GWS Winter Outlook! Intresting!!!

[Guest]

This is very detailed and explains alot of the things that goes into making a winter outlook such as i did........................Enjoy!!!!


GWS

2003-2004 Winter Outlook (Dec-Feb)





Abstract


The winter months of 2003-2004 across the central, Midwestern and Northeastern U.S. are forecast to be dominated by a pattern of below to near normal temperatures and near to above normal precipitation, or snowfall. The current forecast takes into account the expectations for near-normal sea surface temperature patterns, or neutral El-Nino/Southern Oscillation (ENSO), an Artic Oscillation (AO) pattern dominated by a negative cycle, and a neutral effect from the Pacific Decadal Oscillation (PDO) throughout the winter season.

The increased probabilities of below to near normal temperatures across the northern half of the U.S., east of the Rockies, will create a greater demand for natural gas and heating oils, as above normal heating demand occurs throughout the winter season. The potential for near to slightly above normal precipitation, or snowfall, will also impact municipalities throughout these locations, as demand for salt and other anti-ice road treatments is likely to increase.



Analysis of Current and Forecast Trends in the Global Atmosphere


When determining a seasonal forecast, it is important to analysis what atmospheric conditions have dominated the global circulation patterns prior to heading into that season, as well as forecasting any potential changes which could occur in these patterns over the coming months. Although there are numerous global patterns and teleconnections which could be responsible for influencing the U.S. weather on a daily, weekly, seasonal and yearly basis, we have focused on only a few of these patterns.

The patterns selected by GWS were those that have been proven to have an impact on winter temperatures throughout the U.S.



El-Nino/Southern Oscillation(ENSO)

The first trend we examined was the El-Nino/Southern Oscillation, or ENSO. The winter of 2002/2003 was dominated by a relatively weak El-Nino event, which in turn did not end up playing a significant role in influencing our winter weather here in the U.S. However, in the spring, the tropical Pacific Ocean sea-surface temperature anomalies returned to more neutral conditions, producing neutral ENSO conditions, meaning there was no La-Nina or El-Nino event currently occurring.

This pattern has persisted throughout the past several months and nearly all of the forecast models continue to predict neutral ENSO conditions in the tropical Pacific Ocean through early 2004.



Pacific Decadal Oscillation(PDO)

The second trend we analyzed was the pattern known as the Pacific Decadal Oscillation, or PDO. This is a cyclical circulation pattern identified throughout the Pacific Ocean, which has also been proven to have a very strong impact on the climate of the U.S. The pattern is normally a 20-22 year cycle, consisting of either a positive, or warm phase, and a negative, or cool phase.

The PDO impacts the circulation patterns throughout the northern hemisphere, in turn impacting the climate of the U.S during the winter months. The PDO was found to have been in a cool or negative phase from 1890-1924 and again from 1947-1976, while a warm or positive phase was noted from 1925-1946 and from 1977 through the late 1990s. We have since returned to a cool or negative PDO pattern, one that is expected to persist until around 2016.

Although we are in a long-term negative, or cool phase PDO pattern, the PDO has recently fluctuated back towards positive, or a warm phase pattern since the latter part of 2002. Minor fluctuations, or reversals, are common during any particular long-term cycle, and this current one is no exception. These perturbations will, however, have a tendency to negate the current effects normally found in the dominant, long-term cycle.

The PDO is forecast to remain slightly positive or in a warm phase over the next several months and into the winter season, with the possibility of a return to neutral PDO conditions by early 2004.

During a 20-year negative, or cool phase PDO cycle, the U.S. typically experiences colder winters and drought conditions in the desert Southwest, while the opposite is noted during a positive, or warm phase of the PDO. A negative PDO cycle is also associated with weaker El-Nino events and stronger La Nina events, while a positive PDO cycle is associated with stronger El-Nino's and weaker La Nina's.



Artic Oscillation/North Atlantic Oscillation(AO, NAO)

A third trend we examined was the Artic Oscillation and the North Atlantic Oscillation, which are also proven to have a significant impact on the weather in the U.S. The NAO and AO are patterns or indices, which explain the north-south dipole of anomalies in the northern latitudes, ultimately indicating the strength and pattern of the polar jet stream.

The AO covers a larger scale and most of the northern latitudes around the globe, while the NAO is focused on the North Atlantic Ocean between 35 and 40 degrees North latitude. A negative phase of the NAO and AO is normally associated with below normal winter temperatures across the north-central U.S., as well as the eastern half of the nation, while a positive phase is associated with above normal winter temperatures in these locations.

The NAO and AO patterns were predominantly a negative cycle during the winter of 2002/2003, which attributed to the abnormal cold and snowy winter experienced throughout the eastern U.S. These oscillations have continued to sway towards the negative cycle over the past several months, which could have had a strong influence on the cooler and wetter spring and summer the eastern U.S. has continued to see this year.

Although both the AO and NAO will exhibit constant fluctuations during the course of a particular year and season, we feel the overall trend of these oscillations will continue to lean towards a negative cycle during the winter months of 2003/2004.



Regions Analyzed


For the purposes of our study, we chose to focus on the northern half of the U.S. east of the Rockies, as these are the areas responsible for the greatest heating demand in the winter months. The regions used were as follows:



West-North Central: N. Dakota, S. Dakota, Nebraska, Montana, Wyoming

East-North Central: Minnesota, Iowa, Wisconsin, Michigan

Central: Illinois, Missouri, Indiana, Ohio, W. Virginia, Tennessee,

Kentucky

Northeast: Virginia, D.C., Delaware, New Jersey, New York, Connecticut,

Massachusetts, Rhode Island, Vermont, New Hampshire, Maine



Analysis Techniques


The basis for our analysis and forecast was rooted in examining previous years in which similar ENSO, or sea-surface temperature, patterns existed when compared to 2003 and the expected pattern during the winter months. We also used the current AO and NAO trends, combined with the forecast, to develop our winter forecast, while also examining the PDO patterns.

We found 11 years since 1950 where the ENSO patterns were similar to those found currently, mainly near normal ENSO conditions during the spring, summer and fall months and a continued neutral trend into the winter months. Those years were 1952, 1959, 1960-62, 1967, 1978-80, 1996 and 2001.

In all of these years, except 1979, 1980 and 1996, we were under the influence of a negative, or cool, PDO cycle, which initially prompted us to discard these three years, due to the fact that they occurred during a warm PDO cycle and we are currently in a long-term cool PDO cycle.

However, when looking at the recent PDO trend, or short-term trend, the PDO has been predominantly in a warm, or positive phase and the forecast calls for it to remain either slightly positive or return to neutral conditions during the winter months. Based upon this recent occurrence and positive "spike" in the long-term negative cycle, we chose to include the years of 1979, 1980 and 1996 in our analysis and forecast, acknowledging their relevance to the study.

We then looked at the temperature and precipitation during the winter season (December-February) of these years, and performed a statistical analysis regarding whether the temperature and precipitation for those years was rated above normal(A), near normal(N) or below normal(B) for the past 54 years since 1950.



Analysis Findings


Each region listed above was analyzed separately and then ultimately combined to come up with a rating for all of the regions in the northern half of the U.S., east of the Rockies. A percentage of occurrences, for the 11 years analyzed, were calculated for each region and all regions combined. The findings for temperature are listed below in Table 1.



Table 1.




W-N Central
NE
E-N Central
Cntl
All Regions Combined

AVG Occurrence of "B"
55%
45%
45%
36%
45%

AVG Occurrence of "N"
36%
36%
45%
55%
43%

AVG Occurrence of "A"
9%
19%
10%
9%
12%




In regards to temperature, we also ranked the 11 years analyzed from 1895, with 1 being the coolest year and 108 being the warmest year. The rankings for temperature are listed below in Table 2.



Table 2.






W-N Central
NE
E-N Central
Cntl
All Regions Combined

Ranking
39.1
39.5
41.0
34.5
38.5




When examining the above data, one can see that winter temperatures during the 11 years used in this study, which are similar to atmospheric and oceanic conditions this year, lean towards below normal. The combined ranking was 38.5 out of 108, which is below the median of 54 and indicates these years were in the higher rankings of the coolest winter seasons.





Switching to an analysis of precipitation for the 11 years, the findings are listed below in Table 3.



Table 3.




W-N Central
NE
E-N Central
Cntl
All Regions Combined

AVG Occurrence of "B"
9%
45%
19%
36%
27%

AVG Occurrence of "N"
55%
10%
36%
36%
34%

AVG Occurrence of "A"
36%
45%
45%
28%
39%




When the 11 years were ranked from 1895 with 1 being the driest winter and 108 being the wettest winter, the results were as follows in Table 4.



Table 4.




W-N Central
NE
E-N Central
Cntl
All Regions Combined

Ranking
58.6
55.8
58.5
48.8
55.4






When examining the above data, it is difficult to determine a clear-cut bias towards one occurrence over another. Although the overall average occurrences of above normal winter precipitation are the greatest, it is by a very small margin. The ranking of 55.4 for the 11 years is very close to the median of 54, pointing to near normal precipitation occurring more frequently during the winter months of these years.



GWS Forecast/Final Analysis


Based upon the analysis of the 11 years indicated above, which possessed similar atmospheric and oceanic conditions to those observed thus far in 2003 and expected in the winter of 2003/2004, as well as the expectations for the Artic Oscillation(AO) and North Atlantic Oscillation(NAO) to remain predominantly in a negative cycle, GWS is forecasting an increased probability of below normal temperatures across the northern half of the U.S., east of the Rockies, during the winter of 2003/2004. GWS also expects precipitation, or snowfall, will be near to just slightly above normal in these areas.

The colder winter temperatures that GWS is forecasting in the winter of 2003/2004 will ultimately lead to a higher than normal heating demand across the northern half of the U.S., east of the Rockies, prompting an increased demand for natural gas and heating oil this season.

The possibility of increased snowfall, or even near normal snowfall, will also keep the demand for road salt high in most municipalities and states throughout the north this season

[Stephanie]

Very good analysis!

I especially like the explanations given of what the US typically experiences during a cool phase of the PDO.

[weatherlover427]

This doesn't apply to me because they TOTALLY skipped over the WEST.

[GAStorm]

Great discussion KOW! Now all we need to do is sit back and wait for the snowpack to build!! I just read DT's forecast, and he has Ontario and west Quebec getting a major winter storm on 10/1-10/3. Nice start for winter 03/04!!

[JCT777]

Sounds very reasonable to me. Bring on winter!!

[Colin]

I'm sooo ready for winter!!!

[breeze]

Our summer temps ran cooler than the last
few years, rarely getting up in the upper-90°s.
I'd say this forecast may just be right on! I'll
start saving for the heating bills!

Thanks, KOW!

[Anonymous]

BRING ON THAT SNOW!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I'm Ready To Dig!!!!!!! I've got my digging shovel all ready!!! YEAH!!!!!!!


I have a question.........................

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_072l.gif

The GFS has the 540 thickness over SOUTHEASTERN VA only THREE DAYS out, on Friday!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! And GFS has the -3 Line directly over Woodbridge on Friday!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

GFS has the +3 Line at 850 mb over Woodbridge today, our high was 67 degrees, this morning we were at 41 degrees, and DP is 38 degrees.

My Question is, What will the weather be like in northern VA this upcoming Friday? Will I get to enjoy highs in the low 50s and overnight lows in the low 30s or even upper 20s?!!!!!

MAN I LOVE WINTER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

BRING IT ON!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

-Jeb

[JCT777]

Jeb - I would think it is possible that your area has highs in the upper 50's with lows in the mid 30's on Friday. Pretty similar to what I expect in my area. I could be wrong, but I don't think it will be any colder than that.

[Anonymous]

Jeb - I would think it is possible that your area has highs in the upper 50's with lows in the mid 30's on Friday. Pretty similar to what I expect in my area. I could be wrong, but I don't think it will be any colder than that.

I think we will have the usual afternoon clouds, which will cut down on the sunlight and so we will luck out with only a high temp of around 53/54, then that sun goes down and we toboggan down into the low 30s from there. Or maybe we'll REALLY luck out and hit the upper 20s overnight!!!! Frost looks SO GOOD on that pumpkin!!!

I LOVE COLD WEATHER!!!! Bring it ON!!!!!!!!!


-Jeb