Friday, May 30, 2014

Smoke Observations in Fairbanks

While it is still fresh in everyone's minds, I wanted to put up another quick post on smoke from the recent wildland fires. This time, we are looking at the extensiveness of the smoke observations at ASOS sites from Fairbanks southward.

Figure 1 shows the number of hours that a station reported smoke or haze between 5/19 and 5/28. Not all stations are equipped to detect smoke or to provide visibility readings so one cannot infer that dots on the map that did not report smoke were smoke free. Also, all station sites in the database, whether they have current observations or not, are included in the output dump of station coordinates.

The first few for days of the fire saw winds from the north. The fire and smoke moved from north to south during this time period. Beginning on May 24th, a thermal trough developed in the Interior and switched the winds to a southerly direction. Also, a strong inversion below 5,000' acted to prevent vertical mixing and to promote horizontal spreading out (see Figure 1 from previous post).

Somewhat surprisingly, smoke made its way through the Alaska Range and into the Fairbanks area. For 12 consecutive hours, Fairbanks reported smoke with a visibility of 6 miles or less (See Figure 3). So while Fairbanks is frequently inundated with smoke from Interior fires, occasionally they need to keep an eye to the south.

Figure 1. Number of hours with an observations of smoke or haze in the DS 3505 ISH hourly observation database between May 19 and May 28, 2014. 

Figure 2. Same information as Figure 1 but zoomed in to the Fairbanks area.

Figure 3. Twelve consecutive hourly observations from the Fairbanks International Airport on May 26th and May 27th, 2014. A 'K' in the Weather column indicates smoke.


  1. The smoke in Fairbanks from Anchorage earlier this week has been followed wind today. Anchorage news reported 70-80% there were without power this morning due to their extreme southerly winds.

    In Fairbanks we experienced gusts over 40 from the SW. Two more huge White Spruce trees hit our deck and roof...within 3' each of two that fell last November in a similar wind event. We're still waiting for insurance coverage for repairs, so this new damage will be added to the previous claim.

    When I looked this morning there was a surface Low to our SW near Ruby that was forecast to sweep a Cold Front over Interior Alaska, similar to the double Cold Fronts that brought damage to Interior Alaska during last November's wind event.

    Last November we had wind followed by precip, today we experienced wind, blowing dust, and pollen.

    The trees that blew down today were extremely dry from our recent lack of moisture. No tree pitch could be felt on the exposed broken bases when handled, they are that dry.


    1. The front that swept through Anchorage made steady progress northward all the way to Fairbanks and beyond. Here is a map I made for my FB page:

    2. Good FB note, Brian. Thanks for the link.

      When I was flying lots on the job I'd pay particular attention to Occlusions. Even got good natured ribbing at my retirement for that behavior by co-workers that never understood the ramifications of winds and aircraft...both while flying and while parked.

      Anyhow the recent damage is done to the home. We'll have to remove two more 80' healthy Spruce to prevent any further occurrences. The dry climate is taking its toll on Interior trees.


    3. Gary, I was just going through comments after being out of town for several days, and came across your wind damage report. Sorry to hear that you encountered the same thing again! I hope preventive measures can give peace of mind for the future.

      I'll have to look more closely at this issue of recent dryness to see how much it stands out in the historical record.

    4. The arborist that removed the trees in both events (11/13 and 5/14) remarked how dry the White Spruce are in Interior Alaska. It may be that factor, or a combination of weakening from the first wind event in November that caused the fall. Forty to 50 mph seems to be the danger point for our 80 ft+ trees.

      He used a standing Spruce to winch the fallen off the dwelling. It easily bent under the load. That was unexpected and hence the dryness comment.

      Not sure where to search for boreal "dryness", but will ask around at the U of A in Fairbanks.

      But think of this experiment: Take two toothpicks, leave one dry, soak another in water. Bend both with finger pressure. Which snaps, which bends? Ancient builders knew the answer.