ISSUED AT: 06:49 PM

Date: Sunday 10th of January 2021

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 (1^st-9^th) of January 2021.

During the period 1^st to 9^th of January, mostly relatively wet days occurred over Trinidad and Tobago, with the exception of the 1^st, 6^th, 7^th and 8^th; where few areas in Trinidad and Tobago had experience wet days. These wet days were due to cloudiness and rainfall associated with a low-level trough and localize effects. Rainfall totals’ maps for the period 1^st to 9^th of January are located below as figure 1 and figure 2.

 

Figure 1. Rainfall map of Trinidad showing measured rainfall totals for varying districts during period 1^st to 9^th of January 2021.

 

Figure 2. Rainfall map of Tobago showing measured rainfall totals for varying districts during period 1^st to 9^th of January 2021.

 

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 first dekad of January 2021.

Location	Maximum Temperature 0C/ Long term 10 dys average 0C	Minimum Temperature 0C /Long term 10 dys average 0C	Average maximum Relative humidity (%)/ Long term 10 dys average (%)	Average minimum Relative humidity (%)/Long term 10 dys average (%)
Trinidad (Piarco International airport)	31.7/30.8 (1981-2010)	19.0/21.8 (1981-2010)	87/93 (1990-2010)	65/68 (1990-2010)
Tobago (ANR Robinson International airport)	31.3/29.9 (1981-2010)	21.4/23.0 (1981-2010)	90/89 (1990-2010)	64/64 (1990-2010)

 

Table 1 shows the expected weather conditions during the Second Dekad (11^{th –}20^th) of January 2021, for Trinidad and Tobago.

Table 1.

Days:	Expected weather:
11th	Intermittent cloudy patches with a moderate probability (55%) of showers.
12th	Intermittent cloudy patches with a moderate probability (25%) of showers.
13th	Intermittent cloudy patches with a low probability (25%) of showers.
14th	Intermittent cloudy patches with a moderate probability (55%) of showers.
15th	Intermittent cloudy patches with a low probability (25%) of showers.
16th	Intermittent cloudy patches with a low probability (25%) of showers.
17th	Intermittent cloudy patches with a moderate probability (40%) of showers.
18th	Intermittent cloudy patches with a moderate probability (25%) of showers.
19th	Intermittent cloudy patches with a moderate probability (55%) of showers.
20th	Intermittent cloudy patches with a moderate probability (55%) of showers.

 

Table 2 shows the expected temperatures, humidity and dust haze days during the second Dekad of January 2021 for Piarco, Trinidad.

Table 2.

Day	Maximum Temperature 0C	Minimum Temperature 0C	Average Relative humidity (%)	Dust Haze Yes/No
11th	31.7	22.0	78	Yes
12th	31.7	22.0	72	Yes
13th	32.0	21.0	75	Yes
14th	31.5	22.5	75	Yes
15th	32.0	20.5	72	Yes
16th	32.0	21.0	72	Yes
17th	31.5	22.5	76	Yes
18th	31.7	22.0	78	Yes
19th	31.7	22.0	78	Yes
20th	31.7	22.0	78	Yes

 

Table 3 shows the expected temperatures, humidity and dust haze days during the second Dekad of January 2021 for the ANR Robinson, Tobago.

Table 3

Day	Maximum Temperature 0C	Minimum Temperature 0C	Average Relative humidity (%)	Dust Haze Yes/No
11th	30.0	23.0	78	Yes
12th	31.0	23.0	75	Yes
13th	31.0	22.0	72	Yes
14th	31.5	22.0	75	Yes
15th	31.0	22.0	72	Yes
16th	31.0	22.0	72	Yes
17th	30.7	23.0	76	Yes
18th	30.7	23.0	78	Yes
19th	31.0	23.0	78	Yes
20th	31.0	23.0	78	Yes

 

Trinidad’s Mean Daily Rainfall Forecast for the second Dekad of January (11^th -20^th) 2021.

Northern & Northwestern areas:

Moderate chance (60%) of mean daily rainfall up to 2.1 mm.

North-Eastern and Eastern areas:

Moderate chance (68%) of mean daily rainfall up to 2.9 mm.

Central, West-Central and inland areas:

Moderate chance (60%) of mean daily rainfall up to 1.8 mm.

South-Eastern areas:

Moderate chance (68%) of mean daily rainfall up to 3.0 mm.

Southern areas:

Moderate chance (60%) of mean daily rainfall up to 2.1 mm.

South-Western areas:

Moderate chance (60%) of mean daily rainfall up to 1.6 mm.

 

Figure 3. Rainfall map of Trinidad showing possible rainfall totals for varying districts during the second dekad of January 2021 and percentage probability of occurrence.

 

Tobago’s Mean Daily Rainfall Forecast for the second Dekad of January (11^th -20^th) 2021.

Northeastern areas:

Moderate chance (60%) of mean daily rainfall up to 1.5 mm.

South-Western areas:

Moderate chance (68%) of mean daily rainfall up to 2.7 mm.

Figure 4. Rainfall map of Tobago showing possible rainfall totals for varying districts during the second dekad of January 2021 and percentage probability of occurrence.

 

Impacts on Agriculture:

During the second dekad of January 2021, relatively dry days are expected on the 12^th, 13^th, 15^th, 16^th, and 18^th; while relatively wet days are expected on the 11^th, 14^th, 17^th, 19^th and 20^th. There is a moderate (30%) probability that the anticipated rainfall will return sufficient soil moisture across Trinidad and Tobago. The expected rainfall events may result in rivers being at low levels. There is a moderate (30%) probability that some areas will become water-logged especially in low-lying areas during the dekad. Shrubs and grass-growth will continue at a medium pace. Additionally, with low average temperatures at this time and seldom-moist vegetation, there is a moderate (30%) 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 22 degrees South, and with this position, the day-length will be 11.4 hours. There is moderate probability (40%) of intense solar radiation during this second dekad of January, when the sky is generally cloud free. There is also moderate probability (30%) 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 new moon phase will be on the 13^th of January followed by first quarter phase on the 20^th. As a result, there will be low to medium moon illumination over crop fields and livestock at night during the dekad.