A frontal boundary located near the area as well as abundant low-level moisture resulted in heavy showers and isolated thunderstorms across the San Juan area. These showers were slow-moving, therefore, flooding was observed across portions of the 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 frontal boundary located near the area as well as abundant low-level moisture resulted in heavy showers and isolated thunderstorms across the San Juan area. These showers were slow-moving, therefore, flooding was observed across portions of the 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 Apr 5, 3:45 PM AST, 5 hours 17 minutes earlier.
Area Forecast Discussion
National Weather Service San Juan PR
345 PM AST Sun Apr 5 2020
.SYNOPSIS...
A weakening cold front will bring a few showers to the area
through early in the workweek. A northerly swell is causing
hazardous seas and dangerous coastal conditions as well. This
frontal boundary is forecast to once again result in shower
activity by mid-week.
&&
.SHORT TERM...Rest of Today through Tuesday...
Similar to yesterday, a few showers have developed over the
interior of Puerto Rico due to lingering moisture associated with
a dying cold front. Light winds at low levels are causing these
showers to be quite slow, so there will be a threat into the
early evening hours of ponding of water on roadways and low-lying
areas.
Heading into the workweek, we will see a trend towards a more normal
weather pattern. Currently, a large polar trough dominates the mid-
to upper-levels of the atmosphere over the Atlantic, with its
associated large surface low also well established over the central
Atlantic. On Monday, the trough and surface low will head off
towards the east, and high pressure will once again build to our
north by midweek. Furthermore, mid-level temperatures will begin to
warm Monday into Tuesday as a ridge builds to our east, with a weak
inversion forming at lower levels in forecast model soundings. This
of course will suppress cloud development, and only allow for weak
showers on Tuesday.
Thus, isolated to scattered showers will continue into the
nighttime, with isolated showers overnight over the local waters but
not so much over land. Tomorrow afternoon will likely be similar to
this afternoon with a chance for scattered showers over the interior
of Puerto Rico, since atmospheric conditions don't change
substantially between now and tomorrow afternoon. However, on
Tuesday, with warmer temperatures aloft, less CAPE, and weaker lapse
rates, weaker afternoon showers will result in the afternoon hours.
.LONG TERM...Wednesday through Monday...
High pressure at the surface will continue to shift eastward into
the central Atlantic ocean. At the same time the old cold front
will still be near the area in the form of a shear line. This will
provide a focal point--or line--for shower activity.
Low level flow will shift from east northeast on Wednesday to
southeast on Thursday. At least a modest southerly component in
the easterly flow will continue at lower levels during the weekend
and into the next week. The old boundary will finally lift north
on Saturday to complete a warming and drying trend begun on Friday
and peaking on Saturday.
Upper level flow will be mostly west northwest through much of
this week, but will become more northerly as a weak trough forms
southeast of the area and high pressure ridges in from the
southwest across the central Caribbean and into Puerto Rico.
Without a strong upper low nearby, 500 mb temperatures will remain
too warm for serious convection in an atmosphere that remains dry
at mid and upper levels for the entire period, so thunderstorms
are not expected.
These conditions will, however, be favorable for late night and
early morning showers in eastern Puerto Rico, favoring the eastern
and southeastern slopes. During the afternoon flow will favor
shower generations along and north of the Cordillera Central.
Because flow at mid levels is westerly and reaches as low as 850
mb, showers will tend to favor central and east central Puerto
Rico during the afternoons, even though showers in west and
northwest Puerto Rico will occur from time to time. The best
showers should be seen Wednesday through Friday.
&&
.AVIATION...SHRA will develop over the west and central portions of
PR thru 06/02z. Some VCSH possible at JBQ/JSJ/JMZ/JPS. VFR conds are
expected to prevail thru much of the forecast. IST/ISX/KPK can
expect isolated rains at times, especially after 06/00z. Winds will
be dominated by sea breeze variations between 5-15 knots, becoming
calm to light and VRB aft 05/23z, and returning from the NE at 10-15
kt after 06/13z.
&&
.MARINE...
Hazardous seas continue with seas up to 8 feet and winds up to 15
knots over the Atlantic waters and Caribbean Passages. Small craft
advisories are in effect through Monday evening. Seas will
gradually improve by Tuesday. At the beaches, high rip current
risk continues for the north-facing beaches of the islands and for
the eastern-tip of St. Croix.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 75 86 75 84 / 40 30 50 40
STT 75 82 74 85 / 40 50 50 40
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late Tuesday night for Mayaguez
and Vicinity-North Central-Northeast-Northwest-San Juan and
Vicinity-Southeast.
High Surf Advisory until 8 AM AST Monday for Culebra-North
Central-Northeast-Northwest-San Juan and Vicinity-Southeast.
High Rip Current Risk through Tuesday afternoon for Culebra.
VI...High Rip Current Risk through Monday morning for St Croix.
High Rip Current Risk through Tuesday afternoon for
St.Thomas...St. John...and Adjacent Islands.
AM...Small Craft Advisory until 8 PM AST Monday for Atlantic Waters
of Puerto Rico and USVI from 10 NM to 19.5N-Coastal Waters
of Northern Puerto Rico out 10 NM-Coastal Waters of
Northern USVI and Culebra out 10 NM-Coastal Waters of
Northwestern Puerto Rico out 10 NM-Mona Passage Southward
to 17N.
&&
SHORT TERM...RAM
LONG TERM/Public Desk....ERGPerspectivas sobre Condiciones Peligrosas del Tiempo Servicio Nacional de Meteorologia San Juan PR AMZ710>745-PRZ001>013-060915- 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 mar afuera del Atlantico y Caribe- 507 AM AST domingo 5 de abril de 2020 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Puerto Rico y las aguas costeras del Atlantico. .Dia Uno...Hoy y esta noche .Inundaciones...Lluvia fuerte pudiera resultar en estancamiento de agua e inundaciones urbanas y de riachuelos localizadas a traves de sectores del centro de Puerto Rico. .Oleaje...Se espera oleaje peligroso de hasta 8 pies a traves de las aguas del Atlantico y los pasajes locales. .Corrientes marinas...Existe riesgo alto de corrientes marinas para la mayoria de las playas al norte de Puerto Rico y Culebra. .Dias dos hasta el siete...lunes a sabado Oleaje peligroso y corrientes marinas continuaran prevaleciendo hasta temprano la proxima semana laboral. .Comunicado sobre informacion reportada por observadores... No se anticipa activacion de observadores. Favor comunicar cualquier informacion sobre correintes marinas e inundaciones al Servicio Nacional de Meteorologia en San Juan, siguiendo las indicaciones de las autoridades locales y estatales. AMZ715-725-VIZ001-002-060915- San Tomas, San John y Islas Adyacentes- Santa Cruz-Aguas cercanas del Atlantico y aguas costeras adyacentes del Caribe- 507 AM AST domingo 5 de abril de 2020 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Islas Virgenes Estadounidenses y las aguas costeras adyacentes. .Dia uno...Hoy y esta noche .Oleaje...Se espera oleaje peligroso de hasta 8 pies a traves de las aguas del Atlantico y los pasajes locates. .Corrientes marinas...Existe riesgo alto de corrientes marinas para el noroeste de San Tomas y el noreste de Santa Cruz. .Dias dos hasta el siete...lunes a sabado Oleaje peligroso y corrientes marinas continuaran prevaleciendo hasta temprano la proxima semana laboral. .Comunicado sobre informacion reportada por observadores... No se anticipa activacion de observadores. Favor comunicar cualquier informacion sobre correintes marinas al Servicio Nacional de Meteorologia en San Juan, siguiendo las indicaciones de las autoridades locales.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN JUAN PR
814 PM AST SUN APR 5 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0800 PM FLOOD SAN JUAN 18.41N 66.06W
04/05/2020 SAN JUAN PR EMERGENCY MNGR
EMERGENCY MANAGERS REPORTED SEVERAL ROADWAYS WITH PONDING
OF WATER AND ONE STREAM OUT OF ITS BANK. THESE ROADWAYS
INCLUDE VILLA NEVARES, PUERTO NUEVO, 65 DE INFANTERIA,
SIMON MADERA AND BARRIO OBRERO.
&&
ERODThe San Juan radar (TJUA), 31 km away, was scanning. The volume nearest the first event began at 01:04 UTC.
3 flash flood. Local standard time, as filed.
Calle 3 Sector Villa Nevares was completely flooded due to a small stream going out of its banks.
Road PR-19 completely flooded due to Quebrada Margarita going out of its banks.
Calle Antartico in Sector Puerto Nuevo was completely flooded.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2020Every state in 2020This day in weather historyWarnings in Puerto Rico, April 2020
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: 888963, 888964, 888965.