Threat for Strong to Severe Storms Friday

A powerful storm system currently located across the far southwestern U.S. will bring central VA a chance for strong to severe thunderstorms on Friday. It appears as though the best combination of wind shear, moisture, and lift will be across the Mississippi Valley on Thursday, where an outbreak of severe weather is likely. Our atmospheric parameters won't be quite as conducive for severe weather in central VA, but modest heating and very strong wind shear will interact with fairly meager amounts of low-level moisture to give us a slight chance for a few severe storms. The lack of rich low-level moisture will be the limiting factor in what otherwise might be a better event for us. Here's how I think things will play out with this system: We'll see increasing clouds on Thursday, with only a slight chance for a few showers before sunset. Showers will increase in coverage Thursday night into Friday morning, but I don't think we'll have the lift and moisture in place quite yet for thunderstorms during the overnight period. Showery weather will taper off in the morning, with a period of sunshine developing. Temperatures will warm into the upper 60s and low 70s as strong southwesterly winds bring more moisture into the area Friday afternoon. The cold front will move through Richmond at 4 PM, likely accompanied by a broken line of showers and storms. A few storms could be strong to severe, especially east of I-95. All of the activity that develops will be east of the area by 7 PM. Cloud bases will be high, so despite strong wind shear, tornadoes don't appear very likely. Strong mid-level forcing and cold air aloft will result in a hail threat, with strong downburst winds possible as well. Whatever happens, Stay With CBS 6, We'll Keep You Ahead of the Storm. ZD

Long Range Outlook

Brief Summary:

La Nina will continue to weaken heading into spring. NAO (North Atlantic Oscillation) will generally remain neutral or positive. Although we will see a brief cool down for the start of March, temperatures will remain roughly near or above average. Precipitation will stay near or below average. The chances for a significant snow (over 6") look slim to none.

Digging into the data (technical):

Meteorological winter is about to end (December through February), so it is now time to look at the overall pattern heading into spring. Earlier this winter, we had a strong La Nina, which typically brings mild and dry weather to our region. However, we experienced a strong -NAO (North Atlantic Oscillation), which is when a strong ridge in the jet stream persists over western Greenland and eastern Canada. This brought us cold and snowy weather for December and early January. This ridge eroded in late January, and we have been mild and dry ever since.

La Nina is starting to quickly weaken. In fact, we could be in neutral conditions by May or June. This is a plot of sea surface temperatures, which shows that Nina still exists, but it isn't as strong as earlier this winter. In addition, what you can't see is the water below, which is starting to warm.

Past La Ninas have brought us slightly cooler and wetter weather for March through May. However, this might not be the case this year because La Nina is weakening.

Here is a plot of NAO, which shows negative conditions early in the winter, and then neutral/positive conditions ever since mid January.


There are indications that NAO could turn slightly negative in early March, which would typically get any snow-lover excited. However, the ridge is too far east. I've posted the long range outlook for the upper-level atmosphere (first map), and temperatures for the lower atmosphere (second map). Notice on the first map how the ridge, indicated by the yellow blob, is located east of Greenland. Although this could bring us slightly below average temperatures, it is not in an ideal location for significant snow. Average highs for early March are in the mid 50s and average lows are in the mid 30s. We should generally stay near these numbers for early March. Of course, there will be some fluctuations.

Obviously, there could be some changes to the forecast, however, this isn't looking good for snow-lovers.

Highest Gusts From Saturday

Wintergreen saw a gust of 71 mph...that's almost hurricane force winds! Here is a list of highest gusts from other areas across the state. You'll notice that winds were not as strong in southern Virginia.