The combination of abundant tropical moisture from a departing tropical wave interacting with an upper-level trough north of the region produced strong afternoon thunderstorms over northwestern Puerto Rico on the 9th of August. A weak EF-0 tornado and strong outflow boundaries caused thunderstorm wind damage across the municipality of Aguadilla.
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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.
The combination of abundant tropical moisture from a departing tropical wave interacting with an upper-level trough north of the region produced strong afternoon thunderstorms over northwestern Puerto Rico on the 9th of August. A weak EF-0 tornado and strong outflow boundaries caused thunderstorm wind damage across the municipality of Aguadilla.
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 Aug 9, 11:45 AM AST, 1 hour 1 minute earlier.
Area Forecast Discussion
National Weather Service San Juan PR
1145 AM AST Wed Aug 9 2023
...New UPDATE, AVIATION...
.UPDATE...
Another active day is expected due to abundant tropical moisture
along with good daytime heating and marginally unstable conditions
aloft. Passing showers and isolated thunderstorms continued to affect
the coastal waters and portions of the islands. This activity will
continue to spread across the rest of the region including the San
Juan metro area, during the afternoon and evening hours. Areas of
isolated but strong thunderstorms can be expected with periods of
locally heavy rains and good potential for minor urban and small
stream flooding as well as mudslides in areas of steep terrain.
An upper trough will linger just north and east of the region and
thus provide sufficient ventilation for enhanced afternoon convection
in and around the islands. Overall no change in the inherited forecast
grids and reasoning as an active week is still expected to continue
due to a combination of tropical waves, increasing instability aloft
Thursday into early Friday and again on Saturday into Sunday. A surge
of Saharan dust is also expected during this period with saharan dust
particulates expected to accompany and trail the tropical waves along
with increasing trade winds.
&&
.AVIATION UPDATE...Moisture ahead and accompanying a tropical
wave, now crossing the Lesser Antilles will continue to promote
SHRA/ Isold TSRA across the area during the prd. Brief MVFR psbl
due to SHRA/ISOLD TSRA til 09/23Z at all terminals. SCT-BKN lyrs
nr FL025...FL040...FL090. SFC wnds fm the E-SE 12-15 kts with
seabreeze variations and occasionally hir gusts, especially in or
near SHRA/TSRA and along the coastal areas.
&&
.Previous discussion.../issued at 431 AM AST Wed Aug 9 2023/.
.SYNOPSIS...
Throughout the remainder of the week, moisture levels will remain
elevated across the local area. Moderate to fresh trade winds
will persist due to a surface high pressure situated north of the
region, interacting with tropical waves passing over the local
waters. The upcoming tropical wave is forecast to move across the
the local forecast area between Thursday and Friday.
&&
.SHORT TERM...TODAY THROUGH FRIDAY...
The abundant trailing moisture of the tropical wave brought
widespread shower activity across the local waters overnight,
spreading across the islands of St Thomas, St John, and St Croix, as
well as across the windward sections of Puerto Rico. The Doppler
Radar detected periods of moderate to locally heavy rains with this
activity. GOES-E observed isolated thunderstorms across the local
waters too. Low temperatures remain in the upper 70s and low 80s
across the lower elevations and the low and mid-70s in the mountain
areas, while the winds were mainly from the east but under the
influence of the land breeze.
GFS suggested the advection of vorticity into the region later this
morning into the afternoon may result in favorable atmospheric
conditions for another rainy day. The trailing moisture of
yesterday's tropical wave will bring another rainy day today,
combined with vorticity advection, excessive heat, local effects,
and sea breezes, resulting in enhanced convection periods across
most islands. Rain activity will begin across the local waters, the
U.S. Virgin Islands, and windward sections of Puerto Rico during the
morning, spreading into the rest of Puerto Rico late this morning
into the afternoon. Although rainy conditions are likely today, warm
to hot temperatures (with HI up to 107 degrees Fahrenheit or even
more) due to the combination of air temperatures and abundant
moisture will happen across the urban and coastal areas where rain
does not form.
Most islands have an elevated risk of urban and small stream
flooding today. Mudslides along steep terrains and flash flooding
will be possible if widespread activity materializes. The atmosphere
is also favorable for the formation of thunderstorms, so please
remember to avoid outdoor activities if you can hear them.
Although there is a high chance of rain forecasted, it is expected
to clear out of the U.S. Virgin Islands by late morning. This will
create favorable conditions for the heat index to reach 108-111
degrees Fahrenheit, particularly between 11 am and 5 pm. As a
result, a Heat Advisory is currently in effect for St. Thomas, St.
John, and St. Croix.
There is going to be another tropical wave arriving on Thursday
afternoon that will bring wet and unstable weather to the islands.
However, there will be some relief from the rain activity due to
subsidence before the wave bulk of moisture. Despite this, the
moisture levels will remain above average, and combined with high
temperatures, it will promote warm and hot weather. Additionally,
the African Easterly Jet will cause the wind to increase during the
arrival of this tropical wave.
A somewhat drier air mass will set over the islands by Friday,
resulting in periods of sunshine and heat index values between 102-
111 degrees Fahrenheit. The typical August weather pattern consists
of the morning passing showers across the windward sections in
USVI/PR and strong afternoon convection across western PR. Heat
Advisories and Excessive Heat Warning may be required during the
afternoon.
&&
.LONG TERM...Saturday through Wednesday...
Even though there is a slight anticipated decrease in moisture
during Friday, there will still be sufficient moisture present to
trigger showers and thunderstorms across the interior and western
areas of Puerto Rico.
Saturday will see a mid to upper lever trough moving southward,
enhancing the instability in the local area until Sunday. In the
morning, anticipate passing showers than will mainly affect the
northeast portions of Puerto Rico and the U.S. Virgin Islands.
later in the late morning and early afternoon , showers and
thunderstorms will begin to develop and impact the western ,
interior and southwest areas of Puerto Rico. These weather
conditions might persist into the evening due to the continued
movement of the mid to upper level trough across the region,
sustaining and unstable environment throughout this period.
According to the GFS model, there is and indication of steep lapse
rates and colder temperatures than usual at the 500 mb level. the
primarily constraint, however, will be the availability of
moisture.Despite this, there is a potential for strong
thunderstorms on Saturday.
Sunday is anticipated to be a transitional day, with weather
conditions contingent upon the trough's location and moisture
availability. It won't be until Monday when a considerably drier
and more stable airmass arrives to the local region. This dry
weather pattern is forecast to persist at least until Wednesday of
the upcoming week.
&&
.AVIATION...The tropical wave will bring another round with SHRA/TSRA
across the local flying area. IST/ISX may be impacted thru 09/16z.
Periods of VFR conditions are expected, but TSRA will develop by mid-
morning into the afternoon (especially between 09/15-22z). TSRA will
bring gusty winds and frequent clouds to ground lighting. Expect
winds from the E-ESE, with land breeze variations until 09/13z. Then,
they will range between 10 and 15 kt but locally higher in/near SHRA/TSRA
and with sea breeze variations.
&&
.MARINE...Latest observation from CariCOOS buoys indicate seas
between 3 to 5 ft around the islands, with the exception of the
Rincon buoy, which indicates 1.6 ft and the Ponce Buoy indicating
2.3 ft. Small Craft Should Exercise Caution over the offshore
Atlantic waters with seas up to 6 ft. Other seas up to 5 ft.
Additionally, showers and isolated thunderstorms moving over the
waters can promote locally higher seas and winds with frequent
lighting.
Consistent across all global models is the forecast of noteworthy
rise in local winds from Thursday and Friday. This wind increase
is associated to the anticipated tropical wave during this period.
As a result, anticipate breezy conditions across all local waters,
especially in the Caribbean waters and Anegada Passage. Therefore
a Small Craft Advisory will be in effect between Thursday
Afternoon and Friday.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...Heat Advisory until 6 PM AST this evening for VIZ001-002.
AM...Small Craft Advisory from 2 PM Thursday to 8 AM AST Friday for
AMZ723-733.
Small Craft Advisory from 8 PM Thursday to 8 AM AST Friday for
AMZ741.
&&
SHORT TERM...RAM
LONG TERM....MRR
AVIATION...RAMPerspectivas sobre las Condiciones Peligrosas del Tiempo Nacional de Meteorologia en San Juan PR 500 AM AST miercoles 9 de agosto de 2023 AMZ711>745-PRZ001>013-100900- 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- 500 AM AST miercoles 9 de agosto de 2023 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Puerto Rico. .DIA UNO...Hoy y esta noche .Rayos...Tronadas numerosas son posibles a traves de la region, especialmente durante la tarde. Planifique detener las actividades en el exterior y muevase a un lugar seguro. .Lluvia Excesiva...Inundaciones de areas urbanas, carreteras, y riachuelos. Inundaciones repentinas aisladas son posibles. .Calor Excesivo...Indices de calor de 102-107 grados a traves de sectores costeros y urbanos. Agotamiento por calor posible con exposicion prolongada. .Condiciones Maritimas...Operadores de embarcaciones pequenas deben ejercer precaucion a traves de las aguas mar afuera del Atlantico. .Corrientes Marinas...Corrientes marinas amenazantes a la vida son posibles en la zona de resaca particularmente a lo largo de las playas del norte, este, y sureste. .DIAS DOS A SIETE...jueves a martes Una onda tropical promovera tiempo inestable el jueves. Calor excesivo es posible para la mayoria de los dias durante la semana. Las condiciones maritimas se deterioraran con oleaje de hasta 7 pies a traves de las aguas del Atlantico de jueves a viernes. Se espera un riesgo moderado de corrientes marinas durante el fin de semana. .Comunicado sobre informacion reportada por observadores... Se exhorta la activacion de los observadores. Favor enviar cualquier informacion de inundaciones, viento, oleaje y corrientes marinas al Servicio Nacional de Meteorologia en San Juan. AMZ716-726-VIZ001-002-100900- San Tomas, San John y las Islas Adyacentes-Santa Cruz-Aguas cercanas a la Costa del Atlantico y aguas costeras adyacentes del Caribe- 500 AM AST miercoles 9 de agosto 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 son posibles a traves de las islas hoy. Este pendiente a tronadas en su area y preparese para ir a un lugar seguro. .Lluvia Excesiva...Acumulacion de agua en carreteras y areas de pobre drenaje. Inundaciones urbanas y de riachuelos son posibles. .Calor Excesivo...Indices de calor de 108-111 grados a traves de areas urbanas. Agotamiento por calor probable con exposicion prolongada. Golpe de calor posible. .Condiciones Maritimas...Operadores de embarcaciones pequenas deben ejercer precaucion a traves de las aguas mar afuera del Atlantico. .Corrientes Marinas...Corrientes marinas amenazantes a la vida son posibles en la zona de resaca particularmente en St. Thomas, St. John y St. Croix. .DIAS DOS A SIETE...jueves a martes Una onda tropical promovera tiempo inestable el jueves. Calor excesivo es posible para la mayoria de los dias durante la semana. Las condiciones maritimas se deterioraran con oleaje de hasta 7 pies a traves de las aguas del Atlantico de jueves a viernes. Se espera un riesgo moderado de corrientes marinas durante el fin de semana. .Comunicado sobre informacion reportada por observadores... Se exhorta la activacion de los observadores. Favor enviar cualquier informacion de inundaciones, viento, oleaje y corrientes marinas al Servicio Nacional de Meteorologia en San Juan.
The San Juan radar (TJUA), 117 km away, was scanning. The volume nearest the first event began at 16:44 UTC.
5 thunderstorm wind, 1 funnel cloud, 1 tornado. Local standard time, as filed.
Several videos received from the general public, backed up by radar data, indicated a funnel cloud over Aguadilla near road PR-2 and road PR-459.
A report shared by social media indicated wind damage at Borinquen Bilingual School. A zinc roof from a garage was observed on the floor, as well as a few tree branches. Estimated wind gusts were around 40-50 mph.
A weak tornado developed near Highway 2 in Aguadilla early |in the afternoon of Wednesday, August 9, 2023. The brief tornado primarily |impacted a structure, tearing off aluminum roofs from a garage and causing |damage to vehicles in the affected area. Additionally, associated |with this severe thunderstorm, strong gusty winds from the outflow |affected the area near Crash Boat Beach, resulting in trees falling onto |parked cars and fallen power lines.
Emergency managers reported that a zinc roof fell from a garage at the Police Traffic Department in Aguadilla. The estimated wind speed was 40-50 mph.
A report from the media indicated that a Toyota Yaris 2009 was hit by a zinc panel, damaging the bumper and next to the front-left tire. The driver had to take shelter inside a nearby building.
A report received by emergency managers indicated several tree branches on the ground in Barrio Centro Moca, in the direction of the local dairy farm.
A severe thunderstorm that produced a tornado earlier in the day caused strong gusty winds along the western coast of Aguadilla. Particularly across the area near Crash Boat Beach, resulting in trees falling onto parked cars and fallen power lines.
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 historyThe tornado archive for Puerto Rico, 2023Warnings in Puerto Rico, August 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: 1122491, 1122487, 1122492, 1122488, 1122490, 1122489, 1122495.