DC Decemberology

Now

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.

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

Mediarology

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."

Deficit Reduction

Now

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.

Mediarology

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 Capitalweather.com readers is the fact that our own Andrew Freedman was one of the contributors to the writeups of the list members.

DC December Dryness Continues

Now

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.

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

December Rollercoaster

Now

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.

CapitalWeather.com 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. RealClimate.org'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.

Frigid Friday: A Callendar Effect

Now

Sunny, breezy, cold. After last evening's scattered first flurries of the season, temperatures have struggled to get beyond the mid 30s throughout the National Capital region this afternoon under mostly clear skies and brisk northwesterly breezes. Highs were unofficially 35° at National and 33° at Dulles.

Tonight and Tomorrow

Cold, then moderating. Under clear skies and light winds, tonight's lows will be near 20° downtown, ranging as low as the low teens in the 'burbs. Temperatures will rebound to much more seasonable levels tomorrow. Highs will be in the mid 40s with mainly clear skies.

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

Tropical Topics

The Atlantic hurricane season officially ended last week, so it must be time for the 24th annual extended hurricane season outlook for 2007 issued today from land-locked Colorado State. The forecast calls for above-average storm activity, with a total of 14 named storms, including 7 hurricanes, 3 of those severe. The long-term average numbers are 9.6, 5.9, and 2.3, respectively.

Climate Calendar

This Monday, the 11th, from 3-5pm, the Woodrow Wilson International Center is presenting a seminar entitled, "Climate Change: Historical Perspectives and the Current Debate". The speaker, James Fleming, is Professor of Science, Technology, and Society at Colby College. He is the author of "The Callendar Effect", which has just been published by the American Meteorological Society. The book is

the untold story of the remarkable scientist who established the carbon dioxide theory of climate change. Guy Stewart Callendar discovered that global warming could be brought about by increases in the concentration of atmospheric carbon dioxide due to human activities, primarily through burning fossil fuels. He did this in 1938!

The event is also scheduled to be webcast live. The Wilson Center is located adjacent to Federal Triangle Metro.

Transition Thursday; The "S" Word?

Now

Sunny, breezy, turning colder. After temperatures reached an unexpectedly high 56° around noon, the first phase of a double-barreled cold front passed through the metro area, lowering readings mainly into the 40s by early afternoon. At 4pm, Leesburg and Winchester were even into the upper 30s.

By mid afternoon, scattered snow flurries on radar were moving eastward, but only as far as I-81. To mix a metaphor, the other shoe drops tonight, when the Arctic air west of the mountains will come into the region on strong northerly winds. The "S" word of the day is "slight", as in chances of a light flurry east of the Blue Ridge.

Surface weather map at 1pm today from HPC/NCEP/NWS

Tonight and Tomorrow

Much colder. Tonight will be windy and cold under clearing skies; lows will be in the low to mid 20s. There is a slight chance of a passing snow flurry through this evening. Tomorrow will be sunny and brisk, windy with highs only near 36°.

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

El Niño Update

The NOAA/NCEP/Climate Prediction Center (CPC) today published the monthly El Niño Diagnostic Discussion. As shown in the chart, sea surface temperature anomalies have continued to increase in the tropical Pacific. In the month ending last week, the maximum departures from the long-term average were over 2°C (red area) near the International Date Line.

The outlook calls for the El Niño conditions to continue to increase through the winter months, followed by weakening from March to May next year. CPC's Dr. Vernon Kousky said that "typical El Niño effects over the U.S. during January through March 2007" can be expected. These effects are reflected in the NOAA winter outlook, which calls for near to above normal temperatures and near normal precipitation in the Mid Atlantic region, with the polar jet stream remaining primarily in Canada.

The CPC analysis is consistent with the latest report from the UN's World Meteorological Organization (WMO). The WMO notes that El Niño impacts are already significant in the western Pacific, with severe drought occurring in Indonesia and Australia, where the worst conditions in a century are impacting economic growth. Eastern equatorial Africa is also being affected, but by flooding from heavy rains.

Brief Cold Shot on the Way

Now

Sunny, seasonable. Southerly breezes gusting over 20 mph at times have lifted temperatures back to seasonable levels in the Washington metro area this afternoon under sunny skies. Highs were 51° at both National and Dulles as well as at BWI. A new cold shot arriving late tomorrow will be sharp but short in duration as milder air returns by the weekend.

Tonight and Tomorrow

Mostly clear, not as cold. Lows tonight under mostly clear skies will be in the mid 30s in town to near 30 in the cooler 'burbs. Tomorrow will be partly cloudy with highs in the upper 40s but turning windy and colder by late in the afternoon. There is a slight chance of isolated snow flurries.

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

Tropical Topics

As indicated here yesterday, Bill Proenza was announced today as the new Director of the National Hurricane Center. Proenza was appointed Director of the National Weather Service Southern Region in 1999. He was selected as a Fellow of the American Meteorological Society in 2003.

Photo of Bill Proenza from NOAA

A report today by the Government Accountability Office says that FEMA has misspent at least $1 billion of Hurricane Katrina aid on fraud and abuse. The amount includes $20 million paid to thousands of people who filed claims for the same damage from both Katrina and Rita.