Forecasting the volcanic ash plume of Iceland's volcano

By: Dr. Jeff Masters , 2:45 PM GMT on April 19, 2010

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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

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824. funeeeg
5:25 PM GMT on April 22, 2010
Looks like it is erupting again. Still stuck in Toronto but have now got a flight on the 24th instead of the 27th. Link
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823. nrtiwlnvragn
12:59 PM GMT on April 21, 2010
New Blog
Member Since: September 23, 2005 Posts: 14 Comments: 11300
822. hurricane23
12:58 PM GMT on April 21, 2010
Quoting Jeff9641:


C and S FL have been getting rain daily now and more may come this afternoon as our seabreeze fronts get active.


The mean date of the start of the rainy season across southeast florida is May 20, so we probably beginning the transition period. We got very little lightning from the activity yesterday, which means that it's still too early. I'm not sure if whatever is left of El Niño will have an impact on the start of the rainy season. Past starts in El Niño years has varied some, so no clear signal from what I can tell.
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821. aquak9
12:41 PM GMT on April 21, 2010
Sorry jeffs..as Ike willtell ya, CoCoRAHS don't lie. No rain.
Member Since: August 13, 2005 Posts: 175 Comments: 26479
820. KEEPEROFTHEGATE (Mod)
12:35 PM GMT on April 21, 2010
day 2 day 3 severe outlook

Member Since: July 15, 2006 Posts: 176 Comments: 55511
819. Jeff9641
12:32 PM GMT on April 21, 2010
Quoting aquak9:
g'morning ya'll. Another dry fetch. :(


THere was a lot of rain at my house on Seminole Orange County line. You should have gotten some good rain too as there was rain everywhere at about 1am.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
818. IKE
12:26 PM GMT on April 21, 2010
Quoting PcolaDan:


I have not had a drop here. Still bone dry.


The system this weekend should break your dry spell.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
817. aquak9
12:16 PM GMT on April 21, 2010
g'morning ya'll. Another dry fetch. :(
Member Since: August 13, 2005 Posts: 175 Comments: 26479
816. Jeff9641
12:15 PM GMT on April 21, 2010
Quoting PcolaDan:


I have not had a drop here. Still bone dry.


C and S FL have been getting rain daily now and more may come this afternoon as our seabreeze fronts get active.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
815. Jeff9641
12:13 PM GMT on April 21, 2010
Quoting IKE:
I had .60 inches of rain yesterday. 1.59 the last 2 days.

Sunny weather returns today....warmer tomorrow and Friday...chances of rain over the weekend.


I'm glad you guys are getting rain too and it looks like a significant rain event is looming for Florida later this weekend
Member Since: November 4, 2009 Posts: 0 Comments: 6577
814. PcolaDan
12:13 PM GMT on April 21, 2010
Quoting IKE:
I had .60 inches of rain yesterday. 1.59 the last 2 days.

Sunny weather returns today....warmer tomorrow and Friday...chances of rain over the weekend.


I have not had a drop here. Still bone dry.
Member Since: August 22, 2008 Posts: 12 Comments: 6010
813. IKE
12:07 PM GMT on April 21, 2010
I had .60 inches of rain yesterday. 1.59 the last 2 days.

Sunny weather returns today....warmer tomorrow and Friday...chances of rain over the weekend.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
812. pottery
12:07 PM GMT on April 21, 2010
Good Morning.
Gentle showers this morning. Going to be another hot, Humid one.
96.8f yesterday.
Out ....
Member Since: October 24, 2005 Posts: 0 Comments: 24778
811. Jeff9641
12:04 PM GMT on April 21, 2010
With last night's rain I've recieved 21" so far for the year OIA has had near 19" for the year. These totals are extremely amazing considering this is supposed to be our dry season. I hope this keeps up!!
Member Since: November 4, 2009 Posts: 0 Comments: 6577
810. Jeff9641
12:01 PM GMT on April 21, 2010
I picked up 2.7" last night in Longwood,FL. Some areas south of me in Windemere picked up 4" as heavy thunderstorms trained across our area all night. Even had pea size hail at 11.45pm for about a minute.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
809. hydrus
12:00 PM GMT on April 21, 2010
Quoting stoormfury:
morning
the start of the tropical wave train in may could tell us how the season will unfold for the MDR. This all depends on how strong these waves exit the african coast and how long they mentain their identity and strengh
That is a good point. The water is so warm there we may even have a early season Cape Verde type storm.
Member Since: September 27, 2007 Posts: 1 Comments: 22253
808. IKE
10:58 AM GMT on April 21, 2010
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0348 AM CDT WED APR 21 2010

VALID 241200Z - 291200Z

...DISCUSSION...
MEDIUM-RANGE MODELS CONTINUE TO SHIFT A LARGE UPPER SYSTEM EWD
ACROSS THE CENTRAL AND ERN U.S. WITH TIME...WITH A GRADUAL
WEAKENING/DEAMPLIFICATION OF THE SYSTEM PROGGED. AS THE SYSTEM
BEGINS TO OPEN/WEAKEN -- PARTICULARLY FROM DAY 5 /SUN. APR. 25/
ONWARD...MODEL AGREEMENT SLOWLY DECREASES AS WELL. WHILE ENHANCED
SEVERE POTENTIAL WILL LIKELY SPREAD ACROSS THE SERN U.S. UNTIL THE
MAIN SURFACE FRONT MOVES OFFSHORE ON OR AROUND DAY 7 /TUE. APR.
27/...CONFIDENCE WITH RESPECT TO TIMING AND LOCATION DECREASES
STEADILY INTO THE PERIOD.

ATTM...WILL MAINTAIN AN OUTLOOK AREA CENTERED INVOF THE MID AND
LOWER MS AND TN VALLEYS DAY 4 /SAT. APR. 24/...AS A STRONGER
SHORT-WAVE TROUGH EMBEDDED WITHIN THE CYCLONIC FLOW AROUND THE MAIN
UPPER LOW IS PROGGED TO SHIFT ACROSS THIS REGION. WITH STRONG
DEEP-LAYER WIND FIELD AND MOIST/LIKELY UNSTABLE AIRMASS IN PLACE
AHEAD OF THIS FEATURE AND ASSOCIATED SURFACE FRONT...WIDESPREAD
SEVERE WEATHER APPEARS LIKELY.

AGAIN -- WHILE AT LEAST SOME SEVERE THREAT SHOULD SHIFT STEADILY EWD
WITH TIME DAYS 5-6-7...MODEL DIFFERENCES PRECLUDE HIGHLIGHTING
SPECIFIC THREAT AREAS BEYOND DAY 4.

..GOSS.. 04/21/2010
Member Since: June 9, 2005 Posts: 23 Comments: 37860
807. stoormfury
10:52 AM GMT on April 21, 2010
morning
the start of the tropical wave train in may could tell us how the season will unfold for the MDR. This all depends on how strong these waves exit the african coast and how long they mentain their identity and strengh
Member Since: August 22, 2006 Posts: 0 Comments: 2722
806. leftovers
10:10 AM GMT on April 21, 2010
Quoting Tazmanian:
we may see are 1st storm in mid May
the odds say we wont though taz
805. leftovers
9:08 AM GMT on April 21, 2010
little thunderstorm this early morning light rain some heavier nearby good morning
804. xcool
6:59 AM GMT on April 21, 2010
crazy blog 2010 comesoon
Member Since: September 26, 2009 Posts: 2 Comments: 15684
803. HadesGodWyvern (Mod)
6:07 AM GMT on April 21, 2010
Tropical Cyclone Warning Center Perth
TROPICAL CYCLONE OUTLOOK
Forecast for area south of 10S between 90E-125E
2:00 PM WST April 21 2009
=====================================

There is a developing low in the monsoon trough south of Indonesia near 10S 117E. This low is expected to develop into a tropical cyclone late on Thursday or on Friday as it moves to the southwest. It is not expected to affect Christmas or Cocos Islands or the Australian mainland.

There are no other significant systems in the outlook area.

Tropical Cyclone Formation Potential
====================================
Thursday: Moderate
Friday: Moderate
Saturday: High
Member Since: May 24, 2006 Posts: 52 Comments: 46521
801. Tazmanian
5:25 AM GMT on April 21, 2010
we may see are 1st storm in mid May
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
800. Tazmanian
5:24 AM GMT on April 21, 2010
this year is going to go nuts on this blog
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799. NRAamy
5:18 AM GMT on April 21, 2010
spathy!!! I need help on your bog!
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798. Jeff9641
5:16 AM GMT on April 21, 2010
Quoting spathy:
Jeff
Yup!


There are more thunderstorms about to move in from the GULF.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
796. Jeff9641
5:09 AM GMT on April 21, 2010
Windemere has had over 5" in the last 6 hours I've had over 2" in the last 2 hours and it's pouring again.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
795. Jeff9641
5:06 AM GMT on April 21, 2010
Quoting spathy:
Jeff9
Looks like you got what formed over us on the West!


Yeah, all of this built into Orlando from the West coast seabreeze.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
793. peejodo
4:44 AM GMT on April 21, 2010
Quoting pottery:
Greetings.
Another hot one here today, peaked at 96.8f at the airport (no, the guage is not on the paved runway).
But the showers over the past few days seem to have put out the fires. Nice clear night right now.

Good to hear about the fires Pottery. No mud slides? Good luck!
Member Since: February 13, 2004 Posts: 0 Comments: 77
791. Jeff9641
4:30 AM GMT on April 21, 2010
Quoting KEEPEROFTHEGATE:



I live right on the Orange Seminole county line and that purple went right over me and as it did I had pea size hail for about a minute.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
789. Jeff9641
4:28 AM GMT on April 21, 2010
I'm about to get nailed again. Storms are forming all over C FL at this late hour.
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786. KEEPEROFTHEGATE (Mod)
4:20 AM GMT on April 21, 2010
evening pottery or i should say top of the morning to ya

there could be quite a few
Member Since: July 15, 2006 Posts: 176 Comments: 55511
785. KEEPEROFTHEGATE (Mod)
4:19 AM GMT on April 21, 2010
forty days and forty nights
remain till the madness lets loose
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784. xcool
4:15 AM GMT on April 21, 2010
will not Surprise Me if we twenty storm name .imo...
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783. pottery
4:10 AM GMT on April 21, 2010
LOL GAGuy.
How are you faring?
Member Since: October 24, 2005 Posts: 0 Comments: 24778
782. pottery
4:09 AM GMT on April 21, 2010
Quoting Jeff9641:


It supposed to crack 90 in Orlando this weekend for the first time this year.

Well enjoy the "cool weather" while it lasts. Gonna be a hundred in a few...
Member Since: October 24, 2005 Posts: 0 Comments: 24778
780. Jeff9641
4:06 AM GMT on April 21, 2010
Quoting pottery:

Except it is warmer this year...


It supposed to crack 90 in Orlando this weekend for the first time this year.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
779. Levi32
4:06 AM GMT on April 21, 2010
The anomalies for 2010 and 2005 are eerily similar. 2005 is now the most similar SST profile analog we have. 1998 is the 2nd closest.

April 10th 2005 SST Anomalies:




April 10th 2010 SST Anomalies:


Member Since: November 24, 2005 Posts: 635 Comments: 26695
778. KEEPEROFTHEGATE (Mod)
4:06 AM GMT on April 21, 2010
way above friend and thats all i have to say about that 2010 is on left or first 09 follows way more red dark red in 2010
Member Since: July 15, 2006 Posts: 176 Comments: 55511
777. Jeff9641
4:05 AM GMT on April 21, 2010
Very strong thunderstorms with small hail blowing up over C FL right now as upper level energy hits our warm moist atmosphere.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
776. pottery
4:04 AM GMT on April 21, 2010
Quoting xcool:
very close 2010 too 2005

Except it is warmer this year...
Member Since: October 24, 2005 Posts: 0 Comments: 24778
775. pottery
4:02 AM GMT on April 21, 2010
Hi Keeper. You think we will get any hurricanes this year anywhere, Bud, Sir?
heheheheh
Member Since: October 24, 2005 Posts: 0 Comments: 24778
774. xcool
4:02 AM GMT on April 21, 2010
very close 2010 too 2005
Member Since: September 26, 2009 Posts: 2 Comments: 15684

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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