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Monthly Weather Summary



April 2016

Climatologically, the Atlantic High Pressure ridge usually dominates the region during the month of April. Its orientation typically produces a dry southeasterly airflow across the country. At times heat-lows may develop across southern Mexico which causes pressure gradients to tighten over the area resulting in gusty winds. However, when the centres of these systems are over or very near the country, pressure gradients would instead slacken causing light winds and an excessively high heat-index. This overall synoptic pattern for the month normally corresponds with dry and warm weather. The only relief would come in the form of an occasional cold front. On average about two cold fronts would cross the country during the month. These may be accompanied by strong to severe thunderstorms and they are the main producers of the little rainfall for the month.  April 2016 was characteristically warm but much drier than normal. This is likely due to the fact that only one weak frontal boundary affected the country.

The first day of April 2016, started out mainly fair and warm as a dry easterly to southeasterly surface flow dominated the area. A cold front was approaching the next day with a prefrontal trof crossing the country during the night. This supported an increase in moisture with a few showers and thunderstorms. Moisture would continue relatively high during the next few days from the 3rd to the 5th as the weak front stalled just north of Belize and gradually dissipated. Its remnants drifted south during the night of the 5th and by the 6th light showers and rain were confined to the south.

Moisture decreased on the 7th and conditions continued mainly fair and dry for the next few days. However, daytime temperatures were slightly lower than normal up until the 12th. This was largely due to an anomalous easterly to east-northeasterly surface flow.

The normal synoptic pattern became established on the 13th and the warm and dry easterly to southeasterly airflow developed over the area. This continued until the 17th and little to no rainfall was recorded during this period.

Winds backed up once again to the east and then east to northeast between the 18th and the 24th. This wind shift initially supported slightly cloudier conditions across the country on the 19th and 20th as a weak moisture surge developed. This produced a very slight increase in showers across the country. However, by the 21st moisture decreased once more even though the surface flow remained easterly to east-northeasterly.

The high pressure system moved off to the east of the Continental United States on the 25th. Its new orientation caused the surface flow to veer to the east-southeast over Belize and temperatures gradually increased over the area. Additionally, heat lows began developing to the northwest around the 29th. The pressure gradients therefore tightened and the easterly to southeasterly flow became gusty on the last two days of the month.

As mentioned previously rainfall was well below normal during April 2016. Except for the showers experienced between the 2nd and the 6th and the weak moisture surge between the 19th and 20th no significant rainfall occurred. Figure 1, below indicates that most stations across the country recorded below normal rainfall except for Tower Hill in the north and Baldy Beacon over the Mountain Pine Ridge area.

April 2016 rainfall

Figure 1: Normal (Orange) Versus  Actual (Blue) Rainfall recorded in April for some key stations across the country.





R. Gordon