Atlantic Hurricane Season 2024 Storm Names

099
FXCA62 TJSJ 182108
AFDSJU

Area Forecast Discussion
National Weather Service San Juan PR
508 PM AST Tue Feb 18 2025

.SYNOPSIS...

A mix of clear skies and clouds, along with occasional trade wind
showers across the windward areas will prevail during the next
few days. Higher frequency and intensity of showers is expected on
Thursday, with greater chances for afternoon convection across
western PR. For the weekend, a prefrontal boundary and an upper-
level trough will increase moisture and instability across the
region. High risk of life-threatening rip currents will continue
through late tonight, with a few pulses of northerly swells to
increase the risk once again late this week into the weekend.


&&

.SHORT TERM...Tonight through Thursday...

Stable weather conditions prevailed across the region, with mostly
clear skies in the morning. By early afternoon, some cloudiness
developed over the mountains, particularly in the Cordillera
Central, and moved northwestward into the northern sections of
Puerto Rico. Winds remained from the east-southeast at 10-15 mph,
with gusts reaching 20 to 22 mph in coastal areas. These conditions
enhanced the fire weather threat along the southern coastal plains
of Puerto Rico. Maximum temperatures were slightly above
climatological normals, reaching the mid to upper 80s across most
coastal areas of the CWA.

Water vapor imagery from the GOES satellite and derived PWAT data
indicate that a drier air mass dominated the local region. Although
a patch of cloudiness and moisture was present, the bulk of moisture
remained well south of the CWA. By late afternoon, cloudiness across
the region could lead to some localized showers over the western
interior sections of the island.

From Wednesday into Thursday, winds will veer again due to the
interaction between a surface high-pressure system and a frontal
boundary moving westward into the North Atlantic. Embedded within
this wind pattern, a patch of moisture will increase relative
humidity at 850-500 mb, bringing values closer to climatological
normals. This shift will enhance shower activity across the eastern
portions of the islands and the U.S. Virgin Islands. On Wednesday,
shower activity is expected to remain localized, with minimal
rainfall accumulations. However, by Thursday, increased moisture
will push PWAT values up to 1.6 inches in the 75th percentile,
leading to a rise in both the frequency and intensity of showers.
Model ensembles and local guidance suggest that Thursday will be the
wettest day of the short-term period, with showers primarily
affecting the northwestern sections of the island and southeastern
Puerto Rico.

.LONG TERM...Friday through Tuesday...
.PREV DISCUSSION... /issued 503 AM AST Tue Feb 18 2025/

A mid-to-upper-level ridge will weaken even more due to an
approaching trough aloft. A zonal flow will be established on
Saturday and Sunday, with diffluence developing Monday into
Tuesday over the Northeast Caribbean as a jet stream moves arrives
from the west. These factors would promote instability aloft to
increase across the US Virgin Islands and Puerto Rico, giving
place to periods of moderate to locally heavy rains if enough
moisture arrives, especially during the maximum diurnal heating.

On the other hand, across the low level, most of the cold front
will remain away from the islands. However, a prefrontal trough
could form over or near Puerto Rico and the US Virgin Islands on
Saturday and early Sunday. Additionally, the arrival of trade wind
perturbations will be the primary source of moisture in the long
term. A vertical transect in our region indicates an increase
along the column of air Saturday and Sunday, surpassing 700 MB and
reaching almost 600 MB, which could result in scattered to
numerous downpour events. If that moisture pools over the region
during the afternoons, it could be enhanced by sea breeze
variations and across the windward locations by low-level
convergence and local topography. Another sharp increase in the
available moisture is observed late Monday night into Tuesday, and
the arrival of a Jet stream will accompany it. The aforementioned
weather pattern is a rain-producing one. Thus, we should remain
aware of these possible events as we may see a better chance of
flooding rains during these periods.

Seasonal temperatures will remain consistent, with daytime highs
in the mid-80s across the US Virgin Islands and northeastern
Puerto Rico. The southern and western coasts of Puerto Rico may
see highs in the low 90s. Minimum temperatures are expected to
range from the low to mid-70s in coastal areas to the upper 50s to
low 60s in higher elevations.

&&

.AVIATION...
(18Z TAFs)

VFR conditions will prevail across all TAF sites during the period.
Winds will continue from the E at 15 knots or less, diminishing aft
19/03Z, becoming more light and variable. Winds will peak up again
aft 19/15Z. No operational issues expected.

&&

.MARINE...

The surface high pressure across the Central Atlantic will promote
choppy seas due to east to east-northeast winds across the region
during the next few days. Then, the interaction between the frontal
boundary moving across the western Atlantic and the high pressure
will result in moderate to locally fresh east to southeasterly winds
Thursday through Friday. A prefrontal trough will increase shower
activity by the weekend.

&&

.BEACH FORECAST...

San Juan buoy continue to indicate breaking waves between 6 to 7
feet, which will continue into tonight. Therefore, a high risk of
life-threatening rip currents will continue through late tonight
along the north and east facing beaches in PR and Culebra.
Elsewhere, a moderate rip current risk continue, meaning that
life-threatening rip currents are possible. Then, a moderate risk
of rip current will continue during the next few days. Small
pulses of northerly swells will reach the Atlantic beaches of the
islands once again late this workweek and the weekend. This will
increase the potential for life-threatening rip currents in some
exposed beaches, especially along northern PR and Culebra.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through late tonight for PRZ001-002-005-
     008-012.

VI...None.
AM...None.

&&

$$

SHORT TERM...LIS
LONG TERM....CAM
AVIATION...LIS
MARINE/BEACH...KML/CVB/YZR

NWS SJU Office Area Forecast Discussion