A trough across the Atlantic resulted in showers and thunderstorms over PR.
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The episode as NWS SJU wrote it up.
A trough across the Atlantic resulted in showers and thunderstorms over PR.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Juan, PR wrote its last area forecast discussion before the first event at May 31, 11:32 AM AST, 2 hours 22 minutes earlier.
Area Forecast Discussion National Weather Service San Juan PR 1132 AM AST Thu May 31 2018 .UPDATE...Partly cloudy to mostly sunny skies prevailed across the region this morning. By late morning clouds and showers began to develop and stream westwards over parts of the islands and coastal waters. Areas in the San Juan Metro were already receiving periods of moderate to locally heavy rainfall but in isolated areas. No change to the inherited forecast reasoning and package at this time as recent TJSJ 31/12z upper air sounding and model guidance continue to suggest a similar trend and weather pattern with increasing moisture Friday through Saturday as a tropical wave crosses the eastern Caribbean. This will be followed by a drier and "dirty" airmass Sunday through Monday with low to moderate concentration of Saharan dust, and hot weather conditions under prevailing southeasterly wind flow. Afternoon shower development will however remain possible each day but mainly over parts of the interior and northern half of Puerto Rico. && .AVIATION UPDATE...No change to previous AVN Discussion. VFR conds durg rest of the morning hours and for the rest of the day...except for the locally ahd diurnally induced afternoon convection over parts of the central mountain range of Puerto Rico and around TJBQ/TJMZ previously mentioned. SCT ocnl BKN clds nr FL025...FL050 en route btw islands. Few tops btw FL100-FL200 til 31/23z. L/lvl wnds fm E 15-20 kts. Except for sea breeze variations SFC winds fm E 10 to 15 kts w/ocnly hir gusts...bcmg 10 kts or less aft 31/23z. && .MARINE UPDATE...No change to previous marine discussion. Fairly tranquil seas through Friday. Winds 10-15 kts and overall seas between 3 to 5 feet. && .PREV DISCUSSION... /issued 537 AM AST Thu May 31 2018/ SYNOPSIS...As a mid to upper level trough across the tropical Atlantic and into the eastern Caribbean weakens, a ridge pattern aloft is expected to build across the local isles. Tropical wave passage expected on Saturday followed by another wave late Tuesday into Wednesday. East to southeast winds to continue much of the forecast period. SHORT TERM...Today through Saturday... Under the prevailing easterly wind flow another surge of moisture is expected to push patches of clouds with brief showers across the local waters, USVI and eastern PR through the morning hours. The Doppler radar detected scattered showers across the Atlantic Waters and some of these showers have been affecting the northern USVI and east and north PR through the overnight hours. However, rainfall accumulations where less than a quarter of an inch. On the other hand, the rest of Puerto Rico and St Croix observed little or no shower activity with mostly clear to partly cloudy skies. For the afternoon hours, once again expect showers and thunderstorms developing along and to the west of the Cordillera Central due to the combination of the prevailing wind flow, diurnal heating, sea breeze variations and the available moisture. Soils are already saturated and any persistent heavy rain could lead to urban and small stream flooding as well as sudden mudslides especially across the steep terrains in the western interior. A dry slot is forecast to arrive by Friday, limiting shower activity throughout the day. However, the typical afternoon convection across western PR is expected. This dry air will be followed by the arrival of a tropical wave on Saturday. Having said that, the available moisture is expected to increase, which will help in the development of showers and thunderstorms when combines with the local effects. Otherwise the same weather pattern is expected to continue, which has caused urban and small stream flooding as well as sudden mudslides along steep terrains across the interior and western PR, and localized flooding in portions of the San Juan Metro due to its poor drainage. LONG TERM...Sunday through Friday... As a mid to upper level trough across the tropical Atlantic and into the eastern Caribbean weakens, a mid to upper level ridge will build across the local isles. This ridge pattern aloft will then hold much of the next workweek. At lower levels, east southeast winds to continue much of the forecast period with a tropical wave passage expected Tuesday afternoon into Wednesday. Ahead of the aforementioned wave, some haziness is anticipated. If long term forecast holds, expect locally induced showers and thunderstorms across the northwest quadrant of Puerto Rico Sunday afternoon followed by a dry and stable weather pattern with hazy skies and limited shower activity Monday. Warm to hot temperatures are possible Sun-Mon particularly along the northern slopes of Puerto Rico under east southeast winds. The chance for organized convection will increase across the forecast area late Tuesday and Wednesday as a tropical wave and associated moisture moves across the area. As the tropical wave moves away on Thursday, moisture is expected to erode under ridge pattern aloft. This will result in fair weather Thursday and Friday. AVIATION...VFR conditions will prevail across all TAF sites through the morning hours. VCSH can be expected at TIST/TISX/TJSJ/TNCM/TKPK throughout the day. Mountain obscuration across the Cordillera Central is expected as well as SHRA/TSRA development in/near TJBQ/TJMZ which may cause MVFR conds btwn 31/16-23Z. Winds will prevail from the east at around 10-15KT with occasional gusts and sea breeze variations. MARINE...Tranquil marine conditions to continue during the next several days with seas below 5 feet and winds around 15 knots. && .PRELIMINARY POINT TEMPS/POPS... SJU 88 77 89 77 / 20 20 20 40 STT 88 76 89 76 / 40 20 20 70 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && SHORT TERM...RAM LONG TERM....RAM
Perspectivas sobre Condiciones Peligrosas del Tiempo Servicio Nacional de Meteorologia San Juan PR 528 AM AST jueves 31 de mayo de 2018 AMZ710>745-PRZ001>013-010930- San Juan y Vecindad-Noreste-Sureste-Este Interior- Norte Central-Interior Central-Ponce y Vecindad-Noroeste- Oeste Interior-Mayaguez y Vecindad-Suroeste-Culebra-Vieques- Aguas cercanas y lejanas a la costa del Atlantico y Caribe- 528 AM AST jueves 31 de mayo de 2018 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Puerto Rico y las aguas costeras adyacentes del Atlantico. .Dia Uno...Hoy y esta noche .Tronadas...Existe probabilidad de tronadas con lluvia fuerte y vientos en rafaga breves esta tarde a traves de porciones del oeste de Puerto Rico. .Inundaciones...Lluvias fuertes pudieran resultar en inundaciones urbanas y de riachuelos. Los suelos a traves del oeste de Puerto Rico ya estan saturados y cualquier lluvia fuerte persistente resultara en deslizamientos de tierra. .Corrientes marinas...Existe un riesgo moderado de corrientes marinas a traves de las costas del norte y sureste de Puerto Rico, al igual que la mayoria de las playas en el extremo este de Vieques y Culebra. .Dias dos a siete...viernes a miercoles Se esperan aguaceros y tronadas durante los proximos dias, especialmente a traves del cuadrante noroeste de Puerto Rico, produciendo inundaciones urbanas y de riachuelos. Se pronostica que una onda tropical alcance el area local el sabado, aumentando el potencial de aguaceros y tronadas. Se pronostica que otra onda tropical se mueva cerca de las islas entre el martes y el miercoles de la semana proxima. .Comunicado sobre informacion reportada por observadores... No se anticipa activacion amplia de observadores, sin embargo, se les exhorta a los observadores individuales a reportar inundaciones al Servicio Nacional de Meteorologia en San Juan. AMZ715-725-VIZ001-002-010930- San Tomas, San John e Islas Adyacentes- Santa Cruz- Aguas cercanas del Atlantico y aguas costeras adyacentes del Caribe- 528 AM AST jueves 31 de mayo de 2018 Esta perspectiva sobre las condiciones del tiempo peligrosas es para las Islas Virgenes Americanas y las aguas costeras adyacentes. .Dia Uno...Hoy y esta noche .Corrientes marinas...Existe un riesgo moderado de corrientes marinas para las playas del extremo este de Santa Cruz. .Dias dos a siete...viernes a miercoles Se pronostica que una onda tropical alcance el area local el sabado, aumentando el potencial de actividad de aguceros. Se pronostica que otra onda tropical se mueva cerca de las islas entre el martes y el miercoles de la semana proxima. .Comunicado sobre informacion reportada por observadores... No se anticipa activacion amplia de observadores, sin embargo, se les exhorta a los observadores individuales a reportar corrientes marinas al Servicio Nacional de Meteorologia en San Juan.
The national radar mosaic for the moment the first event began.
1 flash flood, 1 heavy rain. Local standard time, as filed.
PR-842 was reported flooded in Barrio Caimito near sector Benitez I, k.m. 4.2 near Plaza San Miguel. Water flooded residences.
Mudslide reported at road PR 408.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2018Every state in 2018This day in weather historyWarnings in Puerto Rico, May 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 762070, 762073.