Friday, August 14, 2015

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.

25 comments:

Digital Sensory said...

You were mentioned near the end of this article
http://www.livescience.com/51859-el-nino-could-rank-among-strongest-on-record.html

Schrauf said...

What is the scale on the UW model map? cin = centi inches? Interesting, never seen that, but I assume common in the weather forecasting biz...

On a related note, seems like with the right weather system and track, the warm water Blob should increase precipitation in the NW due to additional moisture/convection. Or maybe the area of the Blob is too small to have much effect on passing systems.

Matt Crissman said...

So far the radar is dead....but then again I expected this based on the summer so far!

Dave Sailer said...

Not exactly on topic, but maybe interesting: "This Time-Lapse Captures a Wet Microburst Dumping Water Onto Tucson, Arizona" at http://bit.ly/1PdeVhV (Runtime: 51 seconds.)

Scott K. said...

So far, barely any ran in the I-5/405 corridor. Lots of lightning this morning, but the only rain we had was very short (less than 15 minutes).

This rain forecast seems to be correct for SW washington though, Olympia area is getting quite wet! But for the puget sound, not so much.

Lindsey Heuscher said...

THE RAIN HAS ARRIVED!

This is amazing. Some thunder, some lightning and now lovely lovely rain.

ryamkajr said...

Constant, steady rain for the most part of the last hour and a half. Outdoor gauge is showing more than a 1/3 inch so far (West Seattle).

Maria said...

It's here! After a few showers the thunder and rain started in earnest around 12:30 PM near Magnuson Park.

Jim said...

Barely got the pavement wet here in SW Pacific County.

Rod said...

You nailed the forecast, Cliff. Thanks.

Unknown said...

Chalk up another win for the weather channel forecast that showed a lightning bolt for today (yesterday).. everyone else, just rain or showers

JordanP said...

The rain started here in Fauntleroy at 1300 and now at 1520 we are just over an inch. That top blue line may be a bit low by the end of this storm for us. With these cells moving around it looks to be a bit hit or miss as to how much rain you are going to see.

Scott K. said...

Better late than never! I wish we had more days like today!

Rod said...

Gosh, Cliff! This event must be VERY satisfying to you. It sure would be to me, if I had forecast it.

a progressive crank said...

Watching the radar loop from the UW, the center of this storm seems to be parked right over Seattle, swirling around a bit, losing and gaining intensity, but not moving. That seems unusual to me.

Matt Crissman said...

An inch here in Fremont! WAHOOOOOO!

Chris said...

It is just a bit after 4pm, and we have received about two inches of rain in an unscientific bucket on deck measurement. We are near the University Village (which is just east of the Univ. of Washington main campus). For a while there was a river going down our street. I am so glad we put in permeable pavers on the 90 foot long shared driveway so it did not add more to the "river".

Our persimmon tree is going to be so much happier.

Troy Center said...

I too am curious about this "http://www.livescience.com/51859-el-nino-could-rank-among-strongest-on-record.html" and "http://abcnews.go.com/US/godzilla-el-nino/story?id=33089713".

Is this a dramatic change from the last 90 day winter forecasts from NOAA?

Troy - Mill Creek

David B. said...

I've had about 1.25" here on Bainbridge Island since midnight, about 1.15" from the event that started after noon and 0.10" from last night's thunderstorms. Exact total will come once it stops and I can measure the overflow in my gauge.

(I have one of those COCORAHS-style gauges with an inner graduated cylinder that measures the first inch of rain in 0.01" increments. After an inch falls it overflows into the outer cylinder and you have to play empty-and-transfer to get an exact total.)

Rod said...

Hi Cliff,

This November-like deluge might be one for the August record books, eh???

I certainly don't recall an August day like this one in the Seattle area...

Fleetwood said...

Seems we've gotten.89 inches at SeaTac in last 6 hrs. Helluva lot.

Maria said...

Rod, I remember a day in August 2004 when we got an inch or more of rain and there was flooding. Cliff's blog doesn't go back that far but I did some searching and according to this KOMO page it was on August 22, 2004: http://www.komonews.com/news/archive/4141256.html

David B. said...

Final (I think, rain has stopped, sky is lightening, and radar indicates it's basically all over for me) total at my place on Bainbridge is 1.30". Very impressive for mid-August, and very welcome. I'm about to go out and savor the woods being moist and fresh again, instead of dusty and very dry.

JordanP said...

So yesterday was a great relief after an incredibly dry spring and summer.

Here in Fauntleroy in West Seattle we had had 1.62" of rain between April 14 and August 13. We had 1.92" yesterday, more than doubling that previous four months. Won't have to water for a week after that. A nearby weather station showed 2.1" while others not more than two miles away show as little as 1.4". We had a storm cell pass right over us and had a rain rate of around .7"/hr for a full hour. I've seen it rain that hard (or harder) here before, it has just never lasted for more than 10-15 minutes, going for a full hour was like being under a hose.

Rod said...

Thanks, Maria. You, of course, are correct. There have been past heavy rain events in August. I should have looked at the weather history before posting.

I guess this one has never been more welcome (to me). hehe.

-Rod