This is a set of contour plots using data from the NAM model. The output fields are consistent with other models so the models can be compared. This model gives forecast information out to 48 hours and plots are sorted 48 hour 4 panel plots where each plot has a panel for the 12, 24, 36 and 48 hour forecast and individual forecast times from initialization to 60 hours in 6 hour increments. These plots are updated once every 12 hours at roughly 11:15 EST.
Sample 300 mb Plot
The 300 mb chart shows the winds at the 300 mb level. The wind speeds are shown in color contours, the heights in solid white lines and the vectors show wind direction and speed.
300 mb wind speed field
The 300 mb chart investigates the upper portion of the troposphere where most of the weather producing phenomena occur. This level lies around 30,000 feet up and is often referred to as the jet stream level. Areas of strong winds at this level (winds >100 knots or 115 mph), commonly referred to as jets, indicate areas of high atmospheric energy. These are created by strong temperature contrasts in the lower and middle tropopause and reflect areas of potential storm development. A strong jet (winds >130 knots) can indicate the potential for the development of a strong low pressure system especially when if moves over the Rocky mountains and into the Plains states. A strong jet hitting the west coast can indicate the existence of a strong precipitation producing system.
300 mb wind vector field The vector field shows wind direction and speed. Often this can be used to qualitatively show areas of convergence and divergence. In the middle and upper levels of the troposphere, this can be an indicator of existing upward (from divergence) or downward (from convergence) air motion. Upward motion is often linked to precipitation and downward to clear skies.