The PFJ - How to see it on the charts

[chionomaniac]

I wonder could any netweather experts please help me. I have a question regarding the PFJ. Is it possible to work out from the 500hPa charts where this jet boundary is positioned or do I have to refer to the 200hPa or 300hPa wind charts to work this out? I often find these difficult to read when the jet stream is fragmented. Or am I looking in completely wrong place altogether?

Many thanks in anticipation.

[johnholmes]

the 300mb chart is usually the best for being nearest to the jet.

Try the NW Extra charts which shows the msl and jet stream chart on the same chart, thus you can see how each interacts with the other.

maybe its on the free section, check it out.

[West is Best]

the 300mb chart is usually the best for being nearest to the jet.

Try the NW Extra charts which shows the msl and jet stream chart on the same chart, thus you can see how each interacts with the other.

maybe its on the free section, check it out.

There's also a very rough guide to the position of the jet is also visible on the wetter charts under 'jet' tab. You can see the position of the jet. The key to look for in terms of maritime polar set up is the jet running south of the UK.

There's some useful information here, especially under the polar maritime part:

http://www.netweather.tv/forum/index.php?s...mp;#entry437749

The thick black line on the wetter 500hPa charts is a thickness line, but the boundary on this is also a useful guide. Go from that to the jet chart and you can see the position.

Others may be able to put this rather better!!!

The amazing thing about the polar maritime set up is that you can get heavy snow off relatively warm upper temps!

[chionomaniac]

Thank you for your replies.

I have just signed up to netweather extra - the amount of available info is impressive! It is useful to see the 300hPa chart together with the slp.

WIB thanks for this link to TWS BI snow set up article. I have previously read this excellent post a number of times - essential reading for a novice like myself!

[Lettucing Gutted]

The thick black line on the wetter 500hPa charts is a thickness line, but the boundary on this is also a useful guide. Go from that to the jet chart and you can see the position.

Thanks for the PFJ boundary on the 500 HPA charts WIB.

However which line represents the subtropical jet stream on the 500 HPA charts?

[Paul]

The best charts to follow the jet with are the 300hpa ones as these are specifically for the jetstream:

[BrickFielder]

The height of the jetstream changes during summer and winter being higher during the summer(200hpa) and marks the boundary between warm and cold air just below the tropopause. Looking at a 500hpa temperature which is a little lower will give you an idea of where the warm cold boundary is above and where the jet is likely to be.

From the jetstream we get a good idea about where high pressure is likely to be and where air is moving. So we can tell if it is likely to be hot or cold.

The other important point to note is that becuase the jet marks the boundary beteen cold and warm air then this is where cloud and rain is likely to be as warm air is lifted over cold or cold air undercuts warm.

[chionomaniac]

Thanks brickfielder the 500hPa chart you have posted will hopefully allow me to make a quick educated guess where the jet is positioned before confirming this on the 300hPA wind charts.

[Stratos Ferric]

Thanks brickfielder the 500hPa chart you have posted will hopefully allow me to make a quick educated guess where the jet is positioned before confirming this on the 300hPA wind charts.

Just to build on BF's post, don't be deceived into using colours on 500s to plot the jet, though it MIGHT be a good surrogate. The jet will tend lie where the thermal gradient is steepest - hence look for the place where the isotherms or isohyets are closest together.