10/29/2007 

Taken off of the main page of www.wvweather.net, here 
is Rob's winter weather forecast... Check out the website, 
see what you think of their winter weather forecast... 

Local Weather News 

The extended winter forecast for the months of November 
through March calls for a cooler than normal start and end 
but the traditional winter months, December through 
February, may be one of the top 10 warmest winters ever 
for the southeastern United States. The heat will be 
centered over the Tennessee Valley and the Carolinas. For 
the nation as a whole, this winter will be warmer than last 
winter; especially in the second half of January and 
February when last winter season was at its coldest. 

When looking at the past three winters, we find that 
population weighted, this may be as warm as the 1998-99 
winter and the 2001-02 winters. Unlike the winter of 
2005-06 and last winter, where significant shots of cold 
and snow showed up in major areas during 35-50% of the 
winter months, this winter may have over 75% of the days 
above normal in most of the nation southeast of line from 
the Great Lakes to the Southwest. The only signal for 
below normal is over the Pacific Northwest. 

We are heading to the classic cycle of the warm Atlantic 
Multidecadal Oscillation (AMO) and La Niņa and it's the 
ocean that is running the show. La Niņa is officially 
defined as sustained cold sea surface temperatures 
anomalies across the central tropical Pacific Ocean but 
also displays a pressure tendency as well. El Niņo is the 
warm version of this phenomenon. 


The AMO is the sea surface temperature cycle taking place 
in the northern Atlantic Ocean, which, in its warm cycle, 
can contribute enhanced conditions for tropical system 
development during the Atlantic basin hurricane season. 
These two major players appear to have the stage. 
Supporting the theory of what cold there is being early 
and late is an idea from scientists in the Southern 
Hemisphere, which says the Antarctic Oscillation (AAO) 
will telegraph the Northern Hemisphere winter. The AAO is 
a measure to compare certain levels of the atmosphere 
relative to normal from 20 degrees south latitude to the 
South Pole. Their winter season had a quick cold start, and 
a colder end, but the difference is the surrounding water is 
much colder there. 

The effect across the United States may be that we have 
the colder parts of the cold season relative to normal early 
and late. It may feel shockingly cold compared to the 
record setting warmth of October and the warmth of the 
Winter but not extreme compared to normals of the time 
of the year -- in other words, colder than normal but not 
extreme. The warmth coming at the traditionally coldest 
time of the winter will be very unusual. 

Pattern analogs: 
It is rare when the years picked out match so closely 
objective guidance in winter. AccuWeather.com forecasts 
for the last two summers used this technique to produce 
accurate temperature ideas but it is easier to see it in the 
summer. Last winter, there were differing opinions at 
AccuWeather.com on whether the El Nino would collapse 
or maintain its strength. 

This gave us the analog of 1965-1966 to lean on for the 
major reversal. The winter before, the 1933-1934 analog 
ran rampant in the middle of the winter, but the point is, 
in both cases, there were many options to choose from. 
Last year, instead of blending, we worked hard to pick the 
best one out based on our idea of the pattern, and it 
worked. The coming winter season forecast has a higher 
confidence level than those two due to the fact that all 5 
major analogs for the coming season fit to a very similar 
pattern. 

First of all, the La Niņa has gone to AT LEAST where we 
thought it would go and there is no stopping it. We are 
projecting a moderate to strong one well into the winter 
and may wind up with a top 5 ranking as far as the nino3.4 
SST. In addition, the forecast cooler west-than-east idea is 
a known warm signal for the United States as a whole. In 
addition, the warm AMO and the type of autumn we have 
had also fit well into 5 analogs: 1949, 1950, 1954, 1955 
and most recently 1998. 

The most amazing thing is the maps drawn from this 
match extremely closely to the maps that we are seeing 
from two major objective seasonal guidance sources -- the 
European seasonal models (ECMWF) and the US Climate 
Forecasting System (CFS). It's as if those two models 
simply chose our analogs and drew the winter forecast 
from that. The forecast La Niņa plus the trend also lines up 
for a very warm winter, as the La Niņa for the winter will 
be at least moderate. 

 
What can go wrong? 
While the confidence in the forecast warmth is running 
high and as warm as the forecast, it could be even 
warmer. There is some correlation between the phase of 
the quasi-biennial oscillation (QBO), the solar minimum 
that we are in, though coming out of, and a colder version 
of La Niņa for a colder forecast than expected. The QBO is 
a fluctuation of the equatorial zonal wind between 
easterlies and westerlies that has an effect on the upper 
atmospheric circulation during winter in the Northern 
Hemisphere. And the collapsing of the La Niņa and a turn 
to a negative North Atlantic Oscillation (NAO the revenge 
of winter, though that appears more likely late rather than 
early. 

We are, in fact, predicting March to be normal to below 
normal month for much of the nation but an earlier than 
normal onset would lower the warm departures from 
normal. But for the core of the winter, this one looks like 
the warmest of the last three for much of the nation. Once 
it gets warm, it may stay warm all winter and not reverse 
like last year, or it will be cold the first and last 3 weeks of 
the winter like 2005-06. 

The analogs chosen look very, very good, and its not just 
one out of 7 like last year, where we determined the 
correct one from a bunch, or blended them like the year 
before, but the host of them line up nicely with objective 
guidance. We simply feel that these ideas are the players 
that will take over the game, and the other factors will not 
be strong enough to control the ultimate outcome, and if 
they don't show at all, this could be an even warmer 
winter than forecast. 

The evolution of the water temperatures in the Pacific and 
the Atlantic basin feed right into this. The colder water 
developing in the north Pacific with the warmer water 
between it, and the cold la Niņa current, offer the case for 
a stronger than normal "fire-hose" jet into the Pacific 
Northwest that would then lift through southern Canada 
and into the north Atlantic with a stronger than normal 
positive arctic oscillation for the winter season. This will 
be masked in November and again in spring as the jet 
does not reveal its true colors until it matures. 

The weaker jet with the shorter wavelengths very often 
will get winter off to an early start, with November turning 
colder than October in the very places it was warm and 
this can persist into December. However, as the jet 
continues to intensify, the feedback processes cause a 
stronger and stronger vortex to develop and bundle arctic 
air. This does offer some risk as the lack of cold air 
anywhere in North America since the April outbreak will 
not be something that we will have this winter. It will be 
getting very cold in much of western and northern Canada 
and the risk of this coming southeast occasionally means 
that ice storms may be more of problem from the Plains to 
the Northeast than snowstorms this year. 

The characteristic of this winter appears to be that in most 
areas from the Plains east, even when it gets cold, the 
warmth will be seen coming back in a short period of time. 
In other words, sustainable week after week cold like last 
year is not likely. More likely are mid-winter intrusions 
that hit and run, and rarely, if at all, visit the Southeast. rob 

10/31/2007