Darkest Before the Dawn

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The fourth of July should be a decent day across the Northwest...and the trendline is positive towards dry conditions and normal or above-normal temperatures.  This morning's visible satellite image (below) shows clear skies over Oregon and eastern WA, with some broken clouds over the west.  The radar is clear.


Yesterday was pretty exciting for July, with winds gusting to 20-40 mph and some power outages  (including my house in north Seattle).   For example, here are the winds at West Point (admittedly a well exposed site).  Gusts to 33 knots (38 mph).  Admittedly, not as strong as the East Coast derecho a few days ago (where winds gusted to 70-80 mph), but very strong for this season.


 And yesterday's precipitation totals were highly variable and in places quite respectable, particularly in the Puget Sound convergence zone area.  A few locations over the eastern foothills of the Cascades got an inch or more, while south of the convergence line (Seattle south) and over the Sound it was dry.



 Now that the worst is past, it is safe to tell you how bad it was:

(1) The -25.7 C 500 hPa  (roughly 18,000 ft) temperature at Quillayute WA yesterday morning, was the coldest in North America.  AND the coldest July 500 hPa temperature at Quillayute since -26.1 deg C was reported on 2 July 2000.

(2) A number of Washington locations experienced daily record precipitation records (record for that day) and several (particularly over northeastern WA) had MONTHLY record totals (e.g, Republic,
Colville, Boundary Dam, and Newport).  Several  locations had top 10 monthly totals.  Here is a summary from the Office of the WA State Climatologist (OWSC):

Here is the % of normal precipitation for the past 30 days.  Much of eastern Washington, northern Idaho, and the northern Willamette Valley had more than 200% of normal rainfall, and the rest of the region was at 100-200%.  Amazingly, parts of the Southwest U.S. and the intermountain west has received less than 5% of normal rainfall--extraordinary contrasts in such close proximity. 


An important issue with the precipitation and temperature pattern we have had the past few months is the impact it has had on soil moisture.   Take a look at the last soil moisture anomaly map (difference from climatology).  
Much wetter than normal over the NW (surprise!), but huge negative (dry) anomalies over the southwest and the central U.S.   Such dry anomalies have many bad implications:
 (1) enhanced change of wildfires over the southwest (2) damage to crop productivity in the U.S. grain belt (3) more severe heat waves in the dry areas.Why do dry soils make the temperatures warm?   It turns out that a lot of the heat of the sun goes into evaporating water (going into latent heating) rather than warming the surface (sensible heating).   Thus, over a moist surface the surface temperatures don't warm as much, since a lot of the sun's energy is going into evaporating water.   Also moist surfaces and moisture evaporating from them promote clouds, which reflect solar radiation to space.  Thus, we can get into a positive feedback loop where heat produces dry conditions, which promotes more heat, etc.
But no such worries in the moist Pacific Northwest where our forlorn tomatoes finally will get the weather they deserve. 

FINALLY, True Summer Begins

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It happens almost every year, and we sometimes lose faith that it will occur.

The transition to meteorological summer in the Northwest. 

Often, as in this year, it happens right after July 4th, and almost certainly by mid-July, resulting in the oft-noted statement by the meteorological cognoscenti that summer starts on July 12th in western Washington.  The effect is so profound, repeatable, and abrupt that we see it clearly in the climatological data.  For example, here is the climatological daily probability of precipitation for Sea-Tac airport.  On July 1st, the probability of at least .01 inches is still around 30%---but then the bottom drops out, and by mid-month it is in the low teens and around August 1st below 10%.  Folks, this golden time, between July 15th and August 15th, is when you should plan your outdoor weddings, barbecues, and other rain-sensitive activities.  Few areas are as dry as we are during that period.


But what about this year?  Today and tomorrow there will still be come showers and clouds around. Wednesday, July 4th, will be the transition day, but one that should be dry--particularly around fireworks time.  And then we transition to meteorological nirvana, as the persistent trough over the NW moves offshore and ridging develops over western North America. 

Let me show you.


Here are two upper level (500 hPa--roughly 18,000 ft) charts.  The first is for the afternoon of July 4th and the other for Sunday afternoon.  You can see a large transition from a trough off the the west coast to ridging (higher heights) over western North America and strong troughing far out in the Gulf of Alaska.


This transition in atmosphere flow is supported by most major international model systems, such as the gold-standard ECMWF forecast... as shown below.


For longer-term forecasts meteorologists depend more heavily on ensemble-forecast systems in which many forecasts are run, with the ensemble mean  (average) having more skill than any particular forecast.  And the variability of the ensembles gives us information about probabilities.  Here are the differences between the forecast ensemble means for today versus Saturday (actually the differences of the forecast means from normal..the anomalies) for the upper level (500 hPa) flow.  Blue indicates anomalous troughing, green-ridging.  The ensembles concur with the transition to improved conditions.



 The last U.S. Climate Prediction Center graphics reflect the changes, with warm conditions predicted over the western U.S. for July 9-15th.

So, get our your summer clothers, buy that sunscreen, be prepared to water your garden...summer is coming.

KUOW Hike of the week Yellow Hill

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Updated Tuesday July 3, 2012Hike is Yellow Hill in the Teanaway area just east of Cle Elum

Photo below of Mt. Rainier


Check out Green Trails Maps for directions. Map for this week's trip is 209. Click link below for complete list of maps.http:// http://greentrailsmaps.com/maps/index_Map_wa/

Photo below is of Balsamroot: Is that why this is called Yellow Hill?
Photo below is hiker on trail
Photo below is of Stuart Range
Directions: From Seattle drive east on I-90 to East Cle Elum, exit 85. Cross over the freeway overpass and turn right (northbound) on State Route 970. Cross the Teanaway River bridge, and in another mile turn left onto Teanaway Road. Then to go to Middle Fork of Teanaway and turn left drive about 4.5 miles to the Indian Camp Campground. Continue 0.7 mile farther to the trailhead park.

Trail stats: Starts on the right. Trail 1222 (unmarked) Starts as a road walk for about 1.5. At 3 miles (from start) you reach shoulder of Yellow Hill which is at 5527 feet. Miles is 6 rountrip 2700 feet gain

Directions and trail stats are our best estimate however please have a good local map and or a GPS unit.
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Understanding Ellensburg's Wind

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As we move into the late May and June regime of low clouds (a.k.a. June gloom), experienced west side residents know that crossing the Cascades--east of Cle Elum and down into Ellensburg-- can bring welcome sun.  A fancy resort, Suncadia, has been built for sun-starved travelers in Cle Elum, and even more sun can be found if you descend I-90 to Ellensburg and Vantage.  Even Knute Berger, the old mossback, recommends Cle Elum sun in a recent Crosscut piece.

But there is problem.   During just the days when the east-side offers the brightest contrast to the dreary west, westerly winds descend into the Kittitas Valley, causing the stretch from Cle Elum to Vantage to become a wind tunnel, with sustained winds of 20-30 mph and gusts that sometimes hit 50. 

Some folks say that in Ellensburg there is only one four letter word best for cussing: WIND.  And the Ellensburg Safeway has a unique wind measuring devise for their customers.


Now I have enjoyed the Suncadia resort in Cle Elum a few times, but it is sufficiently exposed to the westerly winds that the extensive golf courses are perhaps a bit more of a challenge than novice golfers might have reckoned with.  The golf pro at Suncadia is highly in demand for this insightful lessons in avoiding wind-driven hooks or slices.  Here is a sample (click on picture) that was sent to me by a local golf enthusiast.  Listen to his detailed instructions on the proper swing for windy conditions:


Strong westerly winds are found in this region when there is a large pressure difference across the Cascades, with higher pressure to the west.  Such a large pressure different in most prevalent in the spring and summer.  Why?  In spring high pressure builds northward in the eastern Pacific, while the warming of the interior of eastern Washington leads to pressure falls, since warm air is less dense than cold air.  To illustrate this pressure pattern, here is a 12-h pressure forecast valid 5 PM last Friday, a day when the winds were quite strong in Ellensburg and vicinity:


Air looks for the easiest path across the Cascades, and the Snoqualmie/Stampede Pass complex is the lowest route across (roughly 3000ft) north of the Columbia Gorge.  Cool, cloudy days with strong onshore flow are often associated with high pressure in the west---that can juice the pressure difference and the winds.

Spring and early summer are the best times for strong winds moving into the Kittitas Valley and thus the period of best wind energy potential for the many wind turbines in the area.   Unfortunately, this is the period of greatest snowmelt, streamflow, and hydropower potential--leading to contention between these two sources of clean energy.  Why contention?   Lack of energy transmission capability.  I wish some of the stimulus money could have been used to fix this deficiency.

The UW ultra-high resolution WRF forecasts do a pretty good job in simulating the strong winds along the eastern slopes of the Cascades...here is a sample (the shading shows the sustained wind speed) and the brown lines are sea level pressure.  You will note that the region from Leavenworth to Wenatchee get some winds too..they are downwind of the Stevens Pass gap...a lesser one. 

The strongest winds are often east of Ellensburg on Whiskey Dick mountain--the ridge on which Puget Sound Energy has placed their Wild Horse Wind farm. Very nice visitor center there if you want to visit.  Want sun and no wind?  No problem.  Drive down to Vantage and head north towards Quincy....the winds are less there.


Let me end with a plot of the sustained winds at Ellensburg during the past six months...they can get strong winds any time of the year...but you see the increase around March 1 and the beginning of the spring pressure patterns.

Memorial Day Weekend Outlook

No major storms.Friday and Saturday will be sunny and seasonably warm (60s).Clouds and a few sprinkles on Sunday and Monday-highs around 60.

Cascade Melt Out

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There are few more important questions for Northwest hikers:  when will their favorite trails melt out and the hiking season begin in earnest?  

And few more important questions for those concerned about the local impacta of global warming:  is the Cascade snowpack melting out earlier, thus providing evidence of the effects of increasing greenhouse gases in the atmosphere. 


This truth may surprise some and depress others.  

It turns out that the Cascade snowpack has been trending to melt out LATER during the past thirty years, with the last few years being particularly late.  For example, Stevens Pass finally melted out yesterday--3 weeks later than normal.

Here is a plot of the melt-out date at Stevens Pass from 1981 through this year (courtesy of UW atmospheric scientist Mark Albright).  The y axis shows the melt-out day (days into the year) and the purple line shows a 5-year running average.  The overall trend is clearly for a later melt out.
The mean melt-out dates by decade illustrate this trend:

1980s:  30 May
1990s:  1 June
2000s:  2 June
2003-12:  6 June

Three of the five latest melt-out dates have been during the past five years:

1 July 2011 THE LATEST!
25 June 2008
25 June 1999
24 June 2012
23 June 1997

Paralleling the late snowpack melt-out is the April 1 snowpack amount, which has not shown any decline over the past 30 years.

Does this trend in snow melt out  mean that the Northwest does not have to worry about greenhouse warming? The answer is no.  By the middle of this century the Northwest snowpack should clearly be on decline as the earth warms, but as I have mentioned many times in this blog, the entire world will not warm at the same rate.  Downstream of the eastern Pacific, the coastal portions of the Pacific Northwest (Cascade crest westward) will warm up more slowly than most places, since the eastern Pacific will take its time to heat up.

Let me illustrate this.  Here is the change in global temperature from 1980 through this year for the winter months (courtesy of Goddard Institute for Space Studies).  The eastern Pacific has COOLED, and we have cooled with it.  But we are the exceptions...most of the earth has warmed and the arctic region has really warmed.   So there is global warming (with some contribution from man-caused increasing greenhouse gases), but out neighborhood has cooled...temporarily.

Pretty interesting stuff and with important implications for us here in the NW...we have much more time than most to prepare for the effects of global warming.....at least the temperature/snow part of the changes. So if someone tries to tell you that the coastal NW has already experienced major effects due to global warming, you might question their information.   And if someone says that a stable or increasing snowpack the past few decades proves global warming is nonsense...I would not trust their information either.  

Battling Extremes and the July 4th Forecast

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It is startling to see such weather extremes so close together.

Here in the Northwest we are experiencing wetter and colder than normal conditions on most days, with some locations shivering under daily low temperature records.  Yesterday, temperatures plummeted to 37 at Shelton, 39 in Olympia, and 38 at Yakima.  In some cold hollows near the surface temperatures may have dropped close to freezing.  In late June.

At the same time, temperatures in Colorado have reached over 100F day after day, some all-time high temperature records have been reached, extreme drought is in place, and fires are descending the Front Range of the Rockies into populated areas.

Let me illustrate....here are places that have experienced record low temperatures across the U.S. yesterday--some over the southeast U.S. associated with a trough and clouds and the other over guess
where....

In contrast, here are where the high maximum temperature records occurred--from Wyoming through, Colorado, Oklahoma, to Louisiana on the same day.

Lets look at the differences from climatology (the anomalies) for the past week.  First for maximum temperature.  Extraordinary cold from central CA into the Northwest, with some locations 9-15F below normal, which equally strong but warm anomalies east of the Rockies

These extraordinary warm anomalies are occurring in locations where precipitation has been nearly absent all spring.  Here are the precipitation anomalies for the last month...large areas have had 5% or less of normal precipitation.  No wonder wildfires started so early.  And yes, WE have had wet anomalies...with eastern Washington being particularly wet.  I wonder what that implies for agricultural interests there.

 The reason for all this contrasting weather is due to a highly persistent atmospheric flow pattern with a stubborn trough over the eastern Pacific and a big ridge over the Rockies and middle part of the country.  Here is the mean upper level (500 hPa) flow and the anomaly from climatology.  You can see the troughs on both coasts and the big ridge over the middle of the U.S.  The trough off our coast represents a very large anomaly from normal, if that makes you feel better


But I know what you really want to know, how does July 4th look?  Will this abysmal pattern ruin our fireworks and barbecues?  Here is the answer from the latest European Center model run.  The panel on the right is the average of their ensemble (many model run) system and one on the right is their best single prediction, both for the upper level flow (500hPa).  The SAME pattern is there-troughs over the coast, big ridge over the central U.S.


At least we won't have to worry about wildfires, air conditioning, or firework cancellations.  Just mold and mildew.

Sky Poet

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Photography can be as poetic and compelling as the work of the written masters, and we are lucky to have such a visual poet here in the Northwest--one who specializes in the most dramatic type of local clouds:  lenticular or mountain wave clouds. 

Her name is Darlisa Black and on occasion I have shown her work on this blog and in my book.

Just a sample to show you what I mean.  First, some beautiful lenticular clouds:


She has a way with light and shadow that I really appreciate, as well as the occasional watery reflection of dramatic cloud features.   Lenticular clouds are particularly good photographic subjects, with both subtle, beautiful, and other-wordly features.


If you want to see more of her work, check out her web site:

http://starlisablackphotography.com/

or her facebook page:

 http://www.facebook.com/StarlisaBlack