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.