Monday, January 16, 2017

Major Transition to Warmer and Wetter

It is about time.    A major transition in the atmospheric circulation is occurring over the eastern Pacific that will lead to much warmer and wetter conditions over the Northwest.

Eastern Washington will get out of the endless deep freeze.

Portland will finally warm up enough to rid itself of the icy roadways that have has made driving like a segment of Ice Road Truckers.

Western WA will lose the blue skies and bright sunshine that has been so pleasant for suffers of Seasonal Affective Disorder.

And tragically, Cascade skiers, particularly on the lower slopes, will give up powder conditions for the familiar Cascade Concrete.

Will the History Channel film a segment in Portland?

And there is a major threat tomorrow and in the Columbia Gorge:  an ice storm from freezing rain.

The origin of our unusual cold has been persistent high pressure east of the Cascades that has brought cool, dry easterly flow over much of the region.  A disturbance going south of that high gave Oregon the snow earlier this week.

To show you the changes, here are upper level (500 hPa) maps that illustrate the change.  In the first (for 4 AM Monday), an upper-level ridge is right over us, resulting in dry weather over the region.

In contrast, by 8 AM on Wednesday, the ridge is far east of us, a trough has developed over the eastern Pacific, and moist, warm southwesterly flow is over our region.
The map for 4 AM Friday is amazing...a nearly strait jet stream is directed towards southern California (remember, winds are parallel to the height lines and the wind speed is proportional to the gradient of the height lines).

A HUGE change is going to occur over eastern WA and Oregon, which has been locked in the freezer for weeks.  To illustrate, here are the temperatures at Pasco for the past four weeks (yellow lines), with the normal highs and lows indicated by the red and blue lines.  For virtually all of 2017, Pasco has been well below normal, with the highs on most days not even reaching the normal minima, and a number of hours below zero F.
Another way to see how extreme things have been..here is the deviation of the average minimum temperature from normal for the past month over our region.  From the Cascade crest eastward to the Rockies and beyond, some areas have had minimum temperature 15F below normal or more...virtually all  of that region is a least 9F below normal.  Stunning.


But all this is going to change... in fact, is changing.  Here are the predicted surface (2-m) air temperatures from the European Center model, valid for Hanford, Washington.  A major warming is predicted over the next two days.  Temperatures in the 30sF will feel like spring for the those chilled folks in the Columbia Basin.


What about Seattle and Portland?  The forecasts will warm your heart and your extremities.  Portland temperatures will climb into the forties on Tuesday, as will Seattle's.



Seattle is already in the mid-40s and it feels so mild.

And did I mention precipitation?   We are going to be very wet for the next few days, with the latest high-resolution WRF run suggesting that over the next 72 h as much as 5-10 inches of liquid precipitation will fall in the mountains--most of the that will be rain, except for the higher elevations of the Olympics and north Cascades.


And now we must talk about a problem:  a real threat of freezing rain in Portland on Tuesday during the transition.   It will take a day or two to scour all the cold air east of the Cascade crest and during the interim, some of which will move eastward into the Columbia Gorge towards Portland.  Warm rain from below will drop into this cold air and be chilled, resulting in freezing rain that will freeze on contact.    The NWS has an ice storm warning out for the Columbia Gorge region and Portland.

Over the next 7 days, the National GFS model forecasts suggest a LOT of precipitation along the West Coast (see below), with 5-10 inches being common over West Coast terrain.  As I will describe in a future blog, the West Coast drought is history.  Good for veggie prices next year.

The sun has been nice, but it is time to get back to normal for a while.

13 comments:

Colin said...

I've been wondering if the forecasted precipitation in combination with the temperature increase could cause landslides in western washington. Any thoughts? Thanks

crf450ish said...

I pray this transition is just a small blip on the way to a pattern reset. If this spells the end of winter for my area, I'm going to be extremely pi****!!!!

I love how cold it's been and the snowpack at my house (22") is beautiful.


-Someone that lives in Stevens County WA

Sharon Steinbis said...

Last year 2016 at this time, hellebores and sarcococca blooming. Not so 2017. Way behind.

Eric Blair said...

It would be nice if the MSM would reflect the reality of so much precipitation coming into CA, but for the most part they refuse to acknowledge that their multi - year drought is effectively over. The dominant meme of cataclysmic and historical drought must be maintained at all costs, it would appear.

gregg daugherty said...

Local forecasts; they used to confuse me with Rain vs Showers (never thought about the difference)....but now they combine the words....

What's the point of the varying nouns they use for this water coming down?

ZONE FORECAST PRODUCT FOR WESTERN WASHINGTON
NATIONAL WEATHER SERVICE SEATTLE WA
947 AM PST TUE JAN 17 2017


FRIDAY NIGHT...CLOUDY WITH A CHANCE OF RAIN SHOWERS. LOWS IN THE UPPER 30S.
SATURDAY...CLOUDY WITH A CHANCE OF RAIN SHOWERS. HIGHS IN THE MID 40S.
SATURDAY NIGHT...RAIN SHOWERS LIKELY. LOWS IN THE MID TO UPPER 30S.
SUNDAY...MOSTLY CLOUDY WITH A CHANCE OF RAIN SHOWERS. HIGHS IN THE LOWER TO MID 40S.






John Marshall said...

I'm sitting in S Cal listening to the local TV weather guys. The public story is that the drought looks to be gone this year, with the next week's forecast rains likely to finish putting a stake through the drought's heart. That's the public and popular story. The one that drives household water usage trends.

The problem is that many of the aquifers take many years to recharge, obviously the deep one's in the San Joachin, so they are still very vulnerable to gaps in the rainfall. Reservoirs are filling and this coming round of storms brings big flood worries if reservoirs have to release water because they are full. No flood control.

If reservoirs are full and aquifers are depleted, it may not be a drought, but they have no insurance to handle future droughts. Is this an anomolous year, or the start of a multi-year wet trend? I don't see anyone with the skill to make that call, so cautious consumption of water should remain the plan.

The challenge is to communicate that message of careful consumption without talking about drought worries.

And how good is the Colorado River watershed? That supplies most of the desert cities.

Ansel said...

I do appreciate the higher humidity. Dew points below about 30F make me fell cold and dried out.

TVN said...

Cliff/Eric, is that really accurate? Until the underground aquifers are full again, I would say there is still a CA drought. Will we stop seeing the phenomenon of land slipping down due to lack of water beneath it? I have often been curious what CA has done to prepare for this day...are they capturing all the runoff or is it going straight out to the ocean?

Andrew Lincicome said...

Strait!

Patrick said...

TVN, there are programs/projects to spread and percolate storm water in the LA Basin. As you can imagine, it's difficult with so much much humanity (to "protect from stormwater") and so many impervious surfaces. But much of the opportunity is being realized in the upper watersheds which still have soft bottom channels. There are also many neighborhood projects that are being built to percolate water, using parks, or curbside bioswales to recharge aquifers and treat polluted runoff before it reaches the ocean. Though not a cure for the depleted aquifers in the San Joaquin Valley, it is a start and a model for other areas.

A first read on some of the work and planning: http://riverlareports.riverla.org/water-recharge/where-to-recharge/san-fernando-basin-study/

Alex said...

At this point, give me blue skies and warm sunshine. I've had enough of this freezing!

CC said...

You mentioned it a bit but would be great to hear more about how mountain passes like Snoqualmie or Stevens Pass will get freezing rain or a combination of freezing rain and snow even though the ground temperature can be in the mid-teens. Curious on how high up rain forms and what determines if it then becomes freezing rain or snow on its way down. Thanks.

Eric Blair said...

TVN - If the aquifers are years behind since they've been depleted, then CA should be put on permanent drought conditions, in perpetuity. I'm being totally serious, CA has always been and will always be a dry state during most years, and since additional water reservoirs that were proposed in the 1970's and 80's were negated by the green lobby, there you go. The additional reservoirs were proposed precisely because the state water resource departments had estimated exponential population increases were coming, and coming soon. But their concerns were waved off and now CA is in a situation entirely of their own government's making. While there are certainly damns existing in the West and NW that are not needed anymore, the green lobbies used the Endangered Species Act in ways that were not intended, so now you have billions of gallons of fresh water going into the ocean and no reservoirs available to capture the runoff in water - flush years.