to be a major storm, certainly nowhere near the impact of the storm we had to start February. Storm systems that slide out of the Northwest generally do not give us long and extended periods of snowfall to create a large storm.

My biggest concern at this time is that temperature gradient, there will be a very sharp line of more rain vs. more snow and whichever side your area lands on will see more snow or more rain and less snow. This can be seen quite well on the model runs:

GFS snowfall totals

GFS snowfall totals

NAM total snowfall

NAM total snowfall









You can see the very clear East/West contrast in snowfall and the line sits right over Central Douglas County. If this line should move further east we would see higher snow totals around town, but this looks unlikely at this time. Right now it looks far more likely that the line could shift West and we could see little to no snow accumulation over the immediate suburbs South of Denver.

All models are in agreement with the forecast so far, even the SREF plumes support a good 2-4 inch range for the Castle Rock area and areas South of Denver.

SREF snowfall accumulation

SREF snowfall accumulation

Updated Snowfall Forecast

  • Denver: 0-3 inches of accumulation by Tuesday
  • Castle Rock:  2-4 inches possible; some areas in the Western part of town may see slightly closer to the 3-6 inch range
  • Western Suburbs: 4-8 inches, mainly in the foothills areas West of Denver and Southwestern Douglas County

Overall, very little change in the forecast from yesterday, Denver’s low end got bumped down slightly as some areas have a stronger possibility of no snow. Castle Rock proper has been bumped down slightly, the temperature gradient will play a big part and I think this storm will struggle to produce much more than 4 inches in and around town. The exception will be areas immediately West and South where 3-6 inches will be possible. Foothills have stayed the same, no change there.


The storm still looks on track to affect us late Monday night into Tuesday morning. Probably midnight Tuesday through about noon Tuesday morning looks like the most likely time to see accumulating snowfall. It may begin snowing as early as 9-10pm Monday night though…

  • Strong northwesterly winds
  • Accumulating snow overnight Monday into Tuesday morning
    • Expect a slow commute Tuesday morning into work, especially if travelling from the South and West suburbs into Denver
  • Roads could be slushy and slick in some areas, leave extra time.


**One extra note:

2-22-2016 advisory

Latest Colorado Weather Watches and Warnings

There are Winter Weather Advisories out but currently they do not include Castle Rock, Denver or the other Southern Suburbs. We do not expect enough snowfall accumulation to make travel exceptionally dangerous, however do expect some slick spots coming in from Monument up through Castle Rock and into Denver Tuesday morning. So mainly, just expect a slow commute.

Snow day looks very unlikely with this storm for the Castle Rock area so don’t plan on a day off Tuesday.

I will have one more update regarding this storm late this evening as I get new data in, happy Monday!


Colorado Returns to Winter This Week

A small disturbance will bring an end to our warm and dry weather, at least temporarily late Monday into Tuesday.This is an interesting storm as it is on a track that does not usually equate to lots of accumulation but as it crosses the rockies into Southeastern Colorado it is expected to intensify very rapidly. This means that the short period of time it sits in that position could mean at least somewhat decent snowfall accumulation for certain areas along the front range.

Storm Track and Position

02212016_wxstory1The ridge responsible for our warm weather the last couple of weeks has begun to slide back to the Southwest just a bit. This will make enough room in the atmosphere for a storm system to move into the state late Monday.

Storms like this generally don’t bring us heavy snow accumulations as they are often quick to move through and out of the state before getting a chance to stall and dump snow over the front range.

What is interesting about this storm is how quickly it will intensify after it slides down over the Rockies and where this begins to occur is a quite favorable area for snowfall along the front range.



You can see in this model run of our low level winds, the storm looks to intensify as it moves into the Southeastern corner and off to the South into the Texas Panhandle. This is generally a very good area for big snow storms along the front range of Colorado, the problem is this particular storm system will move very quickly, meaning it won’t sit over Colorado long enough to really dump on us.

Every model has this system moving East very quickly so there is pretty high confidence in that area. Should the storm slow down at all it could mean slightly higher snow totals for some areas, but this looks unlikely at this point.


Model Predictions as of Sunday Afternoon

You can click on any of these images to see them full size, but here’s a quick look at what the models are predicting through Tuesday afternoon:

Nam QPF (how much liquid precipitation to expect)

Nam QPF (how much liquid precipitation to expect)

NAM total predicted snowfall using 10:1 ratio

NAM total predicted snowfall using 10:1 ratio












Nam4K QPF (how much liquid precipitation to expect) The Nam4K is a higher resolution model

Nam4K QPF (how much liquid precipitation to expect) The Nam4K is a higher resolution model

Nam4K snowfall prediction using 10:1 ratio

Nam4K snowfall prediction using 10:1 ratio












GFS QPF (how much liquid precipitation to expect)

GFS QPF (how much liquid precipitation to expect)

GFS predicted snowfall using 10:1 ratio

GFS predicted snowfall using 10:1 ratio





NCEP Snowfall total. This product averages several different model runs together.

NCEP Snowfall total. This product averages several different model runs together.


The general consensus with the major models is that the front range areas South and West of Denver will be the most favored. Temperatures are going to play a huge part of how much snow accumulates as well. With the warmer weather as of late, the ground is a bit warmer so it will take a bit more time to accumulate snow.


Current Forecast predictions:

  • Denver: 1-3 inches of accumulation by Tuesday
  • Castle Rock 3-6 inches possible, right now it looks like the lower end of that is most likely
  • Western Suburbs: 4-8 inches, mainly in the foothills areas West of Denver and Southwestern Douglas County

What to Expect with this Storm

The main impacts of this storm will be felt late Monday night into Tuesday morning:

  • Strong northwesterly winds
  • Accumulating snow overnight Monday into Tuesday morning
    • Expect a slower commute Tuesday morning into work
  • Roads will most likely be slushy and possibly snow packed Tuesday morning, especially for areas South and West of Denver.

As of right now, no weather watches or warnings have been issued, but we will keep an eye on this storm and update our site as needed.

As always, you can check for Colorado watches and warnings here: Mountain Wave Weather Watches and Warnings

Stay tuned!


Castle Rock Weather Weekend Outlook for Feb 19-21


Friday February 19, 2016

The day has started out windy and will remain that way into the afternoon hours. Temperatures will be nice in the mid 60’s but the gusty winds may make it feel a bit cooler. As we move into the evening, winds will slowly begin to let up and skies will clear. Expect warm overnight temperatures in the mid and upper 30’s.

Saturday February 20, 2016

Mostly clear skies with some high clouds will start the day. Temperatures will be just a touch cooler but the winds should be lighter which will make for an excellent day to be outdoors. We will generally see highs in the low to mid 60’s during the day and overnight temperatures in the low to mid 30’s.

Sunday February 21, 2016


Sunday looks to be our transition day… what are we transitioning to next week? A slightly cooler and wetter period and overall the pattern change will be short lived. A cold front will just brush Northeastern Colorado sometime on Sunday which means we will see cooler temperatures.

As this front moves through, it may shift our winds and bring us enough energy for a chance of  precipitation. The bad news for snow lovers is that most models have precipitation falling as rain and no accumulation due to warm temperatures should any switch over to snow.

Sunday will not be a bad day overall, any rain and snow chances show up in the Monday-Tuesday time-frame.

We’ll have any updates on that weak storm system and front should they become necessary.

Have a great weekend!


Blowtorch 2016 Continues: Temperature Records Fall Along Front Range

A very strong down slope event along the front range caused strong winds, high temperatures and very low humidity today. These events are not entirely uncommon, especially for this time of year. I even mentioned in my last post that we had a stretch of weather just like this almost exactly a year ago.

Today many temperature records were tied or broken and strong winds blew cars around all day, exacerbated fires that started and even caused some damage in areas.

Temperature Records

Here’s a few notable temperature records around the area today:

  • Aurora Colorado: 66.0  <Tied Record>
  • Broomfield Colorado 66.2 <Broke Record, previously 66.0>
  • Castle Rock: 68.0 <Broke Record, previously 67.0>
  • Denver Colorado: 73.0 <Broke Record, previously 71.0>

With this pattern in place a few more days, I would not be surprised to see more records tied or broken through at least Saturday. Some areas in and around Denver actually approached 80 degrees!


Strong Wind Gusts

Not only were the temperatures the weather story of the day, winds were whipping up and down the front range. Check out some of these wind gusts recorded by the National Weather Service today:


Weather Pattern Remains in Place

The system responsible for creating our windy conditions will begin to move East away from Colorado. The high pressure system will remain over the area for a little longer, meaning warm and dry conditions will continue through the weekend. I’ve explained how this pattern keeps us very warm and dry before and it looks to persist for a little while longer.

The high pressure ridge looks to break down int o Sunday as a storm system and associated cold front makes its way through the area. This means expect much cooler temperatures on Sunday and even a small chance of rain or snow into Monday. We’ll have some details on that storm system out sometime this weekend, but at this time it looks very minor.


Expect calmer winds on Friday but breezy conditions will remain. Temperatures will be pleasantly warm.

Stay tuned for the weekend outlook on Friday and a preview of our minor storm system early next week!


The Heat is On!

The warm, quiet and relatively calm weather along the front range means most think there as not been much to talk about as far as weather the last few days, but nothing could be further from the truth! There are a few things happening over the next several days and into the next few weeks that look interesting.

Record Setting Heat Possible Over Next Few Days

The biggest thing you will notice will be the incredibly warm temperatures over the next few days. These warm temperatures will affect most of Colorado, mountains included.

Nam4K predicted temperatures for Thursday around 2pm

Nam4K predicted temperatures for Thursday around 2pm

The Nam4k model shown above shows temperatures along the front range comfortably in the 70’s and even some 80’s across the Southeastern part of the state. All models are in agreement that the Wednesday through Saturday period to be abnormally warm, with Thursday being the most notable.

February 2015 data from our weather station in Castle Rock

February 2015 data from our weather station in Castle Rock

Believe it or not, these stretches of well above normal temperatures are not entirely unusual in February. I went back and looked at data last year from my weather station in Castle Rock and noticed we had a very similar warm period.

This is a pattern we see quite often in Colorado right around February. As a Colorado Native I can tell you it is often no surprise to recall wearing shorts and a t-shirt to school in February as a child.

The pattern we are seeing now marks a transitional period, where we begin to come out of the extended colder and snowier period of winter and begin to make the (sometimes slow) transition into spring.

The key to watch during this period is if it indeed transitions into a wetter spring period.  Sometimes we never hit that switch and we experience extended abnormally dry and warm weather into spring and summer. This is usually bad news for our snow-pack, water storage and fire season. Luckily, I don’t see that as the case this season, the why is a long story best saved for another day and another post.





For Reference: Castle Rock Record Highs

If you want to know if we tie or break a high temperature record over the next few days, here is the data. Thursday looks like the most likely day to break a record, but there are decent chances the next few days:

February 17

  • Record High: 67
  • Forecast High: 65

February 18:

  • Record High: 64
  • Forecast High: 70

February 19:

  • Record High: 66
  • Forecast High: 63

February 20:

  • Record High: 66
  • Forecast High: 62

*Temperature records for Castle Rock are recorded at Centennial Airport , this is the data that was used

Wind/Fire Danger

It may be difficult to imagine any threat of wildfires with all the snow and moisture we have had this year, but the main thing to remember during this time of year is that when vegetation is dormant, it can easily catch fire. This is especially true if you have strong winds and low humidity, which we have experienced now for a couple of weeks.

There are two alert products out by the National Weather Service at this time:

Current Weather Alerts.

Current Weather Alerts.

Basically, to sum up these alerts; A Fire Weather Watch means critical fire conditions will be possible. The strong winds and low humidity on Thursday will allow any fires that start to spread rapidly. Probably not a good idea to do any outdoor burning.

The High Wind watch means conditions may develop that allow for strong and damaging winds. Driving, especially for high profile vehicles could become difficult.

We will keep an eye on this and let you know if any of these are upgraded to warnings.

Wednesday – Thursday Weather

Wednesday expect warm temperatures and calmer winds. It may still be a bit breezy in some areas but will be a nice day overall.

High: 65

Low: 38 **becoming windy overnight

Thursday expect a possible record warm day. Strong winds and very low humidity will make for a nice day temperature-wise but probably a bad hair day.

High: 70

Low: 36

That’s it for now folks, I will have another post up Thursday with a more in-depth look at this weather pattern and went we might see a change. Stay tuned!


Warm and Windy Week Ahead for Colorado Front Range

Strong downslope winds will cause warm and very windy conditions throughout the week along the front range. The National Weather Service in Denver put together a neat graphic on how this process works to keep us very warm and dry:


Credit: National Weather Service Denver/Boulder

This setup is commonly called “Chinook Wind” as strong winds come up and over the mountains and as they roll down the foothills of Colorado the air compresses and warms. This causes very windy conditions, especially along the foothills and breezy conditions in most other areas along the foothills. “Chinook”, by the way is the inuit word for “snow eater” as these warm winds commonly melt our snow very quickly.

A Note About our Sunrises and Sunsets


If you’ve been along the front range of Colorado this past week, you’ve probably noticed the amazing sunsets and sunrises we’ve had nearly every day for the week. The mountain wave clouds that have parked over us for the past week are due to the current weather pattern. Again, the National Weather Service has some great graphics that explain a couple of the setups we have seen this week.


Credit: National Weather Service Denver/Boulder



As long as these patterns continue, we will continue to see a wave or wave clouds parked over the front range. This means continue to look for those great sunrises and sunsets, but also continue to look for very warm days and very windy conditions.

How Long Will it Last?

The above model is a look at the upper level wind pattern across the United States from today till about March 6. You’ll notice the large ridge to our West and the jet stream overhead, this will ensure our warm and windy weather for a long period of time. The models for lower and mid level winds show a very similar setup for this period so I feel pretty confident in saying that our chances for any types of large snowstorms are pretty low the rest of February. Even when the ridge breaks down next week, our winds remain westerly which would mean better chances of snow in the mountains but not much for anything East of the divide.

Not to say we won’t get any storms at all, but the chances are quite low. The model shows a couple of disturbances that may provide a bit of spotty rain or snow activity here and there.

One note; the last few days of the model we begin to see some troughs establish in the jet stream signaling a possible weather pattern change. Being at the far end of the model view, it is way too early to take this to the bank but if it materializes, it could be the pattern change we would look for to see  possible blizzard type storms in March. This will need some close watching as if it holds and strengthens into March we could be looking at much more energy entering the state.

The rest of February looks very warm and dry, expect above average temperatures and higher winds. Areas East of the divide will most likely not see snow until sometime in March.


Colorado and Castle Rock February Weather Outlook

Colorado’s front range started the month of February with a large snowstorm that deposited a foot of snow or more for many areas. I’ve heard a lot of discussion about when we can expect our next snowstorm as many are eager to plan their next snow day. February tends to be one of our drier winter months, we often see warm days and little snow during February so it was somewhat unusual to see such high snow amounts in one storm for the month. This is why it’s important to keep in mind throughout this dicussion that just one storm in the entire month can bump February into an over average precipitation situation. The average snowfall for February in the Castle Rock area for example, is 7.2 inches.

I’ve been analyzing outlooks, models and statistics and now have a decent picture of what we can expect in Colorado for the rest of this month.

Wetter Than Average but Any More Snowstorms?

The Climate Prediction Center runs a whole host of products that calculate the probability of temperature and precipitation anomalies. They are a great tool to get a big picture of the weather for the U.S. over periods of weeks or months. Their February prediction was released on January 31 and highlights the following:


CPC February 2016 Temperature Outlook


CPC February 2016 Precipitation Outlook

A quick look at the CPC February temperature outlook to the left shows the probability of temperatures being above or below average. The redder colors signify a higher chance of above average temperatures to finish the month whereas the blues snow a higher chance of below average temperatures.

The February outlook shows a slightly higher chance that most of Central and Southern Colorado will have below average temperatures. The Northern and Northwestern and to some degree the Northeastern corners show equal chances of above or below average temperatures. This is weather speak for, “it could go either way.”

The daily mean temperature for the Castle Rock area is 33.0 degrees and as of this post we are sitting at 21.9. Granted it is still quite early in the month and we are expecting some very warm days in the weeks ahead, this could change. As of right now the CPC outlook is right on target with below average temperatures.

When we look at the precipitation outlooks it shows a pretty decent chance of above average precipitation for the month. This is pretty much verified at this point since our early month snowstorm dropped more than a foot across the front range of Colorado. In addition, the mountains have received large amounts of snow continuously throughout late January and into February.

Since we are already at above average precipitation for the month,we can consider this outlook spot on. Now that we’ve looked at the month as a whole and found that things are pretty much going to plan, now we can start digging down into some deeper details about the next few weeks.


Next 6-10 Days

The CPC outlook for the next week or so essentially paints a bulls-eye for warm temperatures over the Western U.S.



As with many meteorology cases, it is always worth verifying this information. This is essentially a forecast so should this verify, we should see signals in the atmosphere to support it. What we would expect to see in the atmosphere with a period of drier and warmer weather is some sort of ridge building into the Western part of the country.


A look at the GFS model shows a pretty convincing signal. The upper level jet stream (winds at about 30,000 feet above sea level) show a very large and pronounced ridge across the Western U.S. In fact, this feature stays with us for quite a while and that’s why you will see a very similar outlook from the CPC for the next period which is 8-14 days out. A high pressure ridge over the state allows warm air to migrate North but also keeps storms away from Colorado.

Next 8-14 Days

Not much more to explain here, we see a very similar outlook.


A much higher probability of above average temperatures with an equal chance of above or below average precipitation. All indications are at this point that the next 14 days will feature below average precipitation as that ridge is projected to continue over the Western U.S.

February Outlook Summary

With the current signals in the atmosphere here is what you should expect the rest of the month of February:

  • Above average precipitation
    • Mainly from our snowstorm at the beginning of the month, we have already recorded above average snowfall
    • I suspect the rest of February will be quite dry, things may see a change towards the end of the month but next 14 days look like a sure lock on dry weather
  • Average to slightly above average temperatures
    • The first week of the month started off quite cool, so as of this write-up, our mean temperature is well below average.
    • Given the next 2 weeks of much above average temperatures, I can see the mean rising very quickly.
    • I expect temperature to finish above average slightly or very close to average depending on how the last week of the month acts.

This should shine a light on the next 14 days and I think it will be pretty accurate. A look at temperatures for the next 2 weeks shows consistent daily highs in the 50’s and 60’s as far out as I can see. Our nighttime temperatures will be much warmer as well, projected to be in the upper 20’s and even lower 30’s in some cases.

I will be digging through more data in the coming days and should have a spring preview up this week that will highlight what to expect in February through April 2016. It should be a nice sneak preview of spring, stay tuned!


Broncos Parade Day Weather Outlook


The Denver Broncos Superbowl parade is scheduled for Tuesday in Denver. The good new is, the weather is going to be absolutely beautiful! This is not a tricky forecast, expect light winds and warm temperatures throughout the day.


Coming this week… a look at the rest of February and a sneak peak into March. Stay tuned!