Last season was highlighted with some very early openings around Thanksgiving time thanks to a lot of cold air. In many cases it was the best early season ski conditions on record. The cold air was a constant right through the beginning of the year. Even though natural snow was hard to come by, manmade snows were able to be laid continuously for long lengths of time due to cold, dry air early on in the season. The end of the season was warmer with a few bursts of natural snow, but thanks to great snowmaking skiing lasted well into the early spring.

Forecast Methodology

The 2006-2007 winter is shaping up to be cold and wet thanks in part to a weak El Niño, which started to develop this summer. That also helps weaken the 2006 Atlantic hurricane season and strengthen the Eastern pacific hurricane season.

Warmer than average sea surface temperatures off the west coast of South America has and will shift the storm track and allow on average wetter than normal and colder than normal winters in the southeastern United States. This sounds great for skiers in the Southeast, but as often is the case, this could just as well mean cold and rainy as opposed to cold and snowy. Or even worse cold and icy! The climate prediction center has posted their winter outlooks based on the effects of El Niño and here’s what they looks like

What you see from these figures is colder than normal temperatures and western parts drier and coastal sections wetter. The precipitation forecast is clearly just an illustration of the storm track from southern California through the Gulf States and up the Carolina coast. The below normal region over the Ohio valley are indicating the location of persistent high pressure, which during the winter usually means Canadian and Arctic highs with cold air.

Closer inspection of these forecasts does bode well for snow and cold, because if you’ve lived in the Southeast for a while, you know the biggest winter storms usually track from Texas and the Gulf Coast into the Carolina. As is often the case in these parts, getting the moisture and cold air to be here at the same time is the trick. So El Niño isn’t the only factor, let’s explore some other seasonal predictors.

NAO or the North Atlantic Oscillation is a very tried and true predictor of colder weather for the eastern US. Simply put the NAO can be in a positive, neutral or negative phase. The negative phase and the degree of negativity will show colder than normal weather for the eastern US through the following processes:

So when the NAO goes negative we can be expected to experience colder than normal weather with a storm track off the coast. Can you say Nor’easters ?

Two other factors I strongly consider in my winter forecast are both the lunar cycle and solar activity. The sun is a pretty obvious thing to look at, considering it provides all the radiation on this planet for heating. So the more active the sun is the more incoming solar radiation and less active the less. We measure this in two ways: the amount of solar flux and the number of sunspots. The higher those both are the more electromagnetic and solar energy that bombards the Earth. We still don’t understand all the effects from this on our planet, but we know the sunspot activity causes major problem with power grids, cells phones and satellite communications. There are plenty of studies that show highs solar activity may in part be causing or at the least exaggerating the recent “Global Warming”. That being said there is evidence the sun is going into a less active period. As you will see below we have and will be trending to a period of lesser solar activity, especially sunspot activity. This by all accounts should mean slightly cooler weather in our future.

Monthly solar cycle data
Month Average solar
flux at Earth International sunspot number Smoothed sunspot number
2000.04 184.2 125.5 120.8
cycle 23 sunspot max.
2000.07 202.3 170.1 119.8
2001.12 235.1 132.2 114.6 (-0.9)
2005.08 90.5 36.4 27.4 (-1.7)
2005.09 91.1 21.9 25.8 (-1.6)
2005.10 77.0 8.7 25.5 (-0.3)
2005.11 86.3 18.0 24.9 (-0.6)
2005.12 90.7 41.1 23.0 (-1.9)
2006.01 83.4 15.3 20.8 (-2.2)
2006.02 76.5 4.9 18.6 (-2.2)
2006.03 75.4 10.6 17.3 (-1.3)
2006.04 89.0 30.2 (17.1 predicted, -0.2)
2006.05 80.9 22.2 (16.8 predicted, -0.3)
2006.06 76.5 13.9 (15.1 predicted, -1.7)
2006.07 75.7 12.2 (13.2 predicted, -1.9)
2006.08 79.0 12.9 (12.8 predicted, -0.4)
2006.09 77.8 14.5 (12.6 predicted, -0.2)
2006.10 74.2 (1) 12.4 (2) (11.6 predicted, -1.0)

Past and future sunspot activity.

Then there is the moon, which I am a firm believer in causing both cold outbreaks and stormiest during the cool season. The gravitational pull of the moon has a large effect on fluids, such as the oceans with tides. Since the atmosphere behaves like a fluid and is governed by many principle of fluid dynamics it makes sense that the moons gravitation would affect the atmosphere similarly. In the form of atmospheric tides and since during the cool season the atmosphere is on average shallower or its thickness is smaller these “tides” are thus exaggerated, which usually means higher pressures and lower pressures depending on the lunar cycle. Now on a daily bases this is almost undetectable, but at full moon and new moon these effects are noticeable. Most major arctic outbreaks in the Gulf Coast and Southeastern regions of the US coincide with full moons or new moons, plus or minus three days. Just something to keep an eye for medium range forecasting.

Now the forecast!

Based on the trend of a moderate to weak El Niño and the shift of the storm track already this fall, it would appear that southern branch storms system will be a frequent occurrence to the Southeast. Storms will move out of southern California and through Texas and the Gulf states into the coastal Carolinas. So wetter than average precipitation is a sure thing from December through March for the Southeast. The question then is will these be winter storms with rain, snow or ice? We then look at the NAO and lunar and solar cycles to tell me that colder than average temperatures will occur, shich means persistent toughing over the extreme eastern US and Northeast especially with surface high pressure created several cold air damming events in the Carolinas. This combined with the storm track discussed above will lead to several occasions of coastal storm where snow and ice will be the primary precipitation. As for the ski resorts of the Southeast, this pattern can be a blessing in the case of coastal storms, but as often is the case some cold air damming ice and rain can mix in the mountains leading to less then ideal skiing. The one saving grace could be early cold which will lead to ideal snow making in the late fall and early winter with the occasional northwest flow snows. Which by the way will not be as persistent as last season, but should be counted by the synoptic snows based on the forecasted storm track.

Ski Resorts

Virginias, West Virginia and Maryland

Great season ahead. This pattern favors big snows and lots of cold air for these regions. Expect great conditions with frequent natural snowfalls and many hours of ideal snowmaking conditions.

North Carolina

About average season with several big snow storms that move out of the Gulf Coast region. Snowmaking will be good early on and in the February, but expect several cold rain and ice storms in the middle of the season due to cold air damming at lower elevations and warmer air at higher elevations.

Check back for forecast discussions as potential winter storms approach and please feel free to e-mail me with questions and or comments.