Agro-Meteorological Bulletin for the First Dekad (1st - 10th) of December, 2019



ISSUED AT: 12:38 PM

Date: Friday 6th of December 2019

Figure 1.

Figure 2.

Summary:

The forecast for the first dekad of December indicates that farmers can expect similarly mixed conditions as compared to the third dekad of November 2019. Expect relatively wet days on days 1st , 2nd, 3rd, 4th, 5th, 6th and 7th, followed by wet days on days 8th, 9th, 10th. On relatively wet days, expect few cloudy periods, light to moderate rainfall and a moderate probability of isolated thundershowers along the western coast of both islands, especially over urban areas of Trinidad during the dekad. On wet days, a possible visitation of the Inter Tropical Conversion Zone (ITCZ) will produce cloudy periods with scattered showers and thundershowers over Trinidad and Tobago.


Agro-Meteorological Bulletin for the First Dekad (1st - 10th) of December, 2019



ISSUED AT: 12:38 PM

Date: Friday 6th of December 2019


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 Third Dekad (21st – 30th) of November 2019.

A mixture of relatively wet and wet days occurred during the third dekad of November in Trinidad and Tobago. The rainfall total maps for the period 21st to 30th of November are located below as figure 1 and figure 2.

Figure 1. Rainfall map of Trinidad showing measured rainfall totals for varying districts during period 21st  to 30th of December 2019.

Figure 2. Rainfall map of Tobago showing measured rainfall totals for varying districts during period 21st to 30th of December 2019.

 

The observed Temperatures (maximum/minimum), Average Relative humidity (maximum/minimum) and Long term 10 days (10dys) averages for locations: Piarco International airport and ANR Robinson International airport.

 

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)

33.1/31.5

(1981-2010)

22.4/23.1

(1981-2010)

90/97

(1990-2010)

78/65

(1990-2010)

 

Tobago (ANR Robinson International airport)

33.2/30.5

(1981-2010)

24.4/24.0

(1981-2000)

85/91

(1990-2010)

77/69

(1990-2010)

           

 

The Expected Weather conditions during the First  Dekad (1st – 10th) of December 2019, for Trinidad and Tobago, as seen in table 1.

Table 1.

Days:

Expected weather:

1st  

Few cloudy periods with light showers and moderate probability (60% ) of a thundershower over Trinidad and Tobago.

2nd  

Few cloudy periods with light showers and moderate probability (60% ) of a thundershower over Trinidad and Tobago.

3rd  

Few cloudy periods with light showers and moderate probability (60% ) of a thundershower over Trinidad and Tobago.

4th  

Few cloudy periods with light showers and moderate probability (60% ) of a thundershower over Trinidad and Tobago.

5th

Few cloudy periods with light showers and moderate probability (60% ) of a thundershower over Trinidad and Tobago.

6th

Few cloudy periods with light showers and moderate probability (60% ) of a thundershower over Trinidad and Tobago.

7th

Few cloudy periods with light showers and moderate probability (65% ) thundershowers over Trinidad and Tobago.

8th

Mostly cloudy periods with scattered showers and high probability (80%) thundershowers over Trinidad and Tobago.

9th

Mostly cloudy periods with scattered showers and high probability (80%) thundershowers over Trinidad and Tobago.

10th

Mostly cloudy periods with scattered showers and high probability (80%) thundershowers over Trinidad and Tobago.

 

The expected Temperatures, Humidity and Dust haze days during the First dekad of December for Piarco, Trinidad as seen in table 2.

Table 2.

Day

Maximum Temperature

0C

Minimum Temperature

0C

Average Relative humidity (%)

Dust Haze

Yes/No

1st  

33.2

23.6

77

No

2nd

32.8

23.4

77

No

3rd  

32.8

24.0

77

No

4th

32.8

24.0

77

Yes

5th

32.8

23.6

77

Yes

6th

33.0

23.0

77

Yes

7th

32.8

23.6

78

Yes

8th

31.9

23.6

78

No

9th

31.9

23.0

85

No

10th

31.9

23.6

85

No

 

The expected Temperatures, Humidity and Dust haze days during the First dekad of December for Tobago as seen as table 3.

Table3.

Day

Maximum Temperature

0C

Minimum Temperature

0C

Average Relative humidity (%)

Dust Haze

Yes/No

1st

32.5

23.6

74

No

2nd

32.5

24.2

75

No

3rd

32.5

24.2

75

No

4th

32.5

24.0

75

Yes

5th

32.5

24.0

75

Yes

6th

32.8

24.0

75

Yes

7th

32.5

24.0

72

Yes

8th

32.0

23.6

80

No

9th

31.9

24.0

80

No

10th

32.0

23.6

80

No

 

Trinidad’s Mean Daily Rainfall Forecast for the First Dekad of December (1st–10th) 2019.

Northern & Northwestern areas:

Moderate chance (68%) of mean daily rainfall up to 7.0 mm.

North-Eastern and Eastern areas:

Moderate chance (68%) of mean daily rainfall up to 7.1 mm.

Central, West-Central and inland areas:

Moderate chance (60%) of mean daily rainfall up to 5.0 mm.

South-Eastern areas:

Moderate chance (68%) of mean daily rainfall up to 7.1 mm.

Southern areas:

Moderate chance (60%) of mean daily rainfall up to 5.7 mm.

South-Western areas:

Moderate chance (60%) of mean daily rainfall up to 5.0 mm.

 

Figure 3. Rainfall map of Trinidad showing possible rainfall totals for varying districts during first dekad of December 2019 and percentage probability of occurrence.

 

Tobago’s Mean Daily Rainfall Forecast for the First Dekad of December (1st–10th) 2019.

Northeastern areas:

Moderate chance (68%) of mean daily rainfall up to 7.2 mm.

South-Western areas:

Moderate chance (60%) of mean daily rainfall up to 6.5 mm.

Figure 4. Rainfall map of Tobago showing possible rainfall totals for varying districts during first dekad of December 2019 and percentage probability of occurrence.

 

Impacts on Agriculture:

Due to a mixture of dry and wet conditions that occurred during the third dekad of November, the soils have retained some moisture. Vegetation/foliage growth will continue once favourable conditions exist. During the first dekad of December, soil moisture will slightly decrease across Trinidad and Tobago during the first half of the dekad. Some areas that may have experienced waterlogged soils, will dry out slightly; while other areas may experience flash floods owing to the wetter conditions later in the first dekad. Rivers will replenish their waters from surface runoff and ground water flow, while shrubs and grass growth will continue at a steady pace. The expected relatively wet-to-wet conditions of the third dekad of December may require some irrigation at times. Additionally, with the expected lowering mean temperatures and high relative humidity; as expected at this time of the year, there is a moderate (65%) probability of some agricultural insects, pests, fungi and diseases get a foot in and possibly develop.

Sun and Moon positions in the sky:

 The sun is presently at latitude of approximately 22.25 degrees south latitude, and with this position, the day length for this dekad will be 11.4 hours. A low probability (40%) of frequent episodes of intense solar radiation will occur during the third dekad of November when the sky is generally cloud free. There is low probability (40%) of heat stress on certain variety plant seedlings and young/sick/elderly animals from direct exposure to solar radiation and high temperatures. Additionally, the moon’s first quarter phase will be on the 4th and as a result, there will be low to medium moon illumination over crop fields and livestock at night during the dekad.