[Ncep.list.idp.mrms.users] [awips2dev] MRMS
Jeff Waldstreicher - NOAA Federal
jeff.waldstreicher at noaa.gov
Mon Jun 25 13:28:52 UTC 2018
Jeff
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.
https://mrms-dev.nssl.noaa.gov/
https://mrms-dev.nssl.noaa.gov/qvs/gauge_vs_qpe.php
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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