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 (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 (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.
	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 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!