Relief On the Way, But With an Asterisk

Now

Hot, humid, scattered thunderstorms. Relief is arriving for the Washington area's record-breaking heat, but it comes with an asterisk; the temperature drop is likely to be short-lived, and there is little prospect for serious improvement in the deepening drought conditions.

A large complex of thunderstorms extending from north of Harrisburg through the Baltimore metro area to the northern DC suburbs early this afternoon helped reduce temperatures, but precipitation was mainly limited to north of the Beltway. BWI received almost half an inch (0.43") , but National got a mere 0.02" and Dulles had only a trace with some thunder . Despite the fierce appearance of the storms on radar, damage reports were relatively sparse. Temperatures were well into the 90s by 1pm, but they retreated to the 70s in areas with rain, where they have now rebounded to the low and mid 80s.

Another area of storms now in southwestern Pennsylvania is likely to take a similar track toward the northern portions of the region in the next couple of hours.

Tonight and Tomorrow

Hot, humid, scattered thunderstorms possible. There is still a 40% chance of thunderstorms through this evening, especially in northern areas. Lows will be in the upper 70s in the city to the mid 70s in the 'burbs with uncomfortable humidity. Tomorrow will be hot and humid with highs 90-95° and a 30% chance of showers or thunderstorms.

For the outlook through the weekend and beyond with Larson's Long-Range, scroll on down to Josh's post below.

Tropical Topics

The Climate Prediction Center and National Hurricane Center today released an updated hurricane season outlook. It continues to call for an above-normal season, with an 85% chance of greater than average tropical cyclone activity. The forecast includes a range of 13-16 named storms, 7-9 hurricanes, and 3-5 major hurricanes.

Climate Corner

The August issue of Scientific American has an excellent non-technical article on "The Physical Science behind Climate Change". The authors were all members of Working Group I of the 2007 IPCC assessment. Besides reviewing the scientific evidence for global warming, the article also discusses the remaining uncertainties. The key concepts are summarized by the editors in the box to the right.

Humor Dept.: "There Once Was Some Wind Off Nantucket . . . "

The Daily Show's "Jason Jones 180" recently produced a hard-hitting investigation of Big Wind's shameless attempt to exploit the hapless natives of Nantucket.

Swinging for the Record Books: Heat on Steroids

**Heat Advisory in Effect Until 8 PM This Evening **

Now

Sunny, record heat, humid. Unhindered by the clouds of yesterday and helped by a drying westerly breeze, the sun went to bat today chasing a long-standing temperature record. The temperature rose several degrees an hour through the morning, as much as 5° between 9 and 10 am, and by 1:03, the National Airport temperature hit 102°, breaking the record for the date set in 1930. After retreating several degrees temporarily, the temperature was back up to 101° at 4pm. Except for the 97° at 2pm, the reading at National has been at or above 100° for 5 consecutive hours.

Records were also set at both of the other major airports: at least 100° at Dulles and 102° at BWI. Several records were set or tied elsewhere in Virginia as well: Richmond 102°, Danville 100° (tied), Blacksburg 91° (tied).

Humidity is also quite high, although the 8 hours of greater than 75° dewpoints overnight were replaced by readings near or below 70° this afternoon. When combined with the hot temperatures, however, the heat index reached at least 108°. Scattered locally severe thunderstorms fired up in the early afternoon between Pittsburgh and Morgantown WV, but these have so far remained over and west of the mountains.

CapitalWeather.com chart from NWS data, photo © Kevin Ambrose

Tonight and Tomorrow

Hot, humid, scattered thunderstorms possible. Very warm and humid conditions will continue overnight with only a slight chance of scattered thunderstorms through this evening. Lows will be mainly in the upper 70s to near 80° in town and some mid 70s in the 'burbosphere. Tomorrow will be mostly sunny and not quite as hot with highs 93-97° and only a 20% chance of afternoon or evening thunderstorms.

For the outlook through the rest of the week and the weekend, scroll on down to Dan's post below.

Climate Corner

While today's WaPo featured the current heat wave on the front page, inside the A section was an article, "Across Globe, Extremes of Heat and Rain", about a just-released World Meteorological Organization report on recent extreme weather events throughout the globe. Although any individual weather event cannot be directly tied to climate change, widespread extremes are certainly consistent with such a scenario.

Also on today's WaPo front page was an article, "Warming Draws Evangelicals Into Environmentalist Fold", about the developing collaboration between evangelical groups and the environmental movement.

High Summer

**Heat Advisory in Effect Until 8 PM This Evening, 1 PM to 8 PM Wednesday **

Now

Hazy, hot, humid. High summer had many residents of the Washington metro area feeling "down, low down" today, but the most hyped extremes of heat failed to materialize as the core of the heat wave remained to the south and west of the region. At mid afternoon, Culpeper had the lone triple-digit temperature, but the 104° heat index there was exceeded by the 109° reading at Fredericksburg resulting from a 97° temperature/75° dewpoint.

In the immediate vicinity of the Beltway, temperatures at post time are generally in the mid 90s. Thunderstorms on radar are mainly limited to Pennsylvania, although a scattered and weakening line extends through eastern West Virginia.

Very hot temperatures and uncomfortable humidity will continue through at least tomorrow, with one major model predicting a high of 103°.

Tonight and Tomorrow

Hot, humid, scattered thunderstorms possible. There is a very slight chance of an isolated thunderstorm through this evening; otherwise, it will be another warm and sticky night with lows dipping into the upper 70s downtown and the lower 70s in the 'burbs. Tomorrow will be continued hot and humid with highs 96-101° and heat indices as high as 105-107°. There is only a slight chance of an afternoon or evening thunderstorm.

For the outlook through the rest of the week, scroll on down to Jason's post below.

Tropical Topics

Although several typhoons have been active in the Pacific recently, the tropical Atlantic remains quiet.

The Miami Herald and the Palm Beach Post both reported today on the news we posted yesterday regarding the suggestion that ousted National Hurricane Center Director Proenza return to his old job in Texas.

Mediaorology: "Sultry 24/7"

Yesterday's New York Daily News TV section featured a review of The Weather Channel's female talent (Alexandra Steele, Heather Tesch, Stephanie Abrams, Nicole Mitchell).

Alexandra Steele photo from The Weather Channel

DC: Dewpoints Climbing

** Heat Advisory in effect noon to 8pm Tuesday **

Now

Hazy, hot, humid. Yesterday's showers varied widely in amount across the region, from zero in parts of Northern Virginia to over an inch in some eastern locations. (The green areas through much of Prince George's County range from 0.5" to as high as 1.5", while the blues through much of the District and Montgomery County are less than 0.5", and most of Fairfax County is less than 0.1".)

The additional moisture, however, has helped lift dewpoints into the sultry low 70s, a level which pushes the heat index up about 7 or 8 degrees from the temperatures in the low 90s. Both Ft. Belvoir and Manassas were sporting heat indices of 100° by 2pm, and Ft. Belvoir was the hot spot at 4pm with an index of 103°. By mid afternoon, however, radar showed only a few isolated showers, mostly southward along I-95.

Hot temperatures and uncomfortable humidity are likely to continue through the middle of the week.

Chart of 24-hr. precipitation through 8am this morning from NWS Southern Region.

Tonight and Tomorrow

Hot, humid, scattered thunderstorms possible. There is still a slight chance of an isolated thunderstorm through this evening; otherwise, it will be a warm and sticky night with lows barely getting into the upper 70s downtown and the lower 70s in the 'burbs. Tomorrow will be continued hot and humid with highs 95-99° and heat indices approaching 105°. There is only a slight chance of an afternoon or evening thunderstorm.

For the outlook through the rest of the week, scroll on down to Jason's post below.

Tropical Topics

The tropical wave which tracked westward through the Caribbean late last week has pushed onward into Central America without developing.

As the Proenza affair at the National Hurricane Center continues to unfold, the House Committee on Science and Technology announced today that the chairmen of 2 subcommittees have sent a letter to NOAA Administrator Lautenbacher requesting that Proenza be returned as Director of the NWS Southern Region if he is permanently removed from his post at the NHC. According to the letter, NOAA had planned to assign Proenza as training chief of the Office of Climate, Water and Weather Services, a "drastic demotion", before the NHC assessment team had even been formed. An article in Friday's Miami Herald reviews Proenza's campaign to get his job back.

The paper by Holland and Webster on "Heightened Tropical Cyclone Activity in the North Atlantic" which PM Update posted on last Monday has been referenced in the Science Notebook of today's WaPo, but without the crucial caveat that this issue is far from settled because of the limitations of the available data.

Hazy, Lazy Daze of August

Now

Sunny, hot, widely scattered showers. Once again today, temperatures were in the low 90s shortly after lunch time in most of the Washington metro area. A slight increase in humidity has helped widely scattered thunderstorms to develop, mainly southwest of the Beltway and in the immediate Baltimore metro area. At 4pm, Dulles and Manassas were reporting thunder and temperatures down into the 80s.

Hot temperatures and seasonable humidity are likely to continue through next week after a partial respite on Sunday.

Tonight and Tomorrow

Hot, humid, scattered thunderstorms. The chance of scattered thunderstorms will continue through this evening with overnight lows from the mid 70s downtown to some upper 60s in the 'burbs. Tomorrow will be a couple of degrees warmer than today with highs 94-98° and a 20% chance of scattered thunderstorms.

For the outlook through the rest of the weekend, scroll on down to Camden's post below.

Tropical Topics

The tropical wave over the western Caribbean and the low pressure area over the northeastern Gulf of Mexico are still disorganized, although gradual development is still possible for each of them.

Dr. William Gray's Colorado State Tropical Meteorology Project has issued a revised forecast for the remainder of the hurricane season; the Miami Herald has a review, "University team trims hurricane forecast". The new total season predictions vs. the May 31 forecast are (50-year average in parentheses):

• Named storms: 15 vs. 17 (9.6)
• Hurricanes: 8 vs. 9 (5.9)
• Intense hurricanes: 4 vs. 5 (2.3)
• Net tropical cyclone activity: 160 vs. 185 (100)

The probabilities of at least one major (Category 3+) hurricane landfall are (100-year average in parentheses):

• Entire U.S. coastline: 68% (52%)
• East Coast including Florida peninsula: 43% (31%)
• Gulf Coast from Florida panhandle westward: 44% (30%)

The forecast has been lowered from earlier levels because of:

• Cooler sea surface temperatures in the tropical Atlantic
• Significant dust outbreaks from Africa
• Expected cool neutral or weak La Niña conditions in the Pacific

No presentation by Dr. Gray would be complete without an attack on global warming, and the latest forecast is no exception. It contains about 2½ pages of arguments against the "many media references to recent papers claiming to show such a linkage" between global warming and hurricane activity. Despite the peer-reviewed publications by Kerry Emanuel and others to the contrary, Gray, whose techniques are purely statistical, nevertheless asserts, "We have no plausible physical reasons for believing that Atlantic hurricane frequency or intensity will change significantly if global ocean temperatures continue to rise."

Drought Deepens

The MarylandWeather blog reports that half the state is now in the "severe" drought category.

The global warming references are overstated, but the Montgomery Gazette this week reports on the effects of the drought on Potomac River kayaking. The MoCo Council is considering reinstating an emergency assistance program for the county's farmers.

It's August. It's DC. Get Used To It.

Now

Sunny, hot, moderately humid. Temperatures are in the low to mid 90s throughout the Washington metro area this afternoon, while dewpoints are near to slightly below the August average of 66°, so heat indices are mostly within a degree or two of the actual temperature. Leesburg was the local hot spot at 4pm with 97°, but the heat index was only 96°. Except for some very isolated showers in the mountains, radar is clear for several hundred miles.

Hot temperatures and seasonable humidity are likely to continue into the weekend.

Tonight and Tomorrow

Crank up the AC. Tonight will be mostly clear and quite warm with lows in the low 70s to near 75° in the city and some upper 60s in the 'burbs. Tomorrow will be sunny, hot, and seasonably humid with highs 93-96° and a very slight chance of late day thunderstorms.

For the outlook through the the weekend and beyond with Larson's Long-Range, scroll on down to Josh's post below.

Tropical Topics

The tropical wave which is now over the eastern Caribbean was looking more impressive on satellite images today, but was still disorganized. It still has some potential for development. A Hurricane Hunter plane was enroute early this afternoon to investigate.

Another area of interest is a batch of showers in the northern Gulf of Mexico.

The AP is reporting (via WaPo, for some odd reason under a "Global Warming" link) that "Ex-Hurricane Center Chief Wants Job Back". Ousted Director Proenza's lawyers are alleging in an 11-page letter that he was illegally fired.

Mediaorology

The Weather Channel's Dr. Heidi Cullen was interviewed ("Into the Limelight, and the Politics of Global Warming") in Tuesday's New York Times about her career in climate research and reporting.

Photo courtesy New York Times.

Slight Respite from Humidity, But More Heat Ahead

Now

Hot, a little less humid. The brightness of the sunshine and the sharpness of the shadows are signs that drier air has been gradually filtering into the region. Dewpoints in the immediate metro area were in the low 60s by mid afternoon, although the southern fringes of the region were still at or near 70°. Meanwhile, the extra sun has helped push temperatures to 90° or above at nearly all locations; Dulles and National were both 91° at 4pm. The nearest thunderstorms on radar are scattered between Charlottesville and Richmond and along the Virginia Eastern Shore.

The heat is likely to build through the rest of the week as more humidity returns as well.

Tonight and Tomorrow

Hot. Skies will be mainly clear tonight with lows in the low 70s to near 70° downtown and in the mid to upper 60s in the burbs. Tomorrow will be sunny and hot with highs 90-94°.

For the outlook through the rest of the week and into the weekend, scroll on down to Jason's post below.

Tropical Topics

Tropical Depression 3 developed overnight and quickly became Tropical Storm Chantal north of Bermuda this morning. The storm has strengthened to maximum winds of 50 mph as it scoots off to the northeast on its way to brushing by Newfoundland early tomorrow. It is likely to lose its tropical characteristics in the next 24 hours.

The tropical wave now about 520 miles east of the southern Windward Islands was less organized this morning, but it still has the potential to become tropically depressed in the next couple of days.

Cool Guys

This week's episode of the WaPo's Secret Worlds of Summer series profiles the "Faces Behind the Freeze".