From the ABC 7 Weather team

Washington D.C. area snow Tuesday

January 21, 2014 - 07:10 PM
Text size Decrease Increase

Be sure to check here throughout the day for everything related to the snow. We'll be posting about it until it ends.

LIVE DOPPLER  |  SCHOOL CLOSINGS  |  HD CAMERAS

STORMWATCH 7 FACEBOOK  |  WEATHER APP  WARNINGS

10:06PM: Here's a sampling of the snowfall totals in the D.C. area so far.

8:26PM: Here are some of the latest snowfall totals from the National Weather Service office.

3 miles NW Frederick, MD: 10.0"

2 miles SE Westminster, MD: 10.3"

North Beach, MD: 5"

2 miles N Columbia, MD: 7.2"

1 mile ENE Gaithersburg, MD: 8.3"

Damascus, MD: 8"

Laurel, MD: 5.3"

Baileys Crossroads, VA: 5.2"

Alexandria, VA: 4"

Winchester, VA: 8"

Berryville, VA: 7.7"

Centreville, VA: 6"

Herndon, VA: 5"

Dulles International Airport: 7.1"

Ashburn, VA: 6.8"

Leesburg, VA: 7"

Linden, VA: 7"

Martinsburg, WV: 8.7"

7:39PM: Snow will continue to taper off through the next hour or two in the city and by 11pm closer to the Bay. Feel free to track Doppler Radar to watch the last few bands move through your neighborhood!

It's been a fun day watching the snow, but I don't think anyone is looking forward to the extreme cold tomorrow morning with lows in the single digits in much of the area. Chills will be below zero throughout the region and high temperatures Wednesday are only expected to reach the teens.

7:23PM: Here's a nice loop of this last moderate to heavy snow band moving through the region right now. Enjoy this final snow before it ends later tonight!

7:12PM: Some warnings have been cancelled by the NWS as this final snow band pushes east of the Blue Ridge.

Winter Storm Warnings cancelled west

7:04PM:

6:15PM: A moderate band of snow will continue to push to the east over Montgomery, Loudoun, Fairfax into the District and eventually eastward over the next hour. This will allow for additional snowfall accumulations before the end of the event.

Snow should begin to end in the western suburbs around 8pm and closer to 10pm around the Metro.

6:14PM: Here are some of the latest snowfall reports from the National Weather Service. Some areas in Frederick County, MD are reporting over 9 inches!

5:44PM:

5:37PM:

5:33PM:

5:28PM: Here's a good find from Adam Caskey on the effectiveness of road salt from the Wisconsin Department of Transportation.

"Q. What are the limitations of road salt?
The minimum practical application range for salt is a pavement temperature of 15-20°F and above. While salt will melt snow and ice down to a pavement temperature of -6°F, it can melt over five times as much ice at 30°F as at 20°F. Thus the effectiveness of salt is sensitive to small differences in pavement temperature. Counties will attempt to apply only the amount required for temperature, time and use. Too little and the roadway will refreeze, too much is a waste of money and resources.

When the pavement temperature drops below 15°F the effectiveness of salt is decreased significantly. At these lower temperatures, the county highway departments will typically cease straight salt applications and begin adding other chemicals to the salt such as calcium chloride or magnesium chloride that will lower the freezing point even further.

Wind conditions must also be considered when deciding on whether to apply salt or other de-icing agents. As the temperatures drop and the snow becomes dryer, the wind can begin to blow the snow across the pavement. If there is a chemical residue left on the pavement from a previous salt application, blowing snow can be attracted to the residue and stick to the pavement creating hazardous conditions that would not have existed if no de-icing agents were previously applied. This is why counties are sometimes reluctant to apply salt or chemicals when the pavement temperatures are below 15°F. The effectiveness of salt can also be affected by the type of pavement. For example, salt works better on new asphaltic (blacktop) pavements than on tined concrete pavements.

 

 

The salt being used today typically includes other ice melting de-icing agents to increase its effectiveness at lower temperatures and to help it better adhere to the pavement. Adding other de-icing agents to the salt also reduces the number of applications needed. WisDOT is always looking for new ways to reduce the amount of chlorides needed to return the roadways to safe winter driving conditions. Sometimes counties use sand and other abrasives at lower temperatures to improve friction on the roadway. Abrasives have no ice melting properties and thus their use is limited."

5:10PM: Latest snow fall total map across the region

 

ZZZZZ

 

4:15PM: Bethesda, MD at 9AM (left) vs 3PM (right)....Thank you Suzanne Matwyshen-Gillen!

 

ZZZZZ

 

4:00PM: Winter Storm Warnings still posted across the region (until 11PM) and the Wind Chill Advisory kicks in at 6PM

 

ZZZZZ

 

 

3:45: This is what to expect as we continue with the snow 

ZZZZZ

2:42pm: Here are some of the latest snowfall reports across the region with much lower snowfall totals being realized south and west of D.C. Up to 5 inches of snow has been seen in Frederick Counties in MD and VA, Loudoun has seen 4 inches

At this time, snowfall amounts look to be less than the original forecast in the D.C. Metro and points south. Areas north and west still look like they will see 6-10 inches of snow. The Metro itself has a better possibility of 3 to 5 inches of snow and areas south up to 3 inches.

1:15pm: Here's a great comparison of the roads changing in just 15 minutes in D.C. Snow is really beginning to stick on the roads in the D.C. Metro and points northwest.

1:11pm: Snow in Frederick, MD from twitter.

12:49pm: Snowfall totals so far from the National Weather Service Baltimore/Washington Office.

Westminster, MD (Carroll County): 4.8"

Walkersville, MD (Frederick County): 4.5"

Germantown, MD: 2"

Berryville, VA (Clarke County): 3.3"

Stephens City, VA (Frederick County): 2.9"

Purcellville, VA: 2.8"

Herndon, VA: 1.1"

12:35pm:

11:43am: Area roads are starting to become covered. Please tweet me or let us know on facebook how your roads are faring!

11:40am: Not a good day to be flying. Many delays and cancellations across the northeast today.

11:25am: A Mesoscale Discussion has been placed over parts of the D.C. area including the Metro for heavy snowfall potential. Snowfall rates up to 1-2" per hour will be possible through the afternoon.

Mesoscale Discussion area for Heavy Snow

11:05am:

10:57am: Winds tonight will be around 10 to 20 mph with gusts to 35 mph at times. This will make it feel like it is below zero at times. Wind Chill Advisories are posted for the majority of the area with chills from 5 to 15 below zero and even lower in the western surburbs.


10:42am: Temperatures are expected to fall into the single digits tonight with lows near zero in the western suburbs. Here is a look at the forecast temperatures from the 4km NAM courtesy of WeatherBell.com.

4km NAM Forecast low temperatures Wednesday morning (WeatherBELL Models)

10:22am: 2" of snow is being reported so far in Frederick County, VA from the NWS Baltimore/Washington office.

10:13am: Snow is causing slick roads already west of D.C. This picture of a crash was taken near Purcellville, VA by our very own reporter Richard Reeve.


9:56am: The Flightaware Misery Map is showing big time delays and cancellations in Chicago, New York City and Washington D.C. from the weather. Definitely check or call before heading to the airport today!

9:48am: Nice snowfall so far in Winchester, VA.

Winchester Snow from Lauren Torbett

9:34am: Snow coming down in Cumberland, MD. Already covering the roads!

9:21am:

9:18am: This is our latest forecast for snowfall today. A heavier band of 6-10" appears possible north and west of D.C. with slightly lower amounts for D.C. and points south and east. You can already see a heavier band setting up northwest of the city and we think those will be the hardest areas hit by this system.


9:12am: Here's a look at the snow so far in Ijamsville, MD on our HD WeatherBug camera.

Ijamsville High School in Frederick, MD

9:00am: Snow is beginning to move into the region this morning with the heaviest pushing into Loudoun and Frederick Counties right now. Be sure to check out the HD cameras above as snow is entering the region. The ground is already white in Berryville, VA and Frederick, MD.

comments powered by Disqus