unofficial record low pressure 940 mb

[riverwalker]

from Meteorologist (CBM) at ABC News:

Ginger Zee?@Ginger_Zee

Record low pressure 940 mb now unofficially...this means the #superstorm is CRAZY strong.

1hGinger Zee?@Ginger_Zee

Looks like the #superstorm will hit between 6 and 7 pm ET...right in time for @abcworldnews we will be live in Atlantic City.

1hGinger Zee?@Ginger_Zee

Pressure dropped to 943 mb, lowest ever record in the eastern USA. Coming to Atlantic City(center) around 10 pm. #superstorm

[1StrongBlackMan]

1. Question:

I know this is referring to barometric pressure; but what does low (or high, for that matter) pressure mean?

[CorBlimeyGuvnor]

2. I'm no expert, but....

Low pressure means that the isobars (lines of equal pressure) are packed together tightly, imagine the rings of a whirlpool getting smaller and faster as they swirl around - which means you get high winds, stormy weather caused by the disturbance around the "whirlpool" of low pressure. High pressure means the opposite - the isobars are spread wide apart.
When the UK had a major storm in 1987 the pressure reading was 970 at its worst - and that uprooted a million trees !



More here...


http://en.wikipedia.org/wiki/Low-pressure_area

[1StrongBlackMan]

12. Thanks n/t

[Larkspur]

4. From wikipedia...

Low Pressure is a region where the atmospheric pressure at sea level is lower than that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere...

High Pressure is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land....

In short, low and high pressure areas are partly how the Earth balances heat and cold. Think of them as waves on the ocean. The Jet Stream is the current that moves them around the planet.

[Canuckistanian]

5. Quick Scale

Category.............Winds.........................................Surge........................Central Pressure
1 - Minimal...........74 - 95 mph or 64 - 82 kts.............4 - 5 feet.................greater than 980 mb or 28.94 in
2 - Moderate........96 - 110 mph or 83 - 95 kts...........6 - 8 feet..................965 - 979 mb or 28.50 - 28.91 in
3 - Extensive........111 - 130 mph or 96 - 113 kts........9 - 12 feet................945 - 964 mb or 27.91 - 28.47 in
4 - Extreme..........131 - 155 mph or 114 - 135 kts.....13 - 18 feet................920 - 944 mb or 27.17 - 27.88 in
5 - Catastrophic....greater than 155 mph or 135 kts....greater than 18 feet.....less than 920 mb or 27.17 in

From here:
http://www.weather.com/encyclopedia/charts/tropical/saffirscale.html

[Hugabear]

10. So would this be a Category 1 or a Category 4 storm?

Sustained wind speeds around 90mph, but barometric pressure around 940mb...

[Canuckistanian]

11. The pressure drop would be a more reliable indication of it's power.

And certainly it's destructive power to seacoast structures. Notice how it correlates to the surge height.

[Ilsa]

3. I heard Hurricane Gloria's record low pressure

was lower at 930 (maybe they said 920) mb. This was a meteorologist on the Ed Schultz radio show today.
Not that it matters. 940mb is low.

[CorBlimeyGuvnor]

6. It could be worse....

This baby was the lowest ever recorded at 870 in 1979 - 305 k/mph winds !


http://en.wikipedia.org/wiki/Typhoon_Tip

[tkmorris]

7. That's quite low, but not a record

Unless of course they are restricting it to the New England coast or something. Hurricane Wilma for example hit Florida, which is definitely Eastern US, and it's lowest recorded pressure was 882 mb. Several others have been below 940 as well though it is exceedingly rare to see that sort of pressure in a tropical system remain that low that far north. Sandy is an odd beast.

[HopeHoops]

8. Yeah, she's right outside at the moment.

[LeftInTX]

9. It is a record!!!!! Lowest ever recorded North of Cape Hatterras

Emphasis on north

They just said that on CNN

Wilma was 882, Gilbert 888 but those records are in the tropics.