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Monday, May 18, 2015

Mount St. Helens - Pictures During and after

      Mount St. Helens Eruption - May 18, 1980 8;32 am                                      

Mount St. Helens erupted on May 18, 1980 in Skamania County, Wash. It was the deadliest eruption in U.S. history, killing 57 people. (left) Jim Valance, Cascades Volcano Observatory, U.S. Geological Survey (right)


Mount Saint Helens erupts. USGS via Earth Science World Image Bank (above)

Mount St. Helens sends a plume of ash, smoke and debris skyward. The eruption blasted more than 1,300 feet off the mountain's peak. Jack Smith, AP
The Initial Blast  (right) The mushroom cloud of volcanic ash produced by the eruption, as seen from Toledo, Washington, 35 miles away. The cloud was roughly 40 miles wide and 15 miles high.




Ash cloud as seen from space (below)
from Weather Satellite GOES-3 at 1545 UTC




map of eruption depostits

Sequence of events on May 18








                                          











NASA Satellite Image Mount St. Helens 35 Years After Its Historic Eruption


This satellite image of Mount St. Helens comes courtesy of NASA’s Earth Observatory


Today is the 35th anniversary of the volcano’s eruption and subsequent landslide, which killed 57 people. Scientists still keep a close watch on the site from both the air and ground.
As NASA notes:
The volcano has been quiet since 2008, which marked the end of a four-year period of activity.

Thursday, May 14, 2015

Snohomish storm chaser gets 1-in-a-million shot of tornado, rainbow

By Published: May 11, 2015
 


Not sure I've ever seen a photograph that captures the beauty and power of weather in one singular shot.

Snohomish's Benjamin Jurkovich, part of the JWSevere Weather Chasing Team has been out storm chasing in the Midwest for the past few weeks and he's had his share of twisters, super cells, and other images that define Tornado Alley in the spring.

But this one he got near Wiley, Colorado Saturday afternoon might be the most unique in his portfolio -- a tornado at the same time as a rainbow.

"It was pretty darn awesome!" he said.

Jurkovich said most of his storm chases have been in the dusty Midwest as it hadn't rained much, but the night before this photograph, that portion of Colorado had heavy rains, helping to clear the air for this spectacular shot.



He's been lucky so far in not having too many close calls - the one exception was while chasing a storm near Hayes, Kansas, another area of rotation began to develop to their southwest moving northeast:

read the rest of the story at http://ow.ly/MV75N



Wednesday, May 13, 2015

Salmon fishing open one last weekend on Lower Clearwater

By Published: May 13, 2015

CLARKSTON, WA - Idaho Department of Fish and Game is closing salmon fishing on the Lower Clearwater River this Sunday, from the Camas Prairie Railroad Bridge to Cherry Lane Bridge. Fishing ends at 8:30 that night.

Salmon fishing in the Clarkston area is now closed.

The Washington Department of Fish and Wildlife made the decision a little earlier than usual this season.

"Little Goose Fishery, Lower Granite Fishery and Clarkston Fishery remained open this last weekend," said WDFW Fish Biologist, Jeremy Trump. "We saw some really high catch rates and effort at Little Goose and Clarkston. We have reached our harvest target for this season, for the Snake River."

Trump said a total of 1,749 fish have been harvested this season.

Sunday, April 26, 2015

Exploding Trees and Lightning

Cliff Mass Weather Blog Sat. April 25, 2015

If you needed another reason to avoid standing under a tree during a lightning storm, here is another: the tree might explode and shred everything in its environment. 

Such an event happened in the University of Washington Arboretum on March 31st and I visited the site this week during a run.....and I was amazed.   Here I am in front of the tree... this tall fir blew out form the center, with spokes of the trunk projecting out on the ground likes spokes of a bicycle wheel (picture taken by my colleague Lyatt Jaegle).


 Branches and tree shrapnel was obvious HUNDREDS OF FEET from the tree.   Some of the wood was ejected so forcefully that it hit the ground and was deeply embedded--- over 100 feet away!   So deep I could not pull it out.

A view from the air (courtesy of KOMO TV) and on the ground right after it happened (courtesy of the UW arboretum)  are shown below.  The original tree was over 100 ft tall.


Why did it explode?  When lightning hits the tree, it ran down the moist inner sapwood, since that portion of the tree conducts current better.   The huge current produced rapid heating and the water turned to steam, which in turn produced huge pressures that caused explosive expansion.

Can you imagine if you were standing near that tree?  You would have been torn apart or speared by flying debris.   Of course, standing under a tree during a thunderstorm is a bad idea for other reasons, such as getting electrocuted by the lightning current.   When I was a student at Cornell, a bunch of student were sheltering under a tree during a storm.  Lightning hit.  Several were seriously injured with some never recovering.

Friday, April 17, 2015

BASEBALL WEATHER...its in the wind


It's only the second week of the baseball season and already radio and television announcers are bobbling what should be easy weather ground-balls. The most egregious errors are usually misstatements about the humidity and why the ball doesn't go as far.  NOT!

The difference in the distance a 375 foot homerun travels when the humidity is 20% and when it is 60% is less than a foot.  And the difference in the amount that a 90 mph curveball breaks is only a tenth of an inch. (There may be some absorption of moisture by a baseball on a particularly muggy day, but those amounts have been found to also be negligible).

The temperature (and thus the air density) has a slightly greater impact with the difference in the distance of a home run on a 50 degree day being about 16 feet less than on a 90 degree day.  The altitude above sea level and corresponding air lower density difference means a 375 foot homer at sea level would travel about 405 feet at Coors Field in Denver.

But the meteorological element with the greatest impact is the wind.  Just a 5 mph tailwind will carry that 375 foot home run to 415 feet and a 10 mph wind will translate to an epic 455 foot blast.

The bottom line is that if you want to see really long homeruns go to Denver on a hot dry day with the wind blowing out!

A more detailed treatment of the topic can be found in last year’s Jan/Feb issue of Weatherwise Magazine (http://www.weatherwise.org/Archives/Back%20Issues/2014/January-February%202014/rain-delays-full.html )

Play ball.
 
Jan Null, CCM
Golden Gate Weather Service
http://ggweather.com

Tuesday, January 27, 2015

Hurricane Force wind Gusts = Not really a thing

I've heard this term (which makes me wince each time) quite a lot on news channels describing the "Blizzard of 2015".  The following is a 2011 article by my friend,
weather guru, Jan Null:

It seems that anytime there is a wind gust over about 60 mph the airwaves and other sources,
including NWS statements, are rife with the expression “hurricane force” winds. While this
might be good for conveying that it’s windy and might be dangerous, it’s both bad meteorology
and bad physics! (And calling it a hurricane force gust doesn’t make it right either)
Let’s start with some basics. The threshold for hurricane winds is when the 1-
minute sustained winds equal or exceed 74 miles per hour. Please note the word
“sustained”! According to the NOAA Hurricane Research Division, peak 3 to 5-
second gusts are approximately 30% higher than their associated sustained winds.
This means that a 74 mph sustained wind of a minimal hurricane has gusts in the
range of 96 mph. Quite a difference.

But that’s just the wind speed. What about the amount of force from the wind onto a surface that
is perpendicular to the wind? From high school physics we remember that the force associated
with a given speed is proportional to the square of the wind speed. (For the over achievers out
there, the formula to calculate this force is: F = .00256 x V^2, where F is the force in pounds per
square foot (psf), and V is the wind velocity in mph) Consequently, the amount of force with a
74 mph gust is 14.0 psf, while the force from a 96 mph gust is 23.6 psf; or 69% higher.
The bottom line is that a gust to 74 mph is NOT even close to hurricane force!
http://www.examiner.com/weather-in-san-francisco/meteorological-pet-peeves-part-1-of-3.
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Jan Null
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com
Webpage: http://ggweather.com
"Climate is what you expect,
Weather is what you get". ~ R. Heinlein
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