GRLevel3 radar images are not available at this time.
000
FXCA62 TJSJ 220901
AFDSJU
Area Forecast Discussion
National Weather Service San Juan PR
501 AM AST Fri Sep 22 2023
.SYNOPSIS...A tropical wave will continue to move across the area
today. Heavy rainfall over saturated soils will lead to urban and
small stream flooding and mudslides in areas of steep terrain.
Heat indices between 108 and 111 degrees are expected across most
urban and coastal areas of PR and the USVI. Latest guidance
regarding a tropical wave over the Eastern Tropical Atlantic
suggest that development into a tropical system is likely during
the next couple of days, and that it should remain over the open
waters through next week.
&&
.SHORT TERM...Friday through Sunday...
Above normal moisture continues to engulf the northeastern
Caribbean. This moisture is associated mainly with a tropical wave,
but additionally, there is an upper level low northeast of the
Caribbean, and a surface reflection is also evident on satellite
imagery. As a result, showers have been arriving during the night
hours across the U.S. Virgin Islands and eastern Puerto Rico. Some
lightning has been observed as well. Fortunately, these showers have
not leaved significant rainfall accumulation, although a few
sections near Naguabo and Humacao collected nearly half an inch. The
showers will continue into the early morning hours, leaving wet
roads.
The trade winds will be from the east with a southeast component
today, with speeds near 13 knots. These winds are mainly driven by a
surface high pressure over the central Atlantic. There is plenty of
moisture for another active afternoon today. The high resolution
models, as well as the National Blend of Models, show widespread
showers covering the interior and west, as well as portions of the
San Juan metro area. These areas, especially the west, have been
receiving plenty of rain in the past few days, hence the soils are
saturated and some rivers are running high. The risk for urban and
small stream flooding, as well as rapid river rises and mudslides
will be elevated for today. Lightning and gusty winds are also
possible with the strongest activity. Across the Virgin Islands,
Vieques, Culebra and eastern Puerto Rico, passing showers will
continue to move too.
Later in the period, a mid to upper level ridge strengthen, capping
moisture at the lower levels of the atmosphere. The frequency of
showers should diminish, but it won`t be completely dry, as patches
of low level moisture will continue to move in these days. Small
concentrations of dust will be also available this weekend. For each
day, the usual pattern of passing showers in the east in the morning
and afternoon activity for the west will prevail.
In terms of temperatures, 925 mb temperatures continue to be above
the climatological values for this time of year. With plenty of
humidity near the surface, heat indices again will be above 108
degrees for many areas in the west and northern municipalities of
Puerto Rico, Vieques, Culebra and all of the U.S. Virgin Islands.
There is a chance that some areas that receive strong rains in the
afternoon could experience a relief from the scorching heat, at
least later in the day, but it will be steamy everywhere else.
.LONG TERM...Monday through Friday...
Precipitable water content is expected to increase between 2.00-2.25
inches on Monday due to a tropical wave passage. At this moment,
Monday looks to be the wettest day of the long term period.
Thereafter, a northeasterly wind flow is expected to prevail
through much of the period, with diurnally induced afternoon
showers developing over portions of central and southern PR each
day. An advective pattern should prevail during the night and
early morning hours, favoring passing showers along the northern
and eastern sections of PR, as well as across the USVI. Meanwhile,
a tropical wave with a high development chance over the Eastern
Tropical Atlantic is now expected to remain over open waters
through the end of the week. However, we will continue to monitor
the progress of this system as it can produce hazardous seas and
life-threatening rip currents once again by the second part of the
week.
&&
.AVIATION...SHRA will continue across the local waters, and around
the USVI and TJSJ terminals. After 16-17Z, SHRA and TSRA should
develop along the Cordillera Central, and W-NW PR. Periods of
reduced VIS and low ceilings can be anticipated. SHRA could reach
the vicinity of TJSJ and , and the USVI terminals too. Winds will
be from the ESE at 8 to 13 kts, with stronger gusts.
&&
.MARINE...Seas are expected to range between 2 and 5 feet through
early next week. Easterly winds should continue between 10 and 15
knots through the period. A moderate risk of rip currents will
continue for all beaches of the islands through the weekend. Seas
are expected to increase by midweek next week.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
for PRZ001-005-008-010>013.
VI...Heat Advisory from 10 AM this morning to 5 PM AST this afternoon
for VIZ001-002.
AM...None.
&&
$$
SHORT TERM...ERG
LONG TERM....DSR
AVIATION...ERG
