570
FXCA62 TJSJ 290714
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
314 AM AST Wed Apr 29 2026

...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST...

.KEY MESSAGES...
Updated at 304 AM AST Wed Apr 29 2026

* An elevated flooding risk is expected today for portions of the
  interior, northern and northwestern Puerto Rico as strong
  afternoon showers and thunderstorms develops.

* A limited heat risk will continue for the next few days across
  urban and coastal areas of the islands without prolonged rain
  and cloud coverage.

* A gradual drying trend is anticipated by the weekend, leading
  to improving weather conditions across the region.

* A moderate rip current risk continues over north and east-
  facing beaches Puerto Rico and St. Croix. Beachgoers should
  exercise caution along exposed beaches.

&&

.Short Term(Today through Friday)...
Issued at 304 AM AST Wed Apr 29 2026

Relatively calm conditions prevailed across Puerto Rico and the U.S.
Virgin Islands under mostly clear to partly cloudy skies. Doppler
radar and satellite imagery detected a few showers developing off
the southeastern coast of Puerto Rico, moving inland with minimal
rainfall accumulations, specifically across the coastal areas of
Humacao and Yabucoa. Overnight minimum temperatures ranged from the
mid-70s in coastal and urban areas to the low-to-mid 60s across the
mountains. Winds remained light and variable at 5 knots or less.

Today, abundant moisture will continue to filter into the region,
promoting another day of unsettled weather. Precipitable water
analysis (PWAT) indicates above-normal values reaching up to 2.0
inches. This moisture, combined with a weak east-southeast steering
flow, will favor the development of showers and thunderstorms during
the afternoon hours across the interior, western, and northern
sections of Puerto Rico, including the San Juan metropolitan area.
While the heaviest activity is expected to concentrate in these
regions, portions of southern Puerto Rico may also see development
as coverage expands and persists. Given the slow-moving nature of
the expected activity, the risk of flooding is elevated today. Heavy
rainfall, frequent lightning, gusty winds, rapid river rises, and
minor urban flooding are likely in areas where rain persists.

Across the U.S. Virgin Islands, passing showers embedded in the wind
flow are expected to move through during the morning hours,
resulting in minimal impacts across the local islands.

A gradual drying trend is expected to begin Thursday and continue
into Friday as moisture levels decrease and a mid-level ridge builds
over the area. Nonetheless, sufficient moisture, daytime heating,
and local effects could still trigger afternoon showers and isolated
thunderstorms across portions of the interior, west and northwestern
Puerto Rico, potentially leading to localized flooding. Warm to hot
temperatures will persist throughout the week, particularly across
the urban and coastal areas of the islands.

&&

.Long Term(Saturday through Wednesday)...
Issued at 304 AM AST Wed Apr 29 2026

To start the weekend, current guidance has been variable and still
indicates above-normal precipitable water content, around 1.8 to 2
inches, and 500 mb temperatures near -7 degrees C. A high-pressure
system will be positioned over the central Atlantic, leading to a
northeasterly flow at around 10 to 15 mph. The trough pattern aloft
will be exiting the area, allowing for more stability and higher
heights; however, expect wind-driven showers early across eastern
Puerto Rico, followed by afternoon convection across the
northwestern quadrant of Puerto Rico, with the possibility of a few
lightning strikes. Accordingly, a limited flood threat will persist
on Saturday over northwestern Puerto Rico due to the high potential
for ponding of water on roads and in poorly drained areas. By
Sunday, expect a similar pattern with localized showers during the
afternoon, particularly over northwestern Puerto Rico.

Transitioning into early next week, a gradual drying trend is
anticipated, leading to improving weather conditions. The driest
period currently looks to be Monday through Wednesday. Precipitable
water values will decrease to near-normal levels or even below
normal, while 250 mb heights will further increase and 500 mb
temperatures will warm as ridging builds aloft, bringing greater
atmospheric stability. Although afternoon showers may still develop
due to local effects, their coverage and intensity will be reduced.
Any shower activity during this period should be brief and limited.

Even though there will likely be a break from the rain, the main
concern during this period will be persistent warm conditions, as
indicated by temperature guidance at 925 mb and a prevailing east to
southeasterly wind flow, suggesting values will remain above normal
through the forecast period. Maximum surface temperatures will range
from the upper 80s to the low 90s across coastal and urban areas,
and from the low to mid-80s in higher elevations. Heat indices will
likely reach the upper 90s to the low 100s degrees F each day. As a
result, a limited heat threat will remain in place for urban,
coastal, and low-elevation areas. Residents and visitors are
encouraged to stay hydrated and avoid prolonged sun exposure during
peak heat hours.

&&

.AVIATION...
(06Z TAFS)
Issued at 304 AM AST Wed Apr 29 2026

Mainly VFR conds expected at all TAF sites. However, unstable
weather conditions will produce SHRA/TSRA during the afternoon hours
resulting in brief MVFR/IFR conds at TJSJ/TJPS/TJBQ aft 29/17Z.
Light/variable to calm winds early in the morning, becoming ESE btw
8-12 kt after 29/14Z. Winds will turn light/variable aft 29/2223Z.

&&

.MARINE...
Issued at 304 AM AST Wed Apr 29 2026

A series of frontal lows over the western to central Atlantic and a
high over the central Atlantic will prevail over the next few days.
This will result in a weaker pressure gradient that will promote
variable, light to gentle southeasterly winds, becoming east-
southeasterly again on Thursday and east to east southeasterly on
Friday. Moisture over the region and a nearby trough will continue
to result in showers and isolated t-storms over the next few days.
Pulses of small, long- period northeasterly swell will continue to
spread across the Atlantic waters and local passages for the next
few days, though seas should remain between 2 to 4 feet.

&&

.BEACH FORECAST...
Issued at 304 AM AST Wed Apr 29 2026

The moderate risk should prevail over the region as pulses of a
small, long period northeasterly swell spreads across the local
waters and passages. The northern coastline of Puerto Rico, Culebra
and St. Croix will continue to be affected, meaning that life-
threatening rip currents are possible in the surf zone. A low risk
of rip currents will continue over other areas, however, life-
threatening rip currents often occur in the vicinity of groins,
jetties, reefs, and piers. Beachgoers should also continue to
monitor the forecast for showers and afternoon t-storms in the area,
especially near northern coastal areas of Puerto Rico, resulting in
heavy rain, lighting and gusty winds.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...None.
&&

$$

SHORT TERM...GRS
LONG TERM....YZR
MARINE/BEACH FORECAST...MMC

NWS SJU Office Area Forecast Discussion