Friday, July 24, 2009
The Noctilucent Clouds Return and the Upcoming Heat Wave
Many saw the noctilucent clouds again last night and a few of you sent some pictures. Above are some pictures provided by Reid Wolcott (top) and Dennis Bell. The "tendrils" of white and blue-white structures of these extraordinarily high (roughly 50 miles up) clouds are other worldly.
The number of observations of these clouds seem to be increasing and some suggest that global warming is to blame. Global warming? Strangely enough, global warming warms the lower atmosphere (the troposphere), but cools the upper portion of atmosphere in which the noctilucent clouds reside. Very cold temperatures are needed to produce these ice clouds, since so little moisture is available at those levels. Interesting idea, but not proved at this point.
We are on track for an extraordinary heat wave next week...or so the models suggest.We will have very warm air over us. However, to get the real record-breakers, strong offshore and downslope flow is needed and it doesn't look that such easterly flow will develop until mid week. One unusual feature of the predicted heat wave is its duration. Normally, our really hot (above 90F) periods are brief...this could last for days. The warmest days look like Tuesday through Thursday. Some of the media jumped the gun going for the 90s over the weekend. More on this over the weekend...but be ready.
HOT TIP: Nothing does better getting the future temps right than the UW probcast system that uses post-processed ensemble predictions. It always beats other forecast guidance during such warm-up situations. Check it out at:
Right now it is going 89F on Sunday. I bet it is on the mark for this!
Posted by Cliff Mass at 7:43 AM