National Weather Service Weather Forecast Office

The exciting dual-polarization radar upgrade to the Holloman AFB (KHDX) and El Paso (KEPZ) WSR-88D will soon begin!  The scheduled dates for the upgrades are: KHDX May 14th - May 27th; KEPZ June 4th - June 17th.  Radar data will not be available during the upgrade process, which will take about two weeks.   This upgrade incorporates a new technology called dual-polarization (dual-pol) that is part of the NWS vision to build a weather-ready nation to better protect lives, property  and livelihoods.  Dual-pol technology will result in 14 new radar products that will enable us to continue providing our suite of high quality products and services to the citizens of Southern New Mexico and Far West Texas.  This new technology and data will primarily help forecasters identify the type, intensity and precise location of precipitation that is falling and will greatly improve rainfall estimates.

We strongly encourage all users of these new products to complete a series of online training modules that were recorded by the Warning Decision Training Branch (WDTB).  Modules are available for non-NWS meteorologists and non-meteorologists through this website.

The current 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.

Current NWS doppler radar	Dual-polarimetric radar

• Improved accuracy of precipitation estimates, leading to better flash flood detection
  
• Ability to discern between heavy rain, hail, snow, and sleet
• Improved detection of non-meteorological echoes (e.g. ground clutter, chaff, anomalous propagation, birds, and tornado debris)
• Detection of aircraft icing conditions
• Identification of the melting layer (e.g. bright band)

Dual-Pol will not improve tornado lead times or be able to provide exact precipitation type on the ground.

Differential Reflectivity Correlation Coefficient Specific Differential Phase Hydrometeor Classification Algorithm

APPLICATIONS
Using differential reflectivity to identify a hail core
Using correlation coefficient to identify the melting layer and thunderstorm updrafts
Using specific differential phase to identify the melting layer and thunderstorm updrafts
Images courtesy of WDTB

• Dual-Pol Training for NWS Partners (also includes training for non-NWS partners and non-meteorologists)
• National Severe Storms Laboratory Dual-Pol Page