Agro-Meteorological Bulletin for the Third Dekad (21st - 31st) of October, 2020



ISSUED AT: 09:02 PM

Date: Tuesday 20th of October 2020

Figure 1.

Figure 2.

Summary:

During the third dekad of October 2020, relatively wet days are expected on the 21st, 22nd, 25th, 26th, and 27th; while wet days are expected on the 23rd, 24th, 28th, 29th, 30th and 31st. On relatively wet days expect intermittent cloudy patches with a moderate probability of 60% of showers and on wet days expect cloudy periods with a moderate probability of 70% of light to moderate showers.


Agro-Meteorological Bulletin for the Third Dekad (21st - 31st) of October, 2020



ISSUED AT: 09:02 PM

Date: Tuesday 20th of October 2020


Definitions used in the forecast and bulletin:

Term Meaning
Dekad 10 day rainfall measuring period
Rain Day A day with 1.0 mm or more of rainfall amount
Wet Day A day with 10.0 mm or more rainfall amount
Extremely Wet Day A day with 25.0 mm or more of rainfall amount
Normal Rainfall Between 75% and 125% of the average
Below Normal Rainfall Rainfall below 75% of the average
Above Normal Rainfall Rainfall in excess of 125% of the average
Much Below Normal Rainfall Rainfall below 50% of the average
Much Above Normal Rainfall Rainfall above 150% of the average
Scanty Rainfall Less than 1 mm
Moderate Rainfall 1-10 mm
Heavy Rainfall 10-50 mm
Very Heavy Rainfall Greater than 50 mm
Probability of 1-30 % Low Chance
Probability of 30-70 % Moderate Chance
Probability greater than 70 % High Chance
Term Amount of Rain Type of day
Scanty Rainfall Less than 1 mm Relatively dry day
Moderate Rainfall 1-10 mm Relatively wet day
Heavy Rainfall 10-50 mm Wet day
Very Heavy Rainfall Greater than 50 mm Excessively wet day

Weather Assessment for the period (11th-19th) of October 2020.

During the period 11th to 19th of October, mostly relatively wet days occurred over Trinidad and Tobago. In Trinidad, wet days occurred on the 12th, 17th and 18th; with one excessively wet day on the 13th, while in Tobago a wet day occurred on the 18th.  These wet days were due to the passage of active tropical waves and/or localized convective activity due to day-time heating. Rainfall totals’ maps for the period 11th to 19th of October are located below as figure 1 and figure 2.

 

 

Figure 1. Rainfall map of Trinidad showing measured rainfall totals for varying districts during period 11th to 19th of October 2020.

 

Figure 2. Rainfall map of Tobago showing measured rainfall totals for varying districts during period 11th to 19th of October 2020.

 

The observed temperatures (maximum/minimum), average relative humidity (maximum/minimum) and long-term 10-day (10dys) averages for Piarco International Airport and ANR Robinson International Airport during second dekad of October 2020.

Location

Maximum Temperature

0C/ Long term 10 dys average 0C

Minimum Temperature

0C /Long term 10 dys average 0

Average maximum Relative humidity

(%)/ Long term 10 dys average (%) 

Average minimum Relative humidity

(%)/Long term 10 dys average (%) 

Trinidad (Piarco International airport)

35.5/32.4

(1981-2010)

21.6/23.6

(1981-2010)

90/93

(1990-2010)

76/70

(1990-2010)

 

Tobago (ANR Robinson International airport)

33.2/31.1

(1981-2010)

23.9/24.4

(1981-2010)

77/95

(1990-2010)

68/68

(1990-2010)

 

Table 1 shows the expected weather conditions during the third Dekad (21st 31st) of October 2020, for Trinidad and Tobago.

Table 1.

Days:

Expected weather:

21st  

Intermittent cloudy patches with a moderate probability (60%) of showers.

22nd

Intermittent cloudy patches with a moderate probability (60%) of showers.

23rd

Cloudy periods with a moderate probability (70%) of light to moderate showers.

24th

Cloudy periods with a moderate probability (70%) of light to moderate showers.

25th

Intermittent cloudy patches with a moderate probability (60%) of showers.

26th

Intermittent cloudy patches with a moderate probability (60%) of showers.

27th

Intermittent cloudy patches with a moderate probability (60%) of showers.

28th 

Cloudy periods with a moderate probability (70%) of light to moderate showers.

29th

Cloudy periods with a moderate probability (70%) of light to moderate showers.

30th

Cloudy periods with a moderate probability (70%) of light to moderate showers.

31st

Cloudy periods with a moderate probability (70%) of light to moderate showers.

 

Table 2 shows the expected temperatures, humidity and dust haze days during the third dekad of October for Piarco, Trinidad.

Table 2.

Day

Maximum Temperature

0C

Minimum Temperature

0C

Average Relative humidity (%)

Dust Haze

Yes/No

21st 

34.0

22.0

75

Yes

22nd

34.0

22.0

75

Yes

23rd

31.0

23.5

92

No

24th

31.0

23.5

92

No

25th

34.5

22.0

75

Yes

26th

34.5

22.0

75

Yes

27th

34.5

22.0

75

Yes

28th  

31.0

23.0

93

No

29th

31.0

23.0

93

No

30th

31.0

23.0

93

No

31st

31.0

23.0

93

No

 

Table 3 shows the expected temperatures, humidity and dust haze days during the third dekad of October for the ANR Robinson, Tobago.

Table 3

Day

Maximum Temperature

0C

Minimum Temperature

0C

Average Relative humidity (%)

Dust Haze

Yes/No

21st 

33.0

23.9

75

Yes

22nd

33.0

23.9

75

Yes

23rd

31.0

24.5

92

No

24th

31.0

24.5

90

No

25th

33.0

23.9

75

Yes

26th

33.0

23.9

75

Yes

27th

33.0

23.9

75

Yes

28th  

31.0

25.0

90

No

29th

31.0

24.5

93

No

30th

31.0

24.5

93

No

31st

31.0

24.5

93

No

 

Trinidad’s Mean Daily Rainfall Forecast for the third Dekad of October (21st -31st) 2020.

Northern & Northwestern areas:

Moderate chance (65%) of mean daily rainfall up to 8.8 mm.

North-Eastern and Eastern areas:

Moderate chance (68%) of mean daily rainfall up to 11.0 mm.

Central, West-Central and inland areas:

Moderate chance (65%) of mean daily rainfall up to 9.2 mm.

South-Eastern areas:

Moderate chance (68%) of mean daily rainfall up to 11.0 mm.

Southern areas:

Moderate chance (68%) of mean daily rainfall up to 6.3 mm.

South-Western areas:

Moderate chance (65%) of mean daily rainfall up to 8.6 mm.

 

Figure 3. Rainfall map of Trinidad showing possible rainfall totals for varying districts during the third dekad of October 2020 and percentage probability of occurrence.

 

Tobago’s Mean Daily Rainfall Forecast for the third Dekad of October (21st -31st) 2020.

Northeastern areas:

Moderate chance (68%) of mean daily rainfall up to 9.7 mm.

South-Western areas:

Moderate chance (65%) of mean daily rainfall up to 7.3 mm.

Figure 4. Rainfall map of Tobago showing possible rainfall totals for varying districts during the third dekad of October 2020 and percentage probability of occurrence.

 

Impacts on Agriculture:

During the third dekad of October 2020, relatively wet days are expected on the 21st, 22nd, 25th, 26th, and 27th; while wet days are expected on the 23rd, 24th, 28th, 29th, 30th and 31st. There is a moderate (70%) probability that the anticipated rainfall will return sufficient soil moisture across Trinidad and Tobago. The expected rainfall events may return rivers to moderate/high levels. There is a moderate (69%) probability that some areas will become water-logged especially in low-lying areas during the second half of the dekad. Shrubs and grass-growth will continue at a fast pace. Additionally, with warm average temperatures at this time and moist vegetation, there is a moderate (68%) probability for fungi spread, insect pests and warm weather diseases to develop.

Sun and Moon positions in the sky:

The sun is presently at a latitude of approximately 10.5 degrees South, and with this position, the day-length will be 11.7 hours. There is moderate probability (60%) of intense solar radiation during this third dekad of October, when the sky is generally cloud free. There is also moderate probability (55%) of heat stress on a variety of plant seedlings and young/sick/elderly animals from direct exposure to solar radiation, high temperatures with occasional calm winds. Additionally, the moon’s first quarter moon phase will be on the 23rd followed by full moon phase on the 31st of October. As a result, there will be medium to high moon illumination over crop fields and livestock at night during the dekad.