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Heat Wave Holds on Strong
Real relief waits for weekend

Dan Stillman @ 8:30 AM

** Heat Advisory in Effect From 1 PM to 8 PM Wednesday **

Of yesterday's high temperatures -- 96 at National, 97 at Dulles and 97 at BWI -- only Dulles's was a record-breaker, eclipsing the old record of 95 set in 1968. But the heat, combined with oppressive humidity, was nonetheless stifling. Its impacts included slowed Metro trains, stranded motorists and time spent at the skating rink. Extreme heat continues today, and will be slow to relent until real relief makes it here for the weekend.


Forecast Confidence: High-Very HighAs hot as yesterday, if not more so. On a hazy, hot and humid day, high temperatures should fall mostly in the range of 96-101. Dewpoints in the upper 60s to mid 70s will result in heat indices as high as 105-110. There's a slight chance of an isolated thunderstorm in the late afternoon or evening, but most areas are likely to remain dry. Tonight, very warm and humid with lows near 80 in town, mid 70s in the burbs.

Track today's scorching temperatures, courtesy Weather Bonk and Google. Hover and click on readings for location and other information. You can also pan the map and zoom in or out.


Forecast Confidence: Medium-HighHeat holds on, but just how hot? ... small chance of PM showers/storms. It'll remain hot and humid, but the models are uncertain as to exactly how hot. Despite a few more clouds than previous days, I don't see evidence for a dramatic drop off in temps. I'll call for highs in the mid 90s, with some upper 90s possible especially to the south. Heat indices will likely top out as high as 100-105. A warm front ahead of developing low pressure may bring an increased chance, but still only about 30%, of some afternoon and evening showers and thunderstorms. Overnight, a 20-30% chance of a shower or storm, with lows in the mid-to-upper 70s in town, mid 70s in the burbs.


Forecast Confidence: Medium-HighHot, humid, chance of showers or storms. A slow-moving cold front looks like it will lack the punch necessary to give our heat wave a knock-out blow, at least until the weekend. I think we'll easily make the low 90s, and in fact many areas could be up into the mid 90s again, with heat indices reaching 95-105. The cold front in the vicinity should provide partly cloudy skies and a 30-40% chance of some showers and thunderstorms, mainly in the afternoon or evening. Overnight, a diminishing chance of precipitation with lows in the low-to-mid 70s in town, upper 60s to low 70s in the burbs.

The Weekend

Forecast Confidence: HighWarm, less humid. As high pressure moves in behind the cold front, a flow from the north should finally cool things down somewhat. As of now, the weekend is looking mostly sunny and less humid with highs in the mid 80s to near 90, lows in the mid 60s to near 70, and little or no chance of rain.

Too Much Whining? Maybe. But Too Much Warning?

Valerie Strauss, a guest blogger filling in for Washington Post metro columnist Marc Fisher, complains that Washingtonians do too much whining about summer heat: "It has been some time -- say hundreds of years -- that people have noticed it is hot here during the summer ... It's hot, but we knew it would be. It's hot, but plenty of places are hotter. It's hot, but it won't be for long. So let's change the subject."

It's true that the kind of heat we're experiencing this week is not unusual for August in Washington, and I can understand Strauss's desire for a little less whining, though I'm of the opinion that many people whine about the weather to make conversation more than anything else.

I do, however, take issue with Strauss's assertion that the heat is not newsworthy, and her implication that the media shouldn't bother to provide seemingly obvious advice on how to keep cool. "It's not news, though television stations and newspapers cover the heat as if it was. We get tips on staying cool (as if they aren't self-evident)," she says.

If the media didn't warn of heat waves and cover their impacts, then how would anyone know about the onset of extreme heat and be able to prepare accordingly? An annual average of more than 600 deaths in the United States due to extreme heat, according to the Centers for Disease Control, tells me that if anything the media should provide more warnings about the dangers of heat and more tips on how to stay cool, not less.

Fort Collins Flood is Freaky Flashback

Severe flooding occurred in parts of Fort Collins, Colorado, on Thursday night of last week. Incredibly, the timing was almost exactly 10 years after the historic Fort Collins flood of 1997, which according to the City of Fort Collins Utilities killed 5 people, injured 54, and damaged or destroyed nearly 2,000 homes and businesses. Rainfall amounts were not nearly as high this time around -- almost 5.5 inches in the span of a few hours compared to the 14.5 inches that fell over the course of about 30 hours in 1997.

Nevertheless, last week's intense rains were a test of the various efforts the city has made during the past decade to reduce the risk and impacts of flash floods, including new construction requirements, more streamflow and rain gauges, improved communication between the National Weather Service and emergency managers, and installation of a reverse 911 system to warn endangered residents by phone. Russ Schumacher, a Colorado State University Department of Atmospheric Science Ph.D. student, whose research has focused on the meteorology of flash floods, reports:

"Only a few days after the 10-year anniversary of the 1997 Fort Collins flood, the conditions were very similar in the area, and the storms developed in a very similar way. The rainfall amounts weren't nearly what they were in 1997, but the rainfall rates were pretty remarkable nonetheless. One of the automated gauges reported 4.9" in 2 hours, and there were storm totals nearing 5.5". We had about 3" in 2 hours at our house, and I know I've never seen it rain that hard since I've lived here. (For reference, our annual average precipitation is around 14".)

"One mobile home park was hit the hardest, as apparently their storm drain was clogged and about 2 feet of water was in the park. There was significant street flooding during the rain, and also plenty of basements flooded. However, given the amount of rain in such a short time, the damage was pretty minimal: a testament to the excellent flood management system here in town."

As luck would have it, I was with a group in Fort Collins last month and toured the sites of where floodwaters derailed a freight train and swept away a mobile home park in the 1997 flood, which was a real-life nightmare for emergency managers. Officials at the City of Fort Collins Utilities told our group that while action was taken following the 1997 event to restrict development in the floodplain, the city council voted earlier this year to relax restrictions in some places. In fact, according to a July article in The Coloradoan, "city officials are reviewing a proposal to build student housing in an area that was home to the" mobile home park destroyed in 1997. It'll be interesting to see if last week's flooding sinks what, at least on its surface, sounds like a foolish idea.

Pictured: A detention pond does its job last week in Fort Collins, Colorado, courtesy Russ Schumacher. Detention ponds are specially constructed ponds designed to accumulate rain water from surrounding land, protecting downstream areas from flooding. They are often a required element of new developments.

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