30 Jan

First thanks to Louise for chiming in yesterday. I didn’t know about windy.com, and now I will have even more reasons not to sleep. I am looking forward to seeing how Friday and Saturday turn out, but with the slackening of the winds from yesterday morning through today, there is a foreshadowing of some of the issues Louise was raising also in today’s tale of two cities.

Yesterday we found ourselves enveloped in a band of precipitating features (A1) with tops near 4km, and substantial rain. Disdro’s peak rain-rate at 4:30 UTC was about 85 mm/hr.  The heavy rain was associated with stratiform cloud near the convective tops, large-echo fraction , and quite a bit of variability in the wind, characterized by pronounced bustiness and periods of calms lasting 20 min or more as the winds shifted to more southerly in association with sharp temperature drops. Perhaps this could be interpreted as gusts from the south, or south-west on scales of 20 km or so?  All in all, recalling the classification scheme introduced in earlier posts, I’d say: Fish.

What a difference a day makes. Today (A2), after about 0200 UTC we see no more evidence of large-scale wind shifts, or velocity fluctuations. Rather the wind-field (green lines) shows just some background fluctuations characteristic of a convective boundary layer with no mesoscale imprinting. Likewise temperatures and humidity are much less variable on time-scales longer then those of the convective boundary layer (10 min), and there is much less cloud development. Sugar.

It is not that there are no clouds, as a blow up of the radar (A3) for the last hour indicates shallow clouds, but with little vertical development.  Here it is also instructive to compare to the web cam (A4), if only for perspective.  You see our station as the white containers on the point, and the types of clouds all around was probably what we see in the radar near 18 UTC.

So what was the difference? Looking World View is instructive (see links below as the images are larger)

yesterday: https://powerfolder.gwdg.de/dl/fiTbY=uNVTCgAfUZnfS3uSSs/?inline

today: "to be added"

Essentially we just find ourselves in the Fish yesterday, and outside the Fish today … in the Sugar.

Well if you are more curious, then it is also interesting to compare all this to the movies posted here:


Yesterday’s is posted, todays’ will get posted when the day is done; so in due course.

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