Wave Goodbye: Record Heat Peaking

5:45 Update: Other highs: Dulles 99° (tied record), BWI 100° (tied record), Baltimore downtown 102°.
Also setting new records were: Norfolk 102°, Richmond 102°, Salisbury 97°.

Now

Historically Hot: The analysts on CNBC often say, "It's just a number", referring to stock index values ending in multiple zeroes. Psychologically, however, it does have a certain ring to it: At 2:10 today, the official Washington temperature of 101° broke the record set in the historic heat wave of 1930. This morning's low of 81° was also the warmest low for the date, exceeding the 78° in 1995. Other stations joining in the centennial festivity this afternoon included: Ft. Belvoir, Fredericksburg, Leesburg, Winchester, Patuxent River, and BWI. Even at the beach, Ocean City clocked in at 99°. Click here to view the latest hourly heat index values from WUSA-TV9. The Excessive Heat Warning for the area continues until 9pm tonight.

Regional radar is again mainly dry, except for some scattered activity south of Charlottesville.

Tonight and Tomorrow

Not as hot: We have one more stifling night ahead as a cold front gradually approaches from the northwest. Lows will be in the low 80s in the warmest urban areas to the upper 70s in the 'burbs. Tomorrow's highs will be "just" in the low 90s with only a 30% chance of a thundershower.

Scroll down to Josh's post below for the outlook through the weekend and the rest of Larson's Long-Range.

Tropical Topics

Tropical Storm Chris exceeded expectations with 65 mph peak winds yesterday, but the latest advisory puts it down at minimum storm strength of 40 mph. The storm is now considered likely to become tropically depressed as it continues to track west-northwesterly through the northern Caribbean.

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.

Excessive Heat: Record-Breaking or Broken Record?

Now

Very Hot: Barring a very unlikely 3°F jump between hours, the official Washington temperature record for today appears intact. Instead, it's "just" another 90°+ day, adding to July's 14 (which Matt notes below), June's 5, and May's 2. Nevertheless, the combination of temperatures in the high 90s and dewpoints in the mid 70s has produced heat index values in the area approaching, and even exceeding in a few instances, 110. No rain is visible anywhere on regional radar, so be prepared to swelter through tonight as the Excessive Heat Warning continues into Thursday.

Tonight and Tomorrow

Excessively hot: Temperatures will remain very warm overnight, with lows unlikely to break below 80° in urban areas. The cooler 'burbs could reach the mid 70s. Tomorrow will be a little hotter than today, with highs near 100° and heat index values as high as 110-115. There is virtually no chance of a thunderstorm through tomorrow.

Scroll down to Jason's post below for a heat wave chronology and outlook through the weekend.

Tropical Topics

Despite yesterday's pessimistic prospects for development, the tropical wave east of the Leeward Islands became TD 3 last night and Tropical Storm Chris this morning with maximum winds of 40 mph, increasing to 45 mph as of the late afternoon advisory. The forecast track brings the storm on a traditional track through the Bahamas this weekend and onward toward south Florida.

"Washington Coverup"

Having dealt with the subject of shade in general during one of last year's heat waves, the WaPo's Style section turns its attention today to the subject of umbrellas and their use as sun shades.

Trane Spotting: Excessive Heat Warning Tomorrow

5:45 Update: Today's Semi-Official Highs
National 96° (3:50pm)
Dulles 95° (3:08pm)
BWI 97° (2:09pm)
Baltimore Downtown 97° (2pm)

Now

Hot: Whether it's Trane, Carrier, or Kenmore, air conditioning is in high demand in the Washington DC metro area this afternoon as a heat wave begins settling in for the next several days. By 1pm, temperatures were into the 90s in most places. Most locations between the Blue Ridge and the Bay are now reporting heat indexes over 100. The highest hourly temperature at National has been 96° and at Dulles, 94°. By late afternoon, a line of thunderstorms developed from the northern Baltimore suburbs to the far northeastern corner of Maryland.

Tonight and Tomorrow

Excessively hot: Temperatures will remain quite warm overnight, with lows ranging from near 80° in the city to the mid 70s in the 'burbs. There is a slight chance of widely scattered thunderstorms through this evening. Tomorrow will be hotter than today, with highs near 100° and heat index values as high as 110-115.

Scroll down to Jason's post below for a heat wave chronology and outlook through the weekend.

Tropical Topics

The tropics are still relatively quiet, but the National Hurricane Center is tracking a couple of tropical waves in the Atlantic and a low pressure area off the coast of the Carolinas.

TV Weather Rules

Today's WaPo TV section reports that Channel 5 has finally run out of "Seinfeld" and "Friends" episodes and will be starting a new 30-minute news program at 11 tonight. The station is quoted as saying that the show, called "The Edge", will "almost always" lead off with the weather report. Another innovation: a chairless anchor. Good luck, Sue, on your new gig.

Bake, not Shake

Now

The Washington metro area baked under temperatures into the low 90s this afternoon, but there wasn't a whole lotta shakin' goin' on. Although a narrow, but intense, line of thunderstorms extended at mid afternoon from southeastern New York all the way to the lower Potomac, the immediate DC area was mostly bypassed. The temperature dropped to 79° in a thunderstorm at Quantico, but most other locations were partly cloudy to cloudy.

Tonight and Tomorrow

There is a very slight chance of an isolated thunderstorm through this evening; lows will range from the mid 70s in town to the low 70s in the 'burbs with slightly lower humidity. Tomorrow will be warm and humid with highs around 90°.

Scroll down to Camden's post below for the outlook through the rest of the weekend and suggested activities.

Tropical Topics

The National Hurricane Center is tracking two tropical waves, one in the Caribbean and one in the Atlantic, but neither one is showing signs of development.

Capitol Climate

CSPAN-2 last night rebroadcast yesterday's hearing of the House Energy and Commerce Committee on "Climate Change Assessment Methodologies". It was the second of two hearings to discuss alleged flaws in the famous "hockey stick" long-term temperature curve originally published by Michael Mann in 1998. If you've never seen the confrontation of science and politics up close and personal, it's the ultimate example of trying to mix oil and water. The hearings don't seem to have been covered by the "mainstream" press, but the Houston Chron's Science Guy provides some analysis in his blog. The realclimate blog, in which Michael Mann is a contributor, also had a post discussing last week's committee session. For the opposite opinion, see the lobbyist-funded Tech Central Station.

Hanging Out on H Street

Now

The 3 H's of haze, heat, and humidity are hanging out in the Washington metro area this afternoon. As Matt noted earlier, this is hardly unusual for a DC July. Temperatures are mainly in the upper 80s, and dewpoints are in the upper 60s to low 70s. A weak band of scattered thundershowers well to the west has dissipated.

Tonight and Tomorrow

Tonight will be warm and humid with lows in the upper 70s downtown to the low and mid 70s in the 'burbs. Tomorrow will again be warm and humid, but with a little better chance (30%) of afternoon or evening thunderstorms and highs near 90.

Look for Larson's Long-Range late tonight/tomorrow for the extended outlook.

Tropical Topics

The low pressure area associated with some storms in the western Gulf of Mexico has remained over land, between Houston and San Antonio, so no tropical development is expected. However, it is bringing heavy rain and some gusty winds to the Texas/Louisiana Gulf Coast and adjacent Gulf of Mexico.

An Accident at Sea Can Spoil Your Whole Day

Fifty years ago today, the Italian luxury passenger liner Andrea Doria sank after colliding the night before with the Swedish liner Stockholm in fog near Nantucket, killing 51 people. The event was the first major televised disaster, and it marked the end of the golden era of passenger ship travel. The roles of weather and the possible misuse of the then relatively new technology of radar are examined tonight in a new episode of the PBS "Secrets of the Dead" series. The program is broadcast locally on WETA, channel 26, at 8pm.

Image of Andrea Doria travel poster from PBS

Short-Lived Summer Break

Now

As a visitor noted in the previous comments, the weather gods have favored the Washington metro area with a brief respite from summer's mugginess. Temperatures around the region in late afternoon are mostly in the mid 80s. Dewpoints, which dipped into the upper 50s for several hours last evening, are still in the relatively comfortable low 60s to 66. The dry conditions allowed last night's official low to dip to 67°, a level which hasn't been seen since July 9; Dulles was 62&deg.

Tonight and Tomorrow

With the humidity starting to creep up, don't expect such an outstanding night as last night, but lows should still be near 71 in town to the mid and low 60s in the cooler 'burbs. Tomorrow will be sunny and a little more humid, highs around 87&deg.

For the extended outlook through the week, see Jason's post below.

Tropical Topics

The National Hurricane Center is keeping its eye (so to speak) on a stormy area in the western Gulf of Mexico and Bay of Campeche. Some buoys in the area have reported gusts to 40 or 50 mph, and the future upper level winds are looking favorable for development, so this area could become tropically depressed in the next day or two.

Recent Precipitation

Despite the possibility of severe storms, Saturday's precipitation was fairly minimal in the immediate area. Amounts were more significant south of the Beltway and east of Baltimore. Since the copious rains of the first week this month, National Airport has recorded just slightly over 1" in the following nearly 3 weeks. The overall total so far, however, is just 0.1" less than the long-term climatological average for the whole month.

24-hour precipitation totals ending 8am yesterday, from National Weather Service.