Heavy Rainfall and Flooding Concerns in the Southwest; Coastal Low to Impact the East Coast

Deep tropical moisture will lead to widespread showers and thunderstorms capable of producing flash flooding through early next week over the Southwest and Four Corners. A coastal storm is expected to develop off the southeast U.S. coast tonight and is expected to strengthen and bring flooding, dangerous rip currents, gusty winds and heavy rain up much of the East Coast through early next week. Read More >

Picture of WSR-88D Radome

Dual Polarization (or "dual-pol") technology adds an additional 14 products to the suite of data already available to NWS forecasters. These tools will assist forecasters in the warning and forecast process.

Why upgrade to Dual Polarization Radar?

By comparing the power and timing of energy returned to the radar from both horizontal and vertical pulses, we can glean information such as the size, shape, and composition of precipitation particles.

What are the Potential Benefits of Dual-Pol?

Better estimation of total precipitation
Better estimation of the size distribution of hydrometeors (precipitation particles)
Improved ability to identify areas of heavy rainfall (flash flooding potential)
Improved detection and mitigation of non-weather echoes
Easier identification of the melting layer (helpful for identifying snow levels in higher terrain)
Ability to classify precipitation type
New severe thunderstorm signatures

What is polarization?

A radio wave is a set of oscillating electric and magnetic fields, oriented 90 degrees to each other. Polarization of the wave is the direction, or orientation, of the electric field.

Horizontal Polarization

The electric field is oriented horizontally, along the x-axis.

Vertical Polarization

The electric field is oriented vertically, along the y-axis.

"Old" NWS Doppler Radar (horizontally-polarized only) versus "Dual Polarized" Radar

The old Doppler radar capability transmits and receives only horizontally polarized radio wave pulses. Therefore, they measure only the horizontal dimension of cloud and precipitation particles. New dual-pol capability will allow the transmit and receipt of both horizontally and vertically polarized radio wave pulses. Therefore, they measure both the horizontal and vertical dimension of cloud and precipitation particles.

More Information

Local Radar

Weather Map

NWS Huntsville SitRep

HUN RSS Feed

Heavy Rainfall and Flooding Concerns in the Southwest; Coastal Low to Impact the East Coast

Dual Pol Radar Information