A surge of low-level moisture along with east-southeast flow generated a line of persistent showers that affected the San Juan metro area.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SJU wrote it up.
A surge of low-level moisture along with east-southeast flow generated a line of persistent showers that affected the San Juan metro area.
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 Mar 24, 9:55 AM AST, 4 hours 35 minutes earlier.
Area Forecast Discussion National Weather Service San Juan PR 955 AM AST Wed Mar 24 2021 .UPDATE...Forecast remains on track. Latest GOES-16 precipitable water imagery shows a surge in moisture moving into the area through the day. This moisture in combination with a trough axis extending from the Leeward Islands westward into the Central Caribbean along with local and diurnal effects will result in enhanced shower and possibly isolated thunderstorm activity across interior and western Puerto Rico this afternoon. In addition, with the low-level flow being unidirectional from the east to east- southeast, a streamer is likely to develop downwind from El Yunque and affecting portions of the San Juan metro, resulting in additional shower activity. Urban and small stream flooding will be possible with the heaviest activity. Across the USVI, just isolated showers are expected. && .AVIATION...Mainly VFR conditions are expected. SHRA and iso TS expected across interior and western PR between 24/17z and 24/23z. Additional SHRA possible across the San Juan area. The activity over PR will result in VCSH across all PR terminals. Passing SHRA possible from time to time across the USVI and Leeward Island terminals, resulting VCSH across the area terminals there. No significant impacts to operations expected at this time. Low- level winds will be from the E between 10 and 15 kts with sea breeze variations through 24/22z, becoming light and variable overnight. && .MARINE...No changes to the previous marine discussion. Mainly tranquil seas through Thursday, with choppier seas expected by Friday and into the upcoming weekend as winds increase. A moderate risk of rip currents is expected for all the north and some east-facing beaches of the islands today. && .PREV DISCUSSION... /issued 421 AM AST Wed Mar 24 2021/ SYNOPSIS... Showers and possibly even a few weak thunderstorms are possible later today due to above average moisture and favorable atmospheric conditions. Calmer weather is expected for later in the week due to the influence of an upper level ridging. Above average moisture and scattered showers are in the forecast for next week. Calmer seas will prevail with the return to wind-driven hazardous seas for this weekend. SHORT TERM...Today through Friday... A weak trade wind cap will allow low-level moisture to increase today. An area of precipitable water (PWAT) content of around 1.50 inches is currently moving across the Leeward Islands and will reach the local area during the day. At upper levels, a ridge is building west of the region, while the trough is moving further east and away of the region. An induced low-to-mid level trough will promote an east to northeast wind flow and an advective pattern, that will favor night/early morning showers across the U.S. Virgin Islands and portions of east/northeast Puerto Rico. For today, due to the proximity of the upper level trough and surge in low-level moisture, scattered to locally numerous showers with isolated thunderstorms cannot be ruled out in diurnal convection over portions of the interior and west/southwest PR. Urban and small stream flooding is possible with this activity. At least through Friday, PWAT content is forecast to continue between 1.20-1.40 inches, but at the same time, stability aloft should gradually increase as the upper level ridge strengthens west and over the area. LONG TERM...Saturday through Wednesday... Long range models continue to suggest an upper-level trough to our east for the weekend, with a mid to upper level ridge way off to the west. The trough will bring in cooler air aloft and encourage upward motion and the formation of more potent showers for Saturday and possibly Sunday as well. However, a few factors will act to limit the impact of these showers. Surface high pressure to our north will keep east-northeasterly winds fairly breezy, thus the showers will move quickly. Furthermore, there will not be much moisture to work with, and mid-levels are forecasted to be particularly dry. Thus, scattered showers will be possible for northeast Puerto Rico for Saturday and Sunday morning, with afternoon showers and possibly isolated thunderstorms for western and southwestern Puerto Rico. These showers will likely move fast enough so that flooding will not be an issue, but ponding of water over roadways is possible. For the beginning of the workweek, we lose the forcing from the upper level trough as it moves off to the east, but moisture associated with the trough will decouple from the trough and move westward into our region. Winds are expected to remain easterly to east-northeasterly and quite brisk. So fast moving showers will continue to impact eastern and northern Puerto Rico in the morning hours. With afternoon moderate shower activity for western and southwestern Puerto Rico. Winds in the long-term forecast look brisk enough that the marine conditions will be negatively impacted. AVIATION...Mainly VFR conditions are expected to prevail across all the terminals during the next 24 hours. However, SHRA is expected to develop in and around TJSJ/TIST/TISX from 15z-21z, causing tempo MVFR conds. Also, there is a chance for TSRA in and around TJPS fm 16z-22z. East to northeast winds btw 8-15 kt with sea breeze variations expected after 14z. MARINE... Seas will be fairly tranquil for the next few days, with wave heights generally below 5 feet, and regional buoys now reflect these calmer seas. Seas will become choppy once again as winds pick up on Friday and through the weekend. Small Craft Advisories will likely be issued for wind-induced swell event. Isolated showers will continue over the local waters. && .PRELIMINARY POINT TEMPS/POPS... SJU 86 74 85 74 / 30 40 30 40 STT 84 73 85 73 / 50 30 30 30 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && SHORT TERM...GL PUBLIC DESK...CAM/CVB
Perspectivas sobre Condiciones Peligrosas del Tiempo Servicio Nacional de Meteorologia en San Juan PR 409 AM AST miercoles 24 de marzo de 2021 AMZ710>745-PRZ001>013-250815- San Juan y Vecindad-Noreste-Sureste-Este Interior-Norte Central- Interior Central-Ponce y Vecindad-Noroeste-Oeste Interior- Mayaguez y Vecindad-Suroeste-Culebra-Vieques- Las aguas costeras cercanas y lejanas a la costa del Atlantico y Caribe- 409 AM AST miercoles 24 de marzo de 2021 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Puerto Rico y las aguas costeras del Atlantico. .Dia Uno...Hoy y esta noche .Tronadas...Existe una probabilidad de tronadas con fuertes lluvias y rafagas breves esta tarde, sobre el interior y oeste de Puerto Rico. .Inundaciones...Las fuertes lluvias pueden ocasionar inundaciones urbanas y de riachuelos. .Corrientes Marinas...Existe un riesgo moderado de corrientes marinas para todas las islas. .Dias dos hasta el siete...jueves a martes Aguaceros en la tarde el jueves puden ocasionar inundaciones urbanas y de riachuelos sobre el suroeste de Puerto Rico. Un riesgo moderado de corrientes marinas prevalecera a traves de las playas del norte y este de las islas hasta el fin de semana. Se pronostica que el viento y oleaje aumenten gradualmente durante el fin de semana hacia la proxima semana. .Comunicado sobre informacion reportada por observadores... No se espera activacion amplia de observadores. Favor de reportar cualquier informacion sobre inundaciones y corrientes marinas al Servicio Nacional de Meteorologia en San Juan mientras siguen las indicaciones de las autoridades locales y estatales. AMZ715-725-VIZ001-002-250815- San Tomas, San John e Islas Adyacentes- Santa Cruz-Aguas cercanas del Atlantico y aguas costeras adyacentes del Caribe- 409 AM AST miercoles 24 de marzo de 2021 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Islas Virgenes Estadounidenses y las aguas costeras adyacentes. .Dia Uno...Hoy y esta noche .Corrientes Marinas...Existe un riesgo moderado de corrientes marinas para las playas del norte de San Tomas y este de Santa Cruz. .Dias dos hasta el siete...jueves a martes Un riesgo moderado de corrientes marinas prevalecera a traves de las playas del norte de San Tomas, y a traves de las playas del norte y este de Santa Cruz hasta el fin de semana. Se pronostica que el viento y oleaje aumenten gradualmente durante el fin de semana hacia la proxima semana. .Comunicado sobre informacion reportada por observadores... No se espera activacion amplia de observadores. Sin embargo, favor de reportar cualquier informacion sobre corrientes marinas al Servicio Nacional de Meteorologia en San Juan mientras siguen las indicaciones de las autoridades locales y estatales.
The San Juan radar (TJUA), 31 km away, was scanning. The volume nearest the first event began at 18:28 UTC.
2 flood, 1 flash flood. Local standard time, as filed.
Flooding reported along Calle 16 and 52 in Sector Reparto Metropolitano.
Expresso 18 in the San Juan to Caguas direction had a lane that was partially intransitable due to flooding.
Avenida Martinez Nadal was intransitable in the lane from SJU to Guaynabo. Also, the intersection of Road 19 with Ave Luis Vigoreaux was intransitable as well with several cars submerged.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2021Every state in 2021This day in weather historyWarnings in Puerto Rico, March 2021
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: 950894, 950898, 950897.