Tuesday, December 1, 2015

Stormy, Wet Weather Ahead

The weather gods turned off the bad weather over Thanksgiving and like clockwork, turned it back on today.    And folks, we are in for a wet and stormy period during the next week or so.

But there is good news in that weather.  It will further fill our reservoirs, restore our soil moisture, and add considerably more to the mountain snowpack.  It will help guarantee a holiday ski season.  And those worried about drought will finally get some solace.

To get you warmed up (poor choice of words), here is the 10-day total precipitation forecast from the National Weather Service GFS model.  The West Coast gets soaked with 10-15 inches over much of western WA and more than 5 inches from northern CA to SE Alaska.    Very good news for California, since northern CA has many of their big reservoirs.  Lots of snow in the Sierra.

But let's look at our local region in more depth using our high-resolution models (UW WRF_. For the next 72 hr, under persistent southwesterly flow, there will be 5-10 inches over the Olympics and the mountains of SW British Columbia,  with substantial amounts (2-5 inches) over much of the rest of the terrain.

A substantial amount of that precipitation will be snow, with some of the higher terrain getting 2-3 feet.

Now any active period deserves lots of winds and this period won't disappoint.  NW Washington will get hammered by strong southeasterly winds (gusting 50 kts) for many hours and current models show a substantial wind event on Thursday as a low develops off Oregon and moves northward across western Washington (see sea level pressure map for 4 PM Thursday)

The next 72hr?  Wet, wet, wet.  Here are the UW WRF forecasts for that period (through Monday at 4 PM) . Even more precipitation and large amounts even over eastern Washington.

Massive amounts of snow over BC and the north Cascades.  Less to the south because the air mass will be relatively warm.

And now major news.  The U.S. Government's DROUGHT MONITOR has dropped drought over western Washington.  Finally.  They still have drought over the Cascades, which is a bit silly, but at least they are backing off over the west.  Progress.  After the next two weeks, I suspect no one will be talking about drought anywhere in the State.

And those of your worried about the Yakima River Basin (and all lovers of apples, fine wines, and hops should be), the reservoirs there are now at normal (see below) and will soon be zooming to well above normal.


lhsouthern said...

I'm glad I got my birkenstock clogs. The sandals are officially retired!

Cailean said...

Please help explain this as the predictions not long ago said more dry and more warm this winter. Is that time period still to come and this is the only snow in the mountains? Or have things changed for the winter?

John Marshall said...

NOAA's Climate Prediction Center is still forecasting a warm, dry winter thanks to the El Nino. But remember that winter doesn't start for another three weeks. And that El Nino effects often don't kick in full force for our area until January.

Essentially they are saying that a wet Fall does not equal a wet Winter, or so I read it.

So let's enjoy (and store) the moisture while we're getting, just in case Winter goes dry on us, as forecast.

Joseph Ratliff said...

@Cailean - The El Nino forecast doesn't "show" most of its effect until January - early March in Western WA.

It's also not as "binary" (wet or dry) as most of the media might have you believe. Typically, it produces warmer than normal temperatures and a reduced (although not eliminated) snow pack in the mountains.

If I'm not mistaken, our recent and really dry Winter of 2014 - 2015 was an anomaly ... a "weird" (low probability of happening) natural climate event helped along by the widely mentioned "Blob" of warmer water off of the coastal areas of WA.

Our Winter this year doesn't seem to have the same influences, so the resulting "effect" (the Winter of 2015 - 2016) likely won't be as "dry" nor as lacking in snow pack.

For example, Professor Mass has mentioned a good possibility of about 80% of what is considered normal snow pack after this Winter is over. Not a totally dry Winter, but not a totally productive Winter either.

But if it happens as Professor Mass has outlined, a completely normal outcome for an El Nino scenario.

Our water supplies will likely outlast this type of outcome, and IF followed by a La Nina general scenario (wetter, below normal temps etc...) this media influenced "drought panic" (my opinion) will be a thing of the past.

CC said...

Well you've been hyping the snowpack for a month, while we in the central cascades are at about 20% snow depth and SWE and The Summit and Stevens are still not open. Let's hope you finally have it right this time.

sunsnow12 said...

Cailean is absolutely correct on this, the forecast for the fall was a "relatively warm, dry fall" and "For the Northwest, that points to the likelihood of above-normal temperatures and below-normal precipitation from October through February." (Seattle Times, Sept 23, 2015, Headline "Fall and Winter Forecast: warm and dry across the NW")

Water year (beginning Oct. 1) a/o 12/1/15 Sea-Tac Precip Actual: 13.66" vs. Normal 10.25" 133% normal
YTD a/o 12/1/15 Sea-Tac Precip Actual: 34.10" vs. Normal 32.34" 105% normal

And we are about to get more.

But I expect these predictions of impending drought or, as the Times quoted in the 9/23 article "right now, nature seems upside down" (in a year when even at that time W. Wa precip was within 90%+ of normal) to likely continue.

That should be the story. The inaccuracy and alarmism should be the story, or at the very least should be questioned by all of us.

JadeEJF said...

Sooo... Let's say for argument's sake that you had relatives driving on I-90 today towards Seattle, who were camped in Sioux Falls, SD for the night. If it were your family, would you advise them to keep going on I-90 or take an alternate route?

windlover said...

What about Mondays system? Is that one going to be as wet and windy, or worse, than Thursday and Saturdays systems?

lhsouthern said...

What about the systems Saturday and Monday?

Alex said...

Cliff- I very much appreciate (and often cite you on) your push against exaggerating drought conditions, but I do want to highlight why the Yakima is unique, and why simply looking at reservoir contents here doesn't fully predict next year's water supply. For full water supply, the Yakima Basin needs full reservoirs AND decent snow melt runoff after irrigation season begins (April on). If we have full reservoirs but no snow pack or even a decent early snow pack but lots of pre-irrigation season snow pack loss, we can still end up with major water shortages.

Last year is a good example. We went into the fall with fuller than average reservoirs and we filled them faster than we ever have before (they were as full in Feb as they normally are in June). Here's the graph: http://www.usbr.gov/pn-bin/graphwy.pl?yaksys_af - note that last Dec 1 we had 200,000 acre feet more stored than we do now. Thanks to the abysmal snow pack at the start of irrigation season, we had a major water shortage despite having overflowing reservoirs in early spring. As you've often noted, we did not have a precipitation drought last year, and are not in one now, but we did have a 'snow pack drought' last year, and may not know if we'll have one next year until late Feb/March. We will not be able to say what kind of irrigation water year we will have until we know what late spring snow pack looks like (part of what made last year so tough was that it wasn't even apparent there would be a major water shortage until March/April, after many farmers planting decisions were made). While upcoming weather is great news, it's premature to say that our worries for next season are over, just because are reservoirs are now slightly above average.

The Outfield said...

Speaking of the blob, what's the status of it? Is it completely gone now?

mig said...

Alex is right on the mark about the Yakima Basin - they won't be out of the woods until there's a decent snowpack down to 3,000' or a really big one above 4,000.