A localized, persistent, often abrupt lowering from a rain-free base. Wall clouds can range from a fraction of a mile up to nearly five miles in diameter, and normally are found on the south or southwest (inflow) side of the thunderstorm in the Northern Hemisphere. When seen from within several miles, many wall clouds exhibit [...]
According to the National Weather Service, a warning is issued when a hazardous weather or hydrologic event is occurring, is imminent, or has a very high probability of occurring. A warning is used for conditions posing a threat to life or property.
According to the National Weather Service, a watch is used when the risk of a hazardous weather or hydrologic event has increased significantly, but its occurrence, location, and/or timing is still uncertain. A watch is intended to provide enough lead time so that those who need to set their plans in motion can do so.
The state or condition of the atmosphere at a particular place and time; includes temperature, pressure, wind, pressure, cloudiness, precipitation etc.
The Weather Prediction Center (WPC), located in College Park, Maryland, is one of nine service centers under the umbrella of the National Centers for Environmental Prediction (NCEP), a part of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the U.S. government. Until March 5, [...]
The horizontal motion of the air past a given point. Winds begin with differences in air pressures. Pressure that's higher at one place than another sets up a force pushing from the high toward the low pressure. The greater the difference in pressures, the stronger the force.
The rate at which wind velocity changes from point to point in a given direction. May be speed shear, where speed changes between the two points, but not direction; directional shear, where direction changes between the two points, but not speed; or a combination of the two.