Thursday, December 6, 2007


Here in the Houten, the sky was clear this morning, with a beautiful view of the moon and Venus in the sky. Rain is predicted later in the day, looks like the WFS 1 is moving eastwards. Here is a Google Earth Image of a balloon trajectory forecast (0600UTC) using locations of De Bilt. The cloud information is for 0700 UTC, provided by Google Earth. The WFS 1 is in the bottom left corner.

Regarding the SATREP for today. There is a WFS identified by SATREP over Belgium (1) and one over Finland (2). Both have a CF in CA along the vertical element of the letter T which I described in a previous post. WFS 1 is a T rotated from vertical to the right. WFS 2 is more or less straight. Actually, this T in the isotachs looks more like a pickaxe.

The frustrating thing about isotachs is that the direction of motion is not obvious to me. The wind direction from the local station in Houten is coming from the S (0830 UTC). But midnight it was more W-SW, which corresonds with the midnight radiosondes. Belgium, Netherlands and North France all have the wind coming from 270 degrees, i.e. from the west (UTC 0000, 6 hours earlier than the SATREP report I am looking at). There is a strong gradient in the isotachs (oriented North south) at the edge of the WFS1. The whole edge is moving east (Check EUMETSAT loops).


  1. About an hour after the last post, it started pouring rain in the Utrecht area. It rained all day.

  2. I see that the time of day in the blog does not correspond with my local time. This will have to be fixed. For now, my local time is 11:00 a.m.