Start of the Northwest Wildfire Season: Lightning, Winds, and Grassoline

This week the Northwest wildfire season began, with a series of large grass fires on the eastern slopes of the Cascades (map below of current major fires).

One fire, the Sutherland Canyon fire southeast of Wenatchee was quite large, reaching 47,000 acres this afternoon (see map below).

Yesterday's high resolution MODIS satellite imagery shows the smoke from the fire, which was mainly heading southeast towards Moses Lake.

You can actually see the burnt area from space. Here are two images, one from earlier this week and one today.  The blackened area resulted from the fire.

Meteorology had a lot to do with the fire....in fact, it was a classic set up.  We started with the building of high pressure over the region earlier this week that caused temperatures to surge and humidities to plummet.   Here are the temperatures over the past two weeks at Wenatchee.  Temperatures warmed towards a peak on Monday into the mid-90s.  And there was no rain during that period.

So there was considerable drying.

Then there was an initiator of fire:  lightning on Monday night as an upper level trough pushed through (see 500 hPa--around 18,000 ft--weather map at 8 PM)

Take a look at the lightning strike map for the 24 hr ending Tuesday at 1 AM.  You can see the band of lightning, associated with some modest thunderstorms, that ignited some of the grass around Wenatchee.  And started the other fires as well.

But there was something else:  strong winds that fanned the fires.   As the upper level trough went through, it brought cool air and high pressure into western WA/OR (see pressure and temperature map at 5 PM Monday). As a result, winds accelerated over the eastern slopes of the Cascades as illustrated by the forecast wind gust map for 8 PM Tuesday.

You can appreciate the wind acceleration on the eastern Cascade slopes by looking at the sustained winds and gusts at Ellensburg (see below).  Big acceleration on the 27th than extended to mid-day today.

Such winds can really stoke a fire and cause it to rapidly spread.

And there is one more thing.   A bumper crop of dried cheatgrass, also known as grassoline.  Cheat grass is a non-native, invasive grass that has taken over the sagelands of much of the west.  It grows prolifically and crowds out the native grasses, which tend to grow in isolated "clumps".  Cheatgrass not only grows well, it tends to brown out much earlier than native grasses and is highly flammable.

The spread of cheatgrass has made wildfires more severe in eastern WA, irrespective of global warming.  Similarly, poor forest practices and fire suppression on the eastern slopes of the Cascades has made forest fires far worse.  

So we had hot, dry conditions, lightning to initiate the fire, strong winds to stoke it, and an ample and highly flammable fuel supply.  All the ingredients for major grass fires.

And a message for this weekend.... folks should avoid playing with fireworks east of the Cascade crest, since the potential for major grass fires is in place.

from Cliff Mass Weather and Climate Blog http://ift.tt/2tvKzH2

Start of the Northwest Wildfire Season: Lightning, Winds, and Grassoline

This week the Northwest wildfire season began, with a series of large grass fires on the eastern slopes of the Cascades (map below of current major fires).

One fire, the Sutherland Canyon fire southeast of Wenatchee was quite large, reaching 47,000 acres this afternoon (see map below).

Yesterday's high resolution MODIS satellite imagery shows the smoke from the fire, which was mainly heading southeast towards Moses Lake.

You can actually see the burnt area from space. Here are two images, one from earlier this week and one today.  The blackened area resulted from the fire.

Meteorology had a lot to do with the fire....in fact, it was a classic set up.  We started with the building of high pressure over the region earlier this week that caused temperatures to surge and humidities to plummet.   Here are the temperatures over the past two weeks at Wenatchee.  Temperatures warmed towards a peak on Monday into the mid-90s.  And there was no rain during that period.

So there was considerable drying.

Then there was an initiator of fire:  lightning on Monday night as an upper level trough pushed through (see 500 hPa--around 18,000 ft--weather map at 8 PM)

Take a look at the lightning strike map for the 24 hr ending Tuesday at 1 AM.  You can see the band of lightning, associated with some modest thunderstorms, that ignited some of the grass around Wenatchee.  And started the other fires as well.

But there was something else:  strong winds that fanned the fires.   As the upper level trough went through, it brought cool air and high pressure into western WA/OR (see pressure and temperature map at 5 PM Monday). As a result, winds accelerated over the eastern slopes of the Cascades as illustrated by the forecast wind gust map for 8 PM Tuesday.

You can appreciate the wind acceleration on the eastern Cascade slopes by looking at the sustained winds and gusts at Ellensburg (see below).  Big acceleration on the 27th than extended to mid-day today.

Such winds can really stoke a fire and cause it to rapidly spread.

And there is one more thing.   A bumper crop of dried cheatgrass, also known as grassoline.  Cheat grass is a non-native, invasive grass that has taken over the sagelands of much of the west.  It grows prolifically and crowds out the native grasses, which tend to grow in isolated "clumps".  Cheatgrass not only grows well, it tends to brown out much earlier than native grasses and is highly flammable.

The spread of cheatgrass has made wildfires more severe in eastern WA, irrespective of global warming.  Similarly, poor forest practices and fire suppression on the eastern slopes of the Cascades has made forest fires far worse.  

So we had hot, dry conditions, lightning to initiate the fire, strong winds to stoke it, and an ample and highly flammable fuel supply.  All the ingredients for major grass fires.

And a message for this weekend.... folks should avoid playing with fireworks east of the Cascade crest, since the potential for major grass fires is in place.

from Cliff Mass Weather and Climate Blog http://ift.tt/2tvKzH2

The Truth about Northwest UFOs

Recently, the Seattle Times featured a story about a famous 1947 UFO sighting in Washington.... the incident that started the UFO craze around the world.

And this UFO sighting is not the only one in our area.  For example, Ohio Congressman Dennis Kucinich admitted during the Democratic presidential debate on October 30, 2007 that had seen a UFO while visiting our state.  And even Seattle's most recognizable landmark, the Space Needle, is clearly a stylized form of a flying saucer.

What is the truth about this UFO mania in our region?  Is there something about our area that is attractive to visiting aliens?  Or could there be another explanation?  Something more "scientific"?  Perhaps a meteorological explanation?

The original June 24, 1947 incident involved Kenneth Arnold, a businessman from Boise, Idaho who was flying a small plane near Mount Rainier when he spotted a chain of nine "saucer-lie" objects above and east of the mountain.  Brilliant in the sun, these objects darted towards Mt. Adams an "an incredible speed', which he estimated to be at least 1200 mph.  His account went viral across the world and thus started the UFO/flying saucer craze.

 An investigation by the U.S. government revealed little, although some folks suggest that our military knows a lot more about it, including flying a captured saucer in Area 51 in Nevada.

But there is another possible, if not probable explanation.  One suggested by one of my most distinguished colleagues, UW Professor Richard J. Reed:   lenticular clouds associated with atmospheric mountain waves.

As air is pushed up by a mountain range, the air can go into an oscillation over and downstream of the mountain crest (see illustration).   When the air rises, the air can become saturated, producing lens-shaped (lenticular) clouds.

 The lenticular clouds are quite striking, often looking like flying saucers.

Professor Reed, studying the atmospheric conditions during Arnold's 1947 flight, found that they were just those expected during mountain wave cloud periods.

You can read the details in his paper "Flying Saucers over Mt. Rainier" in the April 1958 of Weatherwise Magazine.   And what about the movement of the "flying saucers"?   Dr. Reed noted that if atmospheric conditions approaching Rainier were changing, the location of the lenticular clouds could rapidly shift, give the impression of rapid movement.

But what about Congressman Kucinch?  What did he see?   One might note that Presidential candidates have a tendency to imagine things, but lets put that aside for a moment.  

Where was the Congressman when he saw the flying saucers?   Staying at Shirley McLane's home in Graham, Washington--a location very close to Mt. Rainier!

Mount Rainier, the region's most massive volcano is the most prolific producers of lenticular clouds.  No wonder its a focus of UFO sightings.

When I was an undergraduate at Cornell, I worked with Professor Carl Sagan, who had a lot to say about UFOs.   He told me that that although he was convinced that intelligent life was prolific around the Universe, traveling interstellar distances would verge on the impossible.  He was very cynical that any of the UFO sightings were real...and that they said more about folks psychological state than aliens visiting our planet.

from Cliff Mass Weather and Climate Blog http://ift.tt/2tj8WXF

The Truth about Northwest UFOs

Recently, the Seattle Times featured a story about a famous 1947 UFO sighting in Washington.... the incident that started the UFO craze around the world.

And this UFO sighting is not the only one in our area.  For example, Ohio Congressman Dennis Kucinich admitted during the Democratic presidential debate on October 30, 2007 that had seen a UFO while visiting our state.  And even Seattle's most recognizable landmark, the Space Needle, is clearly a stylized form of a flying saucer.

What is the truth about this UFO mania in our region?  Is there something about our area that is attractive to visiting aliens?  Or could there be another explanation?  Something more "scientific"?  Perhaps a meteorological explanation?

The original June 24, 1947 incident involved Kenneth Arnold, a businessman from Boise, Idaho who was flying a small plane near Mount Rainier when he spotted a chain of nine "saucer-lie" objects above and east of the mountain.  Brilliant in the sun, these objects darted towards Mt. Adams an "an incredible speed', which he estimated to be at least 1200 mph.  His account went viral across the world and thus started the UFO/flying saucer craze.

 An investigation by the U.S. government revealed little, although some folks suggest that our military knows a lot more about it, including flying a captured saucer in Area 51 in Nevada.

But there is another possible, if not probable explanation.  One suggested by one of my most distinguished colleagues, UW Professor Richard J. Reed:   lenticular clouds associated with atmospheric mountain waves.

As air is pushed up by a mountain range, the air can go into an oscillation over and downstream of the mountain crest (see illustration).   When the air rises, the air can become saturated, producing lens-shaped (lenticular) clouds.

 The lenticular clouds are quite striking, often looking like flying saucers.

Professor Reed, studying the atmospheric conditions during Arnold's 1947 flight, found that they were just those expected during mountain wave cloud periods.

You can read the details in his paper "Flying Saucers over Mt. Rainier" in the April 1958 of Weatherwise Magazine.   And what about the movement of the "flying saucers"?   Dr. Reed noted that if atmospheric conditions approaching Rainier were changing, the location of the lenticular clouds could rapidly shift, give the impression of rapid movement.

But what about Congressman Kucinch?  What did he see?   One might note that Presidential candidates have a tendency to imagine things, but lets put that aside for a moment.  

Where was the Congressman when he saw the flying saucers?   Staying at Shirley McLane's home in Graham, Washington--a location very close to Mt. Rainier!

Mount Rainier, the region's most massive volcano is the most prolific producers of lenticular clouds.  No wonder its a focus of UFO sightings.

When I was an undergraduate at Cornell, I worked with Professor Carl Sagan, who had a lot to say about UFOs.   He told me that that although he was convinced that intelligent life was prolific around the Universe, traveling interstellar distances would verge on the impossible.  He was very cynical that any of the UFO sightings were real...and that they said more about folks psychological state than aliens visiting our planet.

from Cliff Mass Weather and Climate Blog http://ift.tt/2tj8WXF

Cool Air is Starting to Move In

Today broke several daily temperature records,  with temperature climbing into the mid nineties around Seattle and upper 90s to the east.  The interior of SW WA and the Portland area jumped to 100F and more, as did the Tri-Cities.

Here in Seattle, temperature were quite pleasant on Puget Sound, but jumped into the mid-90s over NE Seattle.   Even hotter over Bellevue and Redmond.

But as forecast, everything is changing now.  The trough of low pressure (the thermal trough) has jumped over the Cascades and an onshore pressure gradient has developed (see pressure difference table below). The Hoquiam minus Seattle pressure difference jumped to 3.5 hPa...guaranteeing the inland movement of cool air.

The winds  and temperatures above Seattle Tacoma Airport show the incipient changes,  with hot SE winds replaced by cooling southwesterlies aloft.  And temperatures aloft are falling.

Coastal clouds have moving northward and thickening during the day (see satellite image from an hour ago) and those clouds will move in overnight.

I look forward to hearing the tinkling of my wind chimes around midnight, a sign of the influx of welcome marine air.  Our regional AC has been turned on....now it is only a matter of time.

from Cliff Mass Weather and Climate Blog http://ift.tt/2taVUvF

Cool Air is Starting to Move In

Today broke several daily temperature records,  with temperature climbing into the mid nineties around Seattle and upper 90s to the east.  The interior of SW WA and the Portland area jumped to 100F and more, as did the Tri-Cities.

Here in Seattle, temperature were quite pleasant on Puget Sound, but jumped into the mid-90s over NE Seattle.   Even hotter over Bellevue and Redmond.

But as forecast, everything is changing now.  The trough of low pressure (the thermal trough) has jumped over the Cascades and an onshore pressure gradient has developed (see pressure difference table below). The Hoquiam minus Seattle pressure difference jumped to 3.5 hPa...guaranteeing the inland movement of cool air.

The winds  and temperatures above Seattle Tacoma Airport show the incipient changes,  with hot SE winds replaced by cooling southwesterlies aloft.  And temperatures aloft are falling.

Coastal clouds have moving northward and thickening during the day (see satellite image from an hour ago) and those clouds will move in overnight.

I look forward to hearing the tinkling of my wind chimes around midnight, a sign of the influx of welcome marine air.  Our regional AC has been turned on....now it is only a matter of time.

from Cliff Mass Weather and Climate Blog http://ift.tt/2taVUvF