National Weather Service San Juan PR
442 AM AST Thu Jul 14 2022
.SYNOPSIS...
Variable weather conditions will prevail today, passing showers
during the morning hours and afternoon convection over the
western interior. Typical weather conditions will prevail for the
rest of the forecast period. Another pulse of Saharan Dust will
filter into the forecast area on late Friday into Saturday, this
particles will erode the available moisture and will limit the
shower activity. Choppy to hazardous marine conditions are
forecast for the next several days.
&&
.SHORT TERM...Today through Saturday...
The strong TUTT continues to move west and away from the local area,
allowing for a weak upper high pressure to move over the local
islands, which will stay over the area until late Friday. Then a
tilted upper trough will move over the local area on Saturday. The
available moisture will decrease today but moisture will still be
enough to allow locally induced thunderstorms int he afternoon
across western PR. That said, a weak tropical wave will cause a
quick increase in moisture by the late afternoon hours today. This
increase in moisture is expected to cause scattered to locally
numerous showers across the USVI and eastern PR into the evening
hours.
Drier air returns for Friday during the day with some possible
Saharan dust, but once again with enough moisture to allow
afternoon convection across western PR. Then by Saturday, even
though some Saharan dust may still be present, another quick
tropical wave will cause an increase in moisture over the local
area. By Saturday afternoon, the aforementioned tilted upper
trough may be positioned favorably for sustained thunderstorm
development in areas of sea breeze convergence across western PR.
Temperatures are expected to be near normal, with highs in the upper
80s to low 90s across the lower elevations of PR and the USVI. Heat
index values could reach the low 100s in PR, while the USVI may
remain mainly in the mid to upper 90s. Across the highest elevations
of PR, the daytime temps will be in the low to mid 80s.
.LONG TERM...Saturday through Thursday....
A variably weather pattern is forecast for Saturday. Early in the
morning, a wind surge embedded in the easterly trade will filters
into the region increasing the passing showers. After that, by noon
into the night hours, an big pulse of Saharan Dust will move into
the area eroding al the available mostly and result in hazy skies.
Additionally, conditions at the mid to upper levels will remain
stables, therefore, only limited and localized shower activity is
included in the forecast for Saturday. This drier conditions due to
the presence of the Saharan Dust will prevail throught the rest
of the weekend, increasing the water content on later Monday due
to the arrival of a tropical wave.
For the upcoming workweek, conditions at the upper level would
change when a retrogressing upper level trough drifts more into
the area with the axis over the CWA. Meanwhile, at the surface,
several patches of low level moisture with precipitable water
values above normals from a passing tropical wave will increase
the potential for widespread shower activity. As the surface high
pressure sinks more into the Central Atlantic, a more east-
southeasterly wind flow will prevail on Tuesday into Thursday.
This wind flow will drift all the shower activity over the
northwestern sections of Puerto Rico, and could enhance the San
Juan Metro Area streamer each day. A slight increase in the
temperatures is forecast for Tuesday into Thursday for the north
coastal sections of the islands.
&&
.AVIATION...SHRA/TSRA activity expected today across the local flying
area. This will cause VCSH across the local terminals through the
day, possibly brief SHRA at the terminals. After 14/16Z, the
chance for TSRA increases in areas near TJBQ and TJPS possibly
causing VCTS. Winds will be from the east at around 15 knots with
occasional gusts and sea breeze variations.
&&
.MARINE...
A broad surface high pressure over the Central Atlantic will promote
moderate to fresh easterly winds over the local waters. This will
result in choppy seas up to 6 feet for all the Atlantic waters for
today, increasing up to 7 feet tonight. Therefore, small craft
operators are urge to exercise caution across all the local
waters today, then a Small Craft Advisory will go into effect this
evening for the offshore Atlantic waters. There is a high risk of
rip current for all the northwestern exposed beaches of Puerto
Rico, the risk will extend for the rest of the north coast,
Culebra and St. Croix this evening into the upcoming weekend. For
the rest of the exposed beaches, the risk will remain low to
moderate.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 87 78 / 50 60 50 60
STT 89 79 88 79 / 40 40 40 40