Written by Meteorologist Ros Runner (10:00 PM, 1/15/2017)
It's been a week now since we were in the deep freeze with a blanket of snow covering central Virginia! It's amazing how quickly things can change with a record low of 0° occurring early Monday morning and then we reached a high of 70° on Thursday.
As we look ahead to the upcoming week, just about every day is expected to be above average with many days likely to warm into the 50's and even a couple chances that we'll eclipse the 60° mark. The "January Thaw" should continue into the following week as well, however, big changes appear to be brewing by the end of January into early February. WINTER IS FAR FROM OVER!! Let's talk about Ensemble forecasting and what that is showing as we look forward in time.
Ensemble forecasts use many different runs of a particular computer model (European, GFS, Canadian etc.). These various runs may have slightly different initial conditions or model assumptions but the mean of all of them usually results in a more accurate prediction. This is particularly useful in identifying major shifts in the weather pattern more than 7 days out.
For example, the map below is the "Ensemble Mean" of 51 different runs of the European model and it gives us an idea of how the jet stream will be positioned on January 25th. Notice that there is a "trough" in the jet stream located over the western portion of the United States. That's where the COLDEST AIR is located. Here in Virginia, temperatures are still forecast to be warmer than average.
By January 29th, the European Ensemble is forecasting a MAJOR SHIFT in the position of the jet stream with the cold trough now covering a large part of the country. Some of the coldest air is now centered over the central and eastern United States.
BOTTOM LINE? Long range computer guidance is suggesting a return to much colder weather by the end of the month and to start off the month of February. With the cold air taking hold once again, this would greatly increase our potential for another winter storm. Stay tuned and we'll continue to keep you updated as time draws closer.
Posted on 01/15/2017 at 11:10 PM | Permalink
UPDATED by Jim Duncan at 4:43pm 1/13/2017
Updated 8:45am 1/14
It looks like things could turn a little wintry again over parts of northern and western Virginia this morning.
Central Virginia and RVA should be spared with temperatures above freezing, but a wedge of cold air interacting with another advance of moisture will conspire to produce a mix of sleet and freezing rain early this morning mainly north of Caroline-Spotsylvania line, and west of the Blue Ridge with light snow possible over the far northern part of the state closer to DC. This is our First Alert to let you know if your travels will take you north up I-95, or west to the Valley to I-81 early this weekend you may encounter a little freezing rain or sleet. Precipitation will be light, just use caution while driving.
Winter Weather Advisories have been cancelled for the DC area, but still hold for the NW part of the state until this evening for some light sleet or snow accumulations. Areas shown to the west are under a Freezing Rain Advisory through 6pm.
These are the Hour-by-Hour model maps. Note time stamps on banner in upper right.
A little bit of light rain will again be possible this evening. Otherwise cloudy and chilly.
An area of high pressure near New England will be responsible for the big cool-down in temperatures today.
This is NOT a major winter system, but could bring generally very light amounts of freezing rain/sleet over northern and western Va.
Posted on 01/13/2017 at 04:33 PM | Permalink
Written by Meteorologist Ros Runner (9:30 PM, 1/9/2017)
It's been more than 72 hours now since our temperature in Richmond has been above the 32° mark! The combination of Arctic high pressure plus a significant snow pack covering much of the area has resulted in some of the coldest temperatures we've experienced here in central Virginia in many, many years.
Check out the BRUTALLY LOW temperatures experienced around the area on Monday morning, January 9th!
Petersburg was the lowest at -8°. The zero at Richmond International Airport broke the record of 1° set back in 1940. It was also the coldest temperature reading we have had in Richmond since late January 2000.
Below you will see a map showing the departure from "average" (normal) temperatures across the country for January 9th. If you study the map more closely, you'll notice that Virginia, North Carolina, and northern Montana are the COLDEST spots in all of the United States relative to average. Here in central Virginia, our temperatures have been more than 20° BELOW AVERAGE.
Here is a map below showing the GFS forecast for the departure from "average" (normal) temperatures this upcoming Thursday, January 12th. WHAT A FLIP IN THE PATTERN!! In 3 days time we'll go from 20°+ BELOW AVERAGE to 20°+ ABOVE AVERAGE. Now that is a true JANUARY THAW!
Posted on 01/09/2017 at 10:23 PM | Permalink
It's called HOAR FROST and it's beautiful
Most frost doesn't do much-- and just looks like a light film of ice. But in certain circumstances, you can get a special kind of frost form. Here are some pictures my wife took yesterday morning on her morning stroll. She said they were BEAUTIFUL and didn't want to come inside!
After I posted these pictures on Social media, our viewer's photos started coming in:
Elizabeth Ayers Whelan caught this beautiful sight from AFAR
And here it is up close.
This one: From Scott Tucker:
So: What's going on here?
From the American Meteorological Society's Glossary:
A deposit of interlocking ice crystals (hoar crystals) formed by direct deposition on objects, usually those of small diameter freely exposed to the air, such as tree branches, plant stems and leaf edges, wires, poles, etc.
The deposition of hoarfrost is similar to the process by which dew is formed, except that the temperature of the befrosted object must be below freezing. It forms when air with a dewpoint below freezing is brought to saturation by cooling.
HOAR FROST is rare around here because it needs to be very cold and dry. Plus you need a moisture source. Due to Saturday's snow, there was plenty of moisture available all over the place!
Hoarfrost's formation is similar to how snow forms in the atmosphere but we never really get to see that happen.
Posted by Andrew Freiden 1/9/2017.
Posted on 01/09/2017 at 08:55 AM | Permalink
Posted by Jim Duncan 6:12pm on 1/7/2017
The much-advertised snowstorm dumped a lot of snow over central and eastern Virginia, with widespread reports of 5-8 inches over the metro Richmond area. Up to a foot was reported from Williamsburg, and totals around 10" were commonly seen in areas east of RVA. Below is the snow map put out by the National Weather Service this afternoon:
Here is a detailed listing of snow totals, again as reported to the NWS ; Link is >> NWS Snow Totals
Posted on 01/07/2017 at 06:26 PM | Permalink
Updated by Meteorologists Andrew Freiden and Megan Wise at 1/7/17 at 10:25am
*Live coverage on NBC12 TV NOW**Major Impact on Roads*
We have First Alert Weather Days for Today and Tomorrow.
Tomorrow is a "First Alert" for Sunday due to the VERY cold temperatures.
There is a WINTER STORM WARNING from RVA to the south and east, and WINTER WEATHER ADVISORIES north and west for lighter snow. BLIZZARD WARNINGS are in effect for the Norfolk area and parts of the Eastern Shore. All of these warnings go through late in the day.
Here is our snow totals map, with heaviest snow moving to the east by 10am. Snow will tapering off in the afternoon.
We think many areas are headed to the HIGH end of these forecasts!
Have Fun, Stay Safe!
TODAY WILL be snowy, cold, and travel difficult throughout central, southern, and eastern VA
Snow will exit the region during the afternoon-- but the day will stay WINDY AND COLD. Any snow that falls will stick around for a few days..
Posted on 01/06/2017 at 10:36 PM | Permalink
Updated by Meteorologist Andrew Freiden (12:38pm, 1/4/2017)
While the cold air is a sure bet-- snow is not.
Our two Chances both are a bit iffy. Late tomorrow into Friday morning looking less impressive as we get closer (could be just flurries)
And the Late Friday into Saturday Chance looks close to a sure bet at the beach, but less set in stone for us here in Richmond.
It's not much-- but could slow commutes on Friday morning. This graphic shows the computer models showing limited moisture. This still could end up as flurries or NOTHING in Richmond.
Then, attention turns to SATURDAY'S system, which could be bigger, but it still far from set in stone. 3 tracks are possible:
The track that hugs the coast gives us the best chance of snow and we are leaning in that direction-- but still wary that the storm could stay farther off the coast.
Here's what we should prepare for, even as it's too soon right now to forecast amounts. This may end up being Hampton Roads snow only...
-In Richmond, it's a Moderate threat of a few inches of snow.
-From Emporia to Williamsburg and Reedville, the threat is higher.
-North and West, there's less moisture, so the snow threat is lower.
Here's the computer model forecast for Richmond for SATURDAY'S potential snow. A Big disagreement has our confidence level only at "low" but the European model AND the Canadian are in agreement of that closer, coastal track.
There is still wiggle room in this track so this forecast is obviously subject to change.
Our confidence level should grow significantly by tomorrow as the computer guidance will be better able to sample the energy that will help to spawn this early season winter storm. Stay tuned for continued updates!
Posted on 01/02/2017 at 04:41 PM | Permalink
Posted and Updated by Jim Duncan on 12/30/2016 at 1:25pm
Note the discussion below is modified from the original one posted on 12/29 to account for new information. New data in today is indicating the GFS model now matches the Euro, with more of a chilly rain or brief mix set-up beginning as early as late Thursday.
Model trends seem to be converging now for more of a chilly, rain situation from the potential storm setting up for the end of next week. Over the past couple of days there have been some model hints at a winter storm around Jan 6-8 timeframe. The Euro model backed away from this scenario yesterday, and is now being matched by the latest GFS.
Both are showing a faster-moving system with primarily rain with some mix possible, now in the late Thursday-Saturday morning window. Updates will be posted to this blog as needed, but for now it looks like threats of any wintry precipitation could end up being short-duration and mostly at the very beginning and then the tail end of the system. This time of year can be volatile with respect to computer guidance flip-flopping, so we'll continue to monitor for any changes. ANY forecast more than a few days out is almost always very low confidence.
All that said, temperatures will be taking another big tumble that weekend of the 7-8th, with the patterns overall still overall looking a little more wintry than it has been into mid-month.
Posted on 12/29/2016 at 06:05 PM | Permalink
Written by Meteorologist Ros Runner (9:00 PM, 12/28/2016)
While we've had some bouts of cold weather during the month of December and even a minor glazing of ice back on the morning of the 17th, we've really had no significant winter storm threat as of yet. Could that be about to change as we move into 2017? It is looking more promising for cold weather fans and perhaps snow lovers will get rewarded soon as well.
Long range computer guidance is indicating that after another decent warm-up again early next week when temperatures could reach or exceed 60°, a colder weather pattern should begin to take hold by the end of the week. Here is a map from the European model showing forecast temperature anomalies around midday Tuesday, January 3rd. Notice all the red showing up in the areas along and east of the Mississippi River....those are temperatures SIGNIFICANTLY ABOVE AVERAGE.
Here are the European forecast temperature anomalies at the same time on Friday, January 6th. What a big change! Much of the country is now looking MUCH COLDER THAN AVERAGE.
The GFS (American) model is quite similar and also indicates the evolution to this colder pattern by the end of next week. There are also hints that as the cold air arrives, there may be a system running up from the Gulf of Mexico to off the coast of the Carolina's on Friday the 6th or during the weekend of the 7th and 8th.
Here is the European model forecast for Saturday morning, January 7, 2017. It shows the cold air settling into the region and a low pressure system off the southeast U.S. coast.
Keep in mind that this is a forecast map more than 7 days out in time and there is plenty of room for error. Should this map end up being correct, we ***MAY*** end up with our first taste of snow this winter season. This is your FIRST ALERT to the possibility....just keep it in the back of your mind and we'll continue to monitor this closely and keep you updated!
Posted on 12/28/2016 at 10:52 PM | Permalink