Advisory FFA Flood Watch — Thu Oct 27, 2022 10:02 PM

FFASJU) for more information.

Potential hazards during the short-term cycle are still lightning
at limited to elevated risk levels, excessive rainfall at limited
to significant hazard risk levels, and non-thunderstorm wind at
limited risk levels.

The wet and unstable pattern that persisted during the last two
days will continue through the short-term forecast period. The
interaction between an upper-level low and associated surface-
induced trough and abundant moisture from a passing tropical wave
will support these conditions. In this scenario, the potential for
excessive rainfall, lightning, and non-thunderstorm wind impacts
will persist as the resulting band of low-level convergence
continues to bring scattered to numerous showers and isolated to
scattered thunderstorms into the local islands. The highest impact
directly depends on the location of the low-level convergence,
which guidance suggests will remain nearly stationary over Puerto
Rico tonight and slowly drift west-northwestward on Friday,
maintaining above-normal moisture levels around 2.25 inches. As a
result, expect additional rainfall amounts of one to three inches
over the observed rainfall accumulations of one to three inches,
mainly across southern and eastern Puerto Rico. This additional
rainfall could aggravate ongoing flooding impacts, cause creeks
and rivers to flood out of their banks, and promote mudslides in
areas of steep terrain. For that reason, the Flash Flood Watch was
extended through Friday evening for Puerto Rico and the U.S.
Virgin Islands. A more seasonal weather pattern distribution will
return on Saturday with the entrance of somewhat drier air. Still,
favorable conditions generated by the upper-level trough will
boost any shower and thunderstorm development. Thus, the potential
for flooding, lightning, and other flood-related impacts will
prevail.

Due to increased cloud cover, warmer overnight minimums and
cooler daytime maximums will persist. The daily temperature cycle
will range from the mid 60s across higher elevations to the lower
80s across lower elevations of eastern Puerto Rico. Surface winds
will remain variable at 5-15 mph with higher gusts and sea breeze
variations through this evening. After that, expect predominantly
southeasterly winds at 10-20 mph. Slightly higher wind gust speeds
are likely near the shower and thunderstorm activity.

.LONG TERM...Sunday through Friday...

The inherited forecast is still on track. On Sunday, expect
another moisture surge to reach the forecast area, as the low-
pressure system approaches. This wet pattern will prevail through
the first part of the workweek. Latest model run is suggesting
that Tuesday will be the peak of the event, with moisture contents
reaching 2 inches. The National Hurricane Center is monitoring
this system and is giving it a 50% chance of development within
the next five days. At this time, the system does not represent a
direct impact on the local islands other than an increase in
moisture content across the region. The main threats with this
event are flooding and mudslides, due to how saturated the soils
are. Urban and small stream flooding is very likely with the
passage of this weather feature. Expect Wednesday to be a
transition day, as models suggest a more seasonal weather pattern
through at least Friday.

&&

.AVIATION...Unsettled weather conditions will continue across the
local region. Therefore, MVFR conditions across local terminals
will remain possible throughout this evening. JPS/JSJ can expect
TSRA/SHRA through tonight. Another round with +TSRA/+SHRA will
return after 28/04z, affecting IST/ISX/JSJ. Winds will persist VRB
at 6 kt or less, however, gusty winds can be expected within any
thunderstorm activity. Winds will increase after 28/13z out of
SE/ESE.

&&

.MARINE...Moderate to locally fresh winds and a small northeasterly
swell will maintain choppy marine conditions, mainly across the
offshore Atlantic waters and western Puerto Rico coastal waters
into the Mona Passage, where small craft operators should exercise
caution. So far, mariners can expect seas up to 6 feet and east-
to-southeasterly winds up to 20 knots. Elsewhere, except near the
persistent showers and thunderstorms activity, marine conditions
will remain promising, with seas at 5 feet or below and winds at
5-15 knots. A moderate risk of rip currents will persist in north-
central and southwestern Puerto Rico surf zones.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Flood Watch through Friday evening for PRZ001>013.

VI...Flood Watch through Friday evening for VIZ001-002.

&&

$$