From the ABC 7 Weather team

Correction:

D.C. area snow: Timing, location and forecast totals (Live Blog)

January 17, 2013 - 08:00 AM
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11:09pm:  Last post of the night.  No snow this time in D.C., but winter's not over yet.  As always, we'll we back with more live blogs when weather warrents. Goodnight.

10:25pm:  Calvert county has dropped the advisory.  It looks like all the action will stay well South of our viewing area.  In fact, the Eastern shore of Maryland seeing more snow than us here in D.C. 

9:08pm: The only winter weather advisories that remain in effect for the ABC7 viewing area are St. Mary's and Calvert counties in MD.  Even in the advisory area, I do not expect much snow. 

9:02pm:  Sharp cutoff of precipitation extending from the northern Eastern Shore, through southern Maryland, and into central Virginia.  If you're not in an area with precipitation now, don't expect any for the rest of the night.  Moisture moving along the same track, as it moves East over the next few hours.

8:38pm:  Not surprising, the National Weather Service drops the Winter Weather Advisory for Southern Fauquier, Culpeper, Greene, Madison, and Rockingham counties.  The advisory remains in effect over Southern Maryland until 1am.

7:52pm:  Not much new information.  Snow continues over Central Virginia, but still very dry over the D.C. metro.  Spots like Culpeper, Fredericksburg, and southern parts of Charles and St. Mary's counties may see a rain/sleet/snow mix.

6:22pm:  Live Doppler has looked pretty simliar over the past hour.  The only big change noted is the increase in snow intensity South of Fredericksburg.  A few reports of sleet mixing in with some of the precipitation falling over Southern Maryland and the Eastern shore, but see how the D.C. metro remains precipitation-free.

5:55pm:  Still very dry in D.C.  Feeling less confident we'll see much of any precipitation in the D.C. metro.  Temperatures are in the upper 30s to low 40s, but dewpoints are in the upper 20s to low 30s in the metro region.  Basically, drier air equals no precipitation.

5:03pm: Here is a look at the latest MSLP and radar plot from the Storm Prediction Center. The dual surface lows are over South Carolina now with the heaviest snows located in southwest Virginia. One snow report was close to 8 inches in Wise, VA. The low will continue to track into North Carolina through the remainder on the day before exiting off the east coast overnight. Winds will become breezy in the early morning hours before you wake up with much cooler air entering by dawn. Lows should be in the 20s with winds around 10-20 mph leaving chills in the teens.

4:01pm: Surface temperatures are beginning to fall through the region particularly where there is precipitation with 38 degrees now in Fredericksburg, 38 in Stafford and 36 in Orange. A changeover to snow has now occurred in Charlottesville and we believe the same will happen east in the next hour or so. There have also been reports of some rogue snow showers, flurries and some sleet through Northern Virginia.

3:43pm: We've had reports of snow and sleet now in our area as close as Spotsylvania, Charles County and now even as close to the D.C. Metro as Manassas, VA. Keep your reports coming in to our facebook page! Thank you!

3:23pm: You know where else is getting snow? Alabama. How do they get the National Championship and thundersnow within a few weeks time? The doesn't seem very fair. Snow is exiting the Birmingham and Huntsville areas over the next few hours.

3:12pm: Snow!!! At Wintergreen Resort in the mountains southwest of Charlottesville, VA. The rest of our HD cams are a little bare...

2:47pm: Here is a new timeline for this evening through Noon tomorrow. Rain and snow will remain south and end by bedtime tonight. Oddly enough, the worst part of this forecast will be the wind chills tomorrow morning with temperatures in the upper 20s and winds around 10 to 20 mph out of the northwest. Chills will easily be in the teens at times, bundle up! In areas that do see precipitation tonight, watch for some slick spots tomorrow morning.

2:35pm: More advisories and warnings have been dropped by the National Weather Service. The D.C. Metro is currently not under any watches, advisories or warnings. All Winter Storm Warnings have been dropped from the D.C. Metro. Winter Weather Advisories remain until 11pm for Southern Maryland and points west through VA below in purple.

Latest Winter Weather Advisories and Winter Storm Warnings

1:35pm: On the heels of what the Storm Prediction Center is forecasting (see previous post below), this model depicts a very nice graphic of where you will find the heaviest snow totals. Lucky for those snow lovers in the Southwest Virginia where some areas could recieve up to 10" of snow before this is all said and done!

12:54pm: The Storm Prediction Center has actually put of a mesoscale discussion for heavy snow with rates of 1 to 2 inches per hour in parts of the southern Appalachians and Blue Ridge. This is where the heaviest snow will be for this event.

SPC's latest mesoscale discussion for heavy snow

12:07pm: D.C. snow lovers must be living wrong.  Winter storm warnings stretch from Mississippi to southern Virginia. Flurries to a dusting looking more likely in and around the immediate D.C. Metro. - Bob

ZZZZZ

11:53am: What a cool site this is from DC.gov. You can track snow plows over the past few hours in your location. Great idea!

11:37am: Montgomery and Howard Counties in MD and Loudoun County in VA have been dropped for the Winter Weather Advisory. Here is the new map. The Advisory timing has also been changed once again by the NWS, now from 3pm-11pm.

Winter Weather Advisory from 3pm to 11pm, Warnings still in effect south of D.C.

11:27am: Adam Caskey just had a report of sleet in Fredericksburg, VA come in to his facebook page. Does anyone report the same? Relay to us on our Stormwatch 7 facebook page if you can!

11:20am: Here is a look at the latest Mid Atlantic Radar image showing some regions getting some changeover to the southwest over KY, southwest VA and WV. This will be the area that we will be watching closely as it's on the northern side of the low and will be the region that should scrape the D.C. area this afternoon and evening.

Mid Atlantic Radar as of 11:00am

10:35am: Here is the atmospheric sounding from this morning at Dulles Airport.

Dulles Airport Sounding this morning

There are a couple of interesting things to note on this sounding with some very dry air close to but just above the surface. I have highlighted the freezing line with the red line as the temperature which you can see from 1000mb to 300mb and the green line is the dewpoint temperature which is an idea of how much moisture is in the air.

Closer to the surface (900mb to 800mb) there is a dry layer on the sounding which indicates that even though the surface temperatures are in the low to mid 40s, some major cooling will occur when precipitation actually moves into the region later today. Northwesterly surface winds behind a weak front have also dropped the surface dewpoints since then, so we will take that into account as well. It's only 10:45am right now, and precipitation still really isn't anticipated closer to the D.C. Metro until the afternoon hours, so there's still time but it will still be close.

10:14am: St. Mary's County Schools will be closing 2 hours early today as well. Find the latest information on school closings here and throughout the day in the link at the top of this blog.

10:05am: All Charles County public schools are closing two-hours early today. Afternoon and evening activities are canceled due to inclement weather. Stay tuned to ABC7 News at Noon for any additional closings.

9:31am: I wanted to show some graphics that gives an idea of how close the D.C. area is to actually getting in on some heavy, wet snow. This isn't in the cards today, but it was and will be really close! Here is a look at the 500mb vorticity plot for this evening.

GFS 500mb 0Z Friday forecast vorticity plot

This shows the big "ball" of energy sliding into the Carolinas just to the south of the D.C. area. Even with D.C. not in the crosshairs, very heavy rainfall is still likely as this energy moves through N.C., which I will show you in the next few images. Below is a look at the forecast 6-hr precipitation for the same time period.

GFS 6-hr precipitation and SLP 0Z Friday forecast

The red and pink areas is where there could be up to 1 inch of rain in a 6 hour period of time ending this evening. If you look towards the top of the ellipse I drew over the model depiction, you can see that distinct cut-off which moves right through the D.C. area. Where the greens are located from Fairfax Co. and south as well as Southern Maryland and south is where precipitation is modeled to have fallen by this evening, and therefore by this model will have the greatest likelihood of seeing rain or snow. Now I wanted you to see the HPC Precipitation forecast for today.

Thursday's HPC Precipitation Forecast

 

This shows how close the D.C. area is to receiving some heavier precipitation. 2.7 inches of rain is forecast to fall in Western North Carolina with a quarter of an inch of precipitation likely in and around Fredericksburg, VA and south. The D.C. area is only along the line of a tenth of an inch of precipitation to a quarter of an inch. This is another strong case for lesser snow totals in the D.C. area today but more south. You can see how close D.C. was though!

9:19am: As far as the timing of the system, the best chance the D.C. Metro will have for snow will be this afternoon through this evening. The Weather Service continues to trim back on the Winter Weather Advisory (which is a good thing) with the timing of the Advisory now from 2pm to 11pm tonight. Accumulations will still be on par with our current forecast snow maps highlighted above.

9:07am: The main snow shield is currently moving through Mississippi and Alabama. As far as snowfall totals in MS, it looks like areas have only seen 1 to 3 inches. This area of snow is west of the low and will not be the snow that affects our region.

8:41am: The map below acutally may need to be tweaked as where it says flurries, there may actually not be any snow at all. There should be a very fine cut-off with this system the farther north you live. Much drier air is located northwest of D.C. with dewpoints in the 20s (as opposed to the 40s just south) as a cold front pushes into the area.

8:33am: Below is the going forecast from our team which shows just a touch of snow for the D.C. Metro later today into this evening and more snow the farther south you live or travel. For those of you "snow chasers" out there, if you'd like to see some snow, the best place to go will be southwest of D.C. south of Charlottesville, VA.

Current ABC 7 snow forecast

7:57am: From ABC 7 Chief Meteorologist Doug Hill's latest forecast update on the weather homepage, "The last time Washington received an inch or more of snow was in January, 2011. And last winter, only 2 inches fell for the entire season. Today we will be on the northern fringes of a developing snow storm. The storm center will stay well south of our area and snowfall in the metropolitan area will be around one inch...2 or 3 inches will be possible across parts of Southern MD and Stafford and Spotsylvania Counties in VA. Much more significant accumulations will fall farther south and southwest in the Old Dominion. Skies will clear overnight. Icy spots are likely then and for the Friday morning commute." 

7:43am: A Winter Weather Advisory is in effect for the D.C. Metro and a Winter Storm Warning is in effect for the southern portions of the viewing area from 10am this morning through 1am Friday. Here is a look at the warning map put out by the National Weather Service.

Current Warnings and Advisories

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