Trending Upward

18Z GFS Snowfall Totals

GFS Precip TypeWell if you are wanting a white Christmas, things are looking up. Yesterday we first told you about how the models were starting to trend upward. To read that article click here. There will be three possible systems before Christmas, and our first one will be on Sunday into Monday.  A low pressure system will be moving out of the southwest to the northeast and will be tracking right across the eastern part of the state. This will leave much of Iowa in the warm sector, allowing most of the precipitation to fall as rain. The 00Z model runs of the GFS and ECMWF have pushed this low further to the north.

GFS 00Z Snowfall Earlier this low was a tad further to the south, which put snow down across northwest Iowa where temperatures would be below freezing. However, since this low is now further to the north, so is the snow. As the low continues to track off to the northeast, colder air will wrap in on the backside of the low, allowing for a transitions over from rain to snow Monday. Only light accumulations will be possible going off of the 00Z runs. The 18z runs Thursday had an area of 2″ to 4″ of snow across northwest Iowa, but this has now shifted north as shown in the graphic above. After this system pulls out, we will be left with seasonal temperatures through the remainder of the week before our next system which could impact the state Friday into Saturday of next week depending on the track.

18Z GFS Snowfall Totals

18Z GFS Snowfall Totals

Some of you weather enthusiasts messaged us last night asking if we would be showing the 18Z GFS runs knowing what they already looked like. For those of you that have not seen the 18z GFS, the graphic above is of snowfall accumulations through Saturday 12/20. As you can see, this brings hope for a white Christmas. However, 18z model runs are less reliable, let alone with how far this is out, but the 18z model runs do not take into account for upper air data.

00z GFS Snowfall Totals

00z GFS Snowfall Totals

The 00Z GFS has came out and it has backed off on snowfall totals. However, comparing this to the ECMWF 00Z, this is very weak. The ECMWF 12Z had Missouri getting heavy snow, but the 00z is in, and it has shifted snowfall to the north. What does this mean? Well for you snow lovers, if the 00Z ECMWF would verify, the southern two thirds of the state would be on the receiving end of a lot of snow, with southeast Iowa ending up with the most. Due to licensing agreements, we are not allowed to show the ECMWF, but we can tell you that it has moderate snowfall totals. IF this was to happen, this would be a major winter storm. This is a new development, and will need to be closely watched as this would have an impact on Christmas travel. You can count on us to continue to watch all of the latest model trends and bring those to you right here as many of you want to know because of travel. Until then, keep doing your snow dances and lets hope the 00Z ECMWF verifies!

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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