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000
FXCA62 TJSJ 190806
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
406 AM AST Fri Apr 19 2024

.SYNOPSIS...
The risk of flooding will remain elevated today, especially for the
municipalities along the interior. Another active afternoon is
expected under a light wind flow. Soils are saturated and rivers are
running high, so even little precipitation may result in flooding
and mudslides. This afternoon activity will continue for the next
few days. Some Saharan dust could reach the islands early in the
next workweek, and temperatures are expected to warm up too.

&&

.SHORT TERM...Today through Sunday...

Showers lingered across the interior sections of Puerto Rico during
the evening hours however cleared before midnight when an increase
of passing showers over northern Puerto Rico and the USVI were seen.
Winds lightened and became variable with speeds around 3 mph this
morning. Heavy rainfall yesterday caused Rio Grande de Manati and
Rio La Plata to overflow their banks, causing flooding on the
roads they intersect. Due to this, flood warnings were issued
until the morning.

A light lower level steering flow is hinting at another afternoon
of active weather for the interior to southern sections of Puerto
Rico. Meanwhile, passing showers across windward sections will
continue. During the afternoon, convection will likely begin
across southwestern PR, then spreading eastward along the
Cordillera Central. Thunderstorms are possible and will be
capable of producing lightning and strong wind gusts. Heavy
rainfall is very likely with a few inches of accumulation possible
across sections that are already saturated due to previous days
of rainfall. Due to this, there is an elevated to significant
risk of flooding for the central interior sections of Puerto Rico
today. Take caution and watch for rapid river rising, mudslides,
and flooded streets.

Showers are expected to linger through the early evening hours.
However, the arrival of drier air will limit the amount of rain
seem through the night. Passing showers remain possible. As an
area of high pressure at the surface located in the western
Atlantic continues to build, light to moderate NE winds will
continue. This will concentrate Saturday`s afternoon convection
across the southwestern sections of Puerto Rico. However, due to
the arrival of drier air, less rain is forecast compared to the
previous days. A similar pattern is expected on Sunday as the
aforementioned surface high moves north of the region causing
veering in the surface winds to an easterly direction, which will
bring the best chance of rain across the interior to western
sections of Puerto Rico.

.LONG TERM...Monday through Friday...

The next workweek will begin with a 60% chance of experiencing above
normal precipitation across the local islands. First of all, a high
pressure system northeast of the islands will maintain the winds
from the southeast at around 8 knots. A straight line of moisture
stretching from a low pressure system just east of the high pressure
will keep a dense Saharan-Air-Layer just south of the local islands
on Monday. However, small concentrations of these particulates could
reach the islands, so skies may look hazy at times. With moisture
lingering around, showers and isolated thunderstorms are anticipated
to develop along the Cordillera Central in the afternoon. The winds
from 850 to 700 mb are expected to be from the south, so this
convection will move northward, possible reaching portions of the
San Juan metro area.

Then, another low pressure system is expected to exit the eastern
coast of the United States, and the surface high will migrate
northward. The line of moisture will continue to meander around the
northeastern Caribbean, providing enough moisture to fuel afternoon
convection through Thursday. On Friday, additional induced patches
of moisture will be dragged across the region, but more breaks of
sunshine are expected.

Even with the afternoon rains, enough heating is expected late in the
morning, and with a southerly flow, temperatures will be on the hot
side, with highs reaching the upper 80s and low 90s, and heat
indices above the 100 degree mark.


&&

.AVIATION...
(06z) TAFS

Mainly VFR conditions are expected to prevail across all terminals
during the next 24 hours. However, tempo MVFR conds are possible at
TJPS thru 19/19z-22z due to vicinity TS. Low level winds will
continue from the north-northeast around 10 kt.

&&

.MARINE...
A set of surface troughs, one to the northwest and other to the
northeast of the islands will promote light to locally moderate
northeast winds today. A small northeasterly swell will move across
the Atlantic waters through the weekend. The surface trough
northeast of the region and a surface high pressure building across
the western Atlantic will promote moderate trades by the weekend.

&&

.BEACH FORECAST...
A small northeasterly swell will continue to move across the
local islands, maintaining the risk of rip currents moderate for
northern Puerto Rico, Culebra and eastern St. Croix.

&&

.HYDROLOGY...
Another round of strong showers and thunderstorms is expected for
today under a very light wind flow. Due to previous rainfalls,
soils are saturated and rivers are running high in the interior of
Puerto Rico. Therefore, the risk for flooding and mudslides will
be elevated again today. Additionally, it is likely that afternoon
activity will not only focus on the main island of Puerto Rico,
but Vieques, Culebra and the Virgin Islands could see convection
popping up as well.

&&

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

$$

SHORT TERM...RC
LONG TERM....ERG