Question – Polar Lows Vs Hurricanes

[stu]

The question first ~ what is a typical 500mb temp in a hurricane over a surface sea temp of say 28C?

The reason why I ask is that I have been investigating Polar lows today – conditions appear conducive to one forming off the North East UK coast this weekend.

Looking over the internet at polar lows I see that some site advise a 500mb of -40C and a surface sea temp of 6c – that makes a spread of 46C – is this the same for hurricanes

And for kicks and grins what 500mb lift index would this give – I can work that out if I have the values etc.

Cheers

[Stormsfury]

I'm not exactly sure what the general temperature spread is but sometimes the polar lows are referred to as "arctic hurricanes"

But generally speaking, Polar Lows are lows that develop in the higher latitudes that have no cold or warm fronts associated with the low ... and enters a region of warmer water vs its surroundings ... and are thus, similar to its tropical counterpart ...

Nice shot of a polar low ...
and the parent site that this came from ----> http://www.zamg.ac.at/docu/satmanu4.0/s ... PL/pl1.htm

[RNS]

I'm not exactly sure what the general temperature spread is but sometimes the polar lows are referred to as "arctic hurricanes"

But generally speaking, Polar Lows are lows that develop in the higher latitudes that have no cold or warm fronts associated with the low ... and enters a region of warmer water vs its surroundings ... and are thus, similar to its tropical counterpart ...

Nice shot of a polar low ...
and the parent site that this came from ----> http://www.zamg.ac.at/docu/satmanu4.0/s ... PL/pl1.htm

http://www.zamg.ac.at/docu/satmanu4.0/s ... plsa22.gif

Polar lows are cold core systems...tropical cyclones have a warm core. and of course neither have frontal features associated with them.

BTW...awesome pic SF!

[wxman57]

Here's a shot if today's 500mb temps from the mid latitudes to the tropics. Note that in the lower tropics, the temperatures are running from -1 to -2C to -10C. That's pretty much normal for the tropics. The 500 mb temperature is a bit warmer than the surrounding air inside the eye of a hurricane, but I don't really look at the 500 mb temperature as the planes fly at 850 and 700 mb and we don't generally get observations above that in the tropics.

By the way, here's a fairly nice polar low image. I won't even attempt to display it here, as even this 500 meter resolution image is about 3 feet across:

http://modis.gsfc.nasa.gov/gallery/imag ... 3_500m.jpg

<img src="http://home.houston.rr.com/wx/500temps.gif">

[caneflyer]

Actually, the 500 mb temperature inside the eye of any decent hurricane is quite a bit warmer than the surrounding (ambient) temperature. More like 10 degrees C warmer, or more. And the temperature excess increases as you go up, reaching a maximum near 200 mb or so.

[stu]

So the eye of the hurricane would have a Lift Index of -10c. I know that it has been mentioned that the polar low would have a cold core - but is this cold in relation to the enviorment at 500mb? - surly it must also have a negative lift index too in order to provide convection - which would mean that it also has a warm core.

I am trying to understand the mechanism here - polar lows tend to form when very cold -40c air over spills cold SSTs of 6c - but given the thermal gradient - do we still end up with a warm core?

Finally has anyone got a dropsonde Skew-T for a hurricane that I could look at - sadly I do not belive that one exists for a polar low - but I may be wrong.

[caneflyer]

The following article shows and discusses two dropsonde profiles from the eye of Hurricane Gloria:

Franklin, J. L., S. Lord and F. Marks, 1988: Dropwindsonde and radar observations of the eye of Hurricane Gloria (1985). Mon. Wea. Rev., 116, 1237-1244.

You may be able to access this article at the following site:

http://ams.allenpress.com/amsonline/?re ... 6&issue=05

I believe that I have seen articles that include dropsonde profiles of polar lows. A search of the Monthly Weather Review archives during the 1980s or early 1990s might turn something up.