525
FXCA62 TJSJ 022054
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
454 PM AST Sun Jun 2 2024

.SYNOPSIS...

Wet and unstable conditions are expected throughout the week due
to an approaching tropical wave and its moisture field. Therefore,
the risk of flooding rains will be elevated across most of the
forecast area. Improving conditions are foreseen by next weekend.

&&

.SHORT TERM...Today through Tuesday...

Today we have already begun the transition to a wet unstable
pattern fueled by the moisture field of a tropical wave that
approaches the islands from the southeast and a low-level jet. In
the early morning hours, variable and hot conditions under partly
cloudy skies prevailed with scattered showers moving through the
Caribbean Waters, local passages, and east-southeast of Puerto
Rico. Before midday, activity intensified and cloudiness increased
resulting in an active day with multiple flood advisories and
flash flood warnings due to a strong severe thunderstorm that
moved into the southeast bringing periods of heavy rain and wind
gusts. In Guayama and Yabucoa, wind gusts of 50 and 48 mph
respectively were recorded. At this time, the Radar Doppler showed
rainfall estimates between 2 to 5.5 inches. Municipalities of the
eastern and southeastern quadrants of Puerto Rico received the
greatest accumulations. As a consequence, river gauges across area
rivers reported multiple rivers in that region in action stage,
minor, and moderate flood levels. Emergency managers reported some
rescues due to flooding waters in Maunabo and Naguabo. Flood
Warnings continue in effect along Rio Blanco in Naguabo until 6 PM
and Rio Canovanas and its tributaries until 8 PM. Additional
Flood Warning will likely be needed until waters recede, stay
tuned!

Additional periods of rainfall activity are possible tonight into
tomorrow morning, especially across eastern sectors of Puerto
Rico and local islands, and waters. For the remainder of the
period, we are anticipating a wet and unstable pattern. According
to the latest model guidance, the precipitable water content will
remain at above- normal levels throughout the work week,
approximately 2.20 to 2.50 inches, due to the synoptic scenario
and a moist south- southeast wind flow. Therefore, the risk of
flooding rains will be elevated across most of the forecast area.
Flooding of urban areas, roads, and small streams, as well as
isolated flash floods, are possible in the upcoming week.
Residents and visitors should avoid activities in small streams
and waterfalls due to the risk of sudden water rises across the
area rivers, and are encouraged to remain weather- aware for any
future updates.

&&

.LONG TERM...Wednesday through Sunday...
.PREV DISCUSSION... /issued 500 AM AST Sun Jun 2 2024/

Most recent model guidance suggests Precipitable Water(PW) values
ranging from the 75th percentile (above normal values) to above
the 2-standard deviation for this time of the year as lingering
moisture from a departing tropical wave continues to promote
showers and thunderstorm activity across Puerto Rico and the U.S.
Virgin Islands. We forecast the thunderstorm activity to be
stronger over western PR, particularly by the afternoon hours.
However, the stronger or more convective part of the tropical wave
will remain well to the south of the islands. The persistent mid-
to upper-level trough across the northwestern Caribbean will
favor periods of heavy rainfall and thunderstorms near the
forecast area, particularly over the Hispaniola, and potentially
reach some areas of western Puerto Rico through mid-week. At this
time, models suggest Wednesday as the most unstable day of the
long-term period. Therefore, the risk of flooding rains will stay
elevated across all the islands.

As this pattern unfolds, a deep layered ridge will build and hold
just east of the Leeward Islands. The interactions of these
weather features will promote divergence aloft and south-to-
southwesterly wind flow at the surface. That being said, we
foresee warm to hot conditions across the islands. However, it
will depend on how much cloud cover and rainfall materialize over
the islands.

A drying trend is still expected by the end of the workweek into the
weekend as a broad surface ridge becomes the dominant weather
feature.

&&

.AVIATION...

(18z TAFs)

A tropical wave will likely bring VCSH/VCTS across the local area
today. Therefore, areas of MVFR conds and mtn tops obscd can be
expected as the day progresses. Winds will prevail from the east
to southeast at 10-18 kts with higher gusts and sea breeze
variations.

&&

.MARINE...

Moderate to fresh easterly winds will prevail tonight. The rest of
the week expect a dominant southerly to southeasterly component. A
wetter pattern is anticipated through at least mid-week as a tropical
wave approaches the region from the southeast increasing moisture,
seas, and winds, as a result small craft should exercise caution
across most of the regional waters and local passages.

&&

.BEACH FORECAST...

A High Rip Current Risk is in effect from Monday morning to Monday
afternoon for beaches of St Croix. A moderate risk is expected
across most southern and eastern facing beaches of Puerto Rico,
Vieques, Culebra, St Thomas, And St John tonight into Monday,
while a low risk is anticipated for northern beaches of Puerto
Rico. The risk of rip currents is expected to remain between low
and moderate through at least midweek, then return to low by the
end of next week.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.

VI...High Rip Current Risk from Monday morning through Monday
     afternoon for VIZ002.

AM...None.

&&

$$

SHORT TERM...YZR
LONG TERM....MMC
AVIATION...ICP
PUBLIC...CVB