More swellups keep developing:Monthly Weather Summary, May 2019
National Meteorological Service of Belize
Monthly weather summaries are prepared by the climate section of the National Meteorological Service (NMS) 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.
Climatologically May is the warmest month of the year in Belize. The first part of the month is typically characterized by warm, dry and hazy conditions. However, this month is also the transition month from the dry to the wet season across the country. Therefore, the rains usually start in the south after the first week of May and gradually make their way northwards.
Weather conditions across the country in May started out warm and mostly dry. A moderate easterly to southeasterly surface flow prevailed during the first week of the month supported by relatively tight pressure gradients between the Atlantic high pressure ridge and thermal trofs/lows over Mexico. The mid to upper levels were mostly dry. Showers were generally isolated during the first two days, followed by little to no rainfall from the 3rd through to the 5th, except for isolated afternoon thunderstorms inland. Rain and thunderstorms affected central and southern areas on the night of the 5th through early morning on the 6th supported by a relatively divergent southwesterly flow aloft. Warm and mostly dry conditions returned for the remainder of the 6th through to the 7th.
The second week of May 2019 started out cloudy but with no significant rainfall. The cloudiness was due mostly to the advection of mid to high level layered cloud over the area from thunderstorm activity over southern Mexico and Guatemala. Seasonably warm, hazy and dry conditions persisted on the 9th. The 10th, 11th and 12th saw isolated afternoon thunderstorms over the mountains with little to no rain elsewhere. A weak surface trof was analyzed near the cost of Belize on the 12th but this feature was shallow and did not produce any significant weather across the country. A similar trend continued through to the 14th to close out the second week of the month.
The main synoptic pattern to start of the third week of May 2019 consisted of a stationary front well north of Belize over the eastern Gulf of Mexico and southern Florida while a weak surface trof was further south over the western Gulf and Bay of Campeche. This pattern supported a moderate easterly surface flow over the area. Brief and very light isolated showers were noted overnight with mostly warm, hazy and dry conditions during the day of the 15th with only isolated afternoon thunderstorms over the Maya Mountains. A similar trend continued through to the 19th of May. On the 20th isolated showers developed in the extreme north as well as the south while the 21st saw mainly fair weather except for isolated showers over the south during the early morning hours.
Moisture gradually increased over the area during the fourth week of May 2019 signaling that conditions were starting to transition from the dry to the wet season. A broad low was developing over the eastern Pacific which was supporting the advection of deep moisture from the Pacific into Central America. Weather conditions over Belize remained generally fair on the 22nd. Showers were generally isolated that day and affected mostly central areas of the country. The 23rd saw a slight increase in shower activity with a few showers affecting the coast during the morning and most areas by the afternoon. By the following day some showers affected the southern half of the country. The following days (25th to 28th) saw a few showers affecting mainly southern areas of the country. Again this suggested that the rainy season had started in the south. Showers, however, were not confined only to the south during this period.
Moisture decreased a bit on the 29th however isolated and thunderstorms still affected the Toledo district overnight on the 28th through early morning on the 29th. Thunderstorms were also noted over the Maya Mountains on the afternoon of the 29th. The main feature continued to be the broad cyclonic gyre encompassing most of Central America and the eastern Pacific. The 30th saw isolated showers and thunderstorms once more over areas along the western border and over the Maya Mountains. Finally, a further increase in moisture was noted on last day of May 2019. This factor coupled with very divergent upper level conditions supported the development of a few showers and thunderstorms especially in the north, over the Maya Mountains and also along the coast of the country.
In summary May 2019 was characteristically warm, hazy and mostly dry. However, the rainy season which usually starts at least by the 2nd week of May in the south was a bit late this year as it started well into the fourth week of May 2019. The graphs and maps below summarize the total rainfall and average maximum and minimum temperature recorded during the month of May 2019. They also give an indication of how these readings compare to the normal for the month across the stations sampled. As can be seen, rainfall was below normal over the north (Corozal District, Orange Walk and most of the Belize Districts). Rainfall was also above normal in parts of Cayo (Central Farm) and coastal Stann Creek district. Meanwhile rainfall was higher than normal over the Toledo district. Particularly in Punta Gorda rainfall was almost twice the normal for May 2019. Some areas saw near normal rainfall such as Belmopan and Savannah. Both daytime (maximum) and nighttime (minimum) temperatures were above normal for most of the stations sampled with only a few exceptions.Monthly Rainfall SummaryMonthly Maximum TemperaturesMonthly Minimum TemperaturesRainfall Observed: May 2019 (mm)Rainfall Observed: May 2019 (% Above/Below Average)