[Ncep.list.idp.mrms.users] Some bad Canadian Radar data not getting QC'd out of MRMS, impacting QPE

Joseph Moore - NOAA Federal joseph.moore at noaa.gov
Wed Jul 18 13:57:43 UTC 2018

Good morning,

I just wanted to share some feedback on MRMS and Canadian Radar data. We've
noticed that some mornings we see the Canadian radar reflectivity data not
being QC'd out of MRMS, causing errors in QPE. This was an issue a week ago
when we had a period of heavy rainfall, but then the QPE got exaggerated
(values increased due to bad reflectivity) along the international border
in northern Minnesota. I have attached (via Google Drive) a few GIFs of
MRMS products this morning demonstrating the bad reflectivity values being
ingested and accumulating on the QPE product in northern Minnesota.

Problem: Some high reflectivity values from morning inversions are being
ingested into MRMS precip products from our Canadian radars. (Specifically
Dryden radar and occasionally the Superior West (Thunder Bay) radar site.)

Expected behavior: Since there is no precip in the area (no clouds), I
would expect these values to be QC'd out like MRMS usually does.

When the problem occurs: Usually in the morning hours when a strong
inversion is present.

Urgency: This is not an urgent issue, but it would be good to see addressed
eventually since MRMS precip impacts so many things downstream, like FLASH.

Linked GIFs show (from top left, clockwise): GOES-16 Clean IR Ch 11,
GOES-16 Red Vis Ch 2, 0.5 degree NEXRAD Reflectivity composite, and the
MRMS product in question. (In one GIF I included the MRMS 1-hour QPE to
show that MRMS is accumulating these reflectivity values as precip.)

Let me know if you have any other questions. I can continue to send
examples if it would help diagnose the issue.

**NOTE** This has NOTHING to do with the MRMS outage this morning even
though some of the frames in this GIF are from when the issues were

-Joe Moore

*Joseph J. Moore*
Meteorologist | WFO Duluth Social Media & IDSS Program Leader | Open Source
GIS Evangelist
NOAA/National Weather Service Duluth, MN
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