Synoptic Situation: Satellite Images
This chapter on the synoptic situation gives us a firm description on the synoptic
background of this case to later help and explain the weather phenomena of the
2
nd and 3
rd October 2007 in Spain. To start with we first
present the weather charts and give a description on the synoptic situation.
In the Enhanced IR10.8 below loop you see below in a first glance already
reveals the severe convection taking place during these two days. A closer
look even shows some finer structures within the convection like fierce V-shaped
storms depicting the severity of this case.
KNMI weather charts
In this animation the surface analysis from KNMI for 2
nd and 3
rd
October 2007 are presented and described. This should give you some advantage
in finding out what the synoptic background to this case was and which systems
are involved.
Meteosat 9 IR10.8μm: time sequence
In this series of images the synoptic situation and the convective developments
over Spain are described using plain Meteosat infrared 10.8 μm. The channel
is appropriate as it pictures the ice particles from high clouds quite clearly.
In a sequence of 30 minutes the relevant satellite image are presented.
Meteosat 9 Enhanced IR10.8μm: time sequence
In this chapter again Meteosat 9 infrared 10.8 μm is shown, but the images
have been artificially color enhanced. This will improve the discrimination
of where most ice particles form during the several convective stages. In a
sequence of 30 minutes the satellite images are presented and described.
Meteosat 9 WV6.2μm: time sequence
The chapter presents the several convective developments over Spain using Meteosat 9 WV6.2 channel. The channel is suitable as it gives an idea of the upper tropospheric humidity (UTH) and gives a view of the upper air dynamics. 30 minutes sequence of images are presented.
Meteosat 9 Airmass RGB: Time sequence
In the following animation the convection and the processes explaining the weather activity in this case is reflected with the Airmass RGB. The Airmass RGB is combined of the WV6.2 - WV7.3 Brightness Temperature Difference (BTD, on red), the IR9.7 - IR10.8 BTD (on green) and the WV6.2 channel (on blue).
All three features are strongly related to airmass characteristics in cloud-free areas and to the height of the clouds in cloudy areas.
Combined in a RGB, the result is an image where high clouds appear in white
color, mid-level clouds in light ochre color and cloud-frees areas in dark green
color (warm air mass with high tropopause) or blue color (cold air mass with
low tropopause). A particular feature of this RGB is that dry descending stratospheric
air is marked by a reddish color.
Meteosat 9 Satellite Images in combination with Geopotential Height 1000 hPa.: Time sequence
In the following chapter the cloud configurations seen in satellite images are related to the basic field of surface pressure represented by geopotential height in 1000 hPa. 6-hourly sequences are shown.
Meteosat 9 Satellite Images in combination with Geopotential Height 500 hPa.: Time sequence
In the following chapter the cloud configurations seen in satellite images are related to the basic field of the upper level height in 500 hPa. 6-hourly sequences are shown.
HIRLAM: Precipitation forecast
The model runs from HIRLAM of 2nd and 3rd of October 00UTC are the basis for
the total precipitation that was forecasted during the events of this case.
These forecast images are shown in combination with the enhanced IR10.8 satellite
image to make a comparison between model and real time imagery.
MeteoAlarm: Time Sequence
In 2007 the European Weather Services have started a new project called MeteoAlarm
in which all the warning are collected and presented to the public. The following
series of images shows us the warning during those two days. For different time
steps the situation is described.
Summary of the investigations in this chapter
The weather charts give us a good background on the synoptic situation this
case happened in. In the beginning of the case there was a frontal zone seen
covering the Iberian Peninsula. With a cut off low over the Atlantic a constant
flow of warm and humid air was ensured for Spain. The MeteoAlarm sites showed
us in combination with the IR images where the most severe convection and
highest reports of rainfall and thunderstorms where happening. The red warning
showed us that this was an exceptional case. In the second part of this chapter
the different satellite images were presented. Interesting to see where the
before mentioned cut off low and the fierce severe convection in the form
of V-shaped thunderstorms. The Airmass Images also showed us clearly the presence
of the jet in the upper layers which directed the warm moist air towards Spain.
The set of basic parameters showed the same picture. Different structures
where analyzed. In the upper layers at 500 hPa a developing omega-block was
seen which made certain that the depression that later developed over Spain
from a Wave bulge was kept stationary ensuring a continuous setting for bad
weather.
The next chapter deals in more detail the meteorological parameters to help
analyzing the event.