850mb Height (dam)/Temperature (°C)/Relative Humidity (%): An analysis of the weather conditions at approximately 5,000 feet above the earth's surface. Areas shaded green are indicative of low level clouds and potentially precipitation. A gross estimate of surface temperatures may also be obtained by noting the temperatures at this level of the atmosphere and adding approximately 13°C.

Surface Pressure/Temperature Analysis with Jet Stream Overlay: This map is an excellent way to visualize how the jet stream interacts with surface weather features. Forecast afternoon surface temperatures are contoured and surface highs, lows and frontal positions are drawn. The jet stream position is indicated by the arrowed red lines.
700mb Height (dam)/Temperature (°C)/Relative Humidity (%): An analysis of the weather conditions at approximately 10,000 feet above the earth's surface. Areas shaded green are indicative of low to middle level clouds and potentially precipitation. 500mb Height Tendency (m): Falling 500mb heights are a harbinger approaching low pressure at any given location while rising 500mb heights indicate oncoming fair weather. By observing trends in 500mb heights upstream (to the south or west) of Pennsylvania, you may obtain a head start in preparing for changing weather.

500mb Height (dam)/Temperature (°C)/Relative Humidity (%): An analysis of the weather conditions at approximately 20,000 feet above the earth's surface. Areas shaded green are indicative of middle and upper level clouds. Additionally, a feel for the broad weather pattern across the nation can be gained from this map: ridges in the black lines are associated with fair weather while troughs, or dips, in those same lines are associated with potentially inclement weather.

 Global 500mb Height Contours and Anomalies: In long range forecasting, a great way to get started is to look at the current weather pattern across the globe. This map includes 500mb height contours as well as, most importantly, height anomalies. The warmer colors indicate higher heights (thus, generally, milder temperatures) than normal while the cooler colors suggest lower heights (and, subsequently, cooler temperatures) than normal.
300mb Height (dam)/Wind (kts): An analysis of the weather conditions at approximately 30,000 feet above the earth's surface. It is at this level that one finds the various branches of the jet stream. The deeper the red shading on this map, the faster the winds. Upper Air Soundings: By clicking on any station on the Untied States map, you can obtain a vertical profile of such fields as temperature, dewpoint, winds and moisture. Launched at least twice a day (at 8am EDT/8pm EDT), weather balloons carry instrument packets capable of sampling a wide variety of meteorological quantities.