Real-Time Data Access - NWS Radar Imagery

McIDAS-X Learning Guide
Version 2020

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Real-time Data Access - NWS Radar Imagery

Many of the same commands used to display satellite images can be used with National Weather Service (NWS) Radar data as well. In this excercise, you will access real-time NWS Radar imagery, find a NWS Radar station where precipitation exists (if any) and list and display that station's radar image.

The DSINFO and IMGLIST commands list information about the available images. Once located, you can display the images using the IMGDISP command. You can display images one at a time or in a sequence. An entire set of images can be loaded chronologically using one IMGDISP command.

Add the group RTNEXRAD into the client routing table and list all radar datasets from RTNEXRAD of type IMAGE.

Type: DATALOC ADD RTNEXRAD ADDE.UCAR.EDU
Type: DSINFO IMAGE RTNEXRAD

      Dataset Names of Type: IMAGE in Group: RTNEXRAD

 Name         NumPos   Content
 ------------ ------   --------------------------------------
 DAA          99999    Digital Accumulation Array
 DHR          99999    Digital Hybrid Reflectivity
 DOD          99999    Digital One Hour Difference
 DPA          99999    Digital Precipitation Array
 DSD          99999    Digital Storm Total Difference
 DSP          99999    Digital Storm Total Rainfall
 DTA          99999    Digital Storm Total Accumulation
 DVL          99999    Digital Vertical Liquid H2O
 EET          99999    Enhanced Echo Tops
 HHC          99999    Hybrid Scan Hydrometeor Classification
 N0C          99999    Correlation Coefficient Tilt 1
 N0H          99999    Hydrometeor Classification Tilt 1
 N0K          99999    Specific Differential Phase Tilt 1
 N0Q          99999    Base Reflectivity DR Tilt 1
 N0R          99999    Base Reflectivity Tilt 1
 N0S          99999    Storm-Rel Mean Vel Tilt 1
 N0U          99999    Base Velocity DV Tilt 1
 N0V          99999    Radial Velocity Tilt 1
 N0X          99999    Digital Differential Reflectivity Tilt 1
 N0Z          99999    248 nm Base Reflectivity
 N1C          99999    Correlation Coefficient Tilt 3
 N1H          99999    Hydrometeor Classification Tilt 3
 N1K          99999    Specific Differential Phase Tilt 3
 N1P          99999    1-hour Surface Rainfall
 N1Q          99999    Base Reflectivity DR Tilt 3
 N1S          99999    Storm-Rel Mean Vel Tilt 2
 N1U          99999    Base Velocity DV Tilt 3
 N1V          99999    Radial Velocity Tilt 2
 N1X          99999    Digital Differential Reflectivity Tilt 3
 N2C          99999    Correlation Coefficient Tilt 5
 N2H          99999    Hydrometeor Classification Tilt 5
 N2K          99999    Specific Differential Phase Tilt 5
 N2Q          99999    Base Reflectivity DR Tilt 5
 N2S          99999    Storm-Rel Mean Vel Tilt 3
 N2U          99999    Base Velocity DV Tilt 5
 N2X          99999    Digital Differential Reflectivity Tilt 5
 N3C          99999    Correlation Coefficient Tilt 6
 N3H          99999    Hydrometeor Classification Tilt 6
 N3K          99999    Specific Differential Phase Tilt 6
 N3Q          99999    Base Reflectivity DR Tilt 6
 N3S          99999    Storm-Rel Mean Vel Tilt 4
 N3U          99999    Base Velocity DV Tilt 6
 N3X          99999    Digital Differential Reflectivity Tilt 6
 NAC          99999    Correlation Coefficient Tilt 2
 NAH          99999    Hydrometeor Classification Tilt 2
 NAK          99999    Specific Differential Phase Tilt 2
 NAQ          99999    Base Reflectivity DR Tilt 2
 NAU          99999    Base Velocity DV Tilt 2
 NAX          99999    Digital Differential Reflectivity Tilt 2
 NBC          99999    Correlation Coefficient Tilt 4
 NBH          99999    Hydrometeor Classification Tilt 4
 NBK          99999    Specific Differential Phase Tilt 4
 NBQ          99999    Base Reflectivity DR Tilt 4
 NBU          99999    Base Velocity DV Tilt 4
 NBX          99999    Digital Differential Reflectivity Tilt 4
 NCR          99999    Composite Reflectivity
 NET          99999    Echo Tops
 NTP          99999    Storm Total Rainfall
 NVL          99999    Vertical Liquid H2O
 OHA          99999    One Hour Accumulation
 PTA          99999    Storm Total Accumulation

Erase frames 1 through 6.
Type: ERASE F 1 6
Display a map of the United States on frame 1 and show the current weather conditions by displaying weather symbols.
Type: SF 1;MAP USA;SFCPLOT WXS

The parameter WXS displays weather symbols of the current weather conditions.
Choose a station in which rain, snow, or some other type of precipitation is occuring and place the cursor over the symbol.

Find any nearby NWS Radar stations using the STNLIST command.

Type: STNLIST TYPE=N

The TYPE keyword allows you to search for specific types of stations. In this example, you are only searching for NWS Radar stations (N) in the surrounding area.

You should see an output similar to this:

 Center Lat/Lon: 42:48:59 84:18:00
 IDN   ID     Station Name         Data Types        ST CO DIST[KM] LAT         LON       ELE
 ----- -----  -------------------- ----------------- -- -- -------- ----------  --------- ----
  ---  DTX    DETROIT                      N         MI US    68.9   42:41:59   83:28:18   327
  ---  DTW    Detroit TDWR                 N         MI US   101.5   42:06:40   83:30:54   235
  ---  GRR    GRAND RAPIDS                 NW        MI US   101.8   42:53:38   85:32:41   237
 Number of stations listed: 3

Choose a station ID and display the base reflectivity (tilt 1, 248 nmi range) image from that station (in this case, DTX, Detroit, Michigan) with a red map on frame 2.
Type: SF 2;IMGDISP RTNEXRAD/N0Q ID=DTX MAG=-2;MAP X 5

Another way to display the same station is to use the predefined NWS Radar product aliases found in IMGDISP.CORE. For the preprod parameter IMGDISP uses the IMGDISP.* context files, where .* refers to .CORE, .USER, and .SITE. Display the IMGDISP.CORE context file.

Type: SEE IMGDISP.CORE NLINES=ALL

After the comments section of the IMGDISP.CORE file, you will see predefined products in sections like this:

   # Products for WSR Base Reflectivity, tilt 1 (0.5deg)
 RADAR/WSR-BREF1 DATASET=RADAR/WSR-BREF1 EU=WSR-BREF  REQUIRE=ID
 WSR/BREF1       DATASET=WSR/BREF1       EU=WSR-BREF  REQUIRE=ID
 MKX_BREF1  DATASET=RADAR/WSR-BREF1 EU=WSR-BREF ID=MKX MAG=-2 \
          REFRESH='BAR (IMA) GRA=(GRA); \
          EU MAKE 1 1 50 50 50 50 50 50 (IMA) (IMA); \
          EU MAKE 2 2 WHITE WHITE (IMA) (IMA); \
          EU MAKE 3 3 BLACK BLACK (IMA) (IMA); \
          MAP X -8 DASH=1 X 4 COUNTY=ALL GRA=(GRA) IMA=(IMA); \
          MAP X  7 GRA=(GRA) IMA=(IMA); \
          STNPLOT TYPE=FOUS COLOR=7 FONT=HELMO GRA=(GRA) NAV=(IMA); \
          FRMLABEL LEV=2 3 IMA=(IMA) \
          "(ID) WSR - BASE REFLECTIVITY - TILT 1 AT (HHMM) ON (DAY)'

Take a closer look at each individual line of the MKX_BREF1 predefined product, to see exactly what it does.
- DATASET=RADAR/WSR-BREF1 EU=WSR-BREF ID=MKX MAG=-2 \
  The DATASET= keyword defines the ADDE dataset to use, EU= defines the enhancement file to use, ID= keyword defines the default station to display, and MAG= defines the magnification factor to apply when displaying the image. The "\" is the continuation line used by the context file.
  Note: The DATASET= keywords defined in IMGDISP.CORE use the Satellite Data Services/McIDAS-XCD naming convention. Users can define their own DATASET= in IMGDISP.SITE or IMGDISP.USER. Also, keywords can be overridden on the command line. We will do this with DATASET= in the following examples.
- REFRESH='BAR (IMA) GRA=(GRA); \
  The REFRESH= keyword runs the remaining commands on each frame after the image is displayed. (IMA) and (GRA) are used to specify the current image and graphics frame. The BAR command creates and displays a grayscale bar, which turns into a color bar with the effects of the enhancements.
- EU MAKE 1 1 50 50 50 50 50 50 (IMA) (IMA); \
  The three EU commands change the BREF image enhancement to have different background colors.
- MAP X -8 DASH=1 X 4 COUNTY=ALL GRA=(GRA) IMA=(IMA); \
  The MAP command displays a map of gray dashed county lines using the current frame's navigation.
- MAP X 7 GRA=(GRA) IMA=(IMA); \
  The second MAP command displays a high resolution map using the current frame's navigation.
- STNPLOT TYPE=FOUS COLOR=7 FONT=HELMO GRA=(GRA) NAV=(IMA); \
  The STNPLOT command plots all FOUS14 stations in white with a font of HELMO, using the current frame's navigation.
- FRMLABEL LEV=2 3 IMA=(IMA) \
  "(ID) WSR - BASE REFLECTIVITY TILT 1 AT (HHMM) ON (DAY)'
  The FRMLABEL adds a label to the frame, with the (ID), day (DAY), and time (HHMM) of the image.
Display the same station's three most recent NWS Radar images on frame 3-5, using the predefined product, MKX_BREF1, and the station you chose in step 6 (in this case, DTX). Use the RTNEXRAD dataset that was added above. If MKX is the station you chose, you do not need to specify ID=, since ID=MKX is the default.
Type: IMGDISP MKX_BREF1 ID=DTX DATASET=RTNEXRAD/N0Q ALL=3 5
Loop the images to see the movement of the storm.
Type:    LB 3 5
Press:   Alt L
Press:   Alt L
Display the total surface rainfall accumulation from the RTNEXRAD dataset using the predefined PCPT (storm total precipitation) product on frame 6.
Type: SF 6;IMGDISP MKX_PCPT ID=DTX DATASET=RTNEXRAD/NTP
Place the cursor over different areas of precipitation and use IMGPROBE to determine the total amount of precipitation over those selected ares.
Type: IMGPROBE
Press: Alt G

Repeat this as many times as you like.
Exit IMGPROBE using Alt Q.
Press: Alt Q

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