CRUNCHING SUNDAY'S SNOW NUMBERS....

Although details remain uncertain, it is becoming increasingly likely that a winter storm will impact return travel from the Thanksgiving holiday Sunday across parts of Iowa and adjacent states to the south and east. Exact snowfall amounts are yet to be determined for any particular location, but confidence is increasing that appreciable snow accumulations will combine with gusty winds to produce hazardous travel with snow covered roads and limited visibility. If you have travel plans from Saturday night through Sunday evening, please monitor this weather forecast very closely. This system will likely cause significant travel impacts during this time period. Have alternate travel plans in place. Stay prepared, everyone!....NATIONAL WEATHER SERVICE DES MOINES.

The above statement was issued Thanksgiving day by the NWS regarding Sunday's developing winter storm. With 2 days until the event richer data is entering the models and there's enough confidence that the Weather Prediction Center has issued these odds of 1, 4, and 8 inches of snow.

The 51 member EURO EPS ensembles mean shows this for snowfall.

The other major model, the 21 member GEFS ensemble means have totals that look like this.

The thing about ensembles is that they are compilations. Some members are further north or south, others have higher or lower totals. The output is a mean of all the solutions. More of a happy median. Using the ensembles the differences between the GFS and EURO are not that great. Check out the side by side.

But, when you use the high resolution operational runs from Thursday (pretty much the same data the ensembles were created from), the differences are significant, especially in my area. Compare the operational forecasts of the GFS and EURO below.

The GFS.

THE EURO.

In Cedar Rapids the GFS has 0.2" while the EURO has 13". In the Quad Cities the range is 1.2" to 10". Dubuque goes from zero to 13". Needless to say there's a problem with how one of these models is initializing date. Something has to give.

Well, it's early Friday now and the new EURO operational has just come in and it's the model that's made the shift. This is a big score for the GFS if the trend holds.Usually it's the EURO model that leads the charge. So here's what it shows.

You can see how close it is to the OZ operational GFS.

So there you have it. The trend is your friend and for now the big storm just catches my southeastern counties. With 2 days to go there is still time for change in the track but the new solutions deserve respect.

Meantime, if you are traveling Sunday conditions will get rough in some part of my area. Keep abreast of the latest forecasts and make your plans accordingly. Roll weather..TS

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