Flood Watch tonight as more rain approaches

The Potomac River peaked just over flood stage at Great Falls on Tuesday at 2 p.m.

When I arrived at Great Falls National Park Tuesday afternoon, the parking lot was over half full and a steady stream of visitors moved up the trail toward the overlooks. The park always seems to do brisk business during floods. Our recent heavy rain put the Potomac River over flood stage, but it was still far from record levels.

Keep reading for more photos, including two showing how Tuesday's flooding compared to the Great Flood of 1996. More flooding rains on the way? See our full forecast through the weekend and into early next week.

More flooding a threat, but rain totals uncertain

*Flood Watch in effect this evening through Friday morning*

A weak frontal system and an area of low pressure will conspire to bring rain back into the picture tonight, especially after midnight into the first part of the day Friday. Unfortunately for sun-lovers, it looks like clouds will stick around on Friday and for parts of the weekend, though both Saturday and Sunday look predominately dry.

TODAY

Increasing p.m. clouds. Mid to upper 70s. Rain tonight. Despite increasing afternoon clouds, temperatures -- aided by winds from the west at 5-10 mph -- will reach the mid to upper 70s. Tonight will be overcast, with periods of moderate rain moving into the area during the late evening or overnight hours. Expect mild lows near 60.

Keep reading for the forecast through the weekend into the start of next week, and see our forecast for Sunday's Post Hunt.

What: 2008 Post Hunt
Where: Penn Quarter
When: Noon-5 p.m.

Looking for the Sunday forecast? We've hidden it somewhere in downtown D.C. Good luck finding it.

Just kidding... Actually, the Sunday forecast is a bit of a mystery, as the models don't have a very good handle yet as to how much cloud cover and showers will be generated by a piece of energy in the upper levels of the atmosphere. Best guess for now is the rain-or-shine event will see more clouds than sun, temperatures in the 60s and some showers around, but probably not a steady rain.

Confidence: Medium

Check back for updates now through early Sunday. And see our full forecast through the weekend and into early next week.

Last Thursday, Capital Weather Gang's (CWG) newest writer, Steve Tracton, defended meteorologists against the critical points raised in the NY Times Freakonomics blog "How Valid Are T.V. Weather Forecasts?" NBC 4 Chief Meteorologist Bob Ryan agreed with Steve's assessment and weighed in with some insightful comments:

Steve Tracton gives a excellent, useful cogent discussion and answers to the tired cliches and plain errors and misinformation as in the original Freakonomics post and responses and other "rants about the weatherman" for lack of a better term.

Some observations of my own.

1. No matter how much the science and predictability advances, people's expectations will continue to out pace what is possible. A 24 hour forecast accurate close to 90% of the time. . . we want 95% accuracy. 95% accuracy in 10 years. . .we want 99% accuracy. Talk to your parents or grandparents about how accurate forecasts (and more importantly tornado and hurricane warnings) were 40-70 years ago.

Keep reading for more of Bob Ryan's comment. Also, see our full forecast through the weekend.

Transition back to unsettled weather Thursday

Clouds: Latest mid-Atlantic infrared satellite loop, courtesy Unisys. Click here to expand. Refresh page to update.

Today was another welcome respite for weather-weary residents, especially those continuing to clean up from flood damage following recent rain across the area. Even with increasing clouds throughout the day, temperatures have managed to climb into the low and mid 70s as southerly winds help pump in warmer air.

Tonight: Clouds will stick around all night as temperatures fall to around 60 degrees in Washington and the upper 50s in the suburbs. Showers may pass through the region overnight, but little rain is expected across the area, and most of the activity should stay to the north.

Tomorrow: After a risk of very light early morning showers, Thursday will feature more clouds and a growing chance of more numerous showers by the afternoon or evening. Highs will reach the low to mid 70s. The cold front responsible for tomorrow's shower chances will stall in or near the area, leading to more in the way of rain for Thursday night into Friday.

See Dan's full forecast through the beginning of next week.

Tropical Cyclone Nargis, which exacted a staggering human toll on the politically isolated and poor country of Myanmar, has demonstrated once again that there is an urgent need for a more robust infrastructure in developing countries for issuing and disseminating warnings of natural hazards. Unlike when the deadly Indian Ocean tsunami hit in 2004, government officials had at least one and a half days of warning before Nargis' arrival as a Category Three or Four cyclone on May 3rd. However, it's doubtful that the Burmese military-led government was able to get word to the residents of the hardest hit Irrawaddy delta region in time for them to protect themselves. Even if the warnings had reached this area, it's unclear what, if any, storm shelter options were available to people.

Dr. Peter Webster. Photo courtesy Georgia Institute of Technology

To get a firsthand perspective on how to improve the timeliness and effectiveness of weather warnings in developing countries, I turned to Peter J. Webster of the Georgia Institute of Technology, who is one of the lead scientists involved in a flood warning project in Bangladesh, Myanmar's low lying neighbor. Webster has directed the Climate Forecast Applications in Bangladesh (CFAB) project since 1999, and he is also a prominent scholar of tropical cyclones. For example, one study he served as the lead author of in 2005 broke new ground and proved controversial when it demonstrated a potential link between global climate change and tropical cyclone intensity.

The following are portions of our Q&A, which was conducted via email over the weekend. In it, Webster shares his perspective on what went wrong in Myanmar, what is going right in neighboring Bangladesh, and how climate change may complicate matters.

Keep reading for Andrew Freedman's Q&A with Dr. Peter Webster. Also, see our full forecast through the weekend.

More rain on the way for Thursday night and Friday

The conspiracy theorists would say forecasters hedge their predictions toward nicer weather so people will like them. Here on Wednesdays at CWG, there's no hedging necessary. Time and again, the midweek weather has been perfect as can be. And gosh darn it, I think people really like me for it. Just do me a favor and don't hate on my late-week and weekend brethren, ok?. It's not their fault the fair skies never seem to last.

TODAY

Mostly sunny early. Increasing clouds late. Upper 70s. Enjoy a second nice spring day in a row. Skies should be mostly sunny through early afternoon as highs reach the upper 70s on winds from the south near 10 mph. Then, skies cloud over during the late afternoon, followed by a mostly cloudy night with lows in the upper 50s to near 60 downtown, mid 50s in the burbs.

Confidence: Medium-High

TOMORROW

Partly to mostly cloudy. Maybe a passing shower. Mid 70s. A cold front arrives from the west -- and promptly stalls near the area. The result won't be too bad, at least for the time being, with partly to mostly cloudy skies, a chance of a passing shower, and highs in the mid 70s. Then, low pressure, moving in from the southwest along the front, is likely to bring more numerous showers to the region during the evening and overnight hours. Lows in the upper 50s.

Keep reading for the forecast through the weekend. Check back later this morning for Andrew Freedman's weekly column.

More warm weather expected Wednesday

Webcam: Latest view of D.C. from the Netherlands Carillon at Arlington National Cemetery. Courtesy National Park Service.

After all the rain and bad weather of recent, today has been a welcome and beautiful break! Highs are now topping out in the low 70s, just about everywhere, and light winds out of the northeast are the only reminder of the long-lived storm that ended yesterday.

Tonight: Clear and cool conditions will rule the night. Temperatures will range from the mid and upper 40s in the suburbs to right around 50 degrees in Washington. Some patchy fog may form by morning as temperatures cool to near the dew point -- the area remains quite soggy from the last few days.

Tomorrow: Our short-lived spell of nicer weather will continue tomorrow, even as clouds begin to increase again by late in the day. Temperatures should reach the mid and upper 70s on a warm southerly wind that will blow between 10-15 mph by afternoon.

See Jason's latest thoughts on recent drought-busting rains, and Matt's full forecast through the weekend.

Watch the video below to understand why it's a bad idea to be in your car when a tornado strikes. This incredible video was captured by a surveillance camera from an equipment company in northern Alabama on Thursday according to the National Weather Service.

Doppler rainfall estimates from the Sunday-Monday storm. The yellow shade is 2.5", the medium orange shade is 4", and the dark red is 6". Courtesy NOAA.

Related Washington Post story: Deluge Washes Away Area's Drought

It was just this past fall when Reagan National Airport (DCA) observed a record 34 days with no measurable rain. 2007 finished with precipitation 30-40% below average across the region. But for the most part, 2008 has been wet. May already ranks as the 5th wettest on record at DCA, and it's less than half way into the month. So as we've gone from extreme to another, what can we say about the drought? Is it over?

The numbers say yes. After one to three inches of rain Thursday and Friday and another three to five inches from yesterday's storm (with isolated 6"+ totals), we no longer have a short-term or long-term rainfall deficit (before our dry 2007, 2005 and 2006 were both wetter than average). And all drought indicators put us in the "green."

Keep reading and I'll walk you through them. See Matt's full forecast for the outlook through the weekend...