Winter Storm Number Two Headed into Colorado


Satellite Visible Imagery from 3pm to 5pm Mountain Time

Winter storm number two can be seen moving moisture into Colorado from the west with thick bands of cloud moving into the state. It’s looking like it will bring another 5-10″ of snowfall to Denver and the surrounding regions.

Snow will start early tomorrow morning (which means that extra time to get to work/school is a must) and will continue through mid Wednesday. Definitely work from home, if able as the Tuesday afternoon rush hour will likely be a mess.


GFS Forecast Snow Accumulations

There is some small disagreement between models, but it’s currently looking like 5-10″ of snow can be expected for most areas with higher accumulations to the west, south, and east of Denver. The most intense accumulations will begin tomorrow afternoon and will continue over night with the heaviest snow likely falling on Tuesday night.

Denver is under a Winter Storm Warning from 6 am tomorrow through noon on Wednesday. For more information on the warning, visit the National Weather Service page.

Storm liquor suggestion: Manhattan or Old Fashioned cocktails. Something smokey that reminds you that you’re cold, but with a hint of sugar to cut through the bitter cold.

Snow Tonight Through Monday and More Next Week

5-10″ of snow is headed our way!
Cold air is rapidly moving into the state and is bringing another bout of winter weather with it. While we currently have some northeasterly winds that are bringing cool air into Denver, the bulk of the cold temperatures are still along the Colorado and Wyoming border.
Precipitation is expected to start in Denver late tonight/early tomorrow and continue through mid-Monday with the most significant snowfall occurring Sunday night. In addition, temperatures will fall substantially with highs in the upper 20s and lows in the single digits for the late weekend and early next week.
There is a possibility of freezing drizzle and/or light freezing rain with this system that could pose a serious hazard for travel as it could coat the roads as temperatures drop.
Snow accumulations will be highest on the west side of town with lighter accumulations expected to the east.
Then, round two of snow starts on Tuesday and could continue into Wednesday!

Spring Blizzard to Hit Denver and Surrounding Suburbs: 3-6″ of Snow and Hazardous Travel Conditions

Screen Shot 2019-04-10 at 8.55.03 AM.png

Snow accumulation for the Rockies and Plains Regions by Midnight Mountain Time on Thursday Night. Note a reduction in snow along the foothills/west of I-25 due to downslope winds.

Denver is under a blizzard warning beginning tomorrow at noon, which should coincide with the beginning of snowfall that will drop 3-6″ across most of the metro area!

A similar storm system to the one experienced last month will bring high winds, low visibility, and snow to Denver and the front range. Snow will start around noon tomorrow and will continue through noon on Thursday. The highest amounts of snow will be to the east, south, and far west (foothills) of the metro area. This storm is expected to have downslope wind flow that will likely reduce the amount of snow west of I-25 compared to other areas (can be seen above in snowfall totals map).

Remember: A blizzard does not mean that a lot of snow will fall. The definition of a blizzard is a storm with “considerable falling or blowing snow” and winds in excess of 35 mph and visibilities of less than 1/4 mile for at least 3 hours. So, even though snow totals are lighter than the most recent blizzard, travel conditions will still be as hazardous and there is the possibility of wind damage to trees and other objects.

Current DWP Storm Rating: 4/5 – intense: stay at home if possible and ride out with case of beer/couple bottles of wine. Blizzards: for times when you want day-drinking to be socially acceptable.

Updates will be made leading up to and during the storm.


Blizzard Conditions on Colorado’s Eastern Plains, but Modest Snow in the Metro Area

Screen Shot 2019-03-12 at 9.24.50 PMUpdate on snow totals: Areas east of I-25 are looking at slightly more snow now with accumulations in the 5-10″ range for this storm. Areas west of I-25 and leading up to the foothills will likely see 2-4″ of snow from this storm. The metro area is now under a blizzard warning and strong winds with whiteout conditions will be possible.

Well, the hype train has been in full force with this next weather system as predictions of epic snow have popped up all over the place. Even the famous Frankie MacDonald (I’ve been a big fan for years now) has given his forecast for quite a snow storm for Denver! However, while this storm will be quite powerful, the forecast really doesn’t have much in store for the metro area at this point in time compared to the surrounding areas. In fact, this system looks like a basic spring storm without a whole lot of bells and whistles for the metro area, but we’ll dive into why there has been so much hype and the current forecast a bit ahead. All hype aside, this storm looks to be a good one to bring more moisture to the state and, even though our mountain snowpack is way above average, it’s always better to have too much snow than too little.

As always, I’ll break this up into the following sections to make this a bit easier to read:

  1. Storm Timing
  2. Storm Position (1 Foot of Snow vs. 3-6″)
  3. Snowfall Accumulations
  4. Storm Hazards
  5. National Weather Service Blizzard Warning

Storm Timing

This is a fast moving storm system that will impact Denver and the metro area at a time that is rather uncharacteristic of heavier snowfall. Generally with storm events, we see the passage of a cold front in the afternoon and then snow moving in to the area in late afternoon with the most intense snowfall overnight. This storm is a bit different as snowfall currently looks to begin around mid-morning on Wednesday (8-10am) with rain and continue through late evening with the heaviest snowfall occurring between noon and 5-6pm. As mentioned before, this is a fast moving system and will be out of the area quite quickly once the bulk of the snow has fallen. While we may see some flurries late Wednesday, their accumulation will be minimal.

Storm Position

Screen Shot 2019-03-12 at 9.42.35 PMOne of the reasons that there has been so much uncertainty and a little hype surrounding this storm is that it’s a classic spring upslope snow storm. As such, the position of the low pressure center on the east side of the Rockies is critical to determining which areas will get high amounts of snowfall and the areas that get a few inches. Low pressure systems have winds that rotate around them in an anti-clockwise fashion, which means that any area to the north of the low will be getting winds from the east and any area to the south will get westerly winds (in the northern hemisphere). So, when a low develops on the east side of the Rockies, it generally ends up flinging winds up the eastern slope causing the development of clouds and snow like in the figure to the right. As you might guess, there is an optimal area for upslope winds and a difference in the position of the low can determine the amount of snow you’re getting.

For this storm, two of the main weather models disagree on the position of the low pressure center. The GFS (right below) has the low slightly to the south and east near the Colorado/Oklahoma border, which puts the front range under the influence of winds from the north that won’t have much of an upslope component. The NAM (left below) has the low more to the northwest, which would give us a bit more moisture from the east and allow for bigger Denver snow. So far, it looks like the NAM is the outlier and that the low will be closed to the GFS’ position, which means that Denver likely won’t be seeing more than a foot of snow, but there is still some time for the forecasts to come in line with each other and for the low to develop in a location with more of an upslope component.



Snowfall Accumulations

Currently, it’s looking like Denver and the front range will be in a bit of a dead-zone for snow with higher amounts in just about every direction. Currently, it’s looking like areas west of I-25 will get 2-4″ of snowfall and areas to the east of I-25 will get between 5-10″ of snow with locally higher amounts of up to 14″ in some places. The large gradient in snowfall totals is from east to west Denver is primarily due to the storm moving out of the area and causing westerly downslope winds that will reduce precipitation in areas along the foothills. There’s still plenty of time for the forecast to shift, which means that final snowfall totals likely won’t come out until later this afternoon/evening. So check back.

Storm Hazards

This storm will be relatively warm with temperatures only barely dipping below freezing, which means that it will likely start off as rain and continue as wet/heavy snow. Assuming periods of heavy snow on already wet roads, slushy nonsense will be likely and driving may become problematic. The afternoon commute will probably be even worse and working at home may be a good idea to avoid the chaos. Now, the biggest threat out east is blowing snow in intense winds and this is where the blizzard comes into play. While most areas out east will see anywhere from 6-12″ of snowfall, wind speeds could be as high as 75 mph, which will result in near whiteout conditions and is the reason that blizzard warnings have been issued (blizzards aren’t actually defined by big snow accumulations). Winds will also be blustery in the metro area with speeds in the mid 20s to low 40s. So, avoid travel if at all possible on Wednesday.

Thanks for reading!


National Weather Service Blizzard Warning

...Blizzard expected to develop over portions of northeast
Colorado Wednesday afternoon and Wednesday night...

.Heavy snow and very strong winds will develop over most of
northeast Colorado Wednesday afternoon and Wednesday night.
Blizzard conditions are likely to develop along and east of the
I- 25 Corridor where the heaviest snow is expected to fall. Power
outages and wind damage will also be possible as winds gust to
between 60 and 70 mph will be possible.

West of the I-25 Urban Corridor, heavy snow and gusty winds will
also be possible, with significant travel impacts. Rain is
expected to develop Tuesday night, and then change to snow late
Wednesday morning and may become heavy at times with wind gusts
from 40 to 60 mph.

Mountain areas will also see more accumulating snowfall during
this period.

Including the cities of Aurora, Brighton, City of Denver,
Denver International Airport, Highlands Ranch, Littleton, Parker,
Eaton, Fort Lupton, Greeley, and Roggen
1055 AM MDT Tue Mar 12 2019


* WHAT...Blizzard conditions expected. Total snow accumulations of
  5 to 8 inches expected. Winds gusting as high as 60 mph.

* WHERE...Denver and Greeley.

* WHEN...From 10 AM Wednesday to midnight MDT Wednesday night.

* ADDITIONAL DETAILS...Plan on slippery road conditions. Areas of
  blowing snow will reduce visibility to near zero at times. The
  hazardous conditions will impact the evening commute. Very
  strong winds could cause extensive tree damage.


A Blizzard Warning means severe winter weather conditions are
expected or occurring. Falling and blowing snow with strong winds
and poor visibilities are likely. This will lead to whiteout
conditions, making travel extremely dangerous. Do not travel. If
you must travel, have a winter survival kit with you. If you get
stranded, stay with your vehicle.

Snow and Colder Temperatures to Impact Denver Saturday Night into Sunday


Surveying his kingdom in the Snowy Mountains of Australia, the snowman contemplates what his life would be like in Colorado.

It’s that time of the year, we’ve had some cool temperatures and seen a few flakes of snow fall, but it has been relatively light to this point. This looks to change later today and tomorrow when a cold front will move into the region that will bring snow and a large drop in temperatures! A big unknown, however, is how much of this snow will actually stick to the ground after it has fallen. Regardless of the final accumulations, it’s time to brush up on your snowball technique, fire up Netflix, and break out the Irish Hot Chocolate (especially if you’re going to the Broncos game) because snow and cold is on the way!

As always, the forecast will be broken into a few different parts to make it a bit easier to read. It will be structured as such-

  1. Timing and Details of the Weather System
  2. Expected Snowfall Amounts and Accumulation*
  3. Potential Impacts

Timing and Details of the Weather System


GOES-16 Longwave infrared satellite imagery of the high plains. Warmer cloud temperatures (lower altitude) are in whites and purples/pinks, colder cloud temperatures (higher clouds) are in blues and greens. State outlines are in light blue.


Cloud cover from a cold front can be seen developing near the Wyoming/Montana border and moving south towards Colorado (Above Satellite Image Gif). It’s expected to arrive late Saturday afternoon with a nearly a 30 degree drop in temperature in the metro area! This front will change our dominant wind direction from easterly (due to the counterclockwise winds of a Low pressure system centered on the CO/NM border) to northerly that will funnel plenty of cold air into the state from up north. A chance of rain will follow the passing of the cold front and rain should persist around the area until late this evening/early tonight when it should switch to snow. Snow will continue overnight with the heaviest snow falling between midnight and 6am on Sunday morning. Snow will continue through most of Sunday and will eventually reduce to flurries on Sunday afternoon/evening.

Expected Snowfall Amounts and Accumulation

A bit of theory about forecasting snow-

I’m guessing that you probably noticed the asterisk next to this section when I outlined the forecast structure, right? Of course you did, you’re smart. The reason why that asterisk exists in next to the title of this section is because we normally discuss snow storms in terms of accumulated snow on the ground. While this is the most relevant for most people, it isn’t actually the best measure of the amount of snow that will be coming from a storm system. Warm ground temperatures, very dry air, and wind can all alter how much falling snow actually accumulates on the ground. This is particularly true in Autumn and Spring when air temperatures (and subsequent ground temperatures) can fluctuate from very warm to relatively cold in short periods of time. So, the amount of accumulation on the ground could be substantially less than what actually fell.


A graphic snowing sources of energy for a snowpack. We’re only concerned with the ground heat flux for this forecast, but the other information is nice to have as well. Credit: Wasatch Weather Weenies

With the our little excursion into snow/atmospheric energy in our minds, it’s important to note that this system will be coming through after a day with high temperatures in the low to mid-60s. This means that, even though the ground will begin to cool once the cold front comes through, it may still be warm enough to melt initial snowfall. Now, this will depend on a number of factors with the largest being the amount of rain that falls before the snow. Rain is much better at cooling down the surface better than simple swings in temperature. So, if we get enough rain to cover everything relatively well, we’ll probably see most of the snowfall accumulate on the ground. If there is little to no rain, we could see the initial snowfall melt when it hits the ground due to the warm ground temperatures. Anyway, on to with the totals!

Snowfall totals of 2-4″ are expected around the metro area with slightly higher amounts to the west/south and slightly lower amounts to the east. Boulder along with Castle Rock and their surrounding suburbs can expect 3-6″.

Potential Impacts

Roads will be icy late on Saturday and during Sunday. Windchills are expected to be in the teens during the day on Sunday. Make sure that you have an emergency kit in your car if you plan on traveling.


The National Weather Service has issued a Winter Weather Advisory that can be seen below. Please note that my expected accumulations are slightly lower than theirs. As always, please feel free to ask any questions that you may have. Thank you for reading!

Including the cities of Fort Collins, Hereford, Loveland, Nunn,
Arvada, Boulder, Golden, Lakewood, Longmont, Aurora, Brighton,
City of Denver, Denver International Airport, Highlands Ranch,
Littleton, Parker, Castle Rock, Elbert, Fondis, Kiowa, Larkspur,
Eaton, Fort Lupton, Greeley, and Roggen
343 AM MDT Sat Oct 13 2018


* WHAT...Rain and snow showers will develop this evening, then
  turn to all snow overnight tonight. Total snow accumulations of
  3 to 6 inches expected by midday Sunday.

* WHERE...Fort Collins, Boulder and the western suburbs of
  Denver, Denver, Castle Rock and Greeley.

* WHEN...From 8 PM this evening to noon MDT Sunday.
. latest high tendency
* ADDITIONAL DETAILS...Plan on icy and slippery road conditions.


A Winter Weather Advisory for snow means periods of snow will
cause primarily travel difficulties. Expect snow covered roads
and limited visibilities, and use caution while driving.

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

Afternoon Thunderstorm Forecast and Monitoring 6/18

Updates (see original forecast below)-

Thunderstorms have developed along the foothills to the west of Boulder and Longmont. Storms look to be intensifying quickly and one report of pea-sized hail has already been made from the storm northwest of Nederland.

Screen Shot 2018-06-19 at 8.41.16 AM

Thunderstorm Position and Intensity at 4:45pm


A few thunderstorms are in the forecast for this afternoon and evening!

Denver will see a few thunderstorms, but severe storm development should stay far to the east/northeast of the metro area. Thunderstorms should begin to build around town over the next couple hours and will move to the northeast fairly quickly.

Screen Shot 2018-06-19 at 8.29.22 AM

Expected Storm Position and Intensity at 8pm from 20Z HRRR Model Run

Severe Storm Risk- Current models are showing severe storms developing east of DIA and E-470 (picture) with storms continuing to develop and eventually tracking along I-76. Threats from these storms will be large hail, damaging winds, and possibly a tornado.

As always, feel free to ask any questions that you might have.

Severe Storms Possible Along Front Range on Friday

understanding_categoriesSevere storms with damaging hail, wind, and a slight possibility of a small tornado are in the forecast! These storms will be the beginning of what will be a soggy and cool weekend that will have Denver’s high temperatures dipping into the mid-50s. While these storms will have the potential to cause damage, current forecasts suggest that the danger should be minimal. The Storm Prediction Center currently has the front range in a Marginal Thunderstorm Risk and areas to the east, such as Aurora, in a Slight Thunderstorm Risk.


Screen Shot 2018-05-18 at 9.18.50 AM

NAMNEST Simulated Reflectivity (estimated storm position and intensity) at 4pm Local Denver Time


A small lee-side low pressure will develop tomorrow in along the Colorado/New Mexico border that will allow for increased transport of moisture and instability to the front range. All models are currently showing thunderstorm activity around the Denver metro area tomorrow that will start in the early to mid-afternoon. The positioning of the storms (as usual) is fairly hard to predict, but the models are agreeing on the overall intensity of the storms. The GFS has things pushed a bit further east and has the primary wave of storms over eastern Denver and Aurora, whereas the NAM and 3k NAM have the storms developing right along the foothills. I’m inclined to agree with the NAM models at this time as orographic forcing and the boundaries created by the mountains always play an important role in storm development.


Storms will begin developing in early to mid-afternoon (~2-3pm) and will begin moving eastward. This means that there is a high likelihood that there will be storms occurring during rush hour and that it may be a better idea to wait to commute if a storm is nearby. Storm intensities should begin decreasing in the evening and areas of light to moderate rain could occur overnight. The times with the most intense storms should be from 3-7pm.



Primary threats from these storms will be hail and strong winds. Current vertical profiles in the area show a very wet atmosphere high and a drier atmosphere at the surface. This has the potential to create damaging wind events as the rain aloft falls into the drier air beneath it, absorbs heat and evaporates, and then the cooler air around it accelerates towards the ground (cold air is heavy and sinks! Heat rises!). These may or may not be seen as microbursts. While a small tornado is not out of the question, the needed wind shear and helicity don’t look to provide a favorable environment for development.

As always, thanks for reading and let me know if you have any questions! I’ll update when new information is available.