Graphical Hazardous Weather Outlook

FLOOD THREAT

Lightning THREAT

HEAT THREAT

WIND THREAT

WAVES THREAT

RIP CURRENT THREAT

097
FXCA62 TJSJ 020136 AAA
AFDSJU

Area Forecast Discussion...UPDATED
National Weather Service San Juan PR
936 PM AST Fri Nov 1 2024

.UPDATE...

Instability has continued to diminish over Puerto Rico
from 24 hours ago. Water vapor images also show a dry slot
intruding into the area from the southeast. This has pressed the
showers and thunderstorms off of Puerto Rico and into the U.S.
Virgin Islands, although only very minor amounts have fallen in
Saint Croix late this afternoon and evening. Temperatures in the
lower elevations ranged from the upper 70s to lower 80s at 9 PM
AST. Some instability should reappear overnight over the warm
waters surrounding the area.

Marine conditions have dropped some but are still hazardous as
northeast swell continue to move into the area. At 9 PM AST, seas
were running around 8 feet at the inner buoy and 10-12 feet at
the outer buoy with mean wave directions around northeast.

&&

.AVIATION...
(00Z TAFs)

MVFR/IFR conds have moved in to the nrn USVI and will
cont byd 02/08Z. Some clearing with much hir CIGs has occurred
over PR where VFR conds prevail. Winds ovr PR are light land
breezes, while the USVI has experienced some stronger winds due to
SHRA/TSRA in the VCTY with gusts up to 20 knots. LLVL wind flow is
WSW ovr PR as a line of convection moves to the NE ovr the USVI.
This will bcm more southerly aft 02/14Z. Max winds S 35-45 kt btwn
FL355-395, and SW 35-45 kts btwn FL430-470.

&&

.PREV DISCUSSION... /issued 520 PM AST Fri Nov 1 2024/

SYNOPSIS...

The wet pattern will persist across the local islands at least
until Saturday. From Sunday into the upcoming workweek, the
islands will experience a more variable pattern with warmer
conditions and diurnal convection. Hazardous marine conditions
will continue through the weekend and into the upcoming workweek.

SHORT TERM...tonight through Sunday

As forecast, another unsettled morning was observed across
northeastern Puerto Rico and the U.S. Virgin Islands. Showers once
again affected Vieques, Naguabo, Ceiba, and Fajardo at 6 PM, with
activity intensifying over southeastern Puerto Rico, bringing
heavy rain to Maunabo, Patillas, Yabucoa, and adjacent
municipalities throughout the afternoon. Showers also developed
across northern Puerto Rico and the interior. Several Flash Flood
Warnings were issued and remain in effect across much of the area.
Temperature-wise, maximum temperatures stayed in the mid to upper
80s across western and north-central regions, with considerably
cooler temperatures across the mountains.

Conditions will remain wet and unstable from tonight into Saturday
as the upper-level trough persists in a vertically stacked
position, moving slowly northeastward. As this feature remains in
place over the islands, upper-level divergence will induce
ventilation, creating an unstable atmosphere for vertical
development again tonight and tomorrow. According to high-
resolution models and the Galvez-Davison Index (GDI), eastern
Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands have a
high chance of experiencing another wet night with periods of
moderate to heavy showers. By Saturday morning, eastern Puerto
Rico will be the most favorable area for converging cells and
moderate showers, which will spread across northern areas for the
rest of the day. Saturated soil and additional rainfall will
maintain an elevated flood risk across the region for at least
another day. Residents and visitors are urged to monitor weather
updates and avoid activities near rivers.

A more favorable weather pattern is forecast for Sunday; however, while
rain may be more localized, temperatures are expected to rise. As
the upper-level low moves northeastward and the associated
surface trough moves out of the region, a southerly wind pattern
will take over, reducing the prevalence of showers and cloudiness.
However, a continuous moisture flow with PWAT around 2 inches
will persist across the region, bringing warm conditions, followed
by afternoon showers across the interior, moving toward northern
Puerto Rico. The global model shows an increase in 925 MB
temperatures, suggesting the possibility of heat advisory
conditions.

LONG TERM...Monday through Friday...
..from previous discussion issued 501 AM Fri Nov 1 2024...

The long term period is more uncertain, since the trajectory of
the best moisture will depend on the position and strength of the
low generated in the vicinity of the cold front over the weekend.
Nevertheless current model solutions hold the precipitable water
above 2 inches through Wednesday and well above normal for the
season which is about 1.7 inches. Although the best moisture is
expected to be west of the area and southerly flow will contribute
to some above normal temperatures, numerous periods of active
showers and thunderstorms are expected until later next week.
At upper levels a ridge will intrude from the south until a
shortwave passes northeast of the area Tuesday night. This is
forecast to quickly become a TUTT low which returns directly over
eastern Puerto Rico Thursday and pushes over to the Mona Passage
by the end of Friday giving moisture another boost ahead of yet
another easterly wave entering the area. Current indication are
for another wet weekend after Friday the eighth.

AVIATION...
(18Z TAFS)

The presence of a deep layered trough across the region and moist
southeast to south low level winds will aid in maintaining an
unstable weather pattern and mostly cloudy to variably cloudy
conditions across the region through the period. Expect BKN to OVC
CIG nr FL025...FL050...FL080 ovr local islands and en route. TEMPO
MVFR/psbl IFR conds til at least 01/23Z at all PR terminals. Mtn top
obscr due to aftn and evening convection ovr E and Ctrl interior of
PR including ovr EL Yunque. VCSH/Isold TSRA psbl at TIST/TISX til
02/04Z. SFC winds will be generally fm SSE 5 to 10 kts with sea
breeze variations and hir gusts accompanying SHRA/TSRA. Low level
winds veering from S-SW blo FL200. SFC winds bcmg calm to
light/variable aft 02/23z.

MARINE...

Hazardous marine conditions persist across all northern exposed
waters and local passages through the rest of the week and into
the next workweek. A northerly swell, known locally as "La
Marejada de los Muertos," will continue to cause high seas, with
waves up to 10 feet in outer waters and 8 feet in coastal waters.
As a result, several small craft advisories remain in effect for
most local waters. A surface low located northeast of the region
will continue to generate a long period of northeasterly swell,
further increasing seas. Mariners are advised to exercise caution
in local waters.

BEACH FORECAST...

The northerly swell, La Marejada de los Muertos, will continue to
cause large breaking waves along the northern coastal areas. A
high surf advisory is in effect through Saturday afternoon, with
waves of 12-14 feet. A high rip current risk remains in effect for
most of the islands and northern coastal Puerto Rico, including
the northwestern and northeastern coasts. Another long-period
northeasterly swell will bring large breaking waves again by
Monday.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Flood Watch until 8 AM AST Saturday for PRZ001>013.

     High Rip Current Risk through Sunday morning for PRZ001-002-005-
     008-010-012.

     High Surf Advisory until 6 PM AST Saturday for PRZ001-002-005-
     008.

     High Rip Current Risk through Saturday afternoon for PRZ013.

VI...Flood Watch until 8 AM AST Saturday for VIZ001-002.

     High Rip Current Risk through Sunday morning for VIZ001-002.

AM...Small Craft Advisory until 7 AM AST Sunday for AMZ711-712-716-
     741.

     Small Craft Advisory until midnight AST Saturday night for
     AMZ723-742.

&&

$$

SHORT TERM/AVIATION...WS
MARINE/UPPER AIR...LIS
PUBLIC/SOCIAL MEDIA...MNG

NWS SJU Office Area Forecast Discussion

Image

Today

Day 2

Day 3