The Revenge of Kona Hits BOTH Hawaii and Washington State

 There has always been a close connection between Hawaii and Washington, and that relationship was on display over the past few days.

Kona does not kid around

A strong Kona storm, with powerful, southwesterly flow, rammed into the Hawaiian Islands, producing intense rainfall.   Check out the totals over the past 48 h  around Oahu (below)

Many locations received more than 10 inches, with some reaching as high as 20 inches.   Major flooding has resulted.

This moisture continued toward the Pacific Northwest (see the total atmospheric moisture from yesterday morning below).   As you know, these moisture plumes are also called atmospheric rivers.

When that moisture reached our region, it was forced to rise on our terrain, resulting in heavy precipitation.  To see how much...check out the 72 hr totals shown below.   

Wow.  Several locations received over 6 inches,

As a result, several of our rivers are at major flood stage, with the National Weather Service issuing serious flood warnings on BOTH sides of the Cascades.

The NOAA River Forecast Center is predicting serious flooding on many local rivers (see below).

For example, the Snoqualmie River near Carnation is now at major flood stage (see below), something that is unusual this late in the season.

According to the U.S. Drought Monitor, much of the heavy rain/flooding area is "abnormally dry."     I have some colorful language to describe their analysis, but this is a family-friendly blog.   I will Kona deal with them 😁

How Far into the Future Do Weather Prediction Models Have Skill?

30 years ago, providing a forecast of greater than 4-5 days would result in smirks from responsible forecasters.

But times have changed, and today there is substantial skill in the second week.

Let me prove that to you.  The plot below shows how skill declines over time for the American Global Model (the GFS in blue) over the Northern Hemisphere.    1.0 indicates perfect skill by the measure considered (something called anomaly correlation).  Anything above roughly 0.6 indicates useful skill.

So according ot this measure, there is skill through 8 days!   More than a week!

Buit is better than that.  Today, we have enough computer power to run many forecast runs each cycle (called ensembles), and the average of these many runs is even more skillful. 

 The US ensemble (GEFS, red color) has skill out to 10 days!

The European Center forecasts are even better, adding about another day of useful skill--11 days.  Machine learning prediction adds another day.

So what has contributed to the improved skill?  The most important contribution is three dimensional obserservations over the entire planet! No data voids to ruin forecasting skill.  

Plus, more computer power leads to higher resolution simulations, better physics descriptions, and the ability to run ensembles of many forecasts.

Now that I have convinced you of the potential for extended prediction, what is the forecast for Seattle over the next ten days?   Boring highs in the 50s every day (see below).  If you want real warmth, you will have to head to Southern California.