Surface observations and forecasting models

[matt]

John,
Do you rely more on one than the other? Does reliance on surface observations become more important when forecasting for that day's weather, than using models?

Thanks.

[john]

Good question Matt-

For almost all aspects of forecasting I rely on the model data far more than the surface data. The main reason is that the upper air conditions determine about 95% of what happens at the surface. Secondly, surface conditions will change with the warming of the day or with the approach of a weather system.

There are a few instances when looking at the surface conditions can aid in a forecast for the next few hours (nowcasting), but to use surface data for any kind of a forecast out beyond 6-8 hours is not very useful.

-John

[matt]

A follow up:
Are weather baloons still used? What are the various methods used to gather upper air conditions?

[john]

Another good question Matt.

They are, but unlike 20-30 years ago when that was about the only way they gathered upper air data, there are a lot of ways they do it these days, including satellite imagery, ground based wind profilers and even sensors on commercial aircraft.

-John

[matt]

Another question, if you will indulge me? The computer models have shown a storm developing over the Southwest for a good week now. This storm has been predicted to affect the Midwest this weekend. I recall you mentioning it in your long range forecast several days ago. When did it become possible for this type of forecasting, in which a metoerologist can see a storm system develop several days before it actually forms?

Thank you.

[john]

Matt-

For at least 25 years they have been running a model out to 240 hours or 10 days. For quite some time it was the only model, now there are are at least 3 that go out that far. Some model data now goes out as far as 384 hours or 16 days.

-John

[frnash/phx,]

Much of the increase in reach of the long range models is also attributable to the significant advancements in the last decade or so in supercomputers (http://en.wikipedia.org/wiki/Supercomputer#Current_fastest_supercomputer_system ) such as the IBM Blue Gene (http://en.wikipedia.org/wiki/Blue_Gene) series, among others.

Incidentally, here's a cute one, found while browsing: Plan 9 from Outer Space er… Plan 9 from Bell Labs (http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs) http://www.johndee.com/discuss/clipart/happy.gif

[pete]

You didn't mention the much cheaper little brother the PlayStation3 Gravity Grid (http://gravity.phy.umassd.edu/ps3.html). Same processor core('s) just very low relative cost.

Pete