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February, 23 - 2014
Summary
1. General weather condition ................................................................................................ 2
2. Synoptic Scale ................................................................................................................... 2
3. Radar images .................................................................................................................. 10
4. Other instruments ........................................................................................................... 12
1. General weather condition
In February, 23th the temperatures maximum and minimum observed were 28.0°C at 20 UTC
and 22.9°C at 14 UTC, respectively in Manaus. The temperatures, in Manacapuru, were
between 23.6°C at 16UTC and 27.2°C at 13UTC. Manaus in this day, recorded CAPE values
between 402 J/Kg and 384 J/Kg observed at 00 UTC and 12 UTC, respectively. The CINE values
increased from 69 J/Kg to 36 J/kg from 00 to 12 UTC. In the surface a convergence humidity
zone crossing the Brazil. The ITCZ stay acted the east of the continent located slightly to the
south on the west side. In the north of Brazil, the southwestward wind at low levels was well
defined. At high levels the Bolivia high also well defined, but a little dislocated for west. With
the satellite imagery can be seen that north of Brazil was having decrease of our clouds
between 00UTC and 18UTC. With the X-Band Radar was observed a line of rain cells that acted
over cities of Manaus and Manacapuru. The evolution of this precipitation system with a well
defined convective and stratiform portion. Like another, systems have southwestward
propagation like wind direction observed in low levels (about 850hPa). This system showed
high tops during our lifecycle, with top of rain cells higher than 10km, as well as, the bright
band was detected some times during the systems live. The measurements of Average of the
Rain Rate (RR) (mm/h) and reflectivity (dBZ) made with Micro Rain Radar (MRR), showed that
the values associated with rain intensity reached values higher than 135mm/h (between
13:50UTC and 14:00UTC) and reflectivity field, showed the RR signal with values higher than
30dBz. The measurements made with Parsivel disdrometer recorded values higher than 31
mm/h). Can be see the predominance (numerically) of droplets with diameter between 0.7
mm and 2 mm. But many droplets larger than 3 mm also were observed. The rainfall intensity
shown on the bottom of the first figure shows a typical evolution of a convection line, with an
intense rate on the beginning of the event followed by lower values associated with stratiform
rain.
2. Synoptic Scale
Figure 2.1 shows synoptic conditions for February 23th at the a) surface, b) 850 hPa and c) 250
hPa levels at 12 UTC. In the surface chart can be seen a convergence humidity zone crossing
the Brazil. The ITCZ stay acted the east of the continent located slightly to the south on the
west side. In the north of Brazil, the southwestward wind at low levels was well defined. At
high levels the Bolivia high also well defined, but a little dislocated for west. In this level
(250hPa), the wind blowing for northwestward. Also in this level the northeast cost of Brazil
was affected for cyclonic vortex that can be seen in the figures 2.1B and the satellite imagery
in the figures 2.2. With the satellite imagery can be seen that north of Brazil was having
decrease of our clouds between 00UTC and 18UTC.
a)
b)
c)
Figure 2.1: Synoptic conditions for February 23th on a) surface, b) 850 hPa and c) 250 hPa
levels. Source: CPTEC/INPE.
The satellite imagery show that few convective clouds acted over north of Brazil, these
systems was located close to cities of Manaus and Manacapuru, as showed in figures 2.3. Rain
cells were observed at 12:30UTC, near of Manaus and 13:50UTC near of Manacapuru. In this
day a convective system was observed over the Belem state but dissipated faster. Today, like
another days, the propagation of the rain systems show southwestward propagation, similar
to winds direction observed at low levels (850hPa), showed in figure 2.1B.
a)
b)
c)
Figure 2.2 - GOES-13 images for a) 00, b) 12 and c) 18 UTC in February 23th. Source: DSA/INPE.
Figure 2.3 shows thermodynamic profiles for the T3 site at 05:29UTC, 17:26UTC and 20:30
UTC, respectively. At 05:29 UTC the atmosphere was showed a little inversion near of surface.
Can be seen that the humidity enhanced at low levels (from surface to 600hPa) in the times
between 05:29UTC and 14:25UTC. After 14:25UTC a rain band passed over Manacapuru, the
high humidity observed in the diagram showed the cloud presence at low levels. In the next
times, after rain core pass over Manacapuru, can be note that humidity was decline, as show
in figures 2.3D-E.
a)
b)
c)
d)
e)
Figure 2.3 - Thermodynamic profiles for February 23 in the T3 site at 05:29UTC, 11:37UTC,
14:25UTC, 17:28 and 23:30UTC. Source: CHUVA/GOAmazon.
3. Radar images
At February, 23 a line of rain cells acted over the X-Band region. The figure 3.1 showed the
evolution of this precipitation system with a well defined convective and stratiform portion.
Like another, systems have southwestward propagation like wind direction observed in low
levels (about 850hPa). This system showed high tops during our lifecycle, with top of rain cells
higher than 10km, as show in figure 3.2A. The bright band was detected many times during the
systems live in figure 3.2C showed the bright band well define at 17:16UTC.
a)
b)
c)
Figure 3.1: Radar X-Band images of the events which acted on February, 23. The times are: a)
13:00 UTC, b) 14:40 UTC, and c) 16:00 UTC.
a)
b)
c)
Figure 3.2 - X-Band Radar RHI obtained at a) 14:36 UTC, b) 15:46 UTC, 17:16UTC.
4. Other instruments
The measurements of Average of the Rain Rate (RR) (mm/h) and reflectivity (dBZ) made with
Micro Rain Radar (MRR), showed that the values associated with rain intensity reached values
higher than 135mm/h (between 13:50UTC and 14:00UTC) (figure 4.1). In reflectivity field
(figure 4.2), the RR signal also can be note, in this instrument high values (higher than 30dBz)
was recorded. However, this instrument show very attenuation, for this the bright band can’t
be well define like RHI X-Band radar. The measurements made with Parsivel disdrometer
showed in figures 4.3, recorded measured higher than 31 mm/h). In this case there was the
predominance (numerically) of droplets with diameter between 0.7 mm and 2 mm. But many
droplets larger than 3 mm also were observed. The rainfall intensity shown on the bottom of
the first figure shows a typical evolution of a convection line, with an intense rate on the
beginning of the event followed by lower values associated with stratiform rain.
Figure 4.1 - MRR measurements of Average of the Rain Rate for February, 23 (Between
13:30UTC and 15:30UTC).
Figure 4.2 - MRR measurements of Average of the Radar reflectivity for February, 23 (Between
14UTC and 19UTC).
Figure 4.3 - Screen capture of the Parsivel disdrometer software operation made at February,
23. Rain intensity is shown in the bottom of each image and size distribution indication on top.