Model tweets

[Singularity]

Great spot (and insight, Knocker!). This descent is part of why I was talking a week or so ago about a tendency for European heatwaves to take place (via anticyclone development) following a period of strong westerlies across the N. Atlantic that terminate above the continent. 

[knocker]

One also cannot help wondering whether this was also tied in with the apparent problems the models had with the Atlantic trough.

[knocker]

 

[knocker]

 

[knocker]

 

[johnholmes]

On 26/07/2019 at 08:06, knocker said:

 

A really interesting 'find' there knocker. I don't know about you but I never noticed anything of that order during all my 39 years in the UK and abroad?

[Badgers01]

5 minutes ago, knocker said:

 

I wonder if people in Finland are questioning the validity of the above looking at the site !!! 

[knocker]

3 minutes ago, johnholmes said:

A really interesting 'find' there knocker. I don't know about you but I never noticed anything of that order during all my 39 years in the UK and abroad?

No it's a new one on me as well John

[johnholmes]

Just now, knocker said:

No it's a new one on me as well John

It's good how we almost literally learn something new every day. Well it seems new to me but as my memory cells decline it may simply be I cannot remember. Fun getting old 'in it?

[knocker]

15 minutes ago, johnholmes said:

It's good how we almost literally learn something new every day. Well it seems new to me but as my memory cells decline it may simply be I cannot remember. Fun getting old 'in it?

It is indeed. The only advantage I can think of offhand is that one's B******t antenna becomes honed to perfection

[northwestsnow]

wrong thread.

Edited July 28, 2019 by northwestsnow

[Summer Sun]

 

[knocker]

On 26/07/2019 at 08:06, knocker said:

 

Heat bursts

Possibly?

Physical Process

The examples below and several studies including Johnson (1983) show that heat bursts are characterized by:

rapidly increasing surface temperatures

falling relative humidity (or dropping dew point) at the earth's surface

erosion of clouds and radar echoes

strong gusty surface winds

These features are typical of strong dry adiabatic descent reaching the earth's surface. Indications are that this subsidence occurs near the dissipating or rear edge of storms. Lapse rates of sounding taken near heat bursts are strongly dry adiabatic.

These soundings have features similar to High Plains dry microburst soundings identified by Wakimoto (1985). His soundings were characterized by mid-level moisture around 500 mb (near cloud level), a sub-cloud layer with a dry adiabatic lapse rate, and mixing ratio values of 3 to 5 k/kg.

For heat bursts, the physical mechanism usually associated with dry adiabatic descent is evaporational cooling of precipitation beneath a trailing storm anvil. The denser evaporationally cooled air accelerates downward, and if it can penetrate the boundary layer, produces the warming and gusty winds observed in a heat burst.

http://www.wxonline.info/topics/heatburst.html

[knocker]

 

[knocker]

 

[Summer Sun]

 

[Summer Sun]

 

[Summer Sun]

 

[Singularity]

All this Arctic blocking and the south-shifted jet stream may be manner of effect from the record-low sea ice coupled with an easterly (-ve) QBO. I recall seeing a study by Zack Labe recently that discovered such a link for the summer and autumn seasons, while by contrast, when a westerly (+ve) QBO accompanies very low sea ice, it supports low heights in the Arctic... like we saw last summer.

Next summer will be in the late stages of the currently early-stage E QBO.... so it'll be of great educational interest whether we see a lot of HLB again in 2020. Given the potential... I think I might book a long July break abroad .

[summer blizzard]

10 minutes ago, Singularity said:

All this Arctic blocking and the south-shifted jet stream may be manner of effect from the record-low sea ice coupled with an easterly (-ve) QBO. I recall seeing a study by Zack Labe recently that discovered such a link for the summer and autumn seasons, while by contrast, when a westerly (+ve) QBO accompanies very low sea ice, it supports low heights in the Arctic... like we saw last summer.

Next summer will be in the late stages of the currently early-stage E QBO.... so it'll be of great educational interest whether we see a lot of HLB again in 2020. Given the potential... I think I might book a long July break abroad .

I thought the +QBO was just peaking.

[knocker]

 

[knocker]

 

[Summer Sun]

 

[Summer Sun]

Would certainly be typical of recent years mixed August then magically improving as soon as the kids go back to school

 

 

[Singularity]

On 03/08/2019 at 21:17, summer blizzard said:

I thought the +QBO was just peaking.

https://www.geo.fu-berlin.de/met/ag/strat/produkte/qbo/singapore.dat

According to my analysis using this data, it peaked in May.

A mean negative at the mid-levels should be in place by Dec, with the QBO state being descending easterly.

I seem to recall reading last winter that this may be one of the best states for polar vortex disruption via the top-down route, but I can't find the relevant post among the thousands that were made...  - so I could be wrong .