In reply to:

How do you tell the difference between an upper low and a surface low when looking at the satillite loop? Also, what type of data do you use? Toni

'Tis hard to tell sometimes, but I'll try. Using the satellite, it helps to look at the visible presentation. Often, even usually, a Low Level low will cause the clouds you can see rotating around the low being occasionally obscured by the higher level clouds which are often moving in an entirely different direction. If the visible clouds are movining in the same direction as the IR clouds, it *may* be an upper level low, but of course, storms originating from the surface can and do reach up and have colder tops which rotate. Again, the visible satellite is often the best view...if the rotating clouds are not obscured, they probably are higer and therefore associated with an UL low. Obviously, a large storm can confuse the picture, but the question was regarding 'ordinary' lows. Satellite views are not always good enough (might not be 2 layers of clouds to watch), so where possible, you want surface (buoys, ships, etc) data which tell you the pressure at SL. Even wind direction at SL is a clue as it is more ore less at right angles to the direction of the low/high causing the wind. If the winds and pressures suggest a low at the surface, and it agrees with your observations of the satellite pics, you have confirmed that it is a Low Level low you are seeing.

I am sure there are other ways to determine this (ask the professionals who frequent here

) but this is how I have been successful in the past at identifying which is which....