La Nina in DC/Baltimore

[wxmeddler]

TAKEN FROM http://www.erh.noaa..../dcbalt_lanina/

La Nina and Washington D.C.-Baltimore Winters

La Niña, which is a climate phenomenon characterized by unusually cool ocean temperatures in the tropical Pacific Ocean, influences the winter climate pattern across the United States. With the current borderline moderate to strong La Niña episode expected to peak sometime in the late fall or early winter and last through the rest of the winter, La Niña is expected to play a key role in the 2010-11 winter’s climate. Looking back at past winters since 1950, approximately 20 winters were influenced by a La Niña episode.

The figures below are composites of average December, January and February (DJF) temperatures and precipitation, as well as seasonal snowfall at Washington, D.C. and Baltimore. During La Niña years (independent of strength of episode), DJF temperatures averaged near to slightly above normal while DJF precipitation and seasonal snowfall averaged near to slightly below normal.

These composites are further broken down by the strength (weak, moderate and strong) of the La Niña episode. Based on the small dataset, there appears to be some historical correlation between the strength of the La Niña episode and seasonal temperatures locally at Washington D.C. and Baltimore: the stronger the La Niña, the warmer the temperatures averaged. Winter precipitation averaged slightly drier than normal during all La Niña intensities. Seasonal snowfall during La Niña winters averaged below normal during moderate and strong episodes.

For moderate to strong La Niña episodes (like the one expected in the 2010-11 winter), above normal temperatures and below normal snowfall indicated in the composites could in part be due to a westward shift in storm tracks that is often seen during La Nina winters. More storms tracking to the west of the Appalachians would imply the mid-Atlantic region being located on the warmer side of storms, resulting in more mixed or rain events for the area and less snow events.

Not all La Niña winters are alike. Many other shorter- [e.g., North Atlantic Oscillation (NAO), Pacific-North American Pattern (PNA)] and longer-term climate patterns influence the local weather and climate. For example, while almost all of the La Niña episdoes are linked to near or below normal snowfall at Washington D.C. and Baltimore, the weak La Niña episode during the 1995-96 winter was an outlier in the dataset with well above normal snowfall for the season. In this case, the above normal snowfall was weighted heavily by the 6–8 January 1996 blizzard, when 17.1 (22.5) inches of snow fell at Washington D.C. (Baltimore). Aside from the 1996 blizzard, the only other big snowfall events with double digit snowfalls during a La Niña winter (since 1950) were the 10.2 inches recorded on 16–17 December 1973 at Washington D.C. and the 14.9 inches recorded on 25 January 2000 at Baltimore.

Updated by JRK 11/9/2010

[Master of Disaster]

TAKEN FROM http://www.erh.noaa..../dcbalt_lanina/

La Nina and Washington D.C.-Baltimore Winters

La Niña, which is a climate phenomenon characterized by unusually cool ocean temperatures in the tropical Pacific Ocean, influences the winter climate pattern across the United States. With the current borderline moderate to strong La Niña episode expected to peak sometime in the late fall or early winter and last through the rest of the winter, La Niña is expected to play a key role in the 2010-11 winter’s climate. Looking back at past winters since 1950, approximately 20 winters were influenced by a La Niña episode.

The figures below are composites of average December, January and February (DJF) temperatures and precipitation, as well as seasonal snowfall at Washington, D.C. and Baltimore. During La Niña years (independent of strength of episode), DJF temperatures averaged near to slightly above normal while DJF precipitation and seasonal snowfall averaged near to slightly below normal.

These composites are further broken down by the strength (weak, moderate and strong) of the La Niña episode. Based on the small dataset, there appears to be some historical correlation between the strength of the La Niña episode and seasonal temperatures locally at Washington D.C. and Baltimore: the stronger the La Niña, the warmer the temperatures averaged. Winter precipitation averaged slightly drier than normal during all La Niña intensities. Seasonal snowfall during La Niña winters averaged below normal during moderate and strong episodes.

For moderate to strong La Niña episodes (like the one expected in the 2010-11 winter), above normal temperatures and below normal snowfall indicated in the composites could in part be due to a westward shift in storm tracks that is often seen during La Nina winters. More storms tracking to the west of the Appalachians would imply the mid-Atlantic region being located on the warmer side of storms, resulting in more mixed or rain events for the area and less snow events.

Not all La Niña winters are alike. Many other shorter- [e.g., North Atlantic Oscillation (NAO), Pacific-North American Pattern (PNA)] and longer-term climate patterns influence the local weather and climate. For example, while almost all of the La Niña episdoes are linked to near or below normal snowfall at Washington D.C. and Baltimore, the weak La Niña episode during the 1995-96 winter was an outlier in the dataset with well above normal snowfall for the season. In this case, the above normal snowfall was weighted heavily by the 6–8 January 1996 blizzard, when 17.1 (22.5) inches of snow fell at Washington D.C. (Baltimore). Aside from the 1996 blizzard, the only other big snowfall events with double digit snowfalls during a La Niña winter (since 1950) were the 10.2 inches recorded on 16–17 December 1973 at Washington D.C. and the 14.9 inches recorded on 25 January 2000 at Baltimore.

Updated by JRK 11/9/2010

LWX briefed the Council of Governments on Friday with their outlook. Below normal snowfall, a bummer for the snow lovers. Ice storm here and there.

[mappy]

LWX briefed the Council of Governments on Friday with their outlook. Below normal snowfall, a bummer for the snow lovers. Ice storm here and there.

Well as the Master of Disaster you should always be prepared for the worst. You never know when people may freak out over a traffic camera showing "snow".

[Master of Disaster]

Well as the Master of Disaster you should always be prepared for the worst. You never know when people may freak out over a traffic camera showing "snow".

Seriously now, if you arent going to contribute to the discussion, why post at all? Is your sole purpose to hijack the thread?

[mappy]

Seriously now, if you arent going to contribute to the discussion, why post at all? Is your sole purpose to hijack the thread?

To be on topic - I think regardless of what LWX outlook is, you should still prepare for the worst. (Is that better Master of Disaster?)

[Master of Disaster]

To be on topic - I think regardless of what LWX outlook is, you should still prepare for the worst. (Is that better Master of Disaster?)

yes, much better. Thank you.

[mitchnick]

first shot at snow (w/marginal temps) shows up on 12Z GFS today

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer//gfs/12/gfs_ten252288_l.shtml

[SnowJoe]

I enjoyed reading this 2x in a row.