[Ncep.list.idp.mrms.users] [awips2dev] MRMS

Jeff Waldstreicher - NOAA Federal jeff.waldstreicher at noaa.gov
Mon Jun 25 13:28:52 UTC 2018


You can also use the Gauge Comparison Tool on the NSSL MRMS 
development site to do real-time and archived comparisons.  You 
can select the operational (NCO OPS section in the pull-down), 
or the developmental version of the MRMS Q3 products.


Jeff W

On 6/22/2018 3:38 PM, Michael Magsig - NOAA Federal wrote:
> Hi Jeff,
> Have you downloaded our AWIPS bundles from RAC to compare the 
> precip sources? Here is the RAC Procedures Download Page 
> (note you can find this on AWIPS by doing a manual AIR search 
> for rac using the right click on any CAVE text legend):
> https://vlab.ncep.noaa.gov/web/wdtd/racproc
> We have a methodology for quickly assessing differences in 
> precip type for choosing the best precip source and 
> identifying things like melting hail contamination that 
> causes high biases in Dual Pol QPE. A difference like this 
> will stick out like a sore thumb in the instantaneous rate 
> six panel (see image below). You should be able to see how 
> the rates compare to Legacy and Dual Pol and see if there is 
> anything unusual in the patterns of surface precip type. Most 
> likely it is triggering the tropical convective if it is 
> overestimating. Watch for temporal continuity in SPT during 
> the period of heaviest rainfall and see if it is missing any 
> hail signals in the base data.
> I've been looking at a number of heavy rainfall events 
> throughout the country for our flash flood training 
> development, and my perception is that MRMS tends to perform 
> a little better than Dual Pol which performs a bit better 
> than Legacy most of the time but it varies by 
> environment/season and can change during an event, so we 
> recommend starting each event assessing if you have any 
> significant differences between sources and choosing a source 
> that looks to be the most reasonable to start with. Then spot 
> check your precip sources routinely during an event to see 
> who is doing best where it matters most. MRMS typically 
> shines in hail contamination events because its rate cap is 
> 2"/hr for hail which usually lowers MRMS estimates 
> significantly (which is fine until you have heavy rainfall 
> rates >2"/hr with hail). MRMS overestimates like your case 
> are usually tropical convective SPT when it shouldn't be or 
> MRMS not identifying hail.
> Differences of 10-25% are common among all our operational 
> precip sources, and I routinely find differences of 50% or 
> larger at times during heavy rainfall. The biases can 
> sometimes vary spatially and temporally in an event (and 
> during the seasons) for all precip sources, so we preach 
> using all of your observations and giving more weight to 
> those in the strongest cores for flash flood warnings, and 
> only use the mean field bias corrections or the MRMS 
> spatially varying corrections as a first guess. Also pay 
> extra attention to MRMS biases because those biases will 
> propagate to the FLASH streamflows.
> Accurate QPE is still a challenge for all of today's 
> algorithms, and those who rely too heavily on the precip 
> source that worked in the previous event are going to be 
> susceptible to unpleasant surprises (I see that a lot 
> actually with many offices). Maybe we will have more 
> consistent separation for MRMS when it starts using Dual Pol 
> variables in one of the next versions, but I foresee the best 
> warning performance coming from carefully selecting and 
> re-assessing your precip source and blending that with the 
> new streamflow products.
> At least the MRMS overestimates out west should be addressed 
> now that 11.5 has allowed continental ZRs instead of just 
> tropical ZR for heavy rainfall. Feel free to share some of 
> your MRMS screen captures with me offline, as I enjoy the 
> challenge of quickly getting to the bottom line for the 
> differences in QPE.
> Mike
> On 6/22/2018 12:55 PM, Jeffrey Hovis - NOAA Federal wrote:
>> All,
>> I want to thank everyone for answering.  It did answer some 
>> of my questions.  I am going to read through everything and 
>> see where
>> I go with any additional questions.
>> Jeff
>> On Fri, Jun 22, 2018 at 10:54 AM, Joseph Moore - NOAA 
>> Federal <joseph.moore at noaa.gov 
>> <mailto:joseph.moore at noaa.gov>> wrote:
>>     Jeffery, I'll definitely agree with you that for where
>>     the most precip fell, MRMS was on the hot side
>>     (mrms-radar-only.PNG). The gauge-adjusted product
>>     doesn't seem to have really changed much of that
>>     (mrms-gauge-adj.PNG), though looking at the diagnostic
>>     provided by MRMS (the /Gauge Influence Index/, viewable
>>     on MRMS Op Product Viewer site) there doesn't appear to
>>     be /any /gauge correction going on anywhere right now or
>>     in the past 24 hours for any precip accumulation
>>     timeframe. (*I think the issue of no gauge adjustment
>>     happening is an actual problem with MRMS, so I'm looping
>>     the MRMS Users email list on this thread*.)
>>     Compared to the RLX radar (STA, STA-hires, and STP
>>     images), the MRMS data certainly has a broader area of
>>     3"+ and a fairly broad area of 4"+ compared to the
>>     legacy and dual-pol estimates. So even compared to other
>>     precip estimates, MRMS seems on the high side. Why the
>>     MRMS estimates are running too hot? As I said in my
>>     first message, it is probably a case of
>>     mis-classification of the type of rainfall occurring -
>>     maybe using the tropical algorithm when it should be
>>     using a standard convection one. Looking through the
>>     Reflectivity Cube (see the Op Product Viewer), during
>>     the most intense parts of the rain yesterday MRMS
>>     certainly seems to have ingested your radar and
>>     surrounding radars correctly with no gross errors
>>     obvious to me. The MRMS Ops folks on the Users listserv
>>     may be able to diagnose what's going on in this case
>>     better than I can.
>>     We can't expect MRMS to be perfect, just like we know
>>     the radar-based legacy and dual-pol estimates are going
>>     to have errors for various reasons. For what it's worth,
>>     on our recent heavy rainfall event last weekend MRMS
>>     absolutely /nailed /the precip estimation with no strong
>>     high or low bias - it got the maximum amounts just about
>>     as spot-on as you can expect... and that was with our
>>     primary radar down! (MPX's radar provided sufficient
>>     radar data to help fill in the gap to our radar being
>>     down, but at a higher elevation than DLH would have been
>>     scanning if it were up.)
>>     If there is a noticeable problem with MRMS data, this
>>     should be reported to the MRMS/NCEP folks so they can
>>     investigate (I think /ncep.list.idp.mrms.users at noaa.gov
>>     <mailto:ncep.list.idp.mrms.users at noaa.gov>/ is the best
>>     choice but someone else chime in there's a better option!)
>>     -Joe
>>     MRMS Op Product Viewer:
>>     https://mrms.nssl.noaa.gov/qvs/product_viewer.php
>>     <https://mrms.nssl.noaa.gov/qvs/product_viewer.php>
>>     WRH Wx and Hazard Viewer: https://www.wrh.noaa.gov/map/
>>     On Fri, Jun 22, 2018 at 9:19 AM, Timothy Humphrey - NOAA
>>     Federal <timothy.humphrey at noaa.gov
>>     <mailto:timothy.humphrey at noaa.gov>> wrote:
>>         Over the past several days here at the Lake Charles
>>         office, we also noticed that the MRMS-QPE Radar only
>>         was running quite hot compared to our individual
>>         radars' estimates and surface observations.
>>         Comparing this morning's 12Z 72 hour MRMS estimates
>>         to a variety of observation sites including
>>         ASOS/ALERT/COOP confirmed this with a few
>>         comparisons listed below:
>>         JYDT2: 7.91"  MRMS: 10.33"
>>         JYET2: 7.76"  MRMS: 13.18"
>>         JYGT2: 6.38"  MRMS: 7.48"
>>         KBPT:  5.79"  MRMS: 8.11"
>>         ORNT2: 4.91" MRMS: 6.06"
>>         Based on our experience, the QPE-Radar Only seemed
>>         that it was running much hotter compared to previous
>>         events and we were also curious what might have been
>>         causing such a large difference. Our concern is that
>>         these large differences could result in derived
>>         FLASH products being less reliable for warning
>>         decision making.
>>         On Fri, Jun 22, 2018 at 8:54 AM, Jeffrey Hovis -
>>         NOAA Federal <jeffrey.hovis at noaa.gov
>>         <mailto:jeffrey.hovis at noaa.gov>> wrote:
>>             Jack,
>>             It was approximately 10 miles from the area of
>>             heaviest rainfall to the radar site (RLX) .  As
>>             you indicated, COOPS are not included in the
>>             MRMS data.
>>             I just wanted to see what might have caused the
>>             large difference in rainfall amounts.
>>             We issued a Flash Flood Warning based on the
>>             MRMS data. It was a good warning as we did have
>>             lots of flash flooding reports.
>>             Jeff
>>             On Fri, Jun 22, 2018 at 9:42 AM, Jack
>>             Settelmaier - NOAA Federal
>>             <jack.settelmaier at noaa.gov
>>             <mailto:jack.settelmaier at noaa.gov>> wrote:
>>                 I may be mistaken, but I'm guessing MRMS
>>                 does not use COOP data in its algorithms, as
>>                 it's more real-time (not QCd too much) and
>>                 mostly just uses radar data.  How far from
>>                 the nearest radar was the site?
>>                 https://training.weather.gov/wdtd/courses/MRMS/index.php
>>                 <https://training.weather.gov/wdtd/courses/MRMS/index.php>
>>                 On Fri, Jun 22, 2018 at 8:10 AM, Jeffrey
>>                 Hovis - NOAA Federal <jeffrey.hovis at noaa.gov
>>                 <mailto:jeffrey.hovis at noaa.gov>> wrote:
>>                     All,
>>                     I just wanted to give you an update. 
>>                     When I came into the office this
>>                     morning, I checked the MRMS 24 hour QPE
>>                     amount against our COOPs,  We had a COOP
>>                     that was located in the area of heavy
>>                     rain. MRMS indicated that rainfall
>>                     amounts between 3.54 and 5.11 inches
>>                     near the location of our COOP. Our COOP
>>                     actually reported 2.20 inches of rain.
>>                     This is a very big difference.
>>                     There was Flash Flooding in the area.
>>                     However if the MRMS data had verified,
>>                     the flooding would likely have been much
>>                     worse.
>>                     Jeff
>>                     On Thu, Jun 21, 2018 at 3:23 PM, Jeffrey
>>                     S. Hovis <jeffrey.hovis at noaa.gov
>>                     <mailto:jeffrey.hovis at noaa.gov>> wrote:
>>                         All,
>>                         We are currently experiencing an
>>                         area of heavy rain north of our
>>                         office.  The MRMS QPE-Radar Only
>>                         product is indicating as much as
>>                         3.42 inches of rain had fallen over
>>                         a location in the past 3 hours.
>>                         However, none of the surrounding
>>                         radars are indicating that much rain
>>                         has fallen. In fact, the highest 3
>>                         hour rainfall amount based on radar
>>                         that I have found is closer to 2.5
>>                         inches.
>>                         What could be causing this
>>                         difference between these two products?
>>                         Jeffrey Hovis
>>                 -- 
>>                 Jack Settelmaier
>>                 Digital Techniques Meteorologist
>>                 NOAA/NWS, Southern Region HQ
>>                 Fort Worth, TX
>>                 Work: 682 703 3685
>>         -- 
>>         Tim Humphrey
>>         Meteorologist
>>         National Weather Service
>>         Lake Charles, Louisiana
>>         337.477.5285
>>         Follow us on Facebook
>>         <http://www.facebook.com/NWSLakeCharles>, Twitter
>>         <http://www.twitter.com/NWSLakeCharles> and Youtube
>>         <http://www.youtube.com/user/NWSLakeCharles>
>>     -- 
>>     *Joseph J. Moore*
>>     Meteorologist | WFO Duluth Social Media & IDSS Program
>>     Leader | Open Source GIS Evangelist
>>     NOAA/National Weather Service Duluth, MN
> -- 
> Michael A. Magsig - KD5YKJ
> Meteorologist Instructor
> Warning Decision Training Division
> 120 David L. Boren Blvd, Suite 2640, Norman, Oklahoma, 73072
> Email:Michael.A.Magsig at noaa.gov   Phone:(405)-325-2995  Fax:(405)-325-3203
> _______________________________________________
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