Monthly weather summaries are prepared by the climate section of the National Meteorological Service of Belize. The NMS of Belize maintains a network of over 25 weather stations that are situated primarily in the agricultural regions of the country. Temperature and rainfall are read at 9 am each morning and the rainfall total read at this time represents the accumulated rainfall for the previous day.
May is typically one of the warmest and most humid month for the country of Belize. It also is the month in which the country transitions gradually from the dry season to the wet season. The rains usually start off in the south (Toledo district) from around mid-May and then progress gradually north to begin affecting the Orange Walk and Corozal districts in early June.
May 2018 started off typically warm and relatively dry over the country. Showers were generally isolated during the first week of the month, except for a few over the south on the 1st then over central areas on the 2nd. Also, isolated thunderstorms were generally confined to the the Maya Mountains during this period. Automatic weather station data suggests that Middlesex recorded the highest one day total rainfall during the first week with 55.1 mm of rainfall on the 7th. At low levels an easterly flow gradually backed to the northeast and then North to Northeasterly by the 6th of the month as a low level trough moved from the central to the western Caribbean while slowly amplifying. Shallow moisture was confined generally in the low levels. At upper levels the pattern was weakly convergent for most of the time during this period.
During the second week of May 2018, the trough over the northwest Caribbean slowly made its way northwestward while developing into a weak low pressure system in the eastern Gulf of Mexico by the 14th. As the system moved north and west of the country, the flow over Belize veered to the East-Southeast with moisture decreasing. This supported generally fair weather with little rainfall, especially from the 9th to the 11th. Showers increased a bit on the 12th through to the 14th with return moisture on the prevailing East to Southeasterly flow. Ranchito, in the north, recorded the highest one day total during the 2nd week with a total of 16.2 mm of rainfall on the 13th.
Between May 15th and 21st, the highest daily rainfall total occurred on Sunday, May 17th as a plume of moisture drifted from North-Northeast to South-Southwest across the country. The automatic weather station at San Pedro recorded 60.7 mm while at the airport and in Belize City the daily totals were 15.2 and 12.2 mm, respectively. The low over the Gulf of Mexico became less significant for our weather as the North Atlantic High pressure ridge regain dominance during this time. The surface flow was predominantly easterly while at upper levels the pattern was generally convergent under a westerly to northwesterly flow. However, daytime heating was strong enough to generate occasional afternoon thunderstorms inland.
The system that eventually became sub-tropical storm Alberto gradually began affecting the country on the 22nd. This system started off as a persistent low pressure system just east of the country. At first it supported a light and variable flow which eventually became more West to Northwesterly after Alberto formed on the 25th of the month. As the system moved north, the flow became more southwesterly and eventually east to southeasterly. The formation of Alberto on the 25th triggered the wettest day during this third week of the month. A band of showers and thunderstorms in association with Alberto moved from Northwest to Southeast late on the 25th and dumped almost two inches of rainfall over the airport. This was preceded by similar activity on the 23rd but the rainfall totals were not as high during the first event.
As Alberto moved well north of the area rainfall activity decreased once more across the country. The flow remained generally easterly to southeasterly for the remainder of the month and shower activity was generally isolated for the most part between the 28th and 30th. Activity increased a bit on the 31st with the bulk of rainfall concentrated inland and over the Maya Mountains. The automatic weather station in Benque in the extreme west recorded a total of 68.0 mm on the 31st.
The graph and maps below summarize the total rainfall and average maximum and minimum temperature recorded during the month of May 2018. They also give an indication of how these readings compared to the normal for the month across the stations sampled. As can be seen, rainfall was below normal for most of the country except for southeastern coastal areas from Melinda to Savannah where rainfall was as high as 100% above normal. In terms of maximum temperatures, five of the stations sampled recorded warmer than usual daytime temperatures. These include, Tower Hill, the Airport, Central Farm, Pomona and Melinda. Belmopan recorded normal maximum temperature for May while the average maximum temperature for the month was lower than normal at the Belize Zoo, Savannah and Punta Gorda. Meanwhile warmer than normal minimum (nighttime) temperatures were recorded at Tower Hill, the Belize Zoo, Central Farm and Belmopan. The situation was the reverse at the Airport, Pomona, Melinda and Punta Gorda where the minimum was lower than normal.
Forecaster: Gordon, Ronald
Last Updated: Fri, Jun 08, 2018 | 10:43 AM