PM Update: Windy, overnight showers and storms

From which direction can we expect these sustained winds tonight?

What are my odds of losing power overnight..?

Torndao watch now posted in western PA
http://forecast.weather.gov/showsigwx.php?warnzone=PAZ033&warncounty=PAC111&firewxzone=PAZ033&local_place1=3+Miles+SE+Berlin+PA&product1=Tornado+Watch

Min pressure now down to 957 mb -- amazing.

@see1

I think any power outages tonight will be widely scattered. Maybe 10-20% chance?

that's an impressive satellite image.

Weather Channel tweet: Record lowest U.S. land-based pressure! Orr, MN now at 955.5 mb, besting the record from "Superbomb of Jan '78"!

Also--more than 500 flight cancellations today at Chicago O'Hare

Should I be concerned about my flight if I have a 9am flight out of Dulles tomorrow morning? Is it predicted that the strongest winds will be over by then?

Hi gang. I am a little intimidated to ask, but wanted to see if someone can help me understand what the extreme low pressure actually means. I get the storms and tornadoes but want to understand more relative to implications of extreme low pressure and what causes it. Perhaps I have asked a bigger question than makes sense to answer here if there is a link you can send me I would appreciate learning more. Thanks!

I have a long walk to and from yoga class, and it is hard to deny my senses and convince myself it won't storm at some point on the journey.... although the radar looks ok for the more immediate future, It just feels like a storm is closer than midnight.

@DeniseSD

I think the worst of the storms will have passed before 9 a.m. but lingering showers and breezy conditions along with bad weather elsewhere could cause some delays.

According to an article on a NOAA site the 1935 Labor Day hurricane recorded a reading somewhere between 26.75-26.98 (906-914 millibars). However, this was in the Florida Keys and therefore not a land-based reading.

Was the Capital Weather Gang header font changed recently?

test post, really having trouble posting the last several days.

@alcw1

Exceptionally low pressure is simply indicative of a very intense storm - driven largely by temperature contrasts. When the pressure is low, it is conducive to very strong winds due to large differences between the low pressure at the storm's center and higher pressure not far away (differences in pressure cause wind). Low pressure is also conducive to heavy precipitation as it helps the air rise.

You get the strongest lows often in fall in spring because that's when you get the biggest temperatures contrasts.

@JerryFloyd1

Yes--small style change. We also updated the slogan to indicate that, while our focus is local, we will also cover big national/international weather stories.

Discussion for potential tornado watch for western areas... or maybe the whole area if it goes up.

Jerry, the new pressure record is only for non-tropical storms. There have been lower pressures than this in major hurricanes which are less rare. For comparison, the pressure from this storm would be a solid category 3. Apart from the pressure, everything else is different, the winds are much more widespread but less strong, the shape is different (the fronts plus the fold in the tropopause), etc.

Tornado Watch until 3am for DC area. NOAA weather radio just went off. Y'all be safe!!

Looks like there are at least 60 hurricanes that were more intense at U.S. landfall http://www.nhc.noaa.gov/pastint.shtml not including recent years (e.g. Katrina, Rita, Ike, etc).

Thanks, Eric, for your research and the link re: storms with inordinately low barometric pressure.

For a non-tropical, land-based storm, today's Great Lakes Cyclone, which apparently is or will be affecting one million square miles, is an awesome system.

thanks Jason!