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Posted at 9:45 PM ET, 09/30/2010

Torrential rains swamping region

By Jason Samenow

Reagan National sets daily rainfall record

* Flash Flood Warning extended until 12:15 a.m. *
* Storm impact coverage: PostLocal | Live chat transcript *
* Flash Flood Watch thru tonight | Share photos | Dr. Gridlock *
* Citizen observer rain totals: VA, MD | NWS Mesonet rain totals *
* Outside now? Radar, temperatures & more: Weather Wall *

Intense rainfall, with rates as high as 1-2" an hour along the I-95 corridor, is dousing much of the metro region. Storm totals are now in the 3-6" range on average in the immediate metro area, with amounts exceeding 8" from Baltimore south along the western side of the Chesapeake Bay. An additional 1-3" of rain is possible on top of what has already fallen.

Rain still extends all the way down to near the Virginia/North Carolina border and will continue streaming northward overnight. By the time the rain winds down early in the morning, totals will likely average 4-8", with double digit totals (10-12" or so) possible east of town near the Bay. All three airports, Reagan National, Dulles, and BWI, have now cruised past their respective rainfall records for the date of 2.76", 0.86", and 1.60". We'll provide the official totals tomorrow.

Flash flooding is being reported in many areas, including Sligo Creek and Rock Creek in Montgomery County. Stay off the roads if you can this evening and do not attempt to cross flooded roadways if you have to travel.

Refer to Ian's PM Update for additional information on Friday's forecast.

By Jason Samenow  | September 30, 2010; 9:45 PM ET
Categories:  Floods, Updates  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Second wave of heavy rains advancing north
Next: Forecast: 'Rainageddon' out, cooler air in


8 inches so far in Shady Side, MD and it's coming down in buckets again. We're right on the Bay and the tidal surge is flooding the road outside my home and it's two feet deep in my yard. The big waves stopped just before dark otherwise the water would be coming over our bulkhead. Another hour until high tide...

Posted by: rollingphone | September 30, 2010 9:55 PM | Report abuse

My 24hr total here at my home in Falls Church is 4.3", 3.3" overnight, 1.0" this evening so far...

Posted by: KPosty | September 30, 2010 9:55 PM | Report abuse

National picked up .90 last hour, has reported heavy rain steady since 8:46. Over 1 1/4" since this batch started.

Posted by: Ian-CapitalWeatherGang | September 30, 2010 9:57 PM | Report abuse


Posted by: samdman95 | September 30, 2010 10:03 PM | Report abuse

Total rainfall since this rain event began is 5.10" It was not raining when I came home and had a little over 4". This second surge has added a quick 1". I am in S. Arlington (alcova hts area).

Posted by: jojo2008 | September 30, 2010 10:04 PM | Report abuse

but wow--- this would be 60-80 inches of snow depending on the temperature.

Posted by: samdman95 | September 30, 2010 10:06 PM | Report abuse

The Aquapocalypse.

Posted by: SpiralStairs | September 30, 2010 10:07 PM | Report abuse

DCA is also perhaps within striking distance of wettest September day on record. We'll need a little help, but #2 was about 3/4" off as of last ob.

Posted by: Ian-CapitalWeatherGang | September 30, 2010 10:08 PM | Report abuse

Well, this second storm set up right smack over the middle of the Washington Metro area. It has been POURING here in Del Ray (Old Town Alexandria) since around 7:30 pm. Probably close to an inch an hour or more for more than an hour at a time. When the rain stopped this afternoon I was sitting at 4.21". Since this second batch has started Im now up to 5.61". Looks like my rain bucket will be going north of 6" for this event. Pretty impressive! This literally is almost going to bust the 7.44" deficit on the year. Pretty crazy.

Someone earlier was asking/ talking about this drought buster causeing a very colorful fall. It may add some color, but it is very late, probably too late for many trees. Many leaves have already started to drop. Many trees have been showing environmental leaf scorch for well over 1 month now, going well back into August due mainly to drought. Many trees have already begun the fall leaf drop/ color change and well, there is alot of crispy brown. Typically, we need this kind of rain when things are still at least somewhat growing. Early Sept probably would have been early enough to make a big difference. Now, most trees are well on their way to going dormant or have already done so. We will still see some color sure, but I am doubtful that it is going to be anything close to a spectacular colorful show. Btw... I have a background in Horticulture and I am a certified Virginia Master Gardner. Just wanted to qualify. =o)

Posted by: KJ71 | September 30, 2010 10:11 PM | Report abuse

Centreville VA The rain has been unrelenting since nightfall & our rain buckets have overflowed.
Now I know we haven't had a foot of rain, but there is a unobstructed galvanized steel barrel out there on my deck about 12 inches deep with fairly straight sides and it is full to the top.

Posted by: FIREDRAGON47 | September 30, 2010 10:11 PM | Report abuse

CWG-don't you mean posted at 9:45 and not 10:45?

Posted by: 300_sq_ft | September 30, 2010 10:16 PM | Report abuse

I THINK I just heard thunder, outside of Ffx City. But I'm not seeing lightning strikes on the radar...

Posted by: MKoehl | September 30, 2010 10:21 PM | Report abuse

Thanks for the info re: Fall leaves, KJ71!

Posted by: Snowlover2 | September 30, 2010 10:32 PM | Report abuse

Any idea when this is going to let up or slow down?

Posted by: redscott1904 | September 30, 2010 10:33 PM | Report abuse


Back edge is near Richmond--so should start winding down in a few hours

Posted by: Jason-CapitalWeatherGang | September 30, 2010 10:40 PM | Report abuse

3.75" of rain so far today per my local weatherbug station in Ashburn. Can we make 4" before midnight?

Posted by: natsncats | September 30, 2010 10:42 PM | Report abuse

I surrender! Make it stop! Will it ever end? It seems to be getting worse, not better. Yesterday weather forecasters said this would end by evening rush hour today. Now it's been pushed back to ending at morning rush hour tomorrow.

Posted by: rwalker66 | September 30, 2010 10:44 PM | Report abuse

It's funny. I joked a month ago that the one thing we hadn't had yet this year was a major tropical storm or hurricane.

Spoke to soon.

Seriously - isn't anyone else wondering what the HELL is going on this year?

Posted by: SWester2010 | September 30, 2010 11:01 PM | Report abuse

DCA is up to #5 wettest single days in Sept all time.

Posted by: Ian-CapitalWeatherGang | September 30, 2010 11:06 PM | Report abuse

Ian, do you ever sleep?
(Thanks for all your waking hours of trivia, stats, and forecasts).

Posted by: pjdunn1 | September 30, 2010 11:17 PM | Report abuse

AMAZING rain. It keeps coming. DCA rainfall amount is trying to make a run at more records! Pepco in chinatown is about to hit 4" since midnight... wow.

Posted by: Camden-CapitalWeatherGang | September 30, 2010 11:19 PM | Report abuse

It looks like for the most of us in the immediate metro area, the rain will be over by 2 AM, give or take an hour. Impressive totals for the entire region.
Whether or not this can be considered a "drought buster" is debatable. If an area is 5 inches below normal and a rain event drops 5 inches in a 5 hour period, where most water runs off into the bay, is this considered drought relief? Droughts generally need rain over a long period of time, where most precipitable moisture is absorbed into the local aquifers, to be considered "relief". Any other thoughts on this subject?

Posted by: pjdunn1 | September 30, 2010 11:27 PM | Report abuse

4.05" in Ashburn so far today -- holy cow!!

Posted by: natsncats | September 30, 2010 11:29 PM | Report abuse

pjdunn1, hey there. I completely agree with you conceptually--that a rain needs to be slow & steady to be meaningful to agriculture and the deep aquifers-- however, the hydrometeorological discussion on this topic is vast. Over my head in several mathematical respects... check out for more...

Surface-water hydrology = the study of the origin and processes of water in streams and lakes, in nature, and as modified by man. It includes such subjects as infiltration, channel storage, floods and droughts, direct runoff, and base flow. Surface-water hydrology shares with meteorology (my comfortable "expertise" area) the study of precipitation and evaporation. Also, surface-water hydrology shares with geomorphology the study of the shape, size, and number of river channels, because river channels are formed as a consequence of the rates and quantities of water they must carry. Some of the tools used in the study and application of surface-water hydrology are unit hydrographs, flow-duration curves, flood-frequency curves, and correlation...(let's stop here. All of this I probably studied in college, but I found hydrology vast and extremely complicated) - so I am trying to prove to you that this rain REALLY helped, but I can't say how much. I grant your premise that we have to look at MANY criteria to call it a drought buster.

Posted by: Camden-CapitalWeatherGang | September 30, 2010 11:48 PM | Report abuse

Uncle. I love weather. I love severe weather. But 2010 can just end already. I've had enough. Usual spots in and around Arlington are flooding/mucho standing water (GW parkway near 395, Washington Blvd, near, well, everywhere)

Posted by: JJones-CapitalWeatherGang | September 30, 2010 11:50 PM | Report abuse

FIREDRAGON told my friends an fam to do the same in Cville havent heard of their depths yet but dang stay missing the craziest storms cant imagine what this could be in the winter potential sign? haaa stay safe yall floodin numba 1 killa

Posted by: jmc732msstate | September 30, 2010 11:52 PM | Report abuse

Time for bed, last update from Ashburn via my local weatherbug site: 4.21"...

Thanks CWG crew for staying on top of this event all day long and into the late night! Stay safe everyone.

Posted by: natsncats | September 30, 2010 11:57 PM | Report abuse

I teach at sligo ms in silver spring. How bad is the flooding along sligo creek parkway?

Posted by: PoorTeacher | September 30, 2010 11:57 PM | Report abuse

My basement apartment on the Hill has flooded for the third time in a year. All the drains around the house are perfectly fine so it's gotta be groundwater coming up. I think it's time to try and get out of my lease. So frustrating. Wish me luck.

Posted by: janspa | October 1, 2010 12:08 AM | Report abuse

Thanks for the info. I have bookmarked for further study.
Even though my expertise is on a plane way below your meteorological degree, i do understand the complications involved in hydrology and the "drought buster". My point, and you made it clear you are in agreement, is that most people are believing that 5" is 5", no matter what. But ask any local farmer and they will welcome any precipitation but let you know that 5" is not always 5".

Posted by: pjdunn1 | October 1, 2010 12:12 AM | Report abuse

Not sure if it was already posted, but for those interested in river levels and flooding potentials:

That lists all the USGS real-time water reporting stations around the area, including in old town and georgetown. Driving around King St earlier, saw they had the sand bags at the ready but nothing really set up yet.

Posted by: JJones-CapitalWeatherGang | October 1, 2010 12:13 AM | Report abuse

It appears that the back end of the system is finally pushing through the Oakton area. Winds are picking up. Rain bucket is at 6.5" since Wednesday afternoon when it started.

Posted by: FH59312 | October 1, 2010 12:16 AM | Report abuse

Climate change anyone? How many records do we need to break before people start realizing what the scientists have been saying for years now...the most scary thing is that the predictions become absolutely more and more dire since the curve is exponential and not a straight line. People will support climate legislation when it will be too late, just wait and see.....

Posted by: biglio | October 1, 2010 12:38 AM | Report abuse

The year of extremes continues... Snow events;record totals, record warmth for summer; now impressive rainfall. 5.05 inches of rain for September 30 in Springfield, Va. Still raining lightly at midnight.

This deluge underscores that tropical-related events of great magnitude are not always tied to the immediate circulation of tropical cyclones. When tropical and non-tropical elements mix in the mid-Atlantic region, the result can be impressive. Just last November we had Nor'Ida, and now an influx of the moisture that produced Nicole.

Incidentally, the steering currents that exist tonight along the East Coast seem similar to those that steered some of our notable hurricanes of the past, including the Great October Gale of 1878 and Hurricane Hazel of October 1954. Who knows? We may not be done with the tropics this year.

Posted by: ricschwartz | October 1, 2010 12:44 AM | Report abuse

Prelim numbers for each airport only SEPT 30, looks like #1 at BWI for Sept (#2 all time), and #3 for DCA/IAD. If I parsed and added correctly that is..

Posted by: Ian-CapitalWeatherGang | October 1, 2010 1:22 AM | Report abuse

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