Tuesday, December 2, 2008

Hurricane Sesaon Ends, Records Set

The 2008 Atlantic Hurricane Season ended on Sunday with some new records established, including the longest lived July tropical system in the Atlantic basin (Bertha) at 17 days.

Click here to read a complete season summary written by the National Hurricane Center.

Meanwhile, it continues to be an early winter for much of the US east of the Rockies. A large trough of low pressure is keeping the area under a northwest flow, sending waves a cold air down from Canada.

Places in the southeast like Nashville and Atlanta have been seeing conditions more prone to January over the past several days.

They've even seen some snow!

Click here and check out the interactive US snow cover map.

Snow is on the ground from northwest Arkansas to Michigan.

Much of Illinois, Indiana and Missouri have snow on the ground.

All of Wisconsin and Michigan have snow cover.

It is important for a forecaster to look at the extent of snow cover because it can greatly impact the weather.

If northwest winds are blowing across that huge area of snow cover, it could mean locations downwind will be colder than computer forecast models indicate.

You also have to consider snow depth.

In many of these locations, there is snow on the ground but it isn't very deep -- at lower latitudes where the sun angle is a bit higher.

Therefore it will melt quicker than locations immediately off the Great Lakes...so it may or may not have such a large impact on the regional weather.

Just another consideration a forecaster must take into account when working on the daily forecast.

This is one reason why we ask you to report a daily snow depth on your CoCoRaHS report.

Even if there is no precipitation and no new snowfall, you very well may have several days where both of those fields on your report are ZERO, but there is a total in the daily snow depth column.

It gives a history of what is happening at your station regarding the overall, large scale weather pattern.

The data can be very helpful to both a forecaster or a researcher.

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