Models Beginning To Agree on Snow (Apr 15-18 Storm Update)

This will be another lengthy post but it’s important information as we are beginning to see agreement in the models on some aspects of this storm.

I’ll start by saying that while model agreement is starting to gel, it’s still early and I would not be surprised to see changes before the storm’s arrival this weekend.

Latest Model Guidance on Snowfall for Colorado Front Range

 

 GFS_sno_041406Zrun_0419201600z

GFS (Long Range Model)

Storm Total Accumulation by Monday April 18, 2016 18:00 (6:00PM)

The GFS has drastically increased snowfall totals
in the  latest runs, this means it may be seeing
a signal for stronger cold air. This is in line
with that the Euro has been predicting the last few days.

 NAM_sno_041406Zrun_0417201618z

NAM (Medium Range Model)

Snow accumulation by Sunday April 17, 2016 12:00pm

The NAM doesn’t quite have the range to Monday but
when viewing it to the end of its range at noon on
Sunday we can see it has significant accumulation.

 NAM4K_sno_041406Zrun_0416201618z

NAM (Short-Medium Range High Resolution Model)

Snow accumulation by Saturday April 16, 2016 12:00pm

The NAM 4K is a shorter range but higher resolution
model meaning we see finer details. This model only
runs to about Saturday afternoon at this point but you
can see it has significant accumulation by this time.

 SREF_sno_041409Zrun

SREF Ensemble (Short Range Model Ensemble)

Snow accumulation by Monday April 18, 2016 18:00 (6:00pm)

This product takes a bunch of model runs together and
averages them together. This run is for the site at
Centennial Airport. I usually show the Monument
Hill one as well but it is almost exactly the same
plus about an inch or two. The SREF shows
accumulation through Monday evening with an
average of 16.57 inches between all models run.

Please keep in mind, the above are model predictions and not quite yet official forecasts. So while we are seeing agreement, this information should still be taken with a grain of salt.

Preparation/ Possible Impacts

This storm is still not a guarantee, but should it verify folks living especially in areas South of Denver along the Palmer Divide would do best to begin making some preparations for this storm.

A Winter Storm Warning is in Effect for Western Douglas County. This Warning Does Not Include Castle Rock or the Palmer Divide at this time. We will update if this changes.

Impacts

  • Timing of this storm is still tricky so I won’t detail that just yet, but expect a prolonged period of snowfall this weekend
  • Travel may become tricky especially in the higher elevations of Douglas and El Paso Counties
    • The area between Castle Rock and Monument looks particularly concerning as of these model runs
  • This snowfall will be heavy in terms of weight, expect damage to trees and power lines where the heavier stuff accumulates

Preparedness Actions

  • If you’ve turned sprinklers on, may be a good idea to at least drain them
  • If you need to go to the grocery store, probably a good idea. If you have enough food to last through Monday you probably don’t need to rush the store. I imagine folks will still be getting around just fine Saturday morning so a store visit can wait till Friday or early Saturday if needed.
  • Power outages will be possible, so keep that in mind.

Summary

This storm is in no way a sure thing yet, so don’t take my advice above as the sky is falling. That being said, models are locking onto this a bit and it is a good time to start preparing in case this storm does turn out to be a big snow maker.

A lot can still change and there is still plenty of time. I’ve seen storms like this in the past absolutely dump on us and also completely dissipate and leave us with nothing; with no hint from the models until a couple hours before the storm actually arrives. You’ll remember the models didn’t see the blizzard coming in March until about midnight the day the storm arrived.

See Also: The Blizzard the Models Didn’t See Coming (March 2016)

My advice, keep a close eye on the weather in the next day or two. Dust off the snowblower, make sure you have some food (hit the store before the media hype begins if you can and folks clear the place out.) If nothing happens at least you won’t have to make a shopping trip next week. Have some good indoor activities for the family and if you have travel plans keep a very close eye on road/airport conditions.

As things begin to move quicker now, expect more updates throughout the day from me now. I’ve been doing one post a day so far as not much has changed but expect at least 2-3 or more each day starting today if things begin to change in the modeling or forecast. Thanks for sticking with us and stay tuned!

 

John R. Braddock
Storm Chaser/ Amateur Meteorologist at Mountain Wave Weather
John R. Braddock is a NOAA/NWS Certified Storm Chaser and Amateur Meteorologist living in Castle Rock, Colorado. A graduate of Colorado State University with a Bachelor's in Computer Science and a Colorado native, he specializes in short range forecasting, severe weather and mountain weather dynamics.

4 comments

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    • Beth Paulson on April 14, 2016 at 5:19 pm
    • Reply

    Do you only forecast the Denver area?

    1. Hi Beth! I usually focus on the areas South of Denver (Palmer Divide – Parker, Castle Rock, Elizabeth, Kiowa, etc…) As my group has grown here, I’m finding I’m getting a lot of people from outside those areas so may begin to look at forecasting beyond those. What area are you near, I’m trying to get an idea of where everyone is so I can expand a bit!

        • Beth on April 14, 2016 at 5:36 pm
        • Reply

        I live in Custer, SD and find it difficult to locate accurate weather predictions. I work in Denver and commute 2 days a week. Nice to be able to determine if I fly or drive. Glad to be heading home tomorrow a.m. before this storm develops down in Denver. Have 3 kids in the mountains. Leadville and Gunnison. If you live in these remote areas with no TV stations you are kind of forgotten a little bit. Most weather forecasts are limited to what news channels deem viewing audience…it is actually wider than they realize.
        Beth

        1. Ah I know that area, I travel a lot to North and South Dakota for business. I usually stick to Colorado but when something notable is happening I will mention it when possible. I’ll keep an eye on those areas 😉

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