Finally, Some Real Rain.

For almost a week the models have been advertising a significant rain event today (Friday).  And the most recent forecast is no different.  A substantial rain event that will substantially reduce water use for several days and perhaps put some meaningful water into reservoirs.   The first significant rain of the summer.

Let me show you the latest UW WRF model forecasts, starting with the 24h totals ending 5 AM Saturday.  Looking at the regional totals, we see that western WA and southern BC get doused, as does NW Oregon.  Dry over the Columbia Basin and eastern Oregon.

A closer in view suggests that the north Cascades and southern BC will be hit hard, with some locations getting 1-2 inches.  Puget Sound will be moistened by perhaps 1/3 inch. Your plants will be happier.

Now the above is a single, deterministic forecast.   Let's get an idea of the confidence in our Friday forecast by looking at an ensemble prediction using the NWS SREF (Short Range Ensemble Forecast System) in which roughly two-dozen forecasts are made.  The graphic below shows you the accumulated precipitation at Seattle Tacoma Airport for all of these forecasts.  Time is on the bottom axis (in GMT).  The y-axis is accumulated rain.   Each color line is one model.  The black line is the mean of all the forecasts, also known as the ensemble mean.   On average, the ensemble mean is the best forecast.

You will notice that the ensemble mean indicates about .3 inches in total over Seattle, but there is considerable spread, and thus uncertainty, in the forecasts, with totals ranging from .05 to 1.2 inches.

The Cougar Creek fire near Mt. Adams was quite active today, producing huge amounts of smoke, something obvious on the visible satellite photo below.

The amount of smoke was so large that the local weather radars picked up the plume.  An example is shown below from the National Weather Service Portland radar.  Very impressive fire.