Interpreting the Gradient Level Wind Analysis

Thought others might find this interesting as I did...

Reading Current MSLP

The gradient level lies about 1000 metres above the earth's surface, and is the level most representative of the air flow in the lower atmosphere immediately above the layer affected by surface friction. This level is free of local wind and topographic effects (such as sea breezes, downslope winds etc). Streamline charts are much more useful than isobaric pressure (MSLP) charts for showing the weather patterns over tropical areas. While MSLP charts are good for estimating wind direction and strength over mid and high latitudes, in the tropics pressure gradients are weak and often don't give a good indication of the prevailing winds. Meteorologists overcome this difficulty by drawing charts of the actual wind flow. The surface wind may be estimated by decreasing the gradient level wind speed by approximately 20% over the ocean, 40% over land and assuming a direction deviation of about 10-30 degrees. If looking along the direction of the wind, the deviation is to the right if low pressure is on your right (or if high pressure is on your left).

Read more here: www.bom.gov.au/australia/charts/Interpreting_GLW.shtml

Yeh, pretty much, but the isobars are raw data and I often turn to the synoptics to figure things out for myself. I thought it was interesting to gain some insight into how these assumptions (forecasts) are made.