Radar Interpretation Chad Entremont National Weather Service Jackson, MS

Objectives 1.General mechanics of radar 2.Basic radar output – reflectivity, velocity data and precip 3.Radar limitations and extras 4.Identify radar situations during tornado/supercell, hail and squall line scenarios Ask questions

General Radar Products Base Reflectivity (BR) Base Velocity (BV) Storm Relative Velocity (SRV) Precipitation – One Hour, Storm Total

Radar Basics  Sends out a microwave pulse  Listens as energy bounces back  Each pulse lasts about seconds, with a second "listening period" in between  the radar is "on" for a little over 7 sec each hr. The remaining 59 min and 53 sec are spent listening  The more returned, the more dense the object is  Wet objects reflect higher power than ice objects  Multiple scans and elevations

Base Reflectivity (BR) – this is the intensity of precipitation or power returned to the radar site. It is measured in decibels DBZ. Hook Echo

Benefits of Super Resolution 6 Legacy Resolution Super Resolution

Radar Basics - Velocity  Doppler Effect  Higher frequency when target is moving toward radar  Radar measures the change in wavelength  Knows if an object is moving toward/away from radar 7

Base Velocity (BV) Base Velocity (BV) – this feature defines Doppler radar. It revolutionized our ability to detect internal rotation or winds inside storms. This is the true measure of the wind. Red (+) is outbound, Green (-) is inbound. Radar Site

Storm Relative Velocity (SRV) Storm Relative Velocity (SRV)– similar to Base Velocity, but takes into account the motion (subtracts direction and speed) of the storm. Also referred to as Storm Relative Motion (SRM). Displays winds as if the storm were standing still. Radar Site

Radar Est Precip (OHP, STP) Radar Est Precip (OHP, STP)– Radar estimated rainfall both in 1 hour accum (OHP) and storm total (STP) Accumulation can become contaminated by hail or melting ice, resulting in over estimation of rain amounts Storm Total (STP) One Hour (OHP)

Radar limitations Note: Beam is higher off the ground further away from the radar Radar Beam spreads out

Radar Extras  Warning displays – Tor, Svr, Flash Flood warnings  Multiple panel views, different radar products  2D cross sections  3D volume view

Warnings Display

2 Panels 4 Panels

Cross-Section

3D Volume View Algorithms take all scans and produce a 3-D image of a storm. The user can zoom and rotate the storm from virtually any angle.

Getting the Software   Follow the page  Pay Fee  Make sure your computer has correct system requirements!  Follow instructions  Make sure you have the latest version   Web page to get additional maps, color table etc…

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