Official 2011-2012 Winter Forecast

2010-2011

Moderate/Strong La Nina Conditions Strong blocking (-NAO) dominated

conditions for December & January Dominantly –AO and +PNA Above Normal Snowfall Much colder than average December

and January; warmer than average February

2011-2012 Overview

Weak La Nina ENSO Conditions Predominate –NAO; strong blocking -AO, +/- PNA, +AMO, -PDO, -QBO Low Solar Activity Amplifying winter pattern towards the

end of November Southeast ridge may become a factor

Overview (cont.)

Slightly Below Normal to around average temperatures

Cold December/January, warm February

Well above average snowfall Equal Chances for precipitation

Snowfall Prediction

Winston-Salem – 15” (Avg – 9”) Greensboro – 13” (Avg – 8.9”) Raleigh – 11” (Avg – 7”) Hickory – 12” (Avg – 7.2”) Charlotte – 7” ( Avg – 5.4”) Asheville – 22” (Avg – 15.4”) Atlanta – 4.5” (Avg – 2”)

ENSO Conditions

Currently a weak La Nina Forecasted to strength into a Moderate

La Nina I currently do not believe it will

strengthen to anything more than a strong weak Nina.

After this winter, ENSO conditions are forecasted to go positive/neutral.

ENSO Conditions (cont.)

CFS model strengthens Nina into the strong category, but that seems a little bullish at this juncture

I do expect the Nina to position itself more east per the current SST anomalies.

Current ENSO SST Chart

North-Atlantic Oscillation

One of the trickiest Oscillations to forecast

A HUGE determinate for wintry weather in the south

Normally a negative means good news for the south in terms of snow, a positive NAO does not.

Really hard to predict/forecast more than a week or two in advance

NAO (cont.)

If NAO is strong enough, it can override ENSO. Most notably last winter season.

I do expect a large part of this winter season to be dominated by a negative NAO.

A moderate, West-based NAO looks like the most viable option; this is one good for snow and cold in the east/south.

NAO (cont.)

I think that the –NAO will dominate most of December and January (with some relaxes, not many)

The pattern should relax more in February, much like it did last year

Overall, the NAO will likely again, set the stage for wintry weather here in the south

Arctic Oscillation

Increased snow cover causes some increased stratospheric warming, due to the thermal effect

This, in turn causes the Siberian High to strengthen, which allows the Arctic jet stream to dig south every-now-and-then, causing what we call massive arctic air outbreaks.

AO (cont.) Normally as winter progresses, high

pressure anomalies are found in the arctic, while low pressure anomalies are found around the mid-latitude oceanic regions

While this occurs, the energy transfer from the upper to lower parts of the atmosphere weakens, in turn allowing for a more north-south flow instead of an east-west flow

AO (cont.)

All of this allows warmer air to enter the polar parts of the atmosphere

All of this is strongly connected to the NAO.

Currently .82, which is really high This is going to lead to another

negatively-dominated AO, which is another good sign for wintry weather here in the south

Quasi-Biennial Oscillation QBO is another Oscillation we look at to

determine possible blocking This oscillation is located slightly above

the equator Winds normally blow west during a

positive phase, and east during a negative phase

It is forecasted that the QBO will be in a weak/moderate negative phase for the upcoming winter

QBO (cont.) During this phase we can expect the

polar vortex to weaken, with an increased potential for SSW (Sudden Stratospheric Warming)

SSW increases high latitude blocking potential, and it helps develop a –AO

The QBO is a big determinate to the NAO. We should continue to monitor this as we get closer to December for a more accurate forecast

Pacific Decadal Oscillation Dominate negative phase for the last

couple of years of this cycle There is evidence of this with the cooler

anomalies in the Gulf of Alaska as well as warmer anomalies located more west of that area

Atlantic Multi-decadal Oscillation This is the index that refers to the SST

anomalies in the North Atlantic region, normally from the equator to 70o N.

In 2005 the AMO peaked, and has been on the decrease since then

During it’s warm phases, it makes the water warmer than normal, and cooler than normal during its cool phases

AMO (cont.)

This winter, the AMO is expected to continue to be in the positive phase, albeit weakening

It should become neutral/negative sometime between 2015-2020

Climate Indices

Current Fall Pattern

We have seen many deep toughing scenarios, with snow in Colorado, Texas, Oklahoma, Nebraska, Kansas, and the Northeast, all before Halloween

In the SE, we have already seen many CAD events, which leads me to believe, this will somewhat be the pattern throughout most of the winter

Fall Pattern (cont.)

With that which comes with CAD is ice In the SE it has been several winter

seasons that we have made it out without a major ice storm, but our luck may have ran out

With these frequent strong High Pressure systems wedging cold air against the mountains, we are just asking for a major ice storm

Fall Pattern (cont.)

Current models are leading to the possibility of some prolonged blocking beginning towards the end of the month, through at least the first half of winter

There is no guarantee, but I do expect a pattern to establish itself, much like the one we saw last December; lots of cold and snow.

Temperature Forecast

Precipitation Forecast

Snowfall Forecast

Final Word Winter should start within a few weeks, without

much notice I am excited of the possibility of a 3rd

blockbuster winter in a row, with well above average snowfall and below average temperatures

I expect the first winter storm to be within the first 10 days of December, but that’s just my guess.

Lastly, I hope everyone enjoys this winter, and any snow/ice that you get!