Weather Quiz

True or False.

Prior to 2016-2017, the last time Washington, D.C. had below average annual precipitation (39.74”) in consecutive years was in 2001-2002.

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Answer to December 9 Weather Quiz question.

D.  The last time measurable December snowfall occurred in Washington, D.C. was on December 10, 2013 (0.9” at National Airport, DCA).

Frigid weather takes hold

A frigid end to 2017  (Germantown, Maryland on December 30)

Much of the central and northern United States has been experiencing record cold and snowfall. Erie, Pennsylvania, shattered records with more than five feet of snow from December 24 – December 27 (65.1”). While the D.C. Metropolitan Area hasn’t had any record snowfall this month, it has already had the snowiest December since 2010 with a monthly total of 1.9” at National Airport. 

Although that’s below December’s average of 2.3” in the nation’s capital, it’s significant because no measurable December snow had occurred in DC since 2013. Some additional light snow occurred in parts of the DMV (DC, Maryland and Virginia) this morning and is the leading edge of an even colder blast of arctic air. Snow accumulations this morning totaled roughly one-half to one inch of snow in the DC-Baltimore corridor earlier today, including 0.2" at National Airport, 0.4" at Dulles Airport and 1.0" at BWI Airport.

 

DC’s temperatures remained below freezing on consecutive December days on December 28-29, for the first time since December 13-14, 2005. The high temperature of 25° at National Airport on December 28 was DC’s coldest December high temperature since December 20, 2004 (24°). Meanwhile, Dulles Airport’s high temperature of 23° on December 28 set a daily record for coldest high temperature. Baltimore tied its record low and record low-high temperatures on December 28 (24°/10°).

While today's high temperature reached 33°, even colder air will arrive across the DMV tonight. High temperatures are poised to remain in the 20s for three consecutive days in the nation’s capital from December 31 through January 2. Some record low-high temperatures could be set at Dulles Airport where weather records date back to 1960. However, no record low temperatures are expected downtown over the next few days where weather records date back to the 1870s.

NOAA predicts below average temperatures to continue through the first half of January. Although Washingtonians experienced three consecutive days with high temperatures in the 20s from January 7 – 9, 2017, high temperatures are only expected to approach 32° once in the upcoming week on Wednesday. The last time DC residents experienced four consecutive January days with high temperatures at or below freezing was from January 22 – 25, 2013. The last time high temperatures remained at or below freezing for more than four consecutive days in the nation's capital was from January 23 - 28, 2004.

Record Lows / Record Low Highs (*=monthly records)

December 31:

Washington, D.C., National Airport (DCA):  -13° (1880)* / 12° (1917)
Dulles International Airport, Sterling, VA (IAD):  1° (1993) / 20° (1962)
Baltimore, MD (BWI Airport): -1° (1880) / 12° (1917)

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January 1:

DCA:  -14° (1881)* / 17° (1918)
IAD: -6° (1968) / 26° (1977)
BWI: -6° (1881) / 17° (1918)

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January 2:

DCA: -1° (1899) / 15° (1918)
IAD: -7° (1968) / 24° (1968)
BWI: 0° (1968) / 13° (1918)

Bone Chilling Cold to Close out 2017 and Welcome 2018

December is DC's Third Snowiest Month on Average

This year is ending with one of the coldest stretches of December weather in recent memory for much of the Eastern United States.  High temperatures may not reach the freezing mark again in parts of the DC Metro Area until the middle of next week.  Fortunately, for those who don’t like snow, no significant snow is currently expected in the Nation’s Capital.

Cold weather will dominate weather headlines over the next week, unlike past instances when extreme cold has been overshadowed by snow or ice storms.  Although there will continue to be prodigious amounts of lake-effect snow in the Great Lakes Region, the DC Metro Area won’t have any.  NOAA expects below average temperatures to continue in the Mid-Atlantic Region and northeastern United States through the first third of January.  Nevertheless, NOAA expects an “equal chance” that January 2018 will finish with near average temperatures in the Mid-Atlantic Region.

This month has been 1.9° warmer than average (39.7°) in Washington, D.C. through December 26.  The last colder than average December in the Nation’s Capital was in 2010 when there were   13 days with high temperatures below 40°.  By comparison, December’s coldest average high temperature in Washington, D.C. is 44° (from December 25 – December 31), according to the National Weather Service.  December 2000 was an even colder month in the Nation’s Capital with an average monthly temperature of 31.8°, which made it DC’s coldest December since 1989.

The coldest day so far this month was December 15 with a high/low temperature of 31°/25° at National Airport.  The last time Washingtonians had consecutive December days with high temperatures at or below freezing was December 13-14, 2005.  Meanwhile, the last time temperatures remained at or below freezing for four or more December days was from December 10 – 13, 1995.  DC’s coldest December day since 2000 was on December 20, 2004 (24°/11°).  None of those temperatures were record lows, however, as Washington, D.C. hasn’t had a record low temperature in December since 1989.  

By comparison, there have been a total of 21 record high temperatures in the month of December over just the last 20 years.  DC’s warmest December on record was in 2015.  That should help indicate how rare extended subfreezing temperatures are in the Nation’s Capital at any point in time – much less in late December and early January.

Big Weather Headlines of 2017

A Cold Finish to 2017 for the Eastern United States

It’s a good time to reflect upon some of the many weather headlines across the United States as 2017 comes to a close.  A variety of extreme and/or destructive weather occurred nationwide this year, ranging from a record-setting hurricane season to floods and fires on the West Coast.

Even though final damage figures aren’t available yet, the 2017 Atlantic hurricane season has already become the costliest on record.  For the first time, three Category 4 hurricanes (Harvey, Irma and Maria) made landfall in the United States or its territories.  In August, Harvey became the first major hurricane (Category 3/+) to make landfall in the United States since Wilma in October 2005.  Meanwhile, Irma and Maria both reached Category 5 intensity, but weakened prior to making landfall.  This year was one of only six seasons to feature two Category 5 hurricanes in the Atlantic Ocean Basin.

2017 began with California’s most significant rainfall in several years, which helped bring an end to a multi-year drought.  However, following years of drought and multiple wildfires, the ground was ill-equipped to absorb much of the rainfall.  That led to widespread flooding and mudslides, especially in the burn areas.  Most of central and southern California saw a significant reduction in area of drought condition between January 3 and March 7.

Central and northern California also experienced devastating wildfires in October that affected parts of Napa Valley.  Some vineyards not only lost their crop in the fields, but winery facilities were damaged or destroyed in some cases.  Many of these fires were caused by lightning or downed power lines and spread rapidly due to gusty winds and dry conditions.  The LA Metro Area had major wildfires in November and December, some of which are ongoing.  Parts of southern California are experiencing moderate drought conditions according to the latest Drought Monitor Index.

There were several severe weather outbreaks during the course of the year.  A total of 112 tornadoes developed in the Southeast from January 20 – 22 that caused 27 fatalities.  Meanwhile, another 94 tornadoes developed from February 28 – March 1 from the central U.S. to the Great Lakes Region and south to the Tennessee Valley; and six lives were lost.  NOAA defines a severe thunderstorm as containing any of the following: wind gusts of 58/+ mph, hail 1”/+ in diameter, or a tornado.  It’s possible for a severe thunderstorm to contain one of more of the said criteria.  Colorado’s costliest hailstorm on record occurred on May 8, when the Denver Metro Area saw widespread hail 2” in diameter that damaged cars, buildings and property.

It doesn’t take violent weather like flooding or severe thunderstorms to cause damage.  There was a damaging frost and freeze event from March 14 – March 16 from Tennessee to north Florida.  That event had huge impacts on agriculture in the affected areas.  Locally, the DC Metro Region is concluding its second consecutive drier than average year with a rainfall deficit of more than 14” dating back to August 1, 2015.

Longing for a White Christmas ?

Washingtonians know that snow on Christmas is a rarity.  That’s despite the fact that the month of December averages 2.3” of snow.  There two ways you can have a white Christmas.  There can be fresh snowfall on Christmas day or there can be the remains of a previous snowfall.

The National Weather Service (NWS) defines a “White Christmas” as having “…at least 1 inch of snow being on the ground on December 25.”  Areas farther north of the DC Metro Area have considerably higher odds of seeing a white Christmas.  The average high and low temperatures in Washington, D.C. on December 25 are 44°/30°.  Since 1884, Washington, D.C. has had measurable snowfall on Christmas day only nine times or roughly every 15 years. 

The last time accumulating snow occurred on December 25 in the Nation’s Capital was in 2002 (0.2”).  However, the last time Washingtonians had snow on the ground on Christmas day was in 2009.  That’s because the Nation’s Capital had its largest December snowfall on record just the week before when 16.4” was measured at National Airport on December 18-19.  Although more than half had melted by Christmas, 7” remained on the ground, creating DC’s last white Christmas.  

The coldest Christmas day in Washington, D.C. occurred in 1983 with high/low temperatures of 14°/3°.  The last time temperatures remained below freezing on Christmas in the Nation’s Capital was in 2000 when the high temperature was only 28°.  By comparison, DC’s warmest Christmas on record was in 1964 (72°).  More recently, DC residents had a high temperature of 69° on December 25, 2015 that tied with 1965 for third warmest Christmas.  Such temperatures are more common in late April and early May.

Precipitation of any kind, including rainfall, is much more common on Christmas day.  DC residents have had measurable precipitation on December 25 a total of 53 times, dating back to 1871.  Washingtonians had appreciable rainfall Christmas 2014 and 2015.  Moderate drought conditions have enveloped parts of the DC Metro Area following a drier than average 2016-2017, so any precipitation at this point would be beneficial.      

Washington, D.C.’s snowiest Christmas Day’s  (Source: NOAA)

1.  5.4”  (1962)
2.  4.5”  (1909)
3.  4.3”  (1969)
4.  1.0”  (1902)
5.  0.6”  (1935)