Forecasting the volcanic ash plume of Iceland's volcano
The eruption of Iceland's volcano with the unpronounceable name, Eyjafjallajökull, has virtually ceased over the past few hours, with ash only reaching up to 6,000 feet (1800 meters), according to the latest advisory from the UK Met Office. Lightning images from UK Met Office show no new lightning strikes from the volcano's plume since midnight local time today. The relatively small amount of ash present at low altitudes will probably not be able to make it all the way to mainland Europe before falling to the surface and dissipating, since 6,000 feet is below the altitude that the strong winds of jet stream blow. Wednesday through Sunday, the volcano emitted a towering cloud of volcanic ash 6 - 11 km (20,000 - 36,000') high in the air from its 1666 meter (5500') high peak. The jet stream blows strongly at that altitude range, which allowed for efficient transport of the ash cloud to mainland Europe.
Figure 1. Lightning lights up the night sky in this photo of Eyjafjallajökull's eruption taken on April 16, 2010. Ash particles colliding together separate electric charge, much as ice particles in a thunderstorm do, leading to spectacular lightning displays. Image credit: Marco, Fulle, Stromboli Online.
Forecasts of the movement of the ash cloud are made using trajectory models, which have a number of uncertainties to consider. Firstly, the amount of ash ejected by the volcano is highly uncertain, since our measurements of this quantity are limited. Secondly, the models must compute how high the ash cloud will rise (plume rise), based on the best available measurements of atmospheric stability. Since upper air-observations are taken just twice daily by a very coarse network of balloon soundings, our knowledge of the stability is rather crude. Finally, the trajectory models use forecast winds from a global model such as the GFS model to predict where the plume may go. The forecast winds from this model do not capture much of the complicated structure of the wind field over Europe, leading to a rather fuzzy approximation of where the ash will go. Nevertheless, these models have in general done a respectable job forecasting where the ash from Eyjafjallajökull will go over the past few days.
Figure 2. Cross section of the atmosphere over time over Paliseau, France, on April 16, 2010, as observed using ground-based lidar. Image taken using a 532nm cross polarization NFOV telescope. Note how the ash layer sinks closer to the ground as time progresses, as gravity makes the ash sink to the ground. There may also be some atmospheric subsidence occurring (downward moving air due to large-scale atmospheric processes.) Image credit: Ray Hoff, World Meteorological Organization's Global Atmosphere Watch's Aerosol Lidar Network (GALION).
For the next few days, these models continue to indicate that northwest winds at the jet stream level will continue to affect Iceland. As a result, Spain, Portugal, and Greece will offer the best locations to fly from. The northwesterly winds are expected to continue for the remainder of the week, thanks to an upper-level trough of low pressure over northern Europe. On Saturday April 24, the ECMWF model predicts that the trough will slide eastwards, and a ridge of high pressure will build over Europe. This will bring upper-level winds out of the southwest to Iceland, directing any volcanic ash northwards over the North Pole. Thus for the remainder of this week, expect continued ash clouds over much of Europe if the volcano resumes significant eruptions. But by next Sunday, the ash over Europe should decline considerably. For the latest one-day forecasts of where the ash cloud is expected to go, consult the UKMET Office. The Rhenish Institute for Environmental Research at the University of Cologne also has some excellent simulations from an atmospheric dispersion model of Eyjafjallajökull's eruption plume. The Norwegian Institute for Air Research runs a computer trajectory model called FLEXPART that has 1-day forecasts showing a cross section of the atmosphere. NOAA's Air Resources Laboratory (ARL) lets you perform your own model run using their HYSPLIT model, going out up to 48 hours, using the GFS model as input.
Figure 3. NASA's Aqua satellite captured this image of the eruption at 1:20 UTC on April 17, 2010. Image credit: NASA Earth Observatory.
Links
An excellent source of links of information on the eruption is available at http://islande2010.mbnet.fr/2010/04/eyjafjallajok ul-links-liens-a-propos-de-leyjafjallajokul/. My post on Thursday discusses the likely non-impact of this eruption on Earth's climate. Finally, we need to be keeping an eye on earthquake activity at the dangerous Katla volcano next to Eyjafjallajökull. If that volcano blows, it could mean dwarf the headaches caused by Eyjafjallajökull.
Jeff Masters
Reader Comments
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Pardon me if this has already been posted.
More importantly, I've also been taking a look at the computer models ever since this time yesterday, and the GFS is hinting at a significant relaxation of the vertical shear during the final days of this month.
Basically no damage, no injuries, traveling over open grasslands per NWS Amarillo rep on the line with TWC.
TORNADO WARNING
TXC381-210115-
/O.NEW.KAMA.TO.W.0003.100421T0048Z-100421T0115Z/
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE AMARILLO TX
748 PM CDT TUE APR 20 2010
THE NATIONAL WEATHER SERVICE IN AMARILLO HAS ISSUED A
* TORNADO WARNING FOR...
WESTERN RANDALL COUNTY IN THE PANHANDLE OF TEXAS.
* UNTIL 815 PM CDT
* AT 745 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS HAVE
DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THE
MOST DANGEROUS PART OF THIS STORM WAS LOCATED NEAR UMBARGER...OR
ABOUT 9 MILES WEST OF CANYON...MOVING SOUTHEAST AT 15 MPH.
* SOME LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE UMBARGER...
CANYON AND BUFFALO LAKE.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A TORNADO MAY FORM AT ANY TIME...TAKE COVER NOW! ABANDON MOBILE HOMES
AND VEHICLES FOR MORE SUBSTANTIAL SHELTER. AVOID WINDOWS.
TO REPORT SEVERE WEATHER...PLEASE CALL THE NATIONAL WEATHER SERVICE
AT 8 0 6 3 3 5 1 1 2 1.
It has just produced its second tornado. It is traveling toward a small town named Canyon, TX.
The supercell thunderstorm keeps pulsing, strengthening, dropping a tornado. Then it weakens, then strengthens again, dropping its second confirmed tornado.
NATIONAL WEATHER SERVICE AMARILLO TX
759 PM CDT TUE APR 20 2010
TXC381-210115-
/O.CON.KAMA.TO.W.0003.000000T0000Z-100421T0115Z/
RANDALL TX-
759 PM CDT TUE APR 20 2010
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 815 PM CDT FOR WESTERN
RANDALL COUNTY...
AT 754 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS HAVE
DETECTED A POSSIBLE TORNADO. THIS TORNADO WAS LOCATED NEAR
UMBARGER...OR ABOUT 7 MILES WEST OF CANYON...MOVING SOUTHEAST AT 15
MPH.
* LOCATIONS IMPACTED INCLUDE...
UMBARGER...
CANYON...
BUFFALO LAKE...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
HEAVY RAINFALL MAY OBSCURE THIS TORNADO. TAKE COVER NOW. IF YOU WAIT
TO SEE OR HEAR IT COMING...IT MAY BE TOO LATE TO GET TO A SAFE PLACE.
TO REPORT SEVERE WEATHER...PLEASE CALL THE NATIONAL WEATHER SERVICE
AT 8 0 6 3 3 5 1 1 2 1
TORNADO WARNING
NATIONAL WEATHER SERVICE AMARILLO TX
813 PM CDT TUE APR 20 2010
THE NATIONAL WEATHER SERVICE IN AMARILLO HAS ISSUED A
* TORNADO WARNING FOR...
CENTRAL RANDALL COUNTY IN THE PANHANDLE OF TEXAS.
* UNTIL 900 PM CDT
* AT 811 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS HAVE
DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.
THE MOST DANGEROUS PART OF THIS STORM WAS LOCATED 3 MILES
SOUTHWEST OF CANYON...MOVING SOUTHEAST AT 15 MPH.
* SOME LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE CANYON.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A TORNADO MAY FORM AT ANY TIME...TAKE COVER NOW! ABANDON MOBILE HOMES
AND VEHICLES FOR MORE SUBSTANTIAL SHELTER. AVOID WINDOWS.
TO REPORT SEVERE WEATHER...PLEASE CALL THE NATIONAL WEATHER SERVICE
AT 8 0 6 3 3 5 1 1 2 1.
That's an anomaly....means wind shear is 35 knots below normal in that area.
CFS has verified quite nicely in that department
Minor damage reports from areas near Canyon, TX.
Yes it has. The CFS forecasts the low wind shear anomalies to gradually expand westward to encompass the entire Caribbean as we head into the hurricane season.
that's the first time i have seen it. can you post the link? thanks!
latest as storm dives se e
Where do you get those SST charts? Could you also provide a link for it? THX. :)
Link is on the image....lol. Link
R U kidding me?!
Is this unprecedented this early in the season?
There have actually been storms in the Eastern Pacific that have formed during the winter months, so it's not totally unprecedented, but certainly rare.
Keep in mind that we've had a named storm form in May for the last 3 years in a row. It is not uncommon for the first blob to watch to occur in May. If the trends on the models hold true, then the pattern could become conducive to allow something to try to form in the Caribbean during next month. If something forms in the eastern Pacific, it won't be that surprising, as their season starts earlier on May 15th.
You don't find the band of anomalously strong upper level winds in the Gulf Of Mexico that extends out into the Sub-Tropical Atlantic strange since we should be in a La Nina by that time?
It also looks like the storm is starting to weaken substantially as well.
The threat is changing, from rotating supercell/tornado development to a squall line, straight-line winds > 50MH, heavy rain, golf-ball sized hail.
The reason the CFS is showing that is the same reason why it has a cold summer over most of the central-eastern US. I don't believe that will verify, and the shear should be weaker close to the coast than the CFS currently thinks. However, having low shear in the MDR and higher-than-normal shear overall near the coast is still very dangerous. With many storms forming in the tropics, it only takes a few breaks in the shear barrier to allow one or more major hurricanes to come up to the north and hit the US.
Nope lol! It's only the GFS showing this so more model support is necessary.
It may also verify the crash in Global Temps, that it's forecasting for the fall-winter 2010-2011.
Oh you can bet on that.
It will take a while to get that as the GFS is the only model we have that goes out past 240 hours. For now it's just another blip on the long-range GFS that is indicating that the conditions may be there for mischief during the first week of May.
If the CFS is right about the upcoming change in Global Temps, I may have another 80 inches of snow next winter! Yea!
Thanks, Levi.
None so far.
Well....next winter will be nothing like this winter was for the eastern half of the US. Nowhere near as cold.
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