251 lines
18 KiB
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251 lines
18 KiB
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<title>NDFD_QPF_Checks</title>
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<font face="New Century Schoolbook, Times New Roman, serif"><font
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size="5"><b>NDFD_QPF_Checks</b></font></font>
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<br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif"><font
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size="3"><b>What the Procedure Does</b></font></font>
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<br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">The NDFD_QPF_Checks procedure performs two,
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simple consistency checks on the SnowAmt6hr grid:
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<ol>
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<li>1.Where SnowAmt6hr >= 0.5 inches, checks to ensure QPF6hr >= 0.01 inches.</li>
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<li>1.Where SnowAmt6hr >= 0.1 inches, checks to ensure at least one of the overlapping Wx grids
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contains S, SW, and/or IP. The frozen precipitation type can be mixed with any liquid and/or
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freezing precipitation type. The procedure does not consider probability, coverage, intensity, and/or
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visibility of the frozen precipitation in the Wx grid.</li>
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</ol>
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The procedure also performs two, simple consistency checks on the QPF6hr grid:
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<ol>
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<li>1.Where QPF6hr > 0.0, checks to ensure at least one of the overlapping PoP grids is greater than
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zero. The PoP grids here are the “floating” PoP grids.</li>
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<li>1.Where QPF6hr > 0.0, checks to ensure that at least one of the overlapping Wx grids has at least
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one of the precipitating Wx types, which includes L and ZL. The check is made against the Wx type only.
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The procedure does not consider probability, coverage, intensity, and/or visibility of the precipitating
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Wx type.</li>
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</ol>
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Finally, the procedure performs a simple check on the PoP12hr grid: Where PoP12hr >= 50%, checks to ensure
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at least one of the overlapping QPF6hr grids >= 0.01 inches.</font>
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<br>
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<br>
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<big><big><font style="font-weight: bold;"
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face="New Century Schoolbook, Times New Roman, serif">
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Usage Considerations</font><span style="font-weight: bold;">
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</span></big></big><br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">
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<ol>
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<li>It is assumed and recommended that the user derives the QPF6hr, SnowAmt6hr, and PoP12hr grids
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using other GFE procedures and/or smart tools. The National Smart Tool/Smart Initialization Team (STSIT)
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strongly recommends the Collaborate_PoP_SnowAmt_QPF procedure for this task. If NDFD_QPF_Checks finds
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inconsistencies, then you will need to:
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<ol>
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<li>Fix the QPF, SnowAmt, PoP, and/or Wx grids;</li>
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<li>Regenerate the QPF6hr, SnowAmt6hr, and PoP12hr grids;</li>
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<li>Re-run the NDFD_QPF_Checks procedure.</li>
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</ol>
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Finally, the “Send Grids to NDFD” script does not send the QPF6hr, SnowAmt6hr, or PoP12hr grids to NDFD.
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It still sends the QPF, SnowAmt, PoP, and Wx grids. Thus, it is imperative that whatever means you use to
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derive QPF6hr, SnowAmt6hr, and PoP12hr grids emulates what the NDFD server does to create its grids from
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the grids sent from the GFE. The Collaborate_PoP_SnowAmt_QPF meets this need.</li>
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<li>For all checks, if the initial threshold is not triggered, then the grids are considered consistent by
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definition. In other words:
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<ol>
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<li>If SnowAmt6hr < 0.5 inches, then SnowAmt6hr and QPF6hr are always consistent.</li>
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<li>If SnowAmt6hr < 0.1 inches, then SnowAmt6hr and Wx are always consistent.</li>
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<li>If QPF6hr < 0.01 inches, then QPF6hr and PoP are always consistent.</li>
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<li>If QPF6hr < 0.01 inches, then QPF6hr and Wx are always consistent.</li>
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<li>If PoP12hr < 50%, then PoP12hr and QPF6hr are always consistent.</li>
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</ol>
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Later in the documentation, a reference to “control” parameters/grids will be made. For each check listed
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above, the first parameter listed is what will be called the “control” parameter/grid.</li>
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<li>For the checks that involve SnowAmt6hr, QPF6hr, and PoP12hr, the start time and duration of those
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grids are verified. If any of these grids have been stretched, the procedure will not perform the
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associated check and will generate an urgent GFE message. For the SnowAmt6hr and QPF6hr grids, they must
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start at 00, 06, 12, or 18 UTC and be exactly 6 hours in duration. For the PoP12hr grids, they must start
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at 00 or 12 UTC and be exactly 12 hours in duration.</li>
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<li>With no time range selected in the grid manager, the procedure will use 0 to 240 hours, with respect
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to UTC, as the time range. If all of the checked grids exist out to 240 hours, they will all be checked.
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In many WFOs, some of the checked grids do not go out to 240 hours. In those cases, the checks will only
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be done for the time range of the “control” parameter. For example, if your SnowAmt6hr grid spans the 0
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to 72 hour time range, then the two SnowAmt6hr checks will stop at 72 hours. This same idea holds for
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swept out time ranges, i.e., if you sweep out a time range beyond the end of one of the “control”
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parameters, the check will stop with the last “control” parameter grid.</li>
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<li>The procedure makes some attempts to identify missing grids. (It should be noted that these attempts
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are not very robust. There are probably just as many cases of missing grids being identified as there are
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cases of missing grids not being identified.) There is an underlying assumption in those attempts that the
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“control” parameter will not extend later in time than the parameter it is being checked against. This
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assumption breaks down for the PoP12hr/QPF6hr check because NDFD requires the PoP12hr grid at later time
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steps than the QPF6hr grid. To avoid generating a lot of erroneous missing QPF6hr grid warning messages,
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the procedure will compare the end times of the two grid sets. If the PoP12hr grid does extend farther in
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time than the QPF6hr grid, then the time range used in the PoP12hr/QPF6hr check will be dynamically
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adjusted back to the end of the last QPF6hr grid which has an end time of either 00 or 12 UTC.</li>
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<li>When the procedure is installed, it can be configured to use an edit area which covers just your CWA.
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If this is done, then the procedure will only return inconsistencies over that edit area. If this is not
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done, or the procedure has a problem with the CWA edit area, then the procedure will run over the entire
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domain. In the latter case, this means you can get flagged for inconsistent points in your GFE domain that
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are totally outside your CWA. In no case will the procedure run over any edit areas drawn in the GFE
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Spatial Editor window. It always runs over the whole GFE domain.</li>
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<li>1.For each check, the procedure loops over the available “control” grids. For each “control” grid,
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the overlapping “non control” grids are checked for consistency. For the checks involving PoP and Wx,
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it's possible for the “control” grid and the PoP/Wx grid to not be aligned. By this, it is meant a PoP/Wx
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grid could have a start time earlier than the start time of the “control” grid or a PoP/Wx grid could
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have an end time later than the end time of the “control” grid. While the procedure doesn't care if
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this is the case, the results, if there are inconsistencies, could be difficult to interpret since the
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PoP/Wx grid is not only being compared to the current “control” grid but also to the previous or next
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“control” grid. For example, let's say you're running the QPF6hr/Wx check. The QPF6hr grid being check
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runs from 06 to 12 UTC. However, overlapping this QPF6hr grid are two Wx grids. One runs from 06 to
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09 UTC and the other runs from 09 to 15 UTC. The first grid presents no problems since it's aligned
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with the QPF6hr grid. However, the second grid extends beyond the end of the QPF6hr grid (15 UTC
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vs 12 UTC). If an inconsistency arises and the solution is to change the Wx grid, the change will
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have to be made such that two QPF6hr grids are consistent with it, the one running from 06 to 12 UTC
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and the on running from 12 to 18 UTC.</li>
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<li>For the SnowAmt6hr/Wx check, the QPF6hr/Wx check, and the PoP12hr/QPF6hr check, any temporary
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inconsistent grid will span the time range of the “controlling” grid. The temporary inconsistent grid
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will show the points where ALL of the “non controlling” grids were inconsistent. See figures 8 through
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11.</li>
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</ol>
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When the procedure is run, the forecaster is presented with several choices. The first is whether to run
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checks or to “Cleanup”. By default, the procedure will run checks. The “Cleanup” option will undo any
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highlighting and remove any temporary grids. With the “Cleanup” option selected, all other options on the
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GUI are ignored. If you leave “Check” selected, then you can choose which of the checks you wish to run by
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toggling on and off the appropriate button. By default, all checks will be run:<br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks.png"><br><br>
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The procedure will create temporary grids which show where the inconsistencies occur. The values in all the
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temporary grids are either zero (consistent) or one (inconsistent). The temporary grid names are a
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concatenation of the two grid names used in the check with the “control” grid name first. The procedure
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can also be configured to highlight both the temporary grids and the bad “source” grids. In the default
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configuration, highlighting is turned on with the bad “source” grids colored red and the temporary grids
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colored orange. (See Figures 3 through 7.) The procedure does not modify any grids. It's left up to the
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forecaster to determine how, if at all, to handle the inconsistencies. The issue of a check only versus a
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check/force procedure was discussed by the STSIT and the consensus recommendation was a check only
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procedure. The STSIT feels strongly that there are no meteorologically sound ways to force consistency
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of these grids, but we are always willing to listen to and consider other points of view. Any
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inconsistencies will pop up a “significant” GFE message:<br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks1.png"><br><br>
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This is an example of how the GFE will look after the procedure is run and there are inconsistencies.
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In the grid manager, you can see one temporary grid, SnowAmt6hrQPF6hr, has been created and is
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highlighted in the color orange. The corresponding SnowAmt6hr and QPF6hr grids have been highlighted
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in the color red. In the above figure, there is a also second “significant” message. Note the
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“Acknowledge All (1 Pending...)”. That message tells the user the procedure ran over a swept-out time
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range. Since the procedure has no way of knowing whether the user meant to sweep out a time range, It was
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decided to put in a “significant” pop-up to “remind” the user. Finally, while not shown, there are conditions
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that can generate an “Urgent Message” pop-up, the ones that are colored red. Some conditions that cause
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urgent messages are: missing grids, locked grids, and bad time constraints.<br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks2.png"><br><br>
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The SnowAmt6hr/QPF6hr check enforces the following rule:<br>
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If SnowAmt6hr >= 0.5 in, then QPF6hr >= 0.01 in.<br>
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In the above figure, there are four sample points, each in a unique zone. Starting in the “upper-left”
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zone and moving clockwise, the sample points have the following values:<br><br>
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SnowAmt6hr = 0.5 in, QPF6hr = 0.01 in, SnowAmt6hrQPF6hr = 0: This is a good result.<br>
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SnowAmt6hr = 0.5 in, QPF6hr = 0.00 in, SnowAmt6hrQPF6hr = 1: This is a bad result.<br>
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SnowAmt6hr = 0.0 in, QPF6hr = 0.00 in, SnowAmt6hrQPF6hr = 0: This is a good result.<br>
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SnowAmt6hr = 0.0 in, QPF6hr = 0.01 in, SnowAmt6hrQPF6hr = 0: This is a good result.<br><br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks3.png"><br><br>
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The SnowAmt6hr/Wx check enforces the following rule:<br><br>
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If SnowAmt6hr >= 0.1 in, then one of the overlapping Wx grids must contain S, SW, or IP. Only the Wx
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type is important to this check. The Probability/Coverage, Intensity, and Visibility are all ignored.
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Also, the frozen types can be mixed with the liquid and/or freezing types.
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In the above figure, there are four sample points, each in a unique zone. Starting in the “upper-left”
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zone and moving clockwise, the sample points have the following values:<br><br>
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SnowAmt6hr = 0.5 in, Wx = Chc S-, SnowAmt6hrWx = 0: This is a good result.<br>
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SnowAmt6hr = 0.5 in, Wx = NoWx, SnowAmt6hrWx = 1: This is a bad result.<br>
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SnowAmt6hr = 0.0 in, Wx = NoWx, SnowAmt6hrWx = 0: This is a good result.<br>
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SnowAmt6hr = 0.0 in, Wx = Chc S-, SnowAmt6hrWx = 0: This is a good result.<br><br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks4.png"><br><br>
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The QPF6hr/PoP check enforces the following rule:<br><br>
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If QPF6hr > 0.0 in, then at least one of the overlapping PoP grids > 0%.
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In the above figure, there are four sample points, each in a unique zone. Starting with the “upper-left”
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zone and moving clockwise, the sample points have the following values:<br><br>
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QPF6hr = 0.01 in, PoP = 1%, QPF6hrPoP = 0: This is a good result.<br>
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QPF6hr = 0.01 in, PoP = 0%, QPF6hrPoP = 1: This is a bad result.<br>
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QPF6hr = 0.00 in, PoP = 0%, QPF6hrPoP = 0: This is a good result.<br>
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QPF6hr = 0.00 in, PoP = 1%, QPF6hrPoP = 0: This is a good result.<br><br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks5.png"><br><br>
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The QPF6hr/Wx check enforces the following rule:<br><br>
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If QPF6hr > 0.00 in, then at least one of the overlapping Wx grids must contain a precipitating Wx type.
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These are: R, RW, L, S, SW, IP, ZR, and ZL Only the weather type is considered in the check. The
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Probability/Coverage, Intensity, and Visibility are all ignored. In the above figure, there are four
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sample points, each in a unique zone. Starting with the “upper-left” zone, the sample points have the
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following values:<br><br>
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QPF6hr = 0.01 in, Wx = Chc S-, QPF6hrWx = 0: This is a good result.<br>
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QPF6hr = 0.01 in, Wx = NoWx, QPF6hrWx = 1: This is a bad result.<br>
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QPF6hr = 0.00 in, Wx = NoWx, QPF6hrWx = 0: This is a good result.<br>
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QPF6hr = 0.00 in, Wx = Chc S-, QPF6hrWx = 0: This is a good result.<br><br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks6.png"><br><br>
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The Pop12hr/QPF6hr check enforces the following rule:<br><br>
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If Pop12hr >= 50%, then at least one of the overlapping QPF6hr grids must be > 0.00 in.<br><br>
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This is the first figure where the “controlling” grid is shown with more than one overlapping
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“non controlling” grid. The second QPF6hr grid, which is not shown, has 0.00 in assigned to
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the entire grid, which means it cannot be consistent with the PoP12hr grid where it is >= 50%.
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In the above figure, there are four sample points, each in a unique zone. Starting with the
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“upper-left” zone and moving clockwise, the sample points have the following values:<br><br>
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PoP12hr = 50%, QPF6hr = 0.01 in, PoP12hrQPF6hr = 0: This is a good result.<br>
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PoP12hr = 50%, QPF6hr = 0.00 in, PoP12hrQPF6hr = 1: This is a bad result.<br>
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PoP12hr = 49%, QPF6hr = 0.00 in, PoP12hrQPF6hr = 0: This is a good result.<br>
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PoP12hr = 49%, QPF6hr = 0.01 in, PoP12hrQPF6hr = 0: This is a good result.<br><br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks7.png"><br><br>
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The edit areas were constructed from the following query:<br><br>
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wxContains(Wx,[],['<NoWx>', 'BD', 'BN', 'BS', 'F', 'FR', 'H', 'IC', 'IF', 'K', 'T', 'VA',
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'WP', 'ZF', 'ZY',[],[],[]) & (QPF6hr > 0) & ISC_Send_Area (This all fits one the query
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line in the GFE.) Explanation of this figure follows the screen print below.<br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks8.png"><br><br>
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The edit areas were constructed from the following query:<br><br>
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wxContains(Wx,[],['<NoWx>', 'BD', 'BN', 'BS', 'F', 'FR', 'H', 'IC', 'IF', 'K', 'T', 'VA',
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'WP', 'ZF', 'ZY',[],[],[]) & (QPF6hr > 0) & ISC_Send_Area (This all fits one the query
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line in the GFE.) The query simulates the inconsistency for this check: Where QPF6hr > 0,
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the Wx grid has no precipitable type.
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<br><br>
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The two previous screen shots show a case where two “non controlling” grids (Wx) are
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individually inconsistent with the “controlling” grid (QPF6hr), but together are consistent.
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In other words, everywhere the “first” Wx grid is inconsistent, the “second” Wx grid is consistent.
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Similarly, everywhere the “second” Wx grid is inconsistent, the “first” Wx grid is consistent.
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Since, together, the two Wx grids are consistent with the QPF6hr grid, there is no QPF6hrWx
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temporary grid in either of the last two screen shots.<br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks9.png"><br><br>
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The edit areas shown are from the following query:<br><br>
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(PoP12hr >= 50) & (QPF6hr < (0.01-0.0001)) & ISC_Send_Area<br><br>
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Explanation of this figure follows the screen print below.<br>
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<img alt="NDFD_QPF_Checks" src="images/NDFD_QPF_Checks10.png"><br><br>
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The edit areas shown are from the following query:
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(PoP12hr >= 50) & (QPF6hr < (0.01-0.0001)) & ISC_Send_Area
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This simulates the inconsistent condition of the check: Where PoP12hr >= 50, QPF6hr = 0.
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<br><br>
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This example shows a case where one of the QPF6hr grids (06-12 UTC grid) is more inconsistent
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with the PoP12hr grid than the other QPF6hr grid (00-06 UTC). The temporary PoP12hrQPF6hr
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inconsistent grid has the value 1 (bad) only where both QPF6hr grids are inconsistent with the
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corresponding PoP12hr grid.<br><br>
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<b>Tips</b><br>
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If you have inconsistencies, here's an example of how you can quickly generate edit areas
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for the inconsistent areas:
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<ul>
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<li>Left-click on the “?” to open the query dialog.</li>
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<li>Under “Weather Elements”, there should be at least one temporary grid element listed.
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Left-click on one of them, then left-click on the “==”, and finally left-click on the
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number “1”. Then, left-click on “Submit”.</li>
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<li>Move/hide/cancel the query dialog. Now, you can make an temporary grid editable,
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assign a value or run a tool and these actions will apply to the inconsistent areas only.</li>
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</ul>
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</font>
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</body>
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</html>
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