A mid to upper-level low promoted a favorable environment for showers and thunderstorms to develop in the afternoon. This produced heavy rainfall over the San Juan metro area, where flooding was reported.
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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 mid to upper-level low promoted a favorable environment for showers and thunderstorms to develop in the afternoon. This produced heavy rainfall over the San Juan metro area, where flooding was reported.
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 24, 11:41 AM AST, 5 hours 7 minutes earlier.
Area Forecast Discussion
National Weather Service San Juan PR
1141 AM AST Wed May 24 2023
...New UPDATE, AVIATION, MARINE...
.UPDATE...
Issued at 1132 AM AST Wed May 24 2023
Although moisture continues above normal, it is less than the
previous days. Instabilities parameters calculated from this
morning's sounding (TJSJ-24/12z) indicate favorable afternoon
convection atmospheric conditions. Among them, the convective
temperature is 88 degrees Fahrenheit (easily achievable), 250 mb
heights near-normal (typical for a through), steep low-level
lapse rate, and near-normal cold temperatures at 500 MB. All these
instability parameters favor the formation of thunderstorms later
in the afternoon, which, combined with diurnal heating and sea
breeze variations, may enhance the activity. Therefore, we expect
urban and small stream flooding in some locations along and to the
west and north of the Cordillera Central, from the Metropolitan
area of San Juan westward to Mayaguez. In addition, excessive
heating may lead to heat index values between 100 and 111 degrees
Fahrenheit along these areas mentioned above, where a Heat
Advisory is in effect til 4 PM AST. The U.S. Virgin Islands will
have lots of periods of sunshine, but beneficial rains may fall
over St Croix and St Thomas later this afternoon.
&&
.AVIATION...
(18Z TAFS)
Issued at 1132 AM AST Wed May 24 2023
VFR conditions will prevail throughout the forecast period.
Afternoon SHRA/TSRA will develop along and to the north and west
of the Cordillera Central. This activity may create brief MVFR
conditions over JSJ/JBQ; however, it may stay in the vicinity of
the terminals (24/18-23z). Winds will continue from the ESE/SE at
10-15 knots but locally higher in/near TSRA, with sea breeze
variations.
&&
.MARINE...
Issued at 1132 AM AST Wed May 24 2023
Mariner can expect tranquil marine conditions with seas at 5 feet
or less, and east-southeast winds at 18 knots or less.
Thunderstorms will develop across the coastal waters of north and
west Puerto Rico between the afternoon and evening hours. Please
exercise caution near thunderstorms activity.
&&
.SYNOPSIS...
Southeasterly flow will continue, but a departing upper level low
will clear away most the cloud cover and bring warm temperatures
to the local area. A heat advisory is in effect for most of the
northern lower elevations. Increasing stability will limit the
number of thunderstorms and showers that grow over western and
interior Puerto Rico until Sunday when a band of moisture will
bring the best moisture of the next 6 to 8 days. Nevertheless
locally heavy showers will be able to produce spots of urban and
small stream flooding each day through Sunday. Drier weather is
indicated for the U.S. Virgin Islands.
&&
.SHORT TERM... Today through Friday...
The mid/upper-level low continues above the forecast area and is
currently centered northeast of the U.S. Virgin Islands. Although
the trough has weakened somewhat, it continued fostering shower
and thunderstorm activity across the local waters close to USVI,
Vieques, and Culebra throughout the night. This is more or less
where the bulk of the moist plume induced by a surface low
northeast of the Bahamas is located. Convective activity will
continue to fluctuate through the morning hours, with some
affecting southeastern Puerto Rico as well but less intense than
the previous morning. Today will be the wettest day of the short-
term period. The mid/upper trough will continue to move eastward
throughout the day as a mid-level ridge with an axis over
Hispaniola moves in by Thursday. Although weather conditions aloft
will gradually improve as the day progresses, sufficient tropical
moisture and instability will be present during peak hours of the
day, with surface heating and sea breeze convergence further
enhancing deep convective activity. Fewer cloud during the
morning hours will prompt several regions to effortlessly reach
convective temperatures throughout the day. A south-southeasterly
wind flow will cluster activity across the interior, northwest,
and north-central Puerto Rico in the afternoon. A limited to
elevated flood risk will be present with the heaviest downpours.
Thursday and Friday will observe a more typical weather pattern with
overnight and morning showers affecting windward coastal areas at
times. Dynamics mentioned above will turn slightly more stable as
the weak mid-level ridge settles over the northeastern Caribbean
with 700-500 mb relative humidities dropping below 60%. The bulk
of the moist plume will remain mostly east of the forecast area,
but close enough to maintain moisture content within the 50% to
75% percentile of the climatological normal. Therefore, expect
showers and a few isolated thunderstorms to develop each afternoon
due to the combination of diurnal heating and local effects.
Activity should subside during evening hours as diurnal heating
declines.
Unfortunately, temperatures are expected to remain above normal for
this week. High temperatures in combination with high moisture
content will promote heat indices to reach 102 degrees or above in
low-lying areas every day through the workweek.
&&
.LONG TERM...Saturday through Thursday...
Saturday will have only a modest high pressure at the surface over
the central Atlantic that will bring moderate trade winds from
the east over the area. A weak trough at the surface and in the
lower levels will demarcate a band of better moisture that will
move through the area from the northeast. This band will have the
best precipitable water that is expected to be seen until Friday
of next week. High pressure at mid levels centered over the area
on Saturday will move west of the area on Sunday, but this will
still impose a limiting factor in the shower and isolated
thunderstorm activity of the day. Dry air follows the band of
moisture immediately and, if the GFS is correct, Monday morning
will see the driest air of the next 10 days. Moisture then
improves during the week reaching even higher levels than the past
few days by the end of the long term period. This will be due to
a return of southeast flow in the lower levels by Tuesday as high
pressure sinks back into the eastern Atlantic near the Tropic of
Cancer. During this time, locally heavy afternoon showers will
develop along the Cordillera Central and in northwestern Puerto
Rico each day from local effects and strong heating. Urban and
small stream flooding, despite the limited instability cannot be
ruled out. Also, although some cooling will be seen Saturday
through Sunday night, Monday will mark the beginning of a warming
trend that will bring very warm temperatures on the north coast
by the end of the long term period.
&&
.AVIATION...
(06Z TAFS)
Issued at 406 AM AST Wed May 24 2023
Mostly VFR conds durg the entire period. SHRA/TSRA will
remain mostly E of TISX/TIST but may be close enough at times thru
24/14Z. Aftn convection in wrn and nrn PR may cause brief MVFR
and mtn top obscurations. Sct-Nmrs SHRA and isold TSRA are
possible mainly ovr NW and N central PR til 24/23Z. Calm to light
and variable sfc wnds will become SE 10-15 kts aft 24/14Z. Maximum
winds WNW 20-25 kt btwn FL430-480 incrg drg the day.
&&
.MARINE...
East or southeast flow during the next 7 to 10 days will not
generate much more than 5 foot seas during the next severals days
and the general trend for the rest of the period will be for
diminishing seas. No small craft advisories are foreseen during
the next 10 days.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory until 4 PM AST this afternoon for PRZ001-005-008-
010.
VI...None.
AM...None.
&&
CAM,MMC,RCPerspectivas sobre las Condiciones Peligrosas del Tiempo Servicio Nacional de Meteorologia en San Juan PR 457 AM AST miercoles 24 de mayo de 2023 AMZ711>745-PRZ001>013-250900- 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 del Caribe- 457 AM AST miercoles 24 de mayo de 2023 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Puerto Rico. .DIA UNO...Hoy y esta noche .Rayos...Se esperan tronadas de aisladas a dispersas a traves de Puerto Rico y las aguas locales. Este atento a tronadas en su area y planifique para buscar refugio. .Lluvias Excesivas...Inundaciones en areas urbanas, carreteras, riachuelos y areas bajas. Inundaciones repentinas son posibles. .Calor Excesivo...Se esperan indices de calor de 108-111 grados a traves de la costa norte y oeste de Puerto Rico donde esta en efecto una Advertencia de calor. Indices de calor de 102-107 grados a traves de areas urbanas y bajas de Puerto Rico y Culebra. Agotamiento por calor es posible con exposicion prolongada. .Condiciones maritimas...Operadores de embarcaciones pequenas deben ejercer precaucion en las aguas mar afuera del noreste del Atlantico. .Corrientes Marinas...Existe un riesgo moderado de corrientes marinas amenazantes a la vida en la zona de rompimiento de olas, particularmente en las playas con orientacion al norte y este de Puerto Rico. .DIAS DOS A SIETE...jueves a martes El riesgo moderado de corrientes marinas continuara a lo largo de la costa norte hasta principios de semana. Inundaciones urbanas y de riachuelos con areas aisladas propensas a inundaciones repentinas son probables de el jueves y el domingo. Acumulacion de agua en areas de poca elevacion son localmente posibles hasta temprano la proxima semana. Se esperan algunas tronadas durante las tardes. Se espera calor excesivo en areas poca elevacion en Puerto Rico, con algunos dias alcanzando el criterio de Advertencias. .Comunicado sobre informacion reportada por observadores... No es necesario activar a los observadores. AMZ716-726-VIZ001-002-250900- San Tomas, San John y las Islas Adyacentes-Santa Cruz- Aguas cercanas a la costa del Atlantico y aguas costeras adyacentes del Caribe- 457 AM AST miercoles 24 de mayo de 2023 Esta perspectiva sobre las condiciones peligrosas del tiempo es para las Islas Virgenes Estadounidenses. .DIA UNO...Hoy y esta noche .Rayos...Tronadas de aisladas a dispersas seran posibles. Planifique detener toda actividad al aire libre y este listo para buscar refugio. .Lluvia excesiva... Acumulacion de agua en las carreteras y en areas de pobre drenaje es posible. Inundaciones urbanas y de riachuelos son posibles. .Condiciones maritimas...Operadores de embarcaciones pequenas deben ejercer precaucion en las aguas mar afuera del noreste del Atlantico. .Corrientes Marinas...Corrientes marinas amenazantes a la vida son posibles en la zona de rompimiento de olas, particularmente en Santa Cruz. .DIAS DOS A SIETE...jueves a martes Un riesgo moderado de corrientes marinas estara presente en Santa Cruz el jueves. Se espera calor excesivo en areas poca elevacion en Santa Cruz el viernes y sabado. .Comunicado sobre informacion reportada por observadores... No es necesario activar a los observadores.
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
A 911 call center report indicated flooding affecting a residence on Lafayette Street in San Juan.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2023Every state in 2023This day in weather historyWarnings in Puerto Rico, May 2023
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: 1089397.