National Weather Service San Juan PR
448 AM AST Sat Jul 6 2019
.SYNOPSIS...A drier and more stable weather pattern along with
some Saharan dust will prevail throughout the weekend. Afternoon
convection is still expected across western Puerto Rico during the
afternoon hours. Another tropical wave is still expected to
affect the area late Monday into Tuesday, resulting an increase in
shower and thunderstorm activity. More stable weather conditions
will follow by the middle and latter half of the work week.
&&
.SHORT TERM...Today through Monday...
A dry air mass with Saharan air particles will move across the
islands today. Model guidance continues to indicate stable weather
conditions through the rest of the weekend. However, moisture
embedded in the trades will bring passing showers across the local
waters at times. Showers and thunderstorms will develop across the
western sections of Puerto Rico due to the strong daytime heating
and sea breeze convergence. Local effects will aid in the
development of showers downwind from the U.S. Virgin Islands each
afternoon.
Daytime high temperatures are forecast to peak in the upper 80s to
low 90s along coastal areas, and in the upper 70s to mid 80s at
higher elevations each day. The Virgin Islands will observe heat
indices in the low and to mid 100s today.
An upper-level trough will slowly dig into the region increasing
instability by late Sunday night into Monday. This upper level
feature will interact with the leading edge of a tropical wave,
which is forecast to reach the islands by late Monday night or early
Tuesday. This will increase the intensity and frequency of showers
and thunderstorms across the area.
.LONG TERM...Tuesday through Saturday...
The axis of the tropical wave is still on track to move across
the area on Tuesday with precipitable water values approaching 2
inches. At the same time, an upper-level trough will be located
just north of Haiti. Therefore, this upper-level trough could aid
in enhancing the rainfall activity that this wave brings. The
tropical wave departs by Tuesday night and behind it, a drier air
mass follows for Wednesday.
For Thursday through Saturday, patches of low-level moisture
embedded within the easterlies will be moving across the area.
Therefore, some passing showers may affect the regional waters and
eastern portions of Puerto Rico and the USVI during the overnight
and morning hours followed by convection developing across
western Puerto Rico during the afternoon hours as a result of
daytime heating and local effects.
&&
.AVIATION...VFR conditions expected throughout the day. SHRA/TSRA
are expected to develop over western Puerto Rico between 06/16-22z.
This may impact JMZ. Winds less than 10 knots through 06/13z,
increasing around 15 knots from the E with higher gusts and sea
breeze variations after 06/13z.
&&
.MARINE...Moderate to fresh easterly trades between 15 and 20
knots will continue to result in rough and choppy seas across
the regional waters through this afternoon. A small craft
advisory continues in effect through 8 am this morning for the
offshore Atlantic waters and through 2 pm this afternoon for the
offshore Caribbean waters and Mona Passage due to seas of up to 7
feet. Seas of up to 6 feet are expected across the nearshore
Atlantic and Caribbean waters. More tranquil seas are expected by
this evening through Monday as the winds diminish.
For beachgoers, there is a moderate risk of rip currents for most
of the local beaches of the islands, except along the west coast
of Puerto Rico and along the northern coast of Saint Thomas and
Saint John.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 78 / 0 30 30 50
STT 90 79 90 79 / 10 40 30 50