110
FXCA62 TJSJ 072028
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
428 PM AST Fri Feb 7 2025

.SYNOPSIS...

Variable weather conditions will persist across the local islands
from tonight into the weekend. On Sunday, winds will shift more
from the northeast, resulting in cooler temperatures. Wind-driven
seas will continue to create choppy marine conditions across most
exposed waters and local passages. Therefore, several small craft
advisories are in effect for the weekend and into the upcoming
workweek.

&&

.SHORT TERM...Tonight through Sunday...

A variable weather pattern prevailed across the local islands
during the day with frequent lines of showers and gusty winds.
Shower activity was persistent and the rainfall accumulations were
less that one inches along most of the eastern side of the
islands.Around 3 PM, shower activity begun along western interior,
specifically over Hormigueros and San German. Those showers
reported almost one inch of rainfall accumulations reported from
the rainfall estimates from Radar Doppler. Daytime maximum were
in the mid to upper 80s along the coastal areas and in the mid 60
to low 70s in the upper areas along the mountains.

A mid-level high-pressure ridge will continue to prevail across the
forecast area, with a brief weakening expected Saturday night into
Sunday. At lower levels, surface high pressure across the North
Central Atlantic will continue to yield fresh to moderate east-
northeast winds. Consequently, the 925mb winds will continue to
prevail at 20 knots, slightly above the normal range. Moisture-wise,
the latest guidance suggested precipitable water (PW) values near
1.4 inches, with the bulk remaining below 850mb through the forecast
cycle. As a result, showery conditions will continue to prevail
across Puerto Rico as well as the US Virgin Islands tonight into the
weekend. Nevertheless, these fast-moving showers should not cause
flooding. Due to the breezy to windy conditions, afternoon
convection/sea breeze convergence must be limited across western
areas each day.

Overall, the accumulated rainfall forecast for the next 72 hours
specifically favors the north-central, northeast, and east-coastal
regions of Puerto Rico, with the chance of exceeding 0.5 inches
each day remaining low (30%). Maximum temperatures will range in the
upper 80s along coastal areas to the mid-70s in upper elevations.
However, there is a medium (40-60%)chance that maximum temperatures
will exceed 90 degrees across coastal areas in southern Puerto Rico,
particularly on Saturday.

Breezy conditions, combined with drying soils and available fuels,
will increase the fire risk during the next few days; see the fire
section for additional details.

.LONG TERM...Monday through Friday...from previous discussion...

A surface high pressure system extending across the North Atlantic,
along latitudes 25-30N, will maintain a tight pressure gradient
across the islands during the workweek. This will keep breezy to
locally windy east to east-northeasterly winds throughout the week.
These winds will keep an advective pattern with patches of moisture
reaching our area from time to time, increasing the frequency of
passing showers across the windward sections of the islands.

Precipitable Water (PWAT) values will fluctuate between 1.1 and 1.4
inches during the long term period, which is normal to slightly
below normal for this time of the year. Dry air will continue in the
mid levels of the atmosphere due to a mid level ridge building just
north of our area. This will maintain mainly stable conditions most
of the week, with moisture trapped in the low levels of the
atmosphere due to the occasional patches of moisture reaching the
islands. Therefore, no significant flood threat is expected. By
Friday of next week, a mid to upper level shortwave trough could
start to erode the mid-level ridge, increasing instability aloft
across the region. This could help boost the local rainfall pattern
by late next week. However, dry air in the mid levels will
still limit deep convective development.

Temperatures will continue near seasonal levels during the period
with highs ranging from the low to mid 80s across lower elevations
(locally higher over western/southwestern/southern Puerto Rico).
Minimum temperatures will stay in the 60s across higher elevations,
and from the low to mid 70s across lower elevation of the islands.
Patchy fog will continue to be possible during the overnight to
early morning hours across the interior valleys of Puerto Rico.


&&

.AVIATION...
18Z TAFs)

Mainly VFR conditions expected. VCSH, and possibly -SHRA, will
affect TJSJ/TIST/TISX through the forecast cycle. ENE at 15-20 kts,
with gusts at 20-30 kts, becoming at 10-15 kts overnight.

&&

.MARINE...

A strong high-pressure system building over the Central and
Eastern Atlantic will continue to promote moderate to vigorous
easterly to north-northeasterly winds across local waters. As a
result, wind-driven seas will maintain choppy conditions across
all offshore waters and local passages. Recent buoy data indicates
seas ranging from 5 to 7 feet, with winds reaching up to 20 knots.
Small craft advisories are in effect until Sunday night for most
offshore Atlantic waters and the Anegada Passage.

&&

.BEACH FORECAST...

There is a moderate risk of rip currents across most beaches in
Puerto Rico and the U.S. Virgin Islands. Similar conditions are
expected to persist through the weekend. Some localized exposed
beaches along the north and northeast coasts may present a higher
threat due to bathymetric features or jetties along the shore.
Beachgoers are urged to visit designated swimming areas along the
exposed northern coasts of Puerto Rico and the U.S. Virgin
Islands.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...Small Craft Advisory until midnight AST Sunday night for AMZ711-
     723.

     Small Craft Advisory until 6 PM AST this evening for AMZ733-741.

&&

$$

SHORT TERM & AVIATION...OMS
MARINE & BEACH FORECAST...LIS