Twin Cities NWS “Dual Pol” upgrade this week

86F high at MSP Airport Monday

90F in Luverne Monday

62F in Grand Marias at 4pm Monday

"Dual Pol" Twin Cities NWS upgrading doppler this week

Rain chances increase by Wednesday

Source: Twin Cities NWS

Upgrading to "Dual Pol"

The Twin Cities NWS is upgrading the doppler to "Dual Polarization" this week. The change is part of a nationwide upgrade that will bring al the NEXRAD 88D dopplers into the Dual Pol era.

Dual polarization of doppler give both vertical and horizontal pulses and will increase resolution and detection of rainfall intensity, hail cores, and give us better estimates of snowfall intensity and winter precip types.

Current NWS Doppler Radar

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Dual-Pol Radar

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Here's the skinny from the Twin Cities NWS.

Beginning August 6, 2012, the Doppler radar at your National Weather Service Forecast Office will undergo an upgrade to incorporate new technology. While the work is being done, radar data will be unavailable from NWS Minneapolis! . The radar is scheduled to be unavailable for two weeks during this upgrade. Recently, though, technicians have been completing the upgrade in 5 to 6 days, and radar data will become available as soon as the upgrade is complete.

Dual pol will enhance our ability to see into clouds and differentiate drop sizes, spacing and precip types. More from NWS.

Current NWS Doppler radars transmit and receive pulses of radio waves in a horizontal orientation. As a result, the radar only measures the horizontal dimensions of targets (e.g. cloud and precipitation droplets). Dual-polarimetric radar transmits and receives pulses in both a horizontal and vertical orientation. Therefore, the radar measures both the horizontal and vertical dimensions of targets. Since the radar receives energy from horizontal and vertical pulses, we can obtain better estimates of the size, shape, and variety of targets. It is expected that this will result in significant improvements in the estimation of precipitation rates, the ability to discriminate between precipitation types (e.g. hail vs. rain), and the identification of non-meteorological returns, such as chaff, ground clutter, and smoke plumes from wildfires that are not uncommonly detected by weather radar systems such as WSR-88D.

•Better estimation of total precipitation amounts

•Better estimation of the size distribution of hydrometeors (raindrops, snowflakes, hailstones, drizzle)

•Much improved ability to identify areas of extremely heavy rainfall that are closely linked with flash floods

•Improved detection and mitigation of non-weather related radar echoes (chaff, smoke plumes, ground clutter)

•Easier identification of the melting layer (helpful for identifying snow levels in higher terrain)

•Improved ability to classify precipitation type

The full benefit of dual-pol radar, however, will not be fully realized until NWS forecasters and research meteorologists develop real-time expertise.

Still want more? Here's the (substantially cheesey) video from NOAA.

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