EMC's Model Evaluation Group

 The Model Evaluation Group (MEG) community is established to interact with the user community on issues related to the forecast systems of NCEP's Environmental Modeling Center (EMC).    It is used to discuss overall model performance and provide feedback on operational and parallel versions of the models which comprise the production suite.



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angle-left RE: More evidence of FV3 being a bit wetter...
Jack Settelmaier, modified 2 Months ago.

RE: More evidence of FV3 being a bit wetter...

Youngling Posts: 17 Join Date: 11/2/12

I believe I spoke too soon, and too inconclusively, in stating that this Southeast TX event was a clear indication that the FV3 was wetter in its lead-up forecasts than the GFS.  There is obviously A LOT of data to visualize and sift through to make such a comment, and I should be more careful and thorough.  However, I'm also trying to find the right balance in creating content for these model evaluation forums, versus the amount of available time.

Granted the prior (original) post was showing Total Precip (Rainfall) forecasts through 12Z, Sun Jul 8th, around the Houston area, but we've already had an impacting amount of rainfall, as can be seen in the below two graphics.

This first image is showing 72-hr MRMS Q3 rainfall totals (not QCed) with a valid ending time ~17Z, Thu Jul 5th.  On the color scale of this image, the reds begin the amounts equal or greater than 2 inches. The deeper blues and cyan are showing amounts in excess of 6 inches. , A Harris County Flood Control District gauge located at I-10 West and West Loop 610 in Houston reported in excess of 8 inches, all which fell within a mere ~8 hours the morning of the July 4th holiday!!  [Data link and image provided by Victor Murphy.] 

So, suffice it to say, this already has been a significant event, but hopefully one that is mostly over.


In this below 2-panel image, is the same 72-hr MRMS data, as pulled from a UCAR THREDDS data server, and near the same ending time, ~20Z, Thu Jul 6. These images are designed to only BEGIN their color curves at user-selected 72-hr rainfall amount totals.  On the left, the colored areas show where at least 2 inches (50.8mm) of rainfall fell.  So, the areas should roughly match the reds and amounts above from the image above.  Areas in black on the left, are off the high end of the left image's color scale, and are in excess of 6 inches, which is the same amount (6") where the image on the right BEGINS its coloration.  This may seem confusing, but displaying it in this way, using filtered WMS pulls from a THREDDS server allows a user to convey more precisely details about an event (future, present, or past).

So, suffice it to say, some rather HEAVY amounts (amounts exceeding monthly average totals) fell, though these amounts should not have been TOO surprising, given the tropical underpinnings of the low pressure system that produced the rainfall. 


Below, is a cherry-picked image (in contrast to the trend loops posted earlier) from EMC's Geoff Manikin's FV3/GFS compare site that shows the 60-hr forecasts of the 24-hour forecast rainfall amounts from the GFS on the left, and FV3 on the right, ending at 00Z, Jul 5.  This image not only shows this particular GFS forecast indicating higher 24-hr rainfall totals (5-6 inches if I'm seeing the colors right) right over Houston, but also amounts, for this one snapshot, that are in excess of the FV3.   A pretty good forecast.



I will close this updated post out with sharing a GEFS QPF plume for KIAH (available from Tracy's site here) from the 00Z, Jul 2nd run, which shows a >3 inch forecast to fall on July 4th.