Snow Storm Wednesday: The Latest

Big snow storms in March in Washington are rare.{ } As we know, any snowstorm in Washington in the last two winters is rare. . .meaning none.{ } But, there is more and more evidence that a storm will form in the Midwest and move to the East Coast by Wednesday but the forecast of what impact that storm MAY have on Washington is a challenge and still very uncertain.{ } Here's why.{ } Here is where the "storm" is now.{ }

Can you see it? It's just entering the Pacific Northwest and{ } I've circled the wave in the atmosphere as seen in observations of water vapor from the NOAA GOES satellite.{ }

Predicting storms and weather is really predicting the movement, and changes of waves in the atmosphere.{ } Look at the wave with this storm at the level of the jet stream about 5 miles up in the air.{ }

Here is a simulation/projection of where that wave will be Wednesday morning.{ } Very high confidence that this general pattern will happen, a storm at the surface associated with this wave will be in the Southeast.{ }

But what will the storm track be and how close to Washington and what does it mean for snow?{ } One of the best ways to try and figure this out is to look at a number of simulations of the future, not just one.{ } An "ensemble" and here is one solution from the U.S. computers

And one from the european solutions.{ }

Similar, but I've also circled the colored areas that show the areas of highest variability or uncertainty.{ }

Everything has to be "just right" for a big March snow in Washington.{ } Right now with the trends of the simulations and the "storm" just coming into area where more accurate measurements are made, (not many weather stations in the North Pacific) any risk/chance of a "big" snow Wednesday for Washington I think is low.{ } Right now less than 20%.{ } The chance of light-moderate snow (1-4" range) or rain-snow mix I think is moderate (50% chance) and the chance of nothing at all is also low (30% chance).{ } Yes it adds up to 100%. Here is the latest surface map forecast from the National Weather Service.

As the storm develops, moves into the Rockies and Midwest Sunday into Monday and more observations get taken and a better "trend" develops, we can give more confidence to the Wednesday forecast.{ } For now don't get hopes up snow lovers, and snow haters . . . don't worry too much either.{ } More to come.

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the last 2 winters

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