That’s resuspended ash from earlier eruptions.
Yes, volcanoes can still be hazardous decades after they erupt. Several weeks ago, the Alaska Volcano Observatory noted resuspended ash from an eruption up there 106 years ago!
VA ADVISORY
DTG: 20181014/1620ZVAAC: WASHINGTON
VOLCANO: ST. HELENS 321050
PSN: N4611 W12210AREA: US-WASHINGTON
SUMMIT ELEV: 8363 FT (2549 M)
INFO SOURCE: GOES-EAST. GOES-WEST. RADIOSONDE.
NWP MODELS. VOLCANO WEB CAMERA. UA OBSERVATION.
NWS.ERUPTION DETAILS: NO ERUPTION – RE-SUSPENDED VA
OBS VA DTG: 14/1612Z
OBS VA CLD: SFC/FL090 N4614 W12215 – N4614 W12208
– N4609 W12208 – N4610 W12216 – N4614 W12215 MOV
W 20-25KTFCST VA CLD +6HR: 14/2200Z SFC/FL090 N4615 W12216
– N4613 W12208 – N4609 W12208 – N4610 W12216 –
N4615 W12216FCST VA CLD +12HR: 15/0400Z NO RE-SUSPENDED VA EXP
FCST VA CLD +18HR: 15/1000Z NO RE-SUSPENDED VA EXP
RMK: RE-SUSPENDED VA CLD SEEN IN STLT AND
WEB CAM. NWP MODEL GUIDANCE INDICATES WINDS OUT
OF THE E AT 20-25 KTS. WINDS SHOULD LOWER IN THE
LATER FCST PERIOD. FCST THRU T+6 HRS.
…KIBLER
Update, October 15, 2018: No need for another VAAC advisory, apparently (perhaps because it doesn’t get up to flight level), but resuspended ash is apparent again today in the VolcanoCam:
Note the light ash cloud streaming off to the right.
That can’t be fun for the volcano’s human neighbors!
Update, October 21, 2018: Here’s the official word, passed along this past Friday:
CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, October 19, 2018, 7:50 AM PDT (Friday, October 19, 2018, 14:50 UTC)CASCADE RANGE VOLCANOES
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREENActivity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal background levels of activity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; and Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake in Oregon.
Recent Observations: Activity at Cascade Range volcanoes remained at background levels throughout the week. Earlier in the week, strong winds stirred up dust and ash from deposits on the north side of Mount St. Helens, prompting notices of volcanic ash plumes. There was no eruption. As winds die down and rain moves in next week, the lingering dusty haze will dissipate. As we move into winter, snow and moisture will hold these fine particles in place.
The U.S. Geological Survey and Pacific Northwest Seismic Network (PNSN) continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted.
For images, graphics, and general information on Cascade Range volcanoes: http://volcanoes.usgs.gov/observatories/cvo/
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://volcanoes.usgs.gov/vhp/notifications.html
Featured image: Current US Forest Service Mount St. Helens VolcanoCam image.
