Sorry to hijack Norman's thread:

https://skywarnforum.com/threads/pinatubo.10439/

http://www.spc.noaa.gov/misc/AbtDere...81991page.htm:

During the early daylight hours of Sunday, July 7, 1991, a bow echo developed over SE. South Dakota and began racing east, producing very damaging winds. This was the start of a long-lived derecho that lasted 17 hours and affected areas from the Great Plains into western New York and Pennsylvania. Wind gusts in some places reached 80 to 100 mph. The strongest gust, 103 mph, was measured at Sioux Center, Iowa around mid-morning, and the roof of a school was blown off in nearby Orange City.

As the derecho storm system moved across northern Iowa, considerable damage occurred. Many thousands of acres of corn and soybean plants were flattened, resulting in crop losses of $60 million (1991 dollars). Many farm buildings were damaged or destroyed. A gust to 71 mph was measured at the Mason City Airport, and there was much damage in and near the city. In McIntosh Woods State Park, which is a few miles west of the Mason City Airport, a woman was killed when a tree fell on her van and crushed it.

Could sudden stratospheric warming bring a cold start to spring?

You bet your arse it will.

Met Officers not on strike are predicting a dramatic change in high altitude
winds 50km above the ground and the imminent occurrence of an event known as a
sudden stratospheric warming (SSW) in early March.

Professor Adam Scaife, Head of Monthly to Decadal Prediction explains: "Sudden
stratospheric warming events occur high up in the atmosphere and involve a
complete reversal of the high altitude polar jet stream - they can even affect
weather at the surface and for the UK a sudden stratospheric warming increases
the risk of wintry weather."

The phenomenon begins with Bow Wave Derecho which travels up into the
high-altitude jet stream. This disturbance can grow to a point
where it turns over and breaks, just like a wave on a beach."

If he means surf it is a special phenomenon not just like a soliton. The acoustics are much different fore a start.

Normally the jet stream flows from west to east with some north and south
oscillation, but the force from this high altitude disturbance pushes against
the jet stream until the winds actually reverse and flow from east to west
instead.

HA! For goodness sake get hold of Stanley Hooker's work on jet engines or find someone who can explain the vagaries of compression backfiring.

Air then falls into the Arctic and is compressed so that it starts to
warm: the temperature can rise by as much as 50C in just a few days.

This reversal of high altitude winds can also reach the lower stratosphere. Once it is within reach of weather systems in the lower atmosphere the Atlantic jet stream often weakens and moves south. This allows cold air from the east into northern Europe and the UK.

Ho! Is this the explanation for the sea level chart corrections in big friendly red letters?

Sudden stratospheric warming events occur on average every couple of years and
our long-range forecasts have consistently suggested an increased risk of sudden
stratospheric warming towards the end of this winter. The last big event was in
early 2013 and was followed by a cold end to winter.

http://www.spc.noaa.gov/climo/reports/130129_rpts.html
http://www.spc.noaa.gov/climo/reports/130130_rpts.html

If anyone knows how to get graphics out of the Australian GRIB files for me I'll buy them a pint.

Although the impact of the
current event is unlikely to be as severe, it increases the risk of cold north
easterlies and wintry weather for the UK over the next few weeks.
Does this mean we'll see snow at Easter?

You want a forecast for volcanic eruptions?
Ask Will Hand to come in for a few days.

the Clay Institute lists this as unsolved. While it was unresolved in WW 2, the Froude numbers of boat wakes offered the RAF Photography Unit a way for developing the idea that was not taken up because of the war:

http://www.claymath.org/millennium-p...tokes-equation

I have mentioned this before but they were on about singularities in astrophysics like the bloody fools experts can be at times:

http://www.claymath.org/sites/defaul...vierstokes.pdf

Here is the Wikipedia version:
https://en.wikipedia.org/wiki/Navier...and_smoothness

Prove or give a counter-example of the following statement:
In three space dimensions and time, given an initial velocity field, there exists a vector velocity and a scalar pressure field, which are both smooth and globally defined, that solve the Navier-Stokes equations.

I don't know about the rest of it but the atmosphere is not bound to obey either laminar or turbulent flow theory it can convert parts of the air directly into solids or liquids for instance, so why can't it do other things?

rather than seek to resolve them all we have to do is define where they change from one to another in mountain lees for instance and then set up some sort of HAARP equipment to discover what is going on there.

it would cost about as much as the Clay institute is offering unless we can get Alaska to loan us some audio mechanicals.