<div dir="ltr">Chris and other interested parties--<div><br></div><div>This has been a difficult nut to crack for both modelers and operational forecasters. Lots of factors affect snow depth: the vertical temperature profile as you've been discussing, but also wind (which will tend to compact the snow), whether or not there's upward motion in the dendritic growth zone to create those low-density fluffy flakes that can make 20:1 snow depth to WEASD, ground temperatures, and others. It's an entire topic of research in operational meteorology. </div><div><br></div><div>That being said, I'll have to check out that Kucera link also. :-)</div><div><br>Bill</div><div><br></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature">Dr. William R. Bua<br>UCAR/COMET/NCEP/EMC<br>5830 University Research Court #2784<br>
College Park, MD 20740<br>301-683-3806<br></div></div>
<br><div class="gmail_quote">On Tue, Sep 29, 2015 at 9:42 AM, Christopher Gilroy <span dir="ltr"><<a href="mailto:chris.gilroy@gmail.com" target="_blank">chris.gilroy@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Ahh, yea I just do the programming for a degree'd met. He wanted to base a formula around 2m tmp, 700mb temp and 850mb temp. That's an interesting link too.<div><br></div><div><br></div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Sep 29, 2015 at 9:21 AM, Stephen McMillan <span dir="ltr"><<a href="mailto:smcmillan@planalytics.com" target="_blank">smcmillan@planalytics.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Chris,<div><br></div><div>I suppose there are a number of vertical-temperature based formulas/algorithms out there, one of which is the Kuchera method which uses an algorithm based, in part, on the max temperature between 500mb and the surface It seems to work fairly well for most scenarios. Here's a link for more information:</div><div><a href="http://www.wxcaster.com/gfssnow.txt" target="_blank">http://www.wxcaster.com/gfssnow.txt</a><br></div><div><br></div><div>Hope that helps--</div><div>Stephen Mc</div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Sep 29, 2015 at 9:11 AM, Christopher Gilroy <span dir="ltr"><<a href="mailto:chris.gilroy@gmail.com" target="_blank">chris.gilroy@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hey Stephen,<div><br></div><div>Thanks for your response I figured that out after the fact. I appreciate the help you've given me with this the past few days. One last question I have to throw out there, what would your thoughts be on having a "dynamic" ratio based on vertical temperatures? Do you think it'd be wildly inaccurate or? I seen Ryan Maue make a comment one time about it causing confusing and/or being great for certain areas but terrible for other areas.</div></div><div class="gmail_extra"><div><div><br><div class="gmail_quote">On Tue, Sep 29, 2015 at 9:07 AM, Stephen McMillan <span dir="ltr"><<a href="mailto:smcmillan@planalytics.com" target="_blank">smcmillan@planalytics.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Chris,<div><br></div><div>If you want to convert amounts in mm to in, you need to divide by 25.4, not 2.54 (or, multiply by the 0.03937 you had in your example). To go the other way (in to mm), multiply in. amounts by 25.4.</div><div><br></div><div>However, if you are converting mm to in. and using a 10:1 snow-liquid ratio, then simply dividing the weasdsfc amounts by 2.54 should achieve the same result as dividing by 25.4 (multiplying by 0.03937) then multiplying result by 10. Result would be in inches.</div><div><br></div><div>Stephen Mc</div><div><br></div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div>On Tue, Sep 29, 2015 at 8:41 AM, Christopher Gilroy <span dir="ltr"><<a href="mailto:chris.gilroy@gmail.com" target="_blank">chris.gilroy@gmail.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div><div dir="ltr"><div dir="ltr"><div style="font-size:12.8px">Alright, I have two primary questions, and if the answers are yes to both, the follow-up makes no sense to me.</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">1.) weasdsfc is water equivalent based in mm, correct?</div><div style="font-size:12.8px">2.) weasdsfc has no "default" liquid:water ratio, correct? A meteorology friend of mine said 'typically' 10:1 is a good standard, so I'm unsure if the model is based around that or not?</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">I'm fairly certain I'm correct on #1. I'm unsure on the other 2 though, but here's my current situation. If I use the expression below:</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">'d const((sum(maskout(weasdsfc-weasdsfc(t-1),weasdsfc-weasdsfc(t-1)),t=2,t='%i%')/2.54), 0, -u)' <br></div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">I get an identical looking map as another well known sites 10:1 snow accum, in inchs. The confusion part of that equation should be converting (/2.54) IN to MM, no?</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><span style="font-size:12.8px">Now, if on the other hand I do the (if I'm understanding this right) "correct" calculation to convert mm to in:</span><br></div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><span style="font-size:12.8px">'d const((sum(maskout(weasdsfc-</span><span style="font-size:12.8px">weasdsfc(t-1),weasdsfc-</span><span style="font-size:12.8px">weasdsfc(t-1)),t=2,t='%i%')*0.</span><span style="font-size:12.8px">039370), 0, -u)'</span><br></div><div style="font-size:12.8px"><br></div>I get very, very, very little snow plotted.<div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><span style="font-size:12.8px">Now, I am using the sflux files instead of the pgrb2.0p25 files, which I thought the flux files maybe used different units or something but they don't, weasdsfc is still [</span><span style="font-size:12.8px;color:rgb(0,0,0);white-space:pre-wrap">kg/m^2] which should mean (unless my expression is more of a hack than I would have imagine) I should be getting the opposite outputs of what each expression is actually producing?</span><br></div><div style="font-size:12.8px"><span style="color:rgb(0,0,0);white-space:pre-wrap"><br></span></div><div style="font-size:12.8px"><span style="color:rgb(0,0,0);white-space:pre-wrap">I don't know if I'm missing a parenthesis group somewhere and I'm somehow getting an inches, 10:1 snow accum plot with my code by "accident" or what? :-/</span></div></div>
</div>
<br></div></div>_______________________________________________<br>
gradsusr mailing list<br>
<a href="mailto:gradsusr@gradsusr.org" target="_blank">gradsusr@gradsusr.org</a><br>
<a href="http://gradsusr.org/mailman/listinfo/gradsusr" rel="noreferrer" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>
<br></blockquote></div><br></div>
<br>_______________________________________________<br>
gradsusr mailing list<br>
<a href="mailto:gradsusr@gradsusr.org" target="_blank">gradsusr@gradsusr.org</a><br>
<a href="http://gradsusr.org/mailman/listinfo/gradsusr" rel="noreferrer" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>
<br></blockquote></div><br><br clear="all"><div><br></div></div></div><span><font color="#888888">-- <br><div>-Chris A. Gilroy</div>
</font></span></div>
<br>_______________________________________________<br>
gradsusr mailing list<br>
<a href="mailto:gradsusr@gradsusr.org" target="_blank">gradsusr@gradsusr.org</a><br>
<a href="http://gradsusr.org/mailman/listinfo/gradsusr" rel="noreferrer" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>
<br></blockquote></div><br></div>
</div></div><br>_______________________________________________<br>
gradsusr mailing list<br>
<a href="mailto:gradsusr@gradsusr.org" target="_blank">gradsusr@gradsusr.org</a><br>
<a href="http://gradsusr.org/mailman/listinfo/gradsusr" rel="noreferrer" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>
<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div>-Chris A. Gilroy</div>
</div>
</div></div><br>_______________________________________________<br>
gradsusr mailing list<br>
<a href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a><br>
<a href="http://gradsusr.org/mailman/listinfo/gradsusr" rel="noreferrer" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>
<br></blockquote></div><br></div>