Rain Remains

A Severe Thunderstorm Watch and Flash Flood Watch remain in effect for the Washington/Baltimore region; a Flash Flood Warning is in effect for DC and adjacent Virginia until 7:30.

Now

Showers and thunderstorms are located ahead of a cold front slouching southward toward the Washington DC metro area from central Pennsylvania and northern West Virginia. So far this afternoon, storm activity locally has been focused on the District and areas to the south and east. While National had almost half an inch of rain by mid afternoon, Dulles had received only 0.01", and many areas outside the Beltway in MoCo had seen at most a trace. Conditions will remain ripe through this evening for showers and thunderstorms to develop and move eastward to northeastward through the region. Some rainfall amounts may be locally heavy.

Tonight and Tomorrow

Showers and thunderstorms are likely (70% chance) through tonight. Lows will be in the upper 60s to near 70. Tomorrow will see clearing skies, lower humidity, and high temperatures near 80.

For the outlook through the weekend, scroll down to Dan's post below.

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Rain Records

Yesterday was the 50th anniversary of the world record 1-minute rainfall of 1.23" at nearby Unionville MD in 1956. The record lasted only 14 years; it was exceeded by the 1.5" which fell at Barot, Guadeloupe in 1970. The Australian Bureau of Meteorology has published a list of world extreme rainfalls through 1994, along with a comparison to Australian records. The National Academy of Sciences published a report analyzing the bounds on extreme precipitation events in 1994.

Climate Corner: Inconvenient Side Effects

Today's WaPo has a front-page article describing a joint NSF/NOAA/USGS report, "Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers", issued today on a serious side effect from the increase in CO₂ in the oceans.