National Weather Service San Juan PR
510 AM AST Wed Aug 24 2022
.SYPNOSIS...
Improving weather conditions are expected today with only a few
passing showers in the morning and afternoon showers with one or
two thunderstorms across the interior and western sections of
Puerto Rico. Heat index values will reach the 100 degrees
especially along coastal and urban areas. There is a moderate
risk of rip currents for the northcentral and northwest beaches of
Puerto Rico, there is a low risk of rip currents elsewhere.
A broad trough of low pressure is forecast to cross the Lesser
Antilles around late Thursday night or early Friday morning. The
National Hurricane Center is actively monitoring this disturbance;
additional information is available in the Tropical Weather
Outlook (TWOAT) or www.nhc.noaa.gov.
&&
.SHORT TERM...Today through Friday...
Weather conditions should improve today compared with the previous
days. Therefore, expect a few passing showers early in the morning
(but mainly across the local waters), with a mixture of clouds and
sunshine through the morning. The available moisture combined with
maximum temperatures in the upper-80s and low-90s will result in
heat index values in/over the 100s degrees Fahrenheits, especially
along coastal and urban areas. These heat indices may occur the rest
of the days of the workweek. During the afternoon, local effects,
sea breeze, and diurnal heating will promote showers with one or two
thunderstorms across the interior and western PR.
A trade wind perturbation will increase the frequency and intensity
of showers on Thursday, and sea breeze, low-level convergence, and
diurnal heating could enhance the development of afternoon
convection across the interior and western Puerto Rico and downwind
from the Virgin Islands.
A broad trough of low pressure is forecast to cross the Lesser
Antilles around late Thursday night or early Friday morning, with
its bulk of moisture remaining well south over the Caribbean Sea.
However, the typical weather pattern is anticipated for the Virgin
Islands and Puerto Rico. The National Hurricane Center actively
monitors that system; additional information is available in the
Tropical Weather Outlook (TWOAT) or www.nhc.noaa.gov.
&&
.LONG TERM...Saturday through Thursday...
The weekend will start off with humidity related to a low pressure
system reaching our offshore Caribbean waters on Saturday morning
according to model guidance. This humid airmass includes
precipitable water values of above 2 inches, which is above normal
values for this time of the year. This disturbance is currently
being monitored by the NHC, who gave it a low formation chance of
near 0 percent through the next 48 hours and 20 percent through
the next five days. This low formation chance of 20 percent
through the next five days could occur in the Caribbean Sea.
Nevertheless, the humid air related to this disturbance will
increase rain chances, especially in the Caribbean Sea. Meanwhile,
a wind surge along with a band of moist air is also forecast to
reach the region during the late afternoon hours on Saturday. This
band should also have precipitable water values just below 2
inches. Both of these areas of increased moisture can bring
increased shower activity as they affect the forecast area on
Saturday.
GFS model guidance shows humidity related to a tropical wave
affecting our region from Sunday and into the first half of the
workweek. This wave no longer has any cyclonic formation chance,
but current model guidance shows high precipitable water values
over the region. Late Sunday through early Wednesday still show a
deep moist layer reaching the upper levels. These disturbances
promote an increased potential for heavy rainfall, especially to
start the workweek. Weather conditions in the forecast region will
be tied to the development of these systems, we will continue to
monitor the future development of theses system throughout the
coming days and given how the models have been behaving,
especially for the start of the workweek, direct impacts to our
region can vary. A drying trend will be observed from late
Wednesday through the end of the long term forecast period, with
precipitable water values reaching normal values. For this time
expect a generally typical weather pattern of passing showers
mainly over the east and shower activity during the afternoon
hours mainly over the interior and western Puerto Rico due to
diurnal heating and local effects.
&&
.AVIATION...VFR conditions will prevail today. SHRA/TSRA will
form across the Cordillera Central and downwind from the USVI
during the afternoon, btwn 24/17-22z. This activity could impact
local terminals, but most of the activity is expected in the VCTY.
Expect calm to light and VRB winds through 24/13z, returning from
the E at 15-20kt with sea breeze variations and gusty near
TSRA/+SHRA.
&&
.MARINE...Generally moderate easterly winds are expected to
prevail due to a surface high pressure system over the Atlantic.
Quick passing showers and isolated thunderstorms producing brief
wind gusts will continue to affect the coastal waters and local
passages from time to time. Small craft should exercise caution in
the local Atlantic waters due to locally fresh winds. There is
also a moderate risk of rip currents for the northcentral and
northwest beaches of Puerto Rico, there is a low risk of rip
currents elsewhere.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&
$$
SHORT TERM...CAM
LONG TERM....MRR