Rod's Weather Headlines

I often tell people when the east coast is cold and nasty we are high and dry.  Portland was 2 degrees above normal for January, Central Park, New York City was 2 degrees below normal.  Portland snapped a 4 month consecutive streak of wet weather, the east coast got buried in cold and snow.  PDX has enjoyed above normal temperatures 21 of the last 36 days.  

Timberline Lodge received 307" of total snowfall through December 30th.  Since that date, only 37" of snow has fallen.  A base at the resort has fallen from near 100" to  68" on the ground.  

An earlier Headline post talked about a possible wind shift that is pushing the jet stream track farther south than would be typical of La Nina.  It is the southern storm track that has produced the massive snowstorms of the east and left us quiet and mild since the start of the year.  Possible reason for a more southern storm track is wind flow variation possibly caused by shrinking ice over the Arctic region.  (pretty interesting!)

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I continue to track a colder, more active weather pattern for the Northwest, starting this coming weekend.  Much of next week, Feb. 12th - 18th looks wet with snow levels below Cascade passes.  

Likely not a surprise the snowpack on Mt. Hood has fallen to 78% of normal for this time of the season.  Today's measurement taken at 5,400 feet, shows a snow depth of 71", which would melt into 28.4" of water.  The goal is to have enough snow by April 30th to melt into 65" of water.  Today's survey shows we are less than 50% of what would make an average season snowpack for the complete season. 

Snow depth on the mountain was 92" on December 30th.  Since that time, we have lost 21" of snow, due to the warm temperatures and high snow levels.  It is interesting to note that the current snowpack has held some of the rain. Today's survey shows an increase in water content of nearly 2.00" since the Dec. 30th measurement.  Also of note is a complete lack of snow near and below 3,000 feet.  Saddle Mountain, at elevation of 3,110' in the Coast Range has no snow on the ground.  

Ski resort base depths can be misleading because of the constant grooming and in some cases movement of snow. With that said, most resorts reached their highest snow depth Dec. 30th and have steadily lost snow since.  Here are the reports:  

Timberline:  Dec. 30 depth 112"  /  Jan. 27  depth 93"

Meadows:    Dec. 30 depth  94"  /   Jan. 27 depth 69"

Skibowl:      Dec. 30 depth  58" /    Jan. 27 depth 38"

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Current forecast charts show less than a foot of new snow through the 10th day of February.  Much of next week will return to high snow levels, meaning more snow melt.  Colder air is expected by mid February.  

The big weather story all of a sudden is an expected long dry stretch.  With the exception of a slight chance of light rain Sunday and Monday, all models show dry weather all the way through the 7th day of February!  The dry weather will be produced by a centered area of high pressure.  The mid and upper atmosphere will see warm temperatures with the snow level rising to 10,000 feet!  

The forecast assumption is for days of sunny skies with chilly lows and daytime highs in the 50s.  The reality could be morning fog, low clouds become trapped under the inversion and afternoon highs only in the low 40s. For now, lets hope for sunny days with mild temperatures.  

Mt. Hood will see days of clear skies.  Warm temperatures up high will lead to a foot of melting snow - maybe more.  The expected "monster" snow pack has not happened, despite the early start.  Melting snow this coming week will likely drop the base at Skibowl to near 30 inches.

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Winter Outlook:  February is expected to see below normal temperatures with above normal precipitation. The outlook through April calls for cooler than normal temperatures and an equal chance of above or below normal rainfall.  Following our dry stretch of weather, forecast charts are hinting at cold, active weather Feb.  10-20th.  We'll see!

Interesting article,  half way down read about the possible impact connected to a loss of Arctic sea ice.

NASA RESEARCH FINDS 2010 TIED FOR WARMEST YEAR ON RECORD

WASHINGTON -- Global surface temperatures in 2010 tied 2005 as the warmest on record, according to an analysis released Wednesday by researchers at NASA's Goddard Institute for Space Studies (GISS) in New York.

The two years differed by less than 0.018 degrees Fahrenheit. The difference is smaller than the uncertainty in comparing the temperatures of recent years, putting them into a statistical tie. In the new analysis, the next warmest years are 1998, 2002, 2003, 2006 and 2007, which are statistically tied for third warmest year. The GISS records begin in 1880.

The analysis found 2010 approximately 1.34 F warmer than the average global surface temperature from 1951 to 1980. To measure climate change, scientists look at long-term trends. The temperature trend, including data from 2010, shows the climate has warmed by approximately 0.36 F per decade since the late 1970s.

"If the warming trend continues, as is expected, if greenhouse gases continue to increase, the 2010 record will not stand for long," said James Hansen, the director of GISS.

The analysis produced at GISS is compiled from weather data from more than 1000 meteorological stations around the world, satellite observations of sea surface temperature and Antarctic research station measurements. A computer program uses the data to calculate temperature anomalies -- the difference between surface temperature in a given month and the average temperature for the same period during 1951 to 1980. This three-decade period acts as a baseline for the analysis.

The resulting temperature record closely matches others independently produced by the Met Office Hadley Centre in the United Kingdom and the National Oceanic and Atmospheric Administration's National Climatic Data Center.

The record temperature in 2010 is particularly noteworthy, because the last half of the year was marked by a transition to strong La Nina conditions, which bring cool sea surface temperatures to the eastern tropical Pacific Ocean.

"Global temperature is rising as fast in the past decade as in the prior two decades, despite year-to-year fluctuations associated with the El Nino-La Nina cycle of tropical ocean temperature," Hansen and colleagues reported in the Dec. 14, 2010, issue of Reviews of Geophysics.

A chilly spell also struck this winter across northern Europe. The event may have been influenced by the decline of Arctic sea ice and could be linked to warming temperatures at more northern latitudes.

Arctic sea ice acts like a blanket, insulating the atmosphere from the ocean's heat. Take away that blanket, and the heat can escape into the atmosphere, increasing local surface temperatures. Regions in northeast Canada were more than 18 degrees warmer than normal in December.

The loss of sea ice may also be driving Arctic air into the middle latitudes. Winter weather patterns are notoriously chaotic, and the GISS analysis finds seven of the last 10 European winters warmer than the average from 1951 to 1980. The unusual cold in the past two winters has caused scientists to begin to speculate about a potential connection to sea ice changes.

"One possibility is that the heat source due to open water in Hudson Bay affected Arctic wind patterns, with a seesaw pattern that has Arctic air downstream pouring into Europe," Hansen said.

For more information about GISS's surface temperature record, visit:

http://data.giss.nasa.gov/gistemp/ 

The big weather story this morning is receding water.  All rivers are expected to drop below flood stage by this evening!  Here are a few highlights of our wet weekend:

Newport Rainfall:  7.75"

Downtown Portland:  2.25"

Timberline Lodge:  8.50" (all rain)

Estimated Cascade 2-Day Snow Melt:  12"  

PDX Temperature stays above 50 degrees from the afternoon of the 13th, through this morning - the 17th

Residents along the Sandy and other Cascade rivers say it's the highest water since the floods of the 1990s.  

Combination of two days of heavy rain, warm temperatures day and night with snow levels as high as 9,000' producing melting snow in the Cascades all created recipe for flooding.  Coastal rivers flood but would have been much worst if snow pack was in place over the Coast Range.  

Anyone driving prior to sunrise Sunday should use caution and look for ponding of water over roadways.  Johnson Creek is expected to crest Sunday morning at 9:00 a.m. just a foot shy of what is considered a major flood.  Home owners should watch the rising water carefully. 

I am also watching the Sandy, Hood River and Clackamas.  The large rivers flowing out of the Cascades will be at high risk due to heavy rain and snow melt.  Rising snow levels early Sunday could peak near 9,000 feet!  Forecast crest along the Clackamas are projected at 4 feet above flood stage.  Hood River and the Sandy will be close to reaching bank full.  All three rivers should be watched closely through the day Sunday. 

Coast Range rivers are not expected to be much of a concern.  Snow in the Coast Range is mostly melted and not playing a role in this event. 

It is 11:00 p.m. Saturday evening as I write this article,  rain rates in the valley have fallen apart.  I have reason to believe we have seen the heaviest of the rains - lets hope so.  If true, we will likely get through with no big problems!

Great news for residents along Johnson Creek, rising waters are expected to remain below flood stage, crest this morning and recede this afternoon!  The Clackamas is still projected to crest later today 4' above flood stage near Estacada and 2' above near Oregon City.  Hood River is expected to crest 2' above flood stage today.  The Sandy river is projected to crest about a foot above flood stage.  

At the Coast, the Wilson River will crest a few inches above flood stage this morning.  Other rivers expected to produce some flooding today:  the Nehalem at Foss, the Grays at Rosburg, the Tualatin at Dilley and the Cowlitz at Kelso.  

FLOODING POSSIBLE SATURDAY NIGHT THROUGH MONDAY ALONG RIVERS
IN SOUTHWEST WASHINGTON AND NORTHWEST OREGON.

.PERIODS OF HEAVY RAIN WEDNESDAY THROUGH FRIDAY THIS WEEK MELTED
A FAIR AMOUNT OF LOW ELEVATION SNOW AND ICE FROM EARLIER IN THE
WEEK AND PRIMED RIVERS ACROSS MUCH OF SOUTHWEST WASHINGTON AND
NORTHWEST OREGON. ANOTHER PERIOD OF WARM HEAVY RAIN WILL SPREAD
IN OVER THE AREA THIS WEEKEND...AND MAY PUSH SEVERAL RIVERS TO OR
ABOVE FLOOD STAGE SUNDAY AND MONDAY. A WEAKER SYSTEM WILL MOVE
THROUGH ON SATURDAY...THEN THE WARM FRONT FROM THE NEXT STRONGER
SYSTEM WILL BRING THE FIRST SURGE OF HEAVY RAIN TO THE AREA
SATURDAY NIGHT. THE ASSOCIATED COLD WILL MOVE ACROSS THE AREA
SUNDAY FOR MORE HEAVY RAIN. THE RIVERS MOST AT RISK ARE THOSE
DRAINING THE COASTAL MOUNTAINS IN SOUTHWEST WASHINGTON AND
NORTHWEST OREGON...RIVERS DRAINING THE SOUTH WASHINGTON
CASCADES...AND WILLAMETTE RIVER TRIBUTARIES DRAINING THE COAST
RANGE AND THE NORTH CASCADES.

* A SUSTAINED PERIOD OF HEAVY RAIN IS EXPECTED TO DEVELOP
 SATURDAY NIGHT AND CONTINUE THROUGH MOST OF SUNDAY. SNOW
 LEVELS WILL BE AROUND 8000 FEET OR HIGHER THROUGHOUT THIS
 HEAVY RAINFALL EVENT. STORM TOTAL RAINFALL AMOUNTS OF 4 TO 6
 INCHES ARE EXPECTED ALONG THE COAST AND IN THE COASTAL
 MOUNTAINS...WITH 1 TO 3 INCHES IN THE VALLEYS.

* RIVERS OF GREATEST CONCERN TO REACH FLOOD STAGE INCLUDE THE
  GRAYS RIVER IN WAHKIAKUM COUNTY...THE COWLITZ RIVER IN COWLITZ
  COUNTY...THE NEHALEM RIVER IN COLUMBIA AND CLATSOP COUNTIES...
  THE WILSON AND TRASK RIVERS IN TILLAMOOK COUNTY...THE SILETZ
  RIVER IN LINCOLN COUNTY...THE CLACKAMAS RIVER IN CLACKAMAS
  COUNTY...JOHNSON CREEK IN MULTNOMAH COUNTY...THE UPPER TUALATIN
  RIVER IN WASHINGTON COUNTY...THE PUDDING RIVER IN CLACKAMAS AND
  MARION COUNTIES...THE MARYS RIVER IN BENTON COUNTY...THE
  LUCKIAMUTE RIVER IN POLK AND BENTON COUNTIES...AND THE SANTIAM
  RIVER IN LINN AND MARION COUNTIES. THE HEAVY RAIN MAY ALSO CAUSE
  SMALLER CREEKS AND STREAMS TO FLOOD...AS WELL AS CAUSE AREAS OF
  FLOODING IN OTHER RURAL AND URBAN AREAS.


**The combination of heavy rains, already swollen rivers and very high snow levels
     make this a potentially dangerous event.

Monday Evening 9:45 p.m. Update:

New data tonight shows a warmer air mass, meaning a better chance of nothing but rain in much of the metro.  Any snow is looking less possible.  Freezing rain and or sleet remains a possibility Tuesday evening and night.  Surface temperatures will have to be watched closely.  If we dip below freezing ice accumulation could be enough to damage trees and bring down power lines.  To repeat, the chance of all rain in the metro is increasing but the risk of freezing temperatures and ice accumulation Tuesday night remains.

I am forecasting 33 degrees tonight for Salem and Portland.  (It could be warmer!)  So, after all of my talk, most of the metro will see steady rain this evening and heavy rain at times Wednesday and Thursday.  Caution:  Cold pockets will be possible.  Please watch the temperature closely tonight.  If your home warms to 35 degrees, you likely will remain above freezing and in fact will likely warm further by morning.  Any cold pockets could see significant ice accumulation.  The Gorge will be under a Winter Storm Warning tonight and Wednesday morning for ice and snow.  The Coast could see 60 mph wind gusts near the beach overnight as the warm front arrives.  Travelers into the mountains will likely encounter a mix of rain, ice and snow this evening and overnight.  All snow will fall above 5,000 feet Wednesday.