Lightning in the Pretty Island. Photos by Marlena Gomez

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Monthly Weather Summary, July 2021

National Meteorological Service of Belize

July typically is one of the months for the peak of tropical waves which is a contributor to the rainfall normally observed during the month. Rainfall is typically attributed to Upper-Level Troughs, Tropical waves and mid to upper-level lows which moves westward through the Caribbean. An average of three upper-level troughs, four mid to upper level low and eighteen tropical waves would pass over the country in July, however, only five tropical waves crossed the country with only one strong wave and a few dry spells were observed across most areas.

Conditions were relatively moist over the country for the first week of July in both the low and upper levels, with a light to moderate east to south-easterly surface airflow. Tropical Storm Elsa formed and was over the Northern Caribbean with a ridge pattern over the wider Caribbean. An inverted trough near Cuba and Jamaica resulted in a north-easterly upper-level flow which veered to the southwest after the trough moved west and an anticyclone moved into the area. Moisture advected over Belize due to the inverted trough and a tropical waved that crossed the country on July 4, produced a few showers and isolated thunderstorms mostly over central, southern, and coastal portions of the country. A weakly divergent pattern further enhanced showery activity on July 4 while neutral conditions persisted for the remainder of the week. The dry day during this week was on July 2.

Low level moisture decreased in week two, except for July 13 when a tropical wave crossed the country. At the upper levels, a patch of dry air prevailed through to July 10, then an increase in moisture was observed. Near the surface, the North Atlantic Ridge continued to be the dominant feature over the Caribbean Basin with a moderate east to south-easterly flow while an inverted trough over the western Caribbean produced a north-easterly flow and a convergent upper-level pattern up to July 10. These conditions supported mainly fair and windy weather with only isolated showers and thunderstorms, except for a few more over southern areas. The approach and passage of a tropical wave on July 13, supported by an upper-level ridge over Central America leading to a south-westerly flow and an increase in low and upper-level moisture and instability over the area. This wave produced showers and thunderstorms around the country enhanced by a weakly divergent upper-level pattern.

High pressure ridge persisted into week 3 with relatively dry conditions near the surface up to July 17, thereafter, low level moisture began to increase and remained moist until the end of the week. An east to north-easterly surface airflow prevailed throughout the week. Conditions at the upper levels were relatively moist for this week with an upper-level trough over the area, however, the upper-level pattern continued neutral expect for when a tropical wave passed the country. Fair weather prevailed on July 15 and 16 with an upper-level ridge over the area suppressing the development of any deep convective activity and only isolated showers and thunderstorms were observed on radar imagery, except for a few more over inland and southern areas of the 16th. Conditions became moist and unstable on July 17 as one of two tropical waves approached the area. The first wave crossed the country on July 18 and supported several outbreaks of showers and thunderstorms around the country with an extreme thunderstorm cell developing northwest of Sandhill village. The second wave crossed on July 20 with showers and thunderstorms continuing around the country, especially over central, southern and western areas and gusty low-level winds.

A light east to north-easterly surface airflow prevailed for most of the week becoming east to south-easterly flow on the last day of the month. This was as a result of a tropical wave and a TUTT induced trough near Belize and the Yucatan that reflected down to the surface. The week stated off relatively dry with low moisture levels near the surface and generally isolated showers and thunderstorms around the country. Moisture levels increased as the week progressed with the TUU/TI trough lingering over the area producing a weakly divergent upper-level pattern and providing outflow for the development of deep convection. On July 28, the TI/TW supported a few showers and isolated thunderstorms over most areas along with an isolated squall line mostly over the Cayo district. Showers and thunderstorms persisted into July 29 across the country with a temporary break on July 30 and only isolated showers and thunderstorms over central and offshore areas. Moist and unstable conditions prevailed to end the month with some showers and a few thunderstorms around the country as a result a moist south-westerly upper-level flow caused by the upper level TUTT and an upper-level trough over the country.

The graph and maps below summarize the total rainfall and average maximum and minimum temperatures. They also give an indication of how these readings compare to the normal for the month across the stations sampled. As can be seen, despite the passage of several tropical waves and upper-level trough during the month that contributed to the rainfall, the country had a few dry spells with rainfall being concentrated mostly over central and northern areas. Thus, rainfall was normal to above normal over northern and central areas, except for the Belize district and below normal over the south. In terms of temperatures, most of the stations sampled show near normal to slightly above normal maximum/daytime and minimum/night-time temperatures for most the stations except for the Central Farm station where slightly below normal night-time temperatures was observed.

Monthly Rainfall Summary

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Monthly Maximum Temperatures

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Monthly Minimum Temperatures

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Rainfall Observed: July 2021 (mm)

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Rainfall Observed: July 2021 (% Above/Below Average)

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