Friday, December 15, 2006

DC Decemberology


Mostly sunny, mild. Morning fog, mist, and some mid-level clouds sandwiched between 2 weak fronts have once again capped the official Washington temperature below the most optimistic projections this afternoon, but most of the area still had readings in the low 60s by mid afternoon; on the southern fringes of the region, Fredericksburg recorded 70° at 2pm. Following the passage of a very weak frontal system, tomorrow will be a little cooler and dryer.

Tonight and Tomorrow

Mostly clear, a little cooler. Tonight will be mostly clear with lows near 40° in the city to the mid 30s in the 'burbs. Tomorrow will be sunny with highs in the mid 50s.

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

Snow Freqs

The natives have been getting a bit restless in the Comment Gallery recently over the prospects for snow (or the lack thereof), but longtime residents know that snow droughtiness is a common feature of DC December. The exceptions always stand out in the collective memory, but the sad fact for snow lovers south of the Mason-Dixon line is that the long-term monthly snow average for Washington of 1.5" didn't get that way without lots more misses than hits. The measly few flakes last week which went down in the record books as a trace already put this month above 5% of all Decembers dating back to 1888. Over 20% of the months had no more than this amount.

Hope springs eternal, however, when nearly 25% of Decembers have had 5" or more, including almost 1 per decade, on average, with over 10". (The most recent occurrence of a 10+" December was over 3 decades ago, in 1973, but the 1960s, 1930s, and 1900s share the honor of having 2 occurrences in the same decade. The 1960s are distinguished by having both of the top 2 December totals, 16.2" and 16.1".) Although, like Red Sox Nation, the DC snow lover frequently has to be content with the chant, "Wait 'til next year!", in the case of snow season, next year is only a bit more than 2 weeks away. chart from NWS data, photo © Kevin Ambrose


The Weather Channel's Climate Code (Sunday 5pm) is scheduled to cover the 10 biggest climate stories of the year.

WeatherTalkers Berk and Pann have as their guest on Sunday (3:05pm, WCBM-680 AM) Dr. Jeffrey Halverson, Associate Director-Academics at the Joint Center for Earth Systems Technology, UMBC. His research interests include "climatology and severe storms of the Mid Atlantic region, including nor'easters, severe thunderstorms and tropical cyclones undergoing extra-tropical transition."

Thursday, December 14, 2006

Deficit Reduction


Sunny, mild. Heavy fog persisting until a little past noon put a damper on the Washington official high reading of 59° at National Airport this afternoon, but most other locations in the region enjoyed spring-like temperatures in the low and mid 60s. Dulles hit 63°, but fog-plagued BWI still had visibility of 1/8 mile late this afternoon and a high of 55°.

A shot of slightly cooler and drier air should arrive late tomorrow, but generally mild and dry conditions will prevail into next week. Since there are only 6 days in December history which have never observed temperatures of 70° or more, the best chance to set a daily record is Monday, as posted by Josh earlier. Thanks to last week's cold, the month so far was still averaging 0.5° below average through yesterday, but that deficit was erased today.

Tonight and Tomorrow

Mostly clear, mild, some fog possible. Skies will be mostly clear tonight, but the still-moist dewpoints could result in some fog in low-lying areas by morning; lows will be from the low 40s downtown to the upper 30s in the cooler 'burbs. Tomorrow will be sunny and continued mild, highs in the low 60s.

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


One Degree, the online affiliate of The Weather Channel's weekly "Climate Code" series, has posted the 2006 Hot List
to call attention to those around the world who dedicated their time and energy to an issue that exploded into the public's consciousness in 2006 -- global climate change.
The non-partisan list of 10 individuals and groups represents those "policy makers, advocates, skeptics and scientists" who were deemed to have had the most influence during the year on this topic. Of particular note to readers is the fact that our own Andrew Freedman was one of the contributors to the writeups of the list members.

Wednesday, December 13, 2006

DC December Dryness Continues


Sunny, mild. Following this morning's showers amounting to only about 0.1", even the near-solstice low sun angle was enough to push temperatures in the Washington metro region into the upper half of the 50s by mid afternoon in most places. Only National and Quantico lagged behind with 53° and 50°, respectively, at 3pm. Highs were 54° at National, 57° at Dulles, 56° at BWI. More sun following the passage of a "cold" front will give us even milder conditions tomorrow.

Tonight and Tomorrow

Some clouds, seasonably mild. Under mostly clear skies, lows tonight should range from the lower 40s downtown to the mid 30s in the cooler 'burbs. After some possible fog in the morning, tomorrow will be mostly sunny with highs in the lower 60s.

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

Precipitation Perspective

The 0.09" of rain which fell in the light showers at National Airport was exactly "normal" for an average Dec. 13, but it was only the second time measurable precipitation has occurred this month. The last day more than 0.1" was recorded was over 3 weeks ago, on Nov. 22. This continues the common pattern this year in which an above-average total has occurred with a relatively smaller number of precipitation events. Although the yearly total so far is about 25% above the annual average, the 82 days with measurable amounts are nearly 30% below the long-term average. chart from NWS data, photo © Kevin Ambrose

Monday, December 11, 2006

December Rollercoaster


Clear, mild. After a solid week of lows below freezing, this morning's official low was only 33°. Brilliantly clear skies and some downslope air flow have allowed even the weak December sun to push temperatures into the low 60s and above in the Washington metro region this afternoon. Highs were 63° at National and BWI, 62° at Dulles.

Some clouds and a more easterly wind direction will likely put a somewhat lower lid on temperatures tomorrow, although the exact extent of the cooling is a bit uncertain. chart from NWS data, photo © Kevin Ambrose

Tonight and Tomorrow

Some clouds, seasonably mild. With a few scattered clouds, tonight's lows will be near 38° downtown to around 30° in the cooler 'burbs. Clouds will increase somewhat tomorrow with highs in the mid 50s.

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

Climate Corner

The National Center for Atmospheric Research (NCAR) announced today the results of a study being published tomorrow in the scientific journal Geophysical Research Letters. The study results, which are also being presented at the annual Fall Meeting of the American Geophysical Union this week in San Francisco, indicate that Arctic sea ice melting is likely to accelerate to the extent that the polar region will be essentially ice-free in summer as early as 2040. The researchers, from NCAR, University of Washington, and McGill University state
We examine the trajectory of Arctic summer sea ice in future climate projections and find that abrupt transitions are a common feature of 21st century model simulations. These events have decreasing trends in September ice extent that are typically 4 times larger than comparable observed trends. One event exhibits a decrease from 6 million km2 to 2 million km2 in 10 years, reaching essentially ice-free September conditions by 2040. In the simulations, ice retreat accelerates as thinning increases the efficiency of open water formation for a given melt rate and the ice-albedo feedback increases shortwave absorption. In one climate model, the retreat is abrupt when ocean heat transport to the Arctic is rapidly increasing. Analysis from multiple climate models and three different future forcing scenarios suggests that reductions in future greenhouse gas emissions moderate the likelihood and severity of these events.

Political Science: End of an Error

Yesterday's WaPo editorial, "Mr. Inhofe's Last Hearing", bids a not-so-fond farewell to the reign of error by the Senator from Oilahoma.'s post last week, "Inhofe’s last stand", however, admits a touch of nostalgia in noting the last performance at the political theater formerly known as the U.S. Senate Committee on Environment & Public Works.

Seasonal Outlook

Latest seasonal forecast: Click here.

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