Strong Aftershock Rocks Central Virginia

A magnitude 3.2 aftershock occurred at 6:39 PM this evening 5 miles south of Louisa and was felt across much of central Virginia. This aftershock was one of the strongest since the original quake back in August. I've been getting a lot of questions on my facebook page about these aftershocks, and specifically when we can call them a new earthquake. Technically, all of these aftershocks are earthquakes, but we call them aftershocks because they are smaller earthquakes associated with the larger seismic event (the 5.8 magnitude quake). If an aftershock is stronger than the original earthquake, it will be deemed the main quake, and all subsequent seismic activity will be referred to as foreshocks. Here's hoping tonight's was the last of them, but I doubt it. -Zach

Be Careful What You Wish For

I'm a big fan of severe and unusual weather, and find myself always looking forward to the next big storm. I'll never wish for anything that would cause loss of life or widespread property damage, but a good thunderstorm or winter weather event challenges and fascinates the scientist in me. I just returned to Virginia two nights ago from spending a week visiting my in-laws, and on the flight out of Richmond last Saturday, I got what I wished for. Flying with three children ages four and under is no picnic even with no delays, and my wife and I now have a new level of airline stress by which to measure future flights. We were able to get everyone on the plane and in their seats with relative ease, and aside from the constant raising and lowering of tray tables and pushing the flight attendant call button, the kids were behaving pretty well. After waiting on the tarmac for about 15 minutes, the pilot made an announcement that the freezing rain we had been having in Richmond required deicing the aircraft, and we'd have to wait about 30 more minutes for the process to be completed. We finally taxied and took off after the delay on the ground and made our way to Oklahoma City, with a stop in Atlanta. The flight from Richmond to Atlanta is a short one, usually about an hour in the air, but after an hour had passed we were still cruising along at altitude. The pilot then made another announcement confirming my suspicion that something wasn't right, informing us that the Atlanta airport had just shut down due to severe thunderstorms, and we'd be circling until further notice. We circled for about an hour before landing, and were treated to turbulence that rivals even the best Busch Gardens has to offer. Once on the ground, the fun continued with another two hours of delays as severe storms which prompted tornado warnings continued to hammer the airport. (Keep in mind, this is January.) My son was overly tired from missing his nap and somehow ended up running shirtless down the middle of concourse C in the worlds busiest airport. We finally boarded our connecting flight to Oklahoma City and arrived a mere three and a half hours later than scheduled, being treated to a fine dose of winter and spring weather. The second flight was thankfully pretty smooth, and aside from taking a bath in a large cup of iced apple juice that my daughter dumped in my lap, I couldn't complain. So the next time I wish for a little crazy weather, I'll remember this day, and will be very careful of exactly what I'm wishing for. It's good to be back home in Virginia. Have a great week! -Zach

Rain and thunderstorms are likely early Friday

A broad low pressure storm system that has a history of producing severe weather and heavy rainfall from Texas into the Southeast U.S. will reach Virginia in the pre-dawn hours of Friday. Here's a view of the upper level vorticity reaching the Appalachian spine by Friday sunrise:

Thursday, southerly flow into the Mid-Atlantic ahead of the system tracking into the Ohio River Valley is transporting richer low-level moisture. This means that there will be greater instability present overnight into Friday morning once the upper-level lift arrives in addition to the approaching surface cold front. In purple, you'll see some relatively "weak" CAPE (an indicator of instability for thunderstorm development) reaching into central Virginia:

Therefore, a Slight Risk for severe thunderstorms will exist for the areas in yellow on this map, including extreme south-central Virginia:

Even if most of the Commonwealth technically does not have storms that reach severe limits, the rain and storms moving through pre-dawn Friday morning from west to east will likely contain gusty winds and heavy downpours. As of right now, the timing of that line's arrival in western Virginia is around 2-3 a.m. Friday, and affecting the I-95 region by 5-7 a.m. Rain should end in Richmond after 9 a.m., with rapidly clearing skies behind the surface cold front's passage late Friday morning. All of the Commonwealth will be dry by mid-afternoon Friday behind the cold front.

I'll be in early Friday morning monitoring the line of rain and storms as they track into central Virginia. If you're on Facebook, be sure to "Like" my page for updates there. You can also follow me on Twitter @SouthernRedRose.

Stay with CBS 6, we'll keep you ahead of the storm.
--Meteorologist Carrie Rose

Fog developing in parts of Virginia this Tuesday morning

Behind a cold front that is moving through central Virginia early this Tuesday morning, skies are clearing with light winds. Considering the recent dreary, damp days, there's plenty of moisture at the ground to support the development of fog where skies are clearing. As a result, visibilities are dropping to a quarter-of-a-mile in some parts of central Virginia. There is a Fog Advisory until 9 AM for the areas highlighted in grey on this map:

But other locations outside of the Advisory are also getting some light fog, including Jarratt. Here's a picture submitted this morning on Facebook by one of our CBS 6 viewers Debbie Lynn Allen of the fog in Jarratt, VA:

If you have fog pictures to share with us this morning, you can post them at my Facebook page by clicking here for the Wall. You can also tweet your pictures to me @SouthernRedRose.

Stay with CBS 6, we'll keep you ahead of the storm.

Update on Freezing Rain Potential

Evening data continues to suggest the threat for some freezing rain late Friday evening into early Saturday morning. The push of low-level cold air could be far enough south to include all of the metro area in a risk to see some light icing. The primary time period to see freezing will be between 9 PM and 3 AM, with freezing drizzle possible for a few hours longer, especially north of Richmond. I've updated the risk graphic to indicate where I think we'll see the best chance of ice. -Zach

Freezing Rain Possible Saturday Morning

It appears as though the least welcomed type of winter weather could make an appearance in the state this weekend. A fairly strong (1028 mb) area of high pressure will build into New England Friday into Saturday, with the wind flow around this high moving in a clockwise direction. This air mass will be cold and dry, with the coldest air hugging close to the surface because of its relatively high density. The air will move freely southeast, south, and southwest, but will not be able to move west over the Appalachians. Instead of flowing up and over the mountains, the cold air will funnel down the east side of the mountain chain. This process is called "cold air damming", or "the wedge effect", and allows the shallow cold air associated with strong high pressure to spill as far south as Georgia along the east side of the Appalachians. Because the sub-freezing air will be so shallow, rain will fall in liquid form, but will freeze on contact to all objects at the surface. While the rain should be light during the time of sub-freezing surface temperatures, even a minor accretion of ice will cause problems. The graphic I created indicates where I think icing will be possible, and highlights where I think the greatest risk will exist. I'll continue to monitor the latest model data, and will have another update here tomorrow. -Zach

Second coldest morning of Winter

The coldest morning so far this Winter season is still January 4th, when Richmond International Airport reported a low temperature of 17 degrees. But this morning was almost as cold as that, with lows area-wide in the upper teens and low 20s:

Richmond's low of 19 degrees is our second coldest this Winter, and only our second morning this season of falling into the teens.

Here are Richmond's other cold Winter mornings thus far this season:
Jan 15, 2012: 23 degrees
Jan 2, 2012: 23 degrees
Dec 29, 2011: 25 degrees

--Meteorologist Carrie Rose

Gaining Daylight

Update on Snow Chances for the Weekend

So this is what we've been reduced to. The winter of 2011-2012 has been so miserably unfulfilling to snow lovers, that the mere mention of the possibility of seeing a few flakes gets us all giddy. Yes, I said "us". I'm a big fan of Virginia's varied weather with four solid seasons, and a trace of snow just doesn't cut it for me. Perhaps I'm spoiled from the past two winters, but whether you like the cold weather or not, it's just not winter without one good snow. I saw this type of winter coming with a La Nina in full swing ala 2006, but banked on one decent storm this season when I made my winter weather forecast. And I'm still banking on one, it just won't be this weekend. The type of system that will affect the area this weekend is a clipper. It moves quickly, is moisture starved, and rarely produces much of an accumulation around here. Computer models tend to under forecast precipitation in this type of scenario, so I'm putting more weight in the pattern than in what the model actually shows for precip. Even so, much of what develops and falls will evaporate in the very dry air that will be in place. I'm still looking forward to seeing even the lightest of what Mother Nature throws our way. I'll have another update tomorrow. -Zach

Slick spots devloping in western Virginia this morning

As rain expands northeast into the higher terrain of western Virginia this morning, some slick spots are developing while temperatures are below freezing. This Winter Weather Advisory lasts until 10 AM for the purple highlighted areas on the map:

Once temperatures rise above freezing late morning, the hazardous traveling conditions will dwindle. However, heavy rain will overspread all of the Commonwealth mid-day through this evening, making driving hazardous as heavy rain reduces visibilities and creates a hydroplaning risk.
Stay with CBS 6, we'll keep you ahead of the storm.

Tracking the Potential for Snow this Weekend

The pattern for the upcoming weekend continues to look interesting, and several models are now agreeing on bringing some light snow into the area Sunday morning. The nor'easter the GFS was trying to blow up over the area on Monday is gone in the medium range solution, but both the GFS and ECMWF (Euro) are showing a shortwave clipper swinging through the region after very cold air has settled into the state. The GFS has actual precipitation (snow) depicted, while the Euro is dry with generally the same upper-level pattern. Based on the PVA that should be present ahead of the clipper that the Euro is showing, snow would likely be generated in the same manner as the GFS solution. The NAM only goes to 84 hours from the current time, so we can't see what it says for Sunday, but what it does show is in agreement with a short wave affecting the region by Sunday. The amount of snow should be on the light side, but the surface temps will be plenty cold enough for whatever falls to stick. This scenario is still about 4.5 days out, so things will change, but it's the only decent chance I see for us in the next week. I'll have another update tomorrow. -Zach

Dense Fog Tuesday Morning

After Monday's rain, winter mix, and snow (in northern and western Virginia), low-level moisture at the ground remains high causing fog to develop in most of the Commonwealth. The fog is particularly dense in the western third of the state, where some locations there are under a Dense Fog Advisory until mid-morning for significantly reduced visibilities to a quarter of a mile or less.


Visibilities are reduced elsewhere in central Virginia outside of the Advisory, though, so please use caution on your commute this morning. The fog can be at its densest in low-lying spots, along waterways, and in agricultural areas. Use your fog lights or low-beam settings while driving this morning, even after sunrise.

I mentioned the snow from yesterday in parts of Virginia. Here's a beautiful shot of the snow falling Monday in King George, VA by Breanna Marini:

This photo was posted on my Facebook page by Breanna. You can share your snow pictures, at my page by clicking here, too.

--Meteorologist Carrie Rose
Carrie's Facebook Page
Carrie's Twitter

Help Provide Warmth For a Deserving Family

We've only had small doses of frigid temperatures this winter, and only a trace of snow to date, but there have been plenty of cold nights and it's likely wintry weather will make an appearance over the next two months. Most of us are blessed with the means to heat our homes during the winter, but there are families that could really use some help this winter. Woodfin, CBS 6, and the Better Housing Coalition are teaming up to provide a new furnace to a deserving family in need. Go to www.wtvr.com/warmerwinter and fill out the form to nominate a deserving family. Thanks in advance! -Zach

A Question About Wind Chill

I received the following e-mail from a CBS 6 viewer a couple of days ago addressing wind chill, and who or what is affected by it. Read the message first, and then continue reading for my explanation below.

Zach,

While over at a friends farm Monday it was cold and windy. We got in his golf cart to go look at something and the gas engine stumbled and stammered at first and my friend blamed it on the wind and cold. I tried to explain the wind didn’t make the engine any colder but he wouldn’t hear of such a foolish thing. It might be worthwhile if you or Carrie try to explain the difference between wind chill and ambient temp while this dip has everyone's attention!

Thanks,

Mike

A lot of people will tell you that wind chill does not affect inanimate objects, while others will tell you wind chill affects everything, both living and otherwise. The answer is actually not that cut and dry. The simplest way to put it, is to say that wind chill affects all objects that are emitting heat, causing them to cool to the ambient air temperature faster. So in the example above, the cold could be a reason for the engine to struggle, but not the wind. In the same way, if a lake is 33 degrees and the wind is calm, the lake will not freeze if the wind increases to 20 mph and the wind chill drops into the teens. The wind chill will be sensed by humans and other objects warmer than the surrounding air temperature, but the temperature of the water will not cool lower than the air temp and freeze. Wind chill accelerates the cooling process of objects, and if those objects are already at the ambient air temperature, they won't get any colder regardless of how low the wind chill drops. -Zach

A Few Snow Flurries Possible Tonight

The best location will be across the northern half of Virginia as a shortwave trough (indicated by the red and orange colors in the graphic above) moves through the region. Models have not handled the precipitation with this feature very well and there is currently a lot more on radar (shown below) than expected. The air mass is still extremely dry, and the mountains will hurt a little as well, but a few flurries will still be possible north of Richmond. Nothing to write home about, but it's the only shot we have to see a flake or two before temps in the 60s return to the area. -Zach

Coldest morning of this Winter Wednesday morning

Wednesday morning's low temperatures were the coldest of this Winter season thus far, and will likely remain the coldest for the near-future. Here are a selection of low temperatures reported this morning in central Virginia:

As bitterly cold as it was this morning, it still wasn't close to record cold low temperatures for today's date. The record low for Richmond International Airport for January 4th is -1 degree from 1918. The average low temperature is 28 degrees, which means we were about ten degrees colder-than-average across all of central Virginia.

The upper-level trough that has been in our region for the past couple of days providing this cold weather, dry air, and blustery winds will begin moving away from us today. By tomorrow, morning lows will remain in the mid to upper 20s with afternoon highs back to average in the upper 40s and low 50s.

Our next blast of cold air may arrive mid-month, but as of right now, there's still no strong signal for our first significant winter precipitation event in the next couple of weeks. The system that will bring rain to Virginia this Sunday should exit to our northeast before it pulls in cold air deep enough to change the rain over to snow.

Stay with CBS 6, we'll keep you ahead of the storm!
--Carrie
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Coldest Night So Far This Season

And yes, the winter season is still young, but overnight lows in the teens across the majority of the state will easily eclipse our previous coldest night of 25 degrees in Richmond on December 29th. The wind speed will decrease significantly as the night wears on, but even a 3 mph wind at a temperature of 19 degrees will result in a wind chill of 15 degrees. We'll have one more breezy and cold day on Wednesday before a nice warm-up heading into the weekend. A few central Virginians were treated to snow showers this afternoon, but any significant wintry weather might still be quite a stretch away. There are two chances that I see over the next 10 days for wintry weather in and around metro Richmond, and they are both associated with similarly structured storm systems. The big question for each of these systems will be whether or not the air mass will be cold enough to support snow. Most of the rain will be gone by the time the cold air moves in during the first event this Sunday, with still a lot of uncertainty with the second system slated to arrive next Thursday the 12th. Neither system looks impressive at this point. I'll keep one eye on the models tonight, and the other on the Hokies down in New Orleans. Hopefully they can put Michigan away and spread a little warmth north. I'll have another update tomorrow. -Zach

Bitter cold for first meteor shower of 2012

If you can bear the brutally cold wind chills in the teens early Wednesday morning before sunrise, you could be treated to the first great meteor shower of 2012. This will also be the first good shower to view in months because the bright Moon previously interfered with optimal viewing of other showers in 2011.

The Quadrantid Meteor Shower peaks early Wednesday, January 4th, particularly between 2 a.m. and Dawn. At this peak, as many as 100 meteors per hour could be visible! Our visibility should be pretty good in central Virginia with clearing skies and the moon setting around 3 a.m. Best meteor shower visibilities are always a distance away from high concentrations of man-made light. Those of you outside of the cities should see the most meteors. Here's a sky map of where to look (the point of origin from our perspective on Earth of the meteors...look northeast and up):

(IMAGE CREDIT: Starry Night Software)
Notice that the meteors appear to come at us from the constellation of Quadrans Muralis (in between Draco and Bootes), leading to the shower's name. The meteors associated with the Quadrantids originate from asteroid "2003 EH1," which itself is probably a broken piece off of a comet from several hundred years ago. This meteor shower was first documented in 1825. NASA expects the debris from that asteroid to impact Earth's atmosphere at a speed of about 90,000 mph, and disintegrate 50 miles above the ground.

However, please be aware that Wednesday early morning temperatures will fall into the teens and low 20s, with wind chills in the low teens. If you plan to watch this meteor shower for a couple hours, make sure you are well-equipped for the cold weather, paying particular attention to keeping your hands, feet, neck, face and head warm! Take extra blankets, water, snacks, and maybe some hot chocolate to enjoy while you stargaze. You can click here to read more about the bitter cold lingering through Thursday morning.

Other meteor watching tips:
*Allow at least ten to 15 minutes for your eyes to adjust to the dark.
*Lie flat on the ground and scan the sky, not focusing on any specific point.
*Look for flashes of swiftly moving light from the northeast streaking across the sky. Some of these may appear to have various colors other than just a bright white.

Click here to post your meteor sightings at Carrie's Facebook Wall.

Tracking Our Sub-Freezing Wind Chills

The coldest and driest air mass of the season continues to move into the region this evening, and with a persistent and brisk northwesterly wind, the wind chill in Richmond and areas to the north and west will remain below freezing for a fairly long duration. I drew the red line above to indicate what I think the wind chill will register over the next few days, and also drew a light blue horizontal line to show the freezing line at 32 degrees. We'll be close to seeing wind chill values crack the freezing mark Wednesday afternoon, but it's likely we'll experience wind chills at or below freezing for about 63 hours, especially in areas north and west of here. The deep trough responsible for this cold snap will shift east of the area on Thursday, giving us a break from the cold heading into the weekend. And yes, I expect us to be in the low 60s on Saturday, so the confusion to vegetation and wardrobe planning will continue. As for any precipitation, the chances are very slim, with just a slight chance for a little light rain on Sunday. The medium range models continue to show flashes of an east coast winter storm in the extended period, but nothing very focused at the moment. I'll keep an eye on it and let you know if something looks promising. In the meantime bundle up, and check back for another update tomorrow. -Zach