<div dir="ltr"><div dir="ltr"><div>Dear Phellow Phriammers,</div><div><br></div><div>We have to stop meeting this way.</div><div><br></div><div>I am sure you detect procrastination when you see it. So what explains Nicks annual obsession with the dry line? Is this genuine meteorological passion brought on by the annual development of the dry line. Or is Nick procrastinating from getting ready for his annual migration to New England. Please don't be surprised if I have to ditch this project abruptly.</div><div><br></div><div>Here is todays Hazard map. As you see, things have calmed down a lot on the high plains. </div><div>============================<div><img src="cid:ii_mawpwl5g2" alt="image.png" width="428" height="387"><br></div><div><a class="gmail_plusreply" id="m_-2862414422798862549plusReplyChip-2">+++++++++++++++++++++=</a></div><div>Here's the current surface map.</div><div>======================</div><div><img src="cid:ii_mawt9ufr5" alt="image.png" width="428" height="323"><br>======================</div><div>The Map has simplified itself considerably. A long surface trough coming down from a surface low in Iowa to the TX Gulf Coast accompanied by a cold front which has joined forces with dry desert air to produce a very sharp dry line nw of Corpus Christi. Further north, it gets more blousy.</div><div>======================</div><div><img src="cid:ii_mawtpuza6" alt="image.png" width="428" height="277"><br><br></div><div>======================</div><div>Here is the 500mb chart which shows a deep trough/ridge sequence across the central US, along with a vorticity center in Nebraska. <br></div><div>======================</div><div><br></div><div>Since you all love skew-T's I thought I would give you a grid of them to contemplate.. The grid only shows color where there is some Convective Available Potential Energy, CAPE. So basically you are interested in the size of the pink blob in the middle of each sounding. Big pink is Bad. ======================</div><div><img src="cid:ii_mawqfmqv3" alt="image.png" width="428" height="357"><br>====================== <br></div><div>I am focussing on the sounding at Houston TX because it has the largest CAPE but DOESN'T seem to be getting much attention. Why is that? </div><div>======================</div><div>
<img src="cid:ii_mawqk7h03" alt="image.png" width="138" height="84" style="margin-right:0px"> <br></div><div>Somebody made the terrible mistake of encouraging me to explain a skew T Diagram in more detail, so now the rest of you have to suffer. Focus first on the two dashed lines angling up to the right, one red, one black. They are lines of equal temperature. I think the black line is freezing and the red one is -30 C?. They are skewed to the right for graphical convenience. Now ignore them. Now pay attention to the nice green line. That is the dewpoint tracing of the actual sounding. There appear to be two elevated mixed layers in this sounding, shown by where the green line makes a rapid excursion to the left (dryer air) and then wanders back toward the right; forming a sort of a triangle. They are called mixed layers because their potential temperature is relatively constant; but as the water vapor line suggests, they get moister as you go up because water vapor is lighter than the air that it is in and tends to collect at the top of the layer. Now pay attention to the redline which is the actual temperature profile of the sounding. A stable sounding will be more vertical; an unstable sounding will drift diagonally off to the left. Finally, pay attention to the black dotted line that bulges out to the right. That is the "lifted parcel temperature" So imagine that you took a parcel of that nice soupy air near the surface and lifted it until it was saturated and then KEPT LIFTING IT. It would become "warmer" than the air around it (its "environment") The pink area between is all the extra buoyancy that that upward moving moist air would capture because of its water vapor content. The condensation of that moist air would, of course, take the form of rapidly rising towering cumulus. </div><div><br></div><div>Now, the soundings above are all calculated and interpolated from 40 plus actual soundings around the US. Unfortunately the nearest sounding to our "juicy" one is Corpus Christi, which is not very near. <br></div><div>==============================</div><div><img src="cid:ii_mawsmado4" alt="image.png" width="428" height="339"><br><br></div><div>==============================</div><div>Apparently, SPC has taken note of my ambivalence about the S TX situation and has put out a special analysis of that area which shows a the dry line to the NW and a slight cyclonic curvature in the 500mb height contours, and a line of showers developing parallel to the coast already in the morning. <br></div><div>======================</div><div>
<img src="cid:ii_mawpkrk40" alt="image.png" width="378" height="287" style="margin-right:0px">
<br clear="all"></div>=============================<br></div><div><span class="gmail_signature_prefix">I will end with a satellite of the same area. You can see the cold front pushing through the coast but thunderstorm development seemsto be confined to NE Mexico. And there is tons of shear. Go figure!</span></div><div><span class="gmail_signature_prefix"><br></span></div><div><span class="gmail_signature_prefix">=======================================================</span></div><div><a href="https://cdn.star.nesdis.noaa.gov/GOES19/ABI/SECTOR/sp/GEOCOLOR/GOES19-SP-GEOCOLOR-600x600.gif">https://cdn.star.nesdis.noaa.gov/GOES19/ABI/SECTOR/sp/GEOCOLOR/GOES19-SP-GEOCOLOR-600x600.gif</a></div><div><br></div><div><span class="gmail_signature_prefix"> <br></span></div><div><span class="gmail_signature_prefix"> ===========================</span></div><div><span class="gmail_signature_prefix">Nick</span></div><div><span class="gmail_signature_prefix">====================== </span><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>Nicholas S. Thompson</div><div>Emeritus Professor of Psychology and Ethology</div><div>Clark University</div><div><a href="mailto:nthompson@clarku.edu" target="_blank">nthompson@clarku.edu</a></div><a href="https://wordpress.clarku.edu/nthompson" target="_blank">https://wordpress.clarku.edu/nthompson</a></div></div></div>
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