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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hi Miguel,
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<div>This is straightforward in GrADS if you use a combination of functions. It goes like this:</div>
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<div>If you have a variable for precipitation named <b>precip </b>and let say, 100 ensemble members. You do:</div>
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<div>set e 1 100</div>
<div>define prec5mm = const( const( maskout( precip, precip - 5), 1), 0.0, -u)</div>
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<div>The <i>maskout</i> function sets the values to undefined where precip < 5</div>
<div>The inner <i>const</i> function sets the remaining defined values to ones.</div>
<div>And the outer <i>const</i> function sets the undefined values to zeros.</div>
<div>So the new variable prec5mm is made of 1 wherever precip > 5 and 0 otherwise.</div>
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<div>Now you average for all your ensemble members and multiply the results by 100 to get % of ensemble members with precipitation above 5mm .</div>
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<div>set e 1</div>
<div>define percentage5mm = 100 * ave( prec5mm, e=1, e=100)</div>
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<div>Hope this helps.</div>
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<div style="font-family:Tahoma; font-size:13px">Hosmay Lopez<br>
<span style="font-family:verdana,arial,sans-serif; background-color:rgb(255,255,255)">UM/CIMAS/RSMAS NOAA/AOML/PHOD</span><br style="font-family:verdana,arial,sans-serif; background-color:rgb(255,255,255)">
<span style="font-family:verdana,arial,sans-serif; background-color:rgb(255,255,255)">4301 Rickenbacker Causeway,</span><br style="font-family:verdana,arial,sans-serif; background-color:rgb(255,255,255)">
<span style="font-family:verdana,arial,sans-serif; background-color:rgb(255,255,255)">Miami, FL 33149, USA</span><br style="font-family:verdana,arial,sans-serif; background-color:rgb(255,255,255)">
<span style="font-family:verdana,arial,sans-serif; background-color:rgb(255,255,255)">Phone: (305) 361-4329</span><br>
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<div id="divRpF558677" style="direction: ltr;"><font face="Tahoma" size="2" color="#000000"><b>From:</b> gradsusr-bounces@gradsusr.org [gradsusr-bounces@gradsusr.org] on behalf of Miquel Bernis [bernisfeina@gmail.com]<br>
<b>Sent:</b> Friday, June 19, 2015 3:26 AM<br>
<b>To:</b> GrADS Users Forum<br>
<b>Subject:</b> [gradsusr] Probability precipitation map using ensemble forecast<br>
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<div dir="ltr">Hi everyone,
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<div>Do you think is there any way to plot a forecast probability precipitation map, using an ensemble forecast? I mean, calculating which forecasts of the ensemble give, for example, an amount of rain > 5 mm and which not, for an specific moment of time, and
displaying a contour map of the % you can take from that. Watching to the grads functions it seems not possible, but maybe some of you, with more experience on grads than me, can imagine a way to do that. </div>
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<div>Thanks a lot!</div>
<div>Miquel</div>
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