National Weather Service San Juan PR
538 AM AST Sat Sep 17 2022
.SYNOPSIS...
Tropical Storm Fiona started to affect the local islands with
numerous passing showers, strong winds, and thunderstorms across
the eastern half of the region. Conditions will further
deteriorate, with the most significant activity expected
throughout the weekend. So far, the eastern and southern sections
of Puerto Rico should see the worst winds and most rainfall based
on the latest track, but all of the area will see heavy rainfall.
A wet pattern will continue throughout early next week, slowly easing
to a more seasonal pattern.
Based on a strengthening trend, a Hurricane Watch is in effect for
today and tomorrow for Puerto Rico, the Caribbean Waters, and Mona
Passage. This is due to possible hurricane force winds when the
system moves closer to the islands.
&&
.SHORT TERM...Today through Monday...
Tropical Storm Fiona continues to approach the local islands,
causing deteriorating weather conditions. The envelope of tropical
storm force winds is currently forecast to enter southeastern side
of the forecast area this morning, and the system is forecast to
continue to strengthen as it passes close to Cabo Rojo about a
day later. The GFS, which is fairly close to the official forecast
track for Fiona is showing a peak precipitable water of 2.7
inches on 18/12Z Sunday morning. Tropical Storm Fiona will exit
the forecast area around Monday morning. Significant rainfall is
anticipated with and behind this system, which will result in
considerable flood impacts, including flash and urban flooding,
along with mudslides in areas of steep terrain. Based on the
current forecast, eastern, southeastern, and southwestern Puerto
Rico should see the worst winds and rainfall, but the entire area
will see heavy rain. Additionally, tropical-storm-force winds are
expected to affect the area, with the strongest winds and gusts
along the Cordillera Central and southwestern Puerto Rico. The
activity will continue into Sunday, as the center of the storm
moves closer to western Puerto Rico and Fiona continues to
strengthen. For detailed information on Fiona`s impacts across the
island, track and projected intensities, please refer to the
Hurricane Local Statement (HLS) at www. weather.gov/sju.
On Monday, flow will be southeast at the surface and south southwest
at 700 mb and will be one of the main feeds of moisture and heat for
Tropical Storm Fiona. This will prolong showers and thunderstorms
across the area as well as some heavy rain. The threat of
flooding and mudslides will continue throughout the short term
period.
&&
.LONG TERM...Tuesday through Saturday...
By Tuesday, Tropical Storm Fiona will be well northwest of the
region and the threat of strong winds will have passed for the local
islands. However, numerous showers will continue throughout the
day, as generally southerly flow with prevail in the lower level,
blanketing the local atmosphere with saturated air. Stability
will be decreased post-Fiona, therefore thunderstorms are
expected throughout the week. Surface wind flow will prevail from
the southeast, favoring passing showers across the USVI and
eastern Puerto Rico followed by afternoon development across the
Cordillera Central into the western/northwestern quadrant of PR,
with streamer development affecting various eastern/northern
portions of Puerto Rico. Due to days of continuous rainfall, soils
across the islands will be very saturated and the probability for
flooding and landslides will be elevated.
A wet pattern will continue throughout the week, slowly easing to a
seasonal pattern. Precipitable water values will remain above normal
and then will decrease by Thursday into the weekend as patchy
moisture moves over the region. A strong Tropical Upper Tropospheric
Trough (TUTT) may develop east of the region on Friday, which could
support an unstable atmosphere locally. The position of this upper
low for today.level feature will determine how much rainfall
will occur next weekend. Overall, for the long term forecast, a
wet pattern is expected with the greatest hazards being urban and
small stream flooding, isolated mudslides, and daily
thunderstorms.
&&
.AVIATION...
Based on latest guidance from NHC, at 500 AM AST (0600 UTC), the
center of Tropical Storm Fiona was located near lat 16.4 deg N,
long 63.3 W. Fiona is movg twd the W nr 11 kts. Psbl max wnd
55g65 kt. Fiona is movg into the NErn Carib Sea and across the
lcl flying area fm arnd 17/06Z thru Monday morning. SCT SHRA/Isold
TSRA ovr rgnl waters and enroute btwn islands expected, bcmg
numrs aft 17/14Z. SFC wnd fm E 18-20 kts with hir gusts 25-35 kts
and ocnly hir with convective rain bands durg prd thru 17/10Z. Mtn
low for today.tops will be obscured ovr most of USVI/PR. Tropical
storm force winds are expected nr TISX by 17/13Z. Aft 17/14Z
tropical storm force winds and MVFR/IFR conds ovr a wide swath ovr
and south of the USVI/PR.
&&
.MARINE...
Hazardous marine conditions are forecast for all of the local
waters for the next several days as Tropical Storm Fiona moves
across the CWA. Therefore, a Tropical Storm Warning is in effect
for Puerto Rico, the U.S. Virgin Islands, and all the local
waters. A Hurricane Watch is also in effect due to a possible strengthening
of the system over the next couple days. Building seas up to 15
feet are expected through early in the workweek. Seas at the outer
buoy are reading 10 feet at around 12 seconds from the ESE.
Please note that high seas, high surf, and strong rip currents
will be life-threatening to those entering the water.
&&
.HYDROLOGY...
Based on the most recent guidance, the most likely time period for
the heaviest rainfall activity is Saturday into Sunday, while the
areas most likely to receive the highest rainfall accumulations are
portions of eastern and southern Puerto Rico, where there is a
potential for rainfall totals to reach 8 to 10 inches with
locally higher amounts to around 16 inches. Across south-central
Puerto Rico and the US Virgin Islands, Vieques, and Culebra the
potential exists for rainfall totals to reach 4 to 6 inches.
Elsewhere, expect rainfall totals to range between 2 and 4 inches.
Considerable flash and urban flooding impacts are possible across
eastern and southern Puerto Rico on Saturday afternoon and
Sunday. Across central and northwest Puerto Rico as well as the
US Virgin Islands, this rainfall may produce limited flash and
urban flooding impacts. Additionally, mudslides/rockfalls are
possible in areas of higher terrain. The threat of flooding will
continue into Monday-- mainly in Puerto Rico.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Tropical Storm Warning for PRZ001>013.
Flood Watch through Monday afternoon for PRZ001>013.
VI...Tropical Storm Warning for VIZ001-002.
Flood Watch through Monday afternoon for VIZ001-002.
&&
$$
CAM/ICP/RC/GRS