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Doppler Radar Loop Weather in Washington, D.C.Washington, D.C. Radar Weather

Washington Doppler Radar Loop

Weather Radar Loop for Washington, D.C.Doppler Radar Loop Weather in Washington, DC
Lat: 38.91N, Lon: 77.02W  ICAO: KDCA
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Current Conditions: Thunderstorms, the temperature is 62°F17°C, humidity 90%, dew point 59°F15°C. Barometric pressure is 29.71 in1006 mb. Wind direction is N at 12 mph19 km/h with visibility of 4.00 mi6 km. °F Click to change Washington radar loop current conditions to Imperial units.Click to change Washington radar loop current conditions to Metric units. °C
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Washington Weather Warning NWS WEATHER ALERT FOR THE WASHINGTON, DC AREA - Issued: 959 PM EDT Mon Oct 25 2021 Washington Weather Warning  

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Clear Air dBZ Scale Precipitation dBZ Scale
Rainrate - inches per hour

The colors are the different echo intensities (reflectivity) measured in dBZ (decibels of Z) during each elevation scan. "Reflectivity" is the amount of transmitted power returned to the radar receiver. Reflectivity (designated by the letter Z) covers a wide range of signals (from very weak to very strong). So, a more convenient number for calculations and comparison, a decibel (or logarithmic) scale (dBZ), is used.

The dBZ values increase as the strength of the signal returned to the radar increases. Each reflectivity image you see includes one of two color scales. One scale (far left) represents dBZ values when the radar is in clear air mode (dBZ values from -28 to +28). The other scale (near left) represents dBZ values when the radar is in precipitation mode (dBZ values from 5 to 75). Notice the color on each scale remains the same in both operational modes, only the values change. The value of the dBZ depends upon the mode the radar is in at the time the image was created.

The scale of dBZ values is also related to the intensity of rainfall. Typically, light rain is occurring when the dBZ value reaches 20. The higher the dBZ, the stronger the rainrate. Depending on the type of weather occurring and the area of the U.S., forecasters use a set of rainrates which are associated to the dBZ values.

These values are estimates of the rainfall per hour, updated each volume scan, with rainfall accumulated over time. Hail is a good reflector of energy and will return very high dBZ values. Since hail can cause the rainfall estimates to be higher than what is actually occurring, steps are taken to prevent these high dBZ values from being converted to rainfall.