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Posted at 3:40 PM ET, 10/26/2010

PM Update: Windy, overnight showers and storms

By Ian Livingston

Storms after midnight could be strong to severe

* Wind Advisory 8 p.m. to 4 a.m. for far N&W suburbs (see map) *
* Severe weather later? | Historic storm | TWC ditching weather? *
* Outside now? Radar, temps, clouds & more: Weather Wall *

updated at 5:20 p.m.

Where did October go? The warm and muggy air mass continues to sit over the area today as the giant Midwest storm helps funnel more summer-like air northward. Temperatures have made it into the low-and-mid 70s as humidity climbs (dew points in the mid-60s). The stage is set for potential strong to severe showers and storms overnight.

Through Tonight: It's going to be a breezy, muggy and probably increasingly stormy night as the hours wear on. The risk of showers and storms starts around midnight, with the main threat probably between then and dawn for the first round. Sustained winds increase to around 15-25 mph ahead of and within showers and storms, with gusts near or over 50 mph possible (especially west). Wind within the heaviest activity may be briefly higher. A tornado or two can't be ruled out either. Lows fall to near 60 to the mid-60s.

Tomorrow (Wednesday): The front has a hard time pushing through after the initial round showers and storms overnight into early morning. So rain showers and a rumble or two could threaten at times through the day, though the coverage and intensity of the rain is uncertain and there may be extended breaks. It seems most spots should see storm totals of at least .5", but there's the risk for some heavier totals into the 1-2" range. Highs aim for the 70s, but could fall short if the rain is consistent and heavy enough into the afternoon.

See Matt Rogers' forecast through the week. And if you haven't already, join us on Facebook and follow us on Twitter.

midwest-storm-vis.jpg
Visible satellite image of Midwest storm at 4:25 p.m. Source: NASA

Midwest superstorm: The historic storm system moving through the Midwest continues to bottom out pressure-wise. Already breaking all-time pressure records in the state, readings have now fallen to at least 956mb in locations like Orr, Minnesota. In addition to the Minnesota record, Wisconsin has also set a new low pressure record of at least 961.1mb. This storm has lower pressure than the Superstorm of 1993 at it's strongest. At least 10 tornadoes have been spotted today with over 150 reports of wind damage so far.

By Ian Livingston  | October 26, 2010; 3:40 PM ET
Categories:  Forecasts  
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Next: Tornado watch until 3 a.m. for metro region

Comments

From which direction can we expect these sustained winds tonight?

Posted by: hawknt | October 26, 2010 3:59 PM | Report abuse

What are my odds of losing power overnight..?

Posted by: see1 | October 26, 2010 4:17 PM | Report abuse

Posted by: JerryFloyd1 | October 26, 2010 4:18 PM | Report abuse

Min pressure now down to 957 mb -- amazing.

@see1

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

Posted by: Jason-CapitalWeatherGang | October 26, 2010 4:43 PM | Report abuse

that's an impressive satellite image.

Posted by: bgaffney491 | October 26, 2010 4:48 PM | Report abuse

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

Posted by: Jason-CapitalWeatherGang | October 26, 2010 4:49 PM | Report abuse

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?

Posted by: DeniseSD | October 26, 2010 5:08 PM | Report abuse

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!

Posted by: alcw1 | October 26, 2010 5:11 PM | Report abuse

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.

Posted by: Snowlover2 | October 26, 2010 5:12 PM | Report abuse

@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.

Posted by: Jason-CapitalWeatherGang | October 26, 2010 5:25 PM | Report abuse

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.

Posted by: JerryFloyd1 | October 26, 2010 5:34 PM | Report abuse

Was the Capital Weather Gang header font changed recently?

Posted by: JerryFloyd1 | October 26, 2010 5:46 PM | Report abuse

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

Posted by: VaTechBob | October 26, 2010 5:49 PM | Report abuse

@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.

Posted by: Jason-CapitalWeatherGang | October 26, 2010 5:54 PM | Report abuse

@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.

Posted by: Jason-CapitalWeatherGang | October 26, 2010 6:15 PM | Report abuse

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

Posted by: Ian-CapitalWeatherGang | October 26, 2010 6:41 PM | Report abuse

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.

Posted by: eric654 | October 26, 2010 7:08 PM | Report abuse

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

Posted by: southbridgemom | October 26, 2010 7:20 PM | Report abuse

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).

Posted by: eric654 | October 26, 2010 7:28 PM | Report abuse

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.

Posted by: JerryFloyd1 | October 26, 2010 7:53 PM | Report abuse

thanks Jason!

Posted by: alcw1 | October 27, 2010 10:27 AM | Report abuse

The comments to this entry are closed.

 
 
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