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Top Weather Events of 2011
for the Baltimore/Washington Forecast Area

Posted: Dec. 28, 2011 and updated Dec. 31

Wrapping up 2011- During the last four days of the year, we are highlighting 12 of the biggest weather events to impact our area in 2011 (in chronological order)! Scroll through the page to find out more about the events that made the list. Some events are linked to other webpages on our site that provide more information about the event.

- January 26th Snow Blitz

Sometimes the wrong things happen at the wrong times. Heavy snow hit Washington and Baltimore right at the beginning of evening rush hour on January 26th. There were many reports of thunder and lightning occurring with the snow. Heavy snow continued through the evening hours with snowfall rates around 2 to 3 inches per hour during the height of the event.

While the final accumulations were not that notable (only 3-8” for much of the metro areas), the timing and ferocity of the snow caused downed trees and power lines, jack-knifed trucks, and traffic gridlock that lasted deep into the night. There were countless reports of commuters needing 5 to 10 hours to get home from work while others abandoned their vehicles. The Washington Post reported almost 400,000 people lost power in the D.C. area that evening.

- February 19th Wind-driven Wildfires

Very strong winds combined with very dry conditions are not a good combination when it comes to fire threat. While we don't often have these conditions like they do in southern California from the Santa Ana winds, when they do happen, the danger is the same. Winds gusting 40 mph, combined with very dry air and a dry ground, allowed brush fires to pop up across the area. One fire manager described it as the worst fire day in our area he had seen in his 40 years in the department. The most notable fires were along I-95 which closed the interstate at times due to smoke.

- March 10 Tornadoes

The severe weather season for the Baltimore/Washington forecast area had an early start with damaging tornadoes during the first weeks of March. Two tornadoes damaged multiple structures near Chantilly, VA. Take a look at the following link for more information:

- April 16-17 Tornadoes and Flooding

A very active month for tornadoes continued on April 16- 17. Four tornadoes were reported in the forecast area (2 in Virginia and 2 in Maryland).

The same storm system was also accompanied by widespread rainfall amounts of 1-3 inches, with locally higher totals over 5 inches along the Blue Ridge. Significant flash flooding near the Blue Ridge included numerous reports of water rescues and roads washed out in Frederick County, Maryland; and several reports of landslides, and bridges overtopped by water in Warren and Clarke Counties in Virginia.

The Monocacy River reached major flood, cresting at 20.6 feet. Moderate flooding occurred on the Shenandoah River and its headwater tributaries. Water overflowed one of these tributaries on the South Fork Shenandoah River, Rockfish Run, sweeping away a family of 3 who were trying to cross the creek at that time. Although 1 member of the family was rescued, 2 of the 3 could not be reached and were casualties of the floodwaters.

- April 27-28 Tornado Outbreak

This tornado outbreak was the worst outbreak the region had seen since the remnants of Hurricane Ivan swept across in 2004, and was by far the most tornadoes ever recorded in the Baltimore-Washington forecast area for a two-day period in April. It took over two weeks to survey areas suspected of sustaining tornado damage. A total of 19 tornadoes touched down in the forecast area, including one EF-2 (winds up to 130 mph) that tracked 33 miles across northwest Virginia between 2-3 AM on the 28th. This tornado was responsible for two minor injuries, which fortunately were the only two reported in the forecast area during the entire event.

During a 20-hour period from the late afternoon on the 27th through midday on the 28th, WFO Baltimore-Washington issued 38 tornado warnings. This ranks second in total number of tornado warnings compared to the 43 tornado warnings issued during the roughly six-hour period on September 17, 2004 as the remnants of Ivan moved through the region.

This event was also the continuation of one of the largest and deadliest tornado outbreaks in our nationís history that devastated Alabama and Mississippi and much of the Deep South.

- July 7-8 Flash Flooding in Baltimore

Heavy downpours from a line of slow-moving showers and thunderstorms lead to numerous incidences of flash flooding across north-central Maryland from Frederick to Baltimore down to Annapolis. Rainfall rates of over 1 inch per hour with rainfall totals around 3 inches were observed in a short period of time. Numerous swift-water rescues were conducted across the greater Baltimore metropolitan area.

You Tube video of flash flooding in Frederick, Maryland on July 8

- July was the Hottest Month on Record

July 2011 was the hottest month ever recorded for Dulles, Washington and Baltimore (official climate records go back to the 1870s for Washington and Baltimore, and 1960s for Dulles). The monthly high temperature averaged in the mid 90s. There was very little relief from the heat, especially at the end of July, when even temperatures at night never fell below the upper 70s to lower 80s. For a record-long four consecutive days at Reagan National Airport, the thermometer never dropped below 80F. The high temperature of 106F at Baltimore-Washington International Airport on the 22nd was tied for the second all-time highest daily temperature on record for Baltimore.

Check out the climate section of the NWS Baltimore/Washington website for more information: Click on the Monthly Weather Summary (CLM) option.

- Near Record Summer Heat (2nd hottest for Washington and Dulles/ 8th for Baltimore)

The summer of 2011 was the 2nd hottest on record for Washington and Dulles, and the 8th hottest for Baltimore (summer is defined as the three month period from June-August). There were 50 days in Washington that were 90F or above (normal is 31), 42 at Dulles (normal is 30), 46 in Charlottesville (normal is 22), and 40 in Baltimore (normal is 25). The summer 2011 follows on the heels of the record breaking summer of 2010, which was the hottest ever recorded at Dulles, Baltimore and Washington.

Check out the climate section of the NWS Baltimore/Washington website for more information:

- August 27-28 Wind/Heavy Rain from Hurricane Irene

Hurricane Irene affected much of the United States East Coast during late August. While the hurricane force winds from Irene stayed to our south and east, much of our region was impacted. This is especially true of southern Maryland, where tropical storm force winds and 8-12 inches of rain pounded the area. Numerous roads were closed due to flooding from the heavy rainfall, primarily east of Interstate 95. In addition, the river gauge on St. Clement Creek near Clements, Maryland in St. Marys County set a new record level of 6.98 feet. Records at this location date back to 1968.

Fortunately, since the storm stayed east of the Bay, there was much less tidal surge than Isabel in 2003, and impacts from the surge were limited along the western shore of the Bay.

- September 5-9 Flash Flooding from the Remnants of Tropical Storm Lee

As Tropical Storm Lee weakened to a remnant low pressure system, it meandered into the Midwest states where it remained for several days. That slow-moving circulation to our west drew copious amounts of tropical moisture into the mid-Atlantic region for much of the week of September 4th. Bands of heavy rain developed and moved north across the area beginning on September 6th and continued through September 9th. During this period, rainfall totals were excessive, especially in northern Virginia, lower southern Maryland and north-central Maryland, where 10-20 inches of rain fell in just those few days. Many roads and bridges were washed out or damaged, and homes were flooded.

- October 28-29 Early Season Snowfall

Snow fell north and west of Baltimore and Washington into the mountains two days before Halloween this year, the earliest for many since 1979. In a highly elevation dependent storm, over a foot of snow accumulated at higher elevations in the Potomac Highlands, while l
ess than a measurable amount fell at BWI and DCA. Both the northern and western Washington/Baltimore suburbs saw an inch or two (Dulles Airport had almost an inch). But areas further out like Westminster and Winchester saw 3-5”. This snow set a daily record at DCA, BWI and IAD.

The unique combination of heavy wet snow and foliage still on the trees resulted in numerous downed trees and widespread power outages across the higher elevations of the forecast area.

- December 6-7 Heavy Rain

A low pressure system from the Gulf of Mexico tracked to the northeast producing heavy rain along the I-95 corridor. Numerous roads were flooded when a swath of two to four inches of rain fell from near Charlottesville northeast across the Baltimore metro area. Over 3 inches of rain fell at Reagan National (DCA) on December 7th, which was the wettest day on record at DCA for the month of December, in winter and for any day from November through March. The daily rainfall on the 7th also surpassed the (1981-2010) normal monthly rainfall for December. Also, daily precipitation records were set at Dulles (IAD) and Baltimore-Washington International (BWI) for the 7th.

National Weather Service
Weather Forecast Office Baltimore/Washington
43858 Weather Service Rd.
Sterling, VA 20166
Phone: (703) 996-2200
Page last modified: Dec 31, 2011 4:51 PM EST
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