DC, Definitely Cooking: Excessive Heat Warning

5:45 Update: The official Washington high was 99° at 3:28; Dulles was 97° and BWI 99°.

NOAA also reported today, "More than 50 new all-time high temperature records were established in the central and western U.S. during the last two weeks." The records are not final, but July may have been the hottest month ever recorded in the contiguous 48 states.

Now

Extremely Hot: After reaching a low of 80° this morning, the Washington official temperature has tracked a couple of degrees higher than yesterday's pace. By 4pm, the hourly reading was 99°, a level matched by several other stations in the region. Fredericksburg hit the century mark earlier; other Virginia locations in triple digits were Richmond, Petersburg, Hanover, West Point, Williamsburg (102°), and Franklin (102°). The traditional warm spot of Frederick, MD, reported 100°. Even the North Carolina Outer Banks were sweltering, as Kill Devil Hills recorded 100deg;. The Excessive Heat Warning for the area continues until 6pm Thursday.

CapitalWeather.com chart from NWS data, photo by CapitalWeather.com photographer Kevin Ambrose.

Tonight and Tomorrow

Excessively hot: Temperatures will again remain very warm overnight, with lows in the low 80s in heavily urban areas. The cooler 'burbs could reach the mid 70s. The models are almost unanimous in predicting triple digits tomorrow, so expect temperatures near or even slightly higher than today's. Heat index values are likely to reach as high as 110-115. There is virtually no chance of a thunderstorm through tomorrow.

Scroll down to Dan's post below for the outlook through the weekend.

Tropical Topics

After becoming better organized overnight and hitting top winds of 65 mph, Tropical Storm Chris weakened slightly to 60 mph this afternoon. Strengthening to a hurricane is still possible in the next 24 hours. The forecast track takes the storm through the southern Bahamas early this weekend and then possibly into the Gulf of Mexico.

Divine Wind

The latest issue of Physics Today, which arrived through the mail slot as this post was being written, has a cover article (available to non-subscribers) by Prof. Kerry Emanuel of MIT on the thermodynamics of hurricanes. Emanuel is the author of last year's excellent book on hurricanes, Divine Wind.