Flash Flood Warning 25, NWS JSJ

461 
WGCA72 TJSJ 291042
FFSSJU

Flash Flood Statement
National Weather Service San Juan PR
642 AM AST Thu Jun 29 2023

PRC109-291052-
/O.CAN.TJSJ.FF.W.0025.000000T0000Z-230629T1115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Patillas PR-
642 AM AST Thu Jun 29 2023

...FLASH FLOOD WARNING IS CANCELLED FOR PATILLAS AND REPLACED WITH A 
FLOOD ADVISORY...

Flooding conditions will continue to be a concern across portions of 
Patillas, though conditions have improved slightly. A Flood Advisory 
is now in effect.

LAT...LON 1810 6602 1807 6601 1806 6599 1803 6598
      1802 6597 1802 6595 1801 6595 1799 6594
      1798 6591 1797 6597 1797 6598 1798 6600
      1798 6602 1801 6604 1804 6605 1804 6606
      1803 6608 1806 6609 1808 6607 1811 6605

$$

CRS

Area Forecast Discussion
National Weather Service San Juan PR
354 AM AST Thu Jun 29 2023

.SYNOPSIS...A departing tropical wave and a weak upper-level
trough will continue to promote showers with thunderstorm
development, increasing the risk of lightning, flooding, and
mudslides through late tonight. In the wake of the wave, an
extended drier air mass accompanied by Saharan dust particulate
will reach the local islands on Friday and remain over the region
through the weekend into next week. As a result, expect mainly
fair, warm to hot, and hazy conditions.

&&

.SHORT TERM...Today through Saturday...

The night was active across the local islands and waters, with
thunderstorms developing along the northern Virgin Islands and
Culebra, eastern Puerto Rico and for southern Puerto Rico. Rainfall
accumulations were in the range of 1 to 3 inches, with several flood
advisories and special weather statements issued.

The combination of an upper level trough and a tropical wave will
maintain favorable conditions for additional shower and thunderstorm
production. The high resolution and National Blend Model have the
strongest activity developing along the southern and eastern half of
Puerto Rico and the northern Virgin Islands, but all the area will
experience rain, gusty winds and at least some lightning. Rainfall
accumulation should be in the range of 1 to 3 inches, with isolated
higher amounts.  With the heaviest activity, urban and small stream
flooding, as well as water surges along rivers and mudslides can be
expected today. Flash flooding cannot be ruled out.

As the tropical wave departs toward Hispaniola, the air mass will be
substituted by dry air and Saharan dust. Friday should be a
transition day, with some lingering showers drove by the trade winds
along southeastern Puerto Rico and the Virgin Islands, while some
additional showers develop in the afternoon along the interior and
northwestern Puerto Rico. For the Virgin Islands, skies will become
hazy due to Saharan dust. These hazy conditions will quickly spread
across Puerto Rico on Saturday. The mid-levels will also dry out, so
rainfall activity should be limited. Additionally, the 925 mb
temperatures will-once again- warm up, resulting in highs climbing
into the low to mid 90s in the afternoon hours.

.LONG TERM...Sunday through Thursday...

An extended and relatively drier air mass, accompanied by pulses
of Saharan dust particulate, will continue to spread across the
local area through most of the period, causing precipitable water
values to fall further from seasonal levels (around 1.6-1.8
inches) on Sunday and Monday to below seasonal levels (1.2-1.6
inches) from Tuesday through at least Thursday. A weak tropical
wave will cross the region on Monday, but the bulk of the moisture
should remain well south of the local islands. Expect the driest
period after the wave's passage, with precipitable water values
dropping as low as 1.2 inches between Tuesday and Wednesday.
Still, pockets of shallow moisture will stream across the area,
briefly causing precipitable water values to peak slightly higher
but not high enough to enhance significant shower development.
Despite these variations, shower development is possible even
during the driest period, following the seasonal distribution
pattern, with the heaviest rains of any intensity clustering
across Puerto Rico's western interior to western sections.
Elsewhere, little to no anticipated showers are expected,
particularly in fire-prone areas of southern Puerto Rico, Vieques,
Culebra, and the U.S. Virgin Islands.

Breezy conditions with generally east to east-southeast winds at
15-25 mph will persist through the period, generated by a low-to-
mid level high pressure spreading across the North Atlantic. The
strong mid-level zonal flow will bring an even denser cloud of
Saharan dust particulate across the region; hence, expect
persistent hazy conditions throughout the workweek.

Despite expected seasonal high temperatures, ranging between the
upper 80s and the lower 90s across lower elevations and other
urban areas, locally enhanced moisture levels across western,
northern, and eastern sections could yield elevated to significant
excessive heat hazard risks, with 102 degrees or higher heat
indices. In contrast, drier and breezy conditions could lead to
elevated fire weather hazard risks across southern Puerto Rico,
particularly around midweek.

&&

.AVIATION...Numerous SHRA expected to continue throughout the
period across the local waters and land areas. Isolated to scattered
TSRA are also expected along the USVI and PR terminals, with periods
of reduces VIS and low ceilings. Mountain obscuration is also
expected for the Cordillera Central. The wind flow will be from the
SE at 14-23 kts, and stronger gusts.

&&

.MARINE...Recent CariCOOS buoy network observations around Puerto
Rico and the U.S. Virgin Islands indicated seas between 1 and 3
feet. However, seas up to 6 feet are likely with increasing east-
southeasterly wind speeds at 10-20 knots. This wave will also
generate a higher frequency of showers and thunderstorms today
into Friday morning, resulting in locally hazardous marine
conditions. Weather conditions will gradually improve tonight, but
marine conditions will remain choppy through Friday evening.

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
AM...None.
&&

SHORT TERM...ERG
LONG TERM....ICP
AVIATION...ERG
PUBLIC...ICP/ERG

Hazardous Weather Outlook
National Weather Service San Juan PR
352 AM AST Thu Jun 29 2023

AMZ711>745-PRZ001>013-300800-
San Juan and Vicinity-Northeast-Southeast-Eastern Interior-
North Central-Central Interior-Ponce and Vicinity-Northwest-
Western Interior-Mayaguez and Vicinity-Southwest-Culebra-Vieques-
The nearshore and off shore Atlantic and Caribbean Coastal Waters-
352 AM AST Thu Jun 29 2023

This Hazardous Weather Outlook is for portions of Puerto Rico.

.DAY ONE...Today and Tonight

.Lightning...Numerous thunderstorms possible across |the area.
Plan to stop all outdoor activity and move to shelters.

.Excessive Rainfall...Life-threatening flash flooding, possibly
entering structures and cutting off neighborhoods for the south
and southeast. Flooding of urban areas, roads, and small
streams elsewhere, with isolated flash flooding possible.

.Excessive Heat...Heat index 102-107 degrees across the north
central municipalities briefly. Heat exhaustion possible with
prolonged exposure.

.Wind...Breezy conditions for coastal areas. Unsecured items
could blow around.

.Marine Conditions...Small craft should exercise caution across
the offshore waters and passages.

.Rip Currents...Life-threatening rip currents are possible in the
surf zone particularly along southern Puerto Rico, Vieques and
Culebra.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Hazardous marine and life-threatening rip current conditions will
persist through the weekend into early next week. Saharan dust
particulates will likely move over the region from Friday onwards.
Excessive heat hazard risks will return from Friday onward, with
areas experiencing 108 degrees or higher heat indices.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is encouraged. Please relay any information
about flooding, winds, waves, and rip currents to the National
Weather Service in San Juan.

AMZ716-726-VIZ001-002-300800-
St. Thomas St. John adjacent Islands-St Croix-
Nearshore Atlantic and adjacent Caribbean Coastal Waters-
352 AM AST Thu Jun 29 2023

This Hazardous Weather Outlook is for portions of USVI.

.DAY ONE...Today and Tonight

.Lightning...Numerous thunderstorms possible across the islands
and local waters. Plan to stop all outdoor activity and move to
shelters.

.Excessive Rainfall...Flooding of urban areas, roads, small
streams, and washes. Isolated flash floods possible.

.Wind...Breezy conditions. Unsecured items could blow around.

.Marine Conditions...Small craft should exercise caution across
the offshore waters and passages.

.Rip Currents...Life-threatening rip currents are possible in the
surf zone particularly the southern coasts of the islands.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Hazardous marine and life-threatening rip current conditions will
persist through the weekend into early next week. Saharan dust
particulates will likely move over the region from Friday onwards.
Excessive heat hazard risks will return from Friday onward, with
areas experiencing 108 degrees or higher heat indices.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is encouraged. Please relay any information
about flooding, winds, waves, and rip currents to the National
Weather Service in San Juan.

Special Weather Statement
National Weather Service San Juan PR
248 AM AST Thu Jun 29 2023

PRZ002-003-290730-
Northeast PR-Southeast PR-
248 AM AST Thu Jun 29 2023

...A strong thunderstorm will impact portions of northeastern Puerto
Rico, near Humacao and Naguabo through 330 AM AST...

At 246 AM AST, a strong thunderstorm was over Anton Ruiz, or over
Naguabo, moving north at 5 mph.

HAZARD...Up to 40 mph wind, frequent cloud to ground lightning and
         heavy rain.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects. Heavy rain may cause temporary
         street flooding especially in poor drainage areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. If you can hear
thunder, you are close enough to be struck by lightning. Motorists
should slow down and be prepared for possible loss of control due to
hydroplaning.

&&

LAT...LON 1824 6562 1820 6569 1818 6570 1819 6573
      1817 6574 1817 6575 1815 6577 1808 6580
      1811 6587 1819 6582 1829 6579
TIME...MOT...LOC 0646Z 178DEG 5KT 1821 6578

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

ERG

Special Weather Statement
National Weather Service San Juan PR
332 AM AST Thu Jun 29 2023

VIZ002-290800-
St Croix VI-
332 AM AST Thu Jun 29 2023

...A strong thunderstorm will impact portions of Saint Croix  through
400 AM AST...

At 331 AM AST, a strong thunderstorm was near Grove Place, , moving
north at 10 mph.

HAZARD...Up to 40 mph wind, frequent cloud to ground lightning and
         heavy rain.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects. Heavy rain may cause temporary
         street flooding especially in poor drainage areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. If you can hear
thunder, you are close enough to be struck by lightning. Motorists
should slow down and be prepared for possible loss of control due to
hydroplaning.

&&

LAT...LON 1768 6490 1770 6488 1775 6489 1777 6487
      1776 6483 1778 6479 1778 6475 1775 6471
      1777 6465 1775 6460 1773 6461
TIME...MOT...LOC 0731Z 174DEG 23KT 1780 6482

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

ERG