Tuesday, July 22, 2014

Amazingly Wet July Day on Wednesday

8 AM update

Lots of heavy showers and thunderstorms moving through  here is the latest radar.  Yellow are heavy showers....and there are even some reds (downpours or hail) in a few cells.


and the lightning during the half-hour ending 7 AM in shown below.  Not much lighting in easternWA yet. Lots on the eastern side of Puget Sound.




*We are now entering the climatologically driest period of the year, with the last week of July/first week of August being the most arid of the year.  July is usually our driest month, and this year has been drier than most (only a trace of rain so far at Sea-Tac airport).

But everything changes tomorrow, when a July deluge is forecast by our weather forecasting models.

Just to impress you.  Here is the 48h total precipitation predictions to occur starting 5 PM Tuesday and ending 5 PM Thursday.  Wow.  The western slopes and crest of the Cascades get hammered, with totals of 1-3 inches.  Even the western lowlands get quite wet, with modest amounts extending into eastern Washington.  Not a good time for hiking or camping in the Cascades.


This heavy rain is associated with the approach of a sharp upper-level trough/low (see upper-level map for 5 PM on Wednesday.)  Pretty impressive this time of the year.


This air is potentially unstable and there could well be some embedded thunderstorms.

The rain should start moving in around 8 AM

 Strengthen and move northward during the day
Transition to showers as the low passes by on Wed. night


And then we get more rain on the backside of the low on Thursday AM
I am worried about eastern Washington getting light rain, including some thunderstorms--with the potential for more lightning induced fires.  And there is the potential for strong winds over both western and eastern Washington as the trough/low move through.

I expect several local stations to exceed their daily records if the models are right.



Monday, July 21, 2014

Melt-Out Day in Paradise

Yesterday, July 20th, was a big day at Mount Rainier National Park;   melt-out day at the Paradise Ranger Station at 5500 ft.  This reporting site is particularly important and valuable because there is a 98 year record of snow measurements (1917-2014).

It may have been foggy at Paradise, but snow to be seen!

There is, of course, importance in this date because of concerns about global warming. With warming temperatures you would expect less snow and an earlier melt-out date.  A number of media stories have talked about global warming causing mountain snows to melt out early.  So at a long-observed location, what is actually happening?

For the entire 98-year record, the average snow melt-out date is July11th at Paradise.  So the snow stuck around for NINE DAYS more than the long-term average.

Mark Albright, a research meteorologist at the UW, has produced a nice table summarizing melt-out date by decade. The earliest melt-out dates were in the 1930s and 1940s, followed by the 1960s,



What about a nearby station to the south, Mt. Hood, at 5400 ft?   The snow melt date there was July 2nd, which makes sense since Hood is over 100 miles to the south of Rainier.  Mark Nelson, chief meteorologist at channel-12 in Portland, did an analysis of the snow-melt dates at Mt. Hood (found here).   Take a look at the graph that he produced.  The melt out was within a day of the average for the last 33 years (July3).  And it does look like the melt-out date is generally getting later at Mount Hood.


The bottom line of all this analysis (and much more that I am not showing you), is that the snow at mid to upper elevations in the Cascades is not melting out earlier during the past few decades.   As I noted many times in this blog, the Northwest is a favored location when it comes to global warming, with the eastern Pacific showing little warming during the past few decades.   The eastern Pacific determines the nature of the air masses approaching our mountains and thus we can't expect an earlier melt of the snowpack.

Eventually, the eastern Pacific will warm, but its slow change will buy us (and our snow pack) time here in the Northwest.

Global Warming, the Media, and Coal Trains

I will be giving a talk in Friday Harbor and Eastsound, sponsored by the San Juan Island and Orcas Is. libraries.

I will be discussing the serious threat of global warming, how the media is generally doing a poor job in educating about this issue, and how mankind is really not taking it seriously (e.g., the coal trains). 

Friday Harbor: July 22nd, 6:30 PM, The Mullis Community Center, 589 Nash St.

Orcas Island:  July 23rd, 5:30 PM, Orcas Center

Saturday, July 19, 2014

Gusting Winds Result In Explosive Fire Growth

During the past few days, several small fires--most initiated by lightning--exploded as winds have surged due to the cooling and increasing pressure west of the Cascades.

In only a few days, one fire has gone from virtually nothing to over 200,000 acres--the Carlton Complex Fire northwest of Lake Chelan.  And the fire near Leavenworth also grew rapidly as winds increased.

To illustrate the wind speed increase, here are the sustained winds (not gusts) at Ellensburg and Wenatchee over the past two weeks.  The last day has been the windiest in a while.


 The max wind during the 24h period ending 9 PM on Frida, shows gust reaching 40-50 mph (ignore the 159 numbers) along the eastern Cascade slopes.


As I noted earlier, the cooling west of the Cascades causes the pressure differences across the mountains to rise (cooler air is more dense and thus weights more), and that contributes to the stronger westerly winds.  Take a look at the forecast pressure map for 11 AM this morning (solid lines are lines of constant pressure, isobars).  You can see the intense pressure gradient across the Washington Cascades.


The good news is that cooler air is moving across the Cascades and the pressure difference is now dropping, which should allow the winds to relax a bit over the weekend.

Global Warming, the Media, and Coal Trains

I will be giving a talk in Friday Harbor and Eastsound, sponsored by the San Juan Island and Orcas Is. libraries.

I will be discussing the serious threat of global warming, how the media is generally doing a poor job in educating about this issue, and how mankind is really not taking it seriously (e.g., the coal trains). 

Friday Harbor: July 22nd, 6:30 PM, The Mullis Community Center, 589 Nash St.

Orcas Island:  July 23rd, 5:30 PM, Orcas Center

Thursday, July 17, 2014

Picture of the Day

Here is a neat satellite picture from this morning at 9 AM.    Over much of western Washington, there are low clouds, with sinuous channels of stratus where the clouds pushed into the valleys over the western slopes.    In contrast, eastern Washington is filled with smoke from wildfires along the eastern slopes of the Cascades.  And over the ocean it is mainly clear.

No one can say that we don't have contrasting weather around the Northwest.  You can choose heat and smoke, cool and cloudy, and cool and clear.   Never boring in our area.

And to see the degradation of the air air quality in eastern Washington, here is the amount of small particulates at Leavenworth, Twisp, and Moses Lake for the period starting July 1. Yesterday was quite smoky in Leavenworth....and just a bit better today.  But look at Moses Lake....away from the fires but in the path of the smoke plume, as the satellite picture showed clearly above.


Global Warming, the Media, and Coal Trains

I will be giving a talk in Friday Harbor and Eastsound, sponsored by the San Juan Island and Orcas Is. libraries.

I will be discussing the serious threat of global warming, how the media is generally doing a poor job in educating about this issue, and how mankind is really not taking it seriously (e.g., the coal trains). 

Friday Harbor: July 22nd, 6:30 PM, The Mullis Community Center, 589 Nash St.

Orcas Island:  July 23rd, 5:30 PM, Orcas Center

Pyrocumulus

Wednesday, I received nearly a half-dozen emails about strange clouds over the Cascades, many with accompanying pictures.  Here are some samples:

 Picture courtesy of Jeff Boselly
Picture courtesy of Brian Aher

These clouds looked like a tall cumulonimbus but there was a lot of smoke at their base.

The origin? A pyrocumulus cloud caused by the growing Chiwaukum Creek fire.  This feature strengthend rapidly during the afternoon as the surface warmed and the regional winds became more favorable.

It was quite obvious in visible satellite imagery, as this example taken at 4:40 PM Wed. clearly shows (I have circled the feature in red).  You can see the smoke blow off to the west.  The smoke plume from another fire is seen to the northeast of it.


This pyrocumlus cloud was very evident in the Camano Island weather radar yesterday (see image at 5:04 PM, the bright green area is the cloud).  The radar indicated an echo top of approximately 20,000 ft


Pyrocumlus, like all cumulus, are associated with the atmosphere going unstable, which means air parcels are buoyant and accelerate upwards.   Instability is associated with a large change of temperature with height, and having a fire near the ground really helps this along!   The air rises, cools, and the water vapor in it saturates...producing clouds.

There are over a dozen major fires burning over the Northwest and southwest Canada.   The MODIS satellite image today shows considerable smoke over the region:


Lightning on Monday started a number of fires, particularly over northern Oregon.

Wednesday was was a very, very warm day in eastern Washington, with a number of locations getting above 105F.  As noted by past Washington State climatologist Mark Albright:


On Wednesday (16 July 2014) Pasco reached 109 and Hanford 110.  This is the first time Hanford has reached 110 since they recorded 110 on 5 July 2007. The all-time high temperature at Hanford is 113, recorded 3 times on 4 August 1961, 13 July 2002, and 23 July 2006. Records extend back 69 years to 1945 at Hanford.

Wednesday was the last really warm day west of the Cascade crest for a while. Wed. afternooon marine air started to surge in from the Pacific and this (Thursday) morning will bring low clouds.  Expect temperatures to drop by about 10F.

But ironically, this cool down is bad for the wildfires, since it will result in a larger pressure difference across the Cascades and thus stronger westerly winds, winds that can potentially stoke the current fires.  Fire fighting personnel need to be ready for this change.