Friday, December 28, 2007

Raindrops Falling on Your Head


Cloudy, cool. Following sunny skies this morning, clouds have overspread the Washington metro region this afternoon ahead of a low pressure area developing in the Mid-Mississippi Valley. By mid afternoon, rain and showers on radar had reached as far as the southern Blue Ridge and most of West Virginia. At 4pm, Charlottesville reported light rain had just begun, with only a trace accumulated. The rain will move into the area this evening, generally from southwest to northeast.

Temperatures are on the mild side for this time of year, reaching the upper 40s in most places. The daily highs were: National 50°, Dulles 48°, BWI 47°.

Tonight and Tomorrow

Rain, mild. Rain, developing this evening, will continue overnight, with temperatures nearly steady in the low to mid 40s. Rain will end tomorrow morning, with decreasing clouds in the afternoon and highs 50-55°, but turning colder late in the day and at night.

Scroll down for Camden's outlook through the rest of the weekend and New Year's Day.


One of the things the atmosphere does for you is to keep raindrops falling on your head at times, but it also keeps other, nastier stuff from falling and killing you. Today's SciFri on NPR reported that NASA's Near Earth Object Program is tracking a 50-meter wide asteroid, discovered when it was near the Moon, which is on its way to a 25% chance of impacting Mars. The object, if it hits on Jan. 30, could produce quite a show. Since the atmosphere of Mars is less than 1% as dense the Earth's, an object of that size could do some significant damage, creating a crater about half a mile wide.

Mars image from NASA/JPL

Thursday, December 27, 2007

DC: Definitely Changeable


Mostly sunny, mild. While yesterday's coastal storm has pulled away off New England, mostly sunny skies across the Washington metro region have helped temperatures climb above the forecast range, to the mid and upper 50s in most places. On the southern fringe of the area, Culpeper and Fredericksburg broke the 60° mark.

The double-digit above average daily highs were: National 58°, Dulles 54°, BWI 54°. Going into the last few days of the year, the month overall is now running about 1.5° above the long-term average. This keeps 2007 on track for a 4-way tie as the 12th warmest year in Washington records.

As Josh has already noted, a pattern of fast upper-level westerlies will keep things unsettled heading on into the end of the year.

NWS Precipitation Analysis above for the 24 hours ending 7am this morning shows half inch or greater amounts (green) to the southeast of DC and progressively lighter amounts to the north and west. The lightest blue area covering most of Frederick and Loudoun Counties represents less than 0.1", and inside the Beltway was generally in the range 0.1-0.25".

Tonight and Tomorrow

Partly cloudy, cool, then chance of rain. Lows tonight under variably cloudy skies will range from the mid and upper 30s inside the Beltway to 28-32° in the outer 'burbosphere. Clouds will increase tomorrow afternoon with a 30% chance of rain by evening and highs 45-50°.

Scroll down for Josh's outlook through the weekend and into New Year's Day.

Wednesday, December 26, 2007

Seminar Series

The PowerPoint slides from Fred Singer's presentation to this month's DC MIT Club seminar series, "The Great Climate Change Debate", have been posted to the Club web site. Prof. Singer "is a leader among those who have emphasized natural factors over anthropogenic causes to explain global warming."

Next month's lecture is "The Findings and Forecasts of the Climate Change Scientists", by Prof. Ronald Prinn, Director of the Center for Global Change Science at MIT. Having had no takers so far, PM Update's previous offer to host any TV meteorologist at the seminar series still stands, provided seats remain available.

Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.