Wet Heavy Snow

 

The big story today continues to be the weekend system. This system still continues to develop, but we are now starting to get a better idea of what we expect to happen. This system will be coming in two different waves on Saturday. The first chunk of it will begin to move into the southern portion of the state early Saturday morning. The 18z model runs now have this system moving in across southern Iowa after midnight Friday. The first round will then lift off to the northeast during the morning hours Saturday.

gfs_ptype_slp_east_9It does appear possible that a light freezing rain/mix will be possible across southeast Iowa initially Saturday morning. This may lead to a light glazing, between 0.1″ and 0.2″ across the southeast portion of the state. This freezing rain/mix will then transition over to snow as the day progresses.

gfs_ptype_slp_east_11During the afternoon hours on Saturday, the snow will begin to lighten up a bit before the next round moves through Saturday night. The heaviest of the snowfall accumulations will come with this second round of snow, which will be during the evening hours Saturday.

gfs_6hr_snow_acc_east_16The models still continue to show the heaviest of the snow falling through central Iowa. This is where 4″ to 6″ of accumulation could be possible. Right now the system is not in the best area to get the greatest samples by the models. Because of this, we are going to have to wait until tomorrow morning before we can talk snowfall totals that we can write in stone. This snow is going to be a very wet snow with snowfall ratios around 9:1 to 11:1.

This afternoon, the National Weather Service in Des Moines said that “past events have resulted in tree damage and subsequent power outages with as little as 3 to 5 inches of snow under similar circumstances.” This is because winds will be increasing throughout the day Saturday.

wind speedsWinds will be gusting up to 45mph during the overnight hours Saturday. When you combine the strong wind with a wet heavy snow, this leads to tree damage and power outages. This will also lead to reduced visibilities due to the blowing snow.

gfs_windchill_iowa_16After this system departs on Sunday, arctic air will be moving into the state. Wind chills Monday morning will in the -35° to -40° range across northern Iowa.

The two main points to take away from this is if you have travel plans on Saturday, make sure you have a backup.  Secondly, moderate to heavy snowfall totals may be possible across central Iowa, with winds increasing throughout the day Saturday which could lead to tree damage and power outages. There is still a lot to be watched with this system as things are going to have to come together correctly, but it does seem that the models are beginning to tighten in on a solution.

Right now there are no watches or warnings issued for this system, but we expect them to be issued by tomorrow morning. With all of the combined ingredients that we just listed, winter storm warnings will more than likely be issued. As always, our whole team will continue to track all of the very latest developments and will have around the clock updates right here on iowachase.com and on our Facebook and Twitter pages.

 

Zach Sharpe

My name is Zach Sharpe. I am the president and forecaster for the Iowa Storm Chasing Network. You can find me on Twitter @Stormchaserzach and on Facebook at: https://www.facebook.com/stormchaserzach/

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