Winter Storm Brewing?


The million dollar question continues to be, will we have a white Christmas? Well we are here to tell you the very latest. Things are going to be getting active next week, but will it be enough to bring us a white Christmas?

gfs_ptype_slp_conus_21To start off the following is not a forecast as anything more than 3 days out is not reliable. However due to a lot of you traveling, we are simply writing this going off of the latest models. Things will continue to change, so you will want to continue to check back here for all of the very latest updates. Now onto the good stuff. A low will be moving to the southeast across Minnesota and northern Iowa on Monday morning. This will increase our precipitation chances, however, most of this will be falling as rain. As this low dips down into Iowa, it will then be lifted off to the northeast across Wisconsin. What happens next, is where things get interesting and complicated.

SecondAround the same time, a second low will be developing over Oklahoma and will be moving up the east coast. Eventually the GFS and ECMWF have both of these lows combining and forming into one low, also referred to as phasing. Phasing is when two low pressure systems combine into one low pressure system, and when this happens, the newly formed low become stronger and more intense. This makes forecast complicated. If this phasing doesn’t take place, then this will throw a wrench in the forecast. But for now, since both the GFS and ECMWF are agreeing upon this phasing, and continue to in the past few model runs, this is a good sign.

gfs_ptype_slp_conus_32As you can see from the graphic above, the newly formed low has a pressure of 958mb! That is a very intense low, which would then translate to a powerful winter storm with strong winds, also noted by the tight pressure gradient. This timing of this phasing would occur Christmas Eve.

gfs_6hr_snow_acc_conus_32Looking at the accumulated snowfall totals, heavy snowfall is likely across the northeast if this was to verify. Back here in Iowa, me might get a few snow showers depending if we can transition the rain over to snow quick enough as the colder air begins to move in on Monday the 22nd before the phasing takes place. Any accumulations would be very light. The snowfall accumulations across Kansas and Missouri is from the snowfall that they are receiving today. The ECMWF differs slightly than the GFS. It brings enough cold air in time that northeast Iowa could see light accumulations up to a few inches. It also differs by that there will be enough wrap around on the backside of the low, that snowfall accumulations will also be possible across western Iowa of up to a few inches as well.

Christmas GFSAfter this system continues to pull off to the northeast and continues to impact the northeast, another system will then be right behind it. This next system will then move in on Christmas evening. The latest GFS is not impressed with this system, however, the GFS beta which is in a higher resolution than the standard GFS, and is being developed to take over the current GFS, does have a better handle with this system. It is more in line with the ECMWF. This system which will move in late on Christmas is taking the perfect track to bring a decent amount of snow across central Iowa.

gfs_ptype_slp_iowa_36From the graphic above, going off of the 12 GFS beta, a heavy band of snow will be across central Iowa, with a mix across southeast Iowa. As this system continues off the the east, the southeast corner of the state will then transition over to snow, but the mix early on would have an impact on snowfall totals. The ECMWF has a similar storm, however, it is further to the south the the GFS beta.

gfs_6hr_snow_acc_iowa_36This system does produce some moderate snowfall totals, especially in the areas that do see the more intense snow bands. We would like to stress again that do not take the graphic above as a forecast. Just simply showing the latest outputs. These numbers and locations will continue to change.

gfs_t2max_iowa_39After the second system moves out, colder weather will be moving in, and will be here through the new year. Things may actually start and feel a lot more like winter AFTER Christmas.

A lot will need to be watched in the coming days as things will continue to change. Phasing and timing will be key. If things fall into place, then we may have a chance at seeing a little snow before Christmas, and a good amount after Christmas. Until then, continue to check back here for all of the very latest developments as things are going to be very interesting to watch.


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:

(2) Comments

  1. Traveling from Cleveland to mt. Pleasant Iowa from dec 23- 28. Snow has me concered, but more worried about ice and it causing power outages. How worried do I need to be about loose of power?

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