206
FXCA62 TJSJ 290842
AFDSJU
Area Forecast Discussion
National Weather Service San Juan PR
442 AM AST Tue Oct 29 2024
.SYNOPSIS...
A gradual transition into a wetter and more unstable weather
pattern is expected over the next few days, particularly between
late Wednesday into Thursday. Several features will combine to
maintain this weather pattern over the next 4-7 days, including
the proximity of a tropical disturbance by early next week.
Extremely hazardous marine and coastal conditions are also
anticipated from Thursday through the weekend. Please continue to
monitor the forecast as this event unfolds.
&&
.SHORT TERM...Today through Thursday...
A broad surface high-pressure building over the western Atlantic is
promoting moderate to fresh east-to-northeast winds across the
northeastern Caribbean. Under these northeasterly steering winds, a
meandering frontal boundary to our north will move over the islands
today through early Wednesday. As shower and cloud coverage
increases over the islands, daytime temperatures will decrease by a
few degrees across Puerto Rico and the U.S. Virgin Islands.
Furthermore, another front will arrive across the area on Thursday
as the surface high centers near Bermuda. Therefore, a wetter
pattern is expected to unfold across the area, with showers and
thunderstorms increasing in areal coverage. In addition, a polar
trough is forecast to move over the region by Thursday, providing
more instability and favorable conditions for thunderstorm
development. Meanwhile, over the southwestern Caribbean Sea, a broad
area of low pressure is forecast to develop, and this will continue
to promote the pooling of tropical moisture under southerly winds
across the Caribbean. Urban and small stream flooding is expected
each day across the islands, with localized flash flooding and
mudslides in areas of steep terrain.
Tightening of the local pressure gradient and a shearline associated
with the front on Thursday will increase winds between 20 and 25
knots or higher across the Atlantic waters. Therefore, breezy to
windy conditions are possible along the Atlantic coastal
municipalities of Puerto Rico and across the northern U.S. Virgin
Islands.
&&
.LONG TERM...Friday through Tuesday...
The most recent guidance continues to suggest a deep mid-to
upper-level trough across the forecast area by the end of the
workweek. This weather feature will create favorable conditions
for thunderstorm development. A broad area of low pressure at the
surface is expected to develop under the influence of the trough,
and a southerly wind flow is expected to prevail from Friday
onwards. This pattern usually favors the pooling of tropical
moisture over the islands.
A wet and unstable period could unfold during the end of the
month/beginning of November as the National Hurricane Center is
monitoring an area of low pressure that is likely to develop over
the southwestern Caribbean Sea. They anticipate a gradual
development late this week or over the weekend as the system
begins to drift northward or northeastward and potentially
approach the forecast area. This area of low pressure continues to
have a 40 percent chance of development in the next 7 days.
However, it is far in the forecast, and we encourage people to
stay informed with each update.
In the long term, we anticipate temperatures below 90 degrees across
most areas as the cloudiness increases over the region.
&&
.AVIATION...
(06Z TAFS)
Mainly VFR conds expected early in the forecast cycle. SHRA/TSRA are
expected to increase aft 29/12z across the northern and eastern
terminals of the islands as a frontal system over the Atlantic
waters approach the area. Tempo MVFR to brief IFR conds and mtn tops
obscd are possible from around 29/16z onwards. Winds will prevail
from the ENE at 12-17 kt with sea breeze variations across the
southern coast of PR. Stronger gusts and lower CIGS due to FROPA aft
29/20z.
&&
.MARINE...
Moderate to fresh easterly winds will prevail through Wednesday. A
broad surface high pressure building over the western Atlantic will
yield moderate to locally strong, northeasterly winds today, pushing
the remnants of a front across the local area through midweek. An
increase in shower and thunderstorm activity is also expected across
the regional waters and passages through the rest of the workweek
into the weekend.
&&
.BEACH FORECAST...
A northerly swell will continue across the Atlantic waters and
passages today. There is a high risk of rip currents for
northwestern to eastern beaches of Puerto Rico. Thunderstorms with
occasional lightning strikes are expected this afternoon. Across
the USVI and Culebra, a moderate risk of rip currents continues.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for Prz005-002-005-
008-012.
VI...None.
AM...None.
&&
$$
SHORT TERM/AVIATION...DSR
LONG TERM/MARINE/BEACH FORECAST...MMC
NWS SJU Office Area Forecast Discussion