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Posted at 10:50 AM ET, 10/ 1/2010

Rainfall records for D.C., Baltimore

By Ian Livingston

Baltimore breaks single-day September rain record

* Cool weekend: Full Forecast | Citizen observer rain totals: VA, MD *

Top 10 list of single-day September rainfall events at Reagan National (DC), BWI (Balt) and Dulles (IAD) airports.

After months of mostly dry, it's been quite the wet week, especially yesterday. All three area airports crushed rainfall records for the day of Sept. 30:

*National (DCA): 4.66" yesterday (previous record: 2.76" in 1924)
*Dulles (IAD): 4.74" yesterday (previous record: 0.86" in 1976)
*Baltimore-Washington (BWI): 6.02" yesterday (previous record: 1.60" in 1920)

Comparison of Baltimore's rainiest days in September.

BWI's 6.02" yesterday was not only a record for the day of Sept. 30, but also the one-day rainfall record for the month of September, surpassing the previous September record of 5.97" on Sept. 24, 1912. Numbers 3 and 4 in Baltmore were a bit more recent, occurring in Sept. 1999 (Hurricane Floyd) and Sept. 1985. The 6.02" is also the second most rain in a 24 hour period during the whole year; only Aug. 23, 1933, when 7.62" fell, is ahead of it.

How close did D.C. come to also breaking the single-day September rain record? Keep reading for that and a look at the multi-day storm totals.

The single-day September rain record came close to falling in D.C. as well (as observed at Reagan National Airport), but ended up at number three all-time with 4.66" yesterday compared to 5.16" on Sept. 2, 1922, and 4.76" on Sept. 16, 1976.

A similar story emerged at Dulles (IAD), where yesterday's 4.74" put it behind readings above 5" on Sept. 14, 1966, and Sept. 6, 2008 (the latter being from Tropical Storm Hanna).

Doppler estimated storm rainfall totals. Source of imagery, Weather Underground.

Total rainfall for the multi-day event (Wednesday through today) stands at 5.04" for DCA, 5.05" at Dulles and 6.11" at Baltimore. These amounts are characteristic of most of the region where generally 4-6" of rain fell. The big exception is along the western shore of the Chesapeake Bay where amounts reach as high as 10-15".

Factoring in yesterday's rain, DCA now has a rainfall surplus in September of 2.23", but still a slight deficit on the year of 2.67".

(CWG's Jason Samenow contributed to this post.)

By Ian Livingston  | October 1, 2010; 10:50 AM ET
Categories:  Floods, Local Climate  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: 'Rainageddon' out, cooler air in
Next: Rain review: Took some time to get it right


More records for freak year 2010.
Three more months to go. What's next?

Posted by: FIREDRAGON47 | October 1, 2010 11:30 AM | Report abuse

Every single record, for all three stations, happened in September. Can someone say hurricane season.

Posted by: johnnyd2 | October 1, 2010 11:32 AM | Report abuse


The chart only shows September records, not any other months.

Posted by: CapitalWeatherGang | October 1, 2010 11:38 AM | Report abuse

Well that makes way more sense, guess I missed the month in BOLD type! lol

Posted by: johnnyd2 | October 1, 2010 11:42 AM | Report abuse

CWG, thanks for this information. What I find so interesting is how the numbers really vary between these three locations. I think many of us see a weather report for the metro region and tend to think it applies across the board. This shows that it really doesn't. From my perspective of having property damage from flooding in 2008 from TS Hanna, I was surprised to see that only Dulles reported more rain on that day then yesterday. (Thankfully, no property damage yesterday.) So before CWG you beat yourselves up too much on predictions, I think the scale of the metro region needs to be considered. I would love to know ahead of time whether my part of the village will be getting 4.5 inches or over six, but I am not sure forcasting models are that great yet. Anyway, you all are the best!

Posted by: erbele | October 1, 2010 11:47 AM | Report abuse

I'm in Springfield, and I'm sure glad the power didn't go out and that the round 2 rain ended at about 12:15am this morning. Round 1 was considerably worse for us. Sump pump was going off literally once a minute for several hours yesterday and overnight. Don't think the backup pump would've been able to keep up if we had lost power, which meant I would've been bailing water. We got 5 inches or so. Feel bad for folks who got twice as much as we did and live where the water table is high.

Posted by: mbcnewspaper | October 1, 2010 11:50 AM | Report abuse

mbcnewspaper, my sump pump was running quite a bit as well, and it will continue to run for the next several days until the water table goes down. I too have a battery backup, but I doubt it could have kept up with the volume of water we had.

My suggestion is to replace the pump once every five years or so just to be on the safe side. In addition, a backup generator is good to have if the power goes out for an extended time.

I have thinking about installing two pumps in the sump pit if they'll fit just for redundancy in the event one fails.

Posted by: david_in_stafford | October 1, 2010 12:16 PM | Report abuse

Glad to see that 1966 storm of four-plus inches is listed. This was definitely a droughtbuster rain, at least partly responsible for the fall foliage miracle that year.

(One problem problem is that rain came a couple of weeks earlier in September. This year, we don't yet know if the heavy rain came too late.)

Re: the forecast, this was a tough one and on the whole I think CWG stayed on top of it. Epic fail? Hardly.

Finally, "Floyd" was about to claim he didn't recall being a hurricane in the D.C. area, but a check of "Hurricanes and the Middle Atlantic States" reveals a gust of 76 MPH at the Bay Bridge, even though Floyd's eye was 100 miles away.

Posted by: JerryFloyd1 | October 1, 2010 1:02 PM | Report abuse

@FIREDRAGON47..Freak early snowstorms..tornadoes in November...plague of stinkbugs....I'm ruling nothing out!

Posted by: SPS1 | October 1, 2010 2:35 PM | Report abuse

Rain event summary...not as bad as I feared; Iwas able to finish errands yesterday afternoon and this morning and am free to stay home until dance time.

I think I saw a figure of 4.6 inches for DCA, could be for the full event, not just yesterday. I'm still mystified by the "thunderstorm" references despite no lightning or thunder here for the entire event. There were several heavy convective showers, however.

FIREDRAGON47, maybe we'll finish our freak weather year with another huge December would be nice to break that puny 5-inch Christmas record with a foot and a half on Dec. 24/25...we could use a white Christmas. Funny, but Brownsville, Corpus Christi, Houston and the Outer Banks all seem to have had at least one white Christmas in recent years while we've had nothing save for the melting snow piles of 2009 left over from the week-too-early blizzard of last December. Or perhaps December, 2010 will go down in the books for a couple of good ice storms, though I suspect PEPCO would once again have issues with electric power reliability in that event.

Posted by: Bombo47jea | October 1, 2010 2:41 PM | Report abuse

How about a couple more 90 degree days....right around Halloween?!?

Posted by: FIREDRAGON47 | October 1, 2010 2:49 PM | Report abuse

Galveston had two snows in recent years, one of which was on Christmas Eve. Victoria, TX, near the coast, had about 14" from that storm.

There was a signifcant pre-Christmas snowfall here Dec 23-24, 1966: 9.2" IAD, 8.5" BWI (don't know the DCA total, c.a. 7"). We had 10" in College Park and went skiing in Cockeysville, MD, north of Baltimore, just after Christmas. (That slope closed a few years later.)

It would only be fitting to end 2010 with a flakey December.

Posted by: JerryFloyd1 | October 1, 2010 3:55 PM | Report abuse

FIREDRAGON47, ha. I think it's fairly safe to say we're done with 90+ at this point. :)

Posted by: Ian-CapitalWeatherGang | October 1, 2010 4:18 PM | Report abuse

now imagine if this was snow....

Posted by: paul-Sterling | October 1, 2010 4:25 PM | Report abuse

Hey, CWG, what's this talk of a nor'easter with lots of rain on Monday? (Was just watching WRC.) Hardly enuf time to exhale and another storm??

Posted by: JerryFloyd1 | October 1, 2010 4:28 PM | Report abuse

The comments to this entry are closed.

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