Post by cycloneye on Jun 20, 2017 4:23:28 GMT -6
Area Forecast Discussion
National Weather Service San Juan PR
516 AM AST Tue Jun 20 2017
.SYNOPSIS...Upper trof will continue to move west and away of the
forecast area as ridge builds on Wednesday from the east. TC Bret
is forecast to move well south of the area...across the Caribbean
Sea through Wednesday. Surface ridge will continue across the
Central Atlantic. Moderate to locally fresh trade winds will
continue for the next several days. Another trof pattern aloft is
expected during the weekend.
&&
.SHORT TERM...Tuesday through Thursday...
A trough aloft/TUTT will continue to prevail across the eastern
Caribbean through early Wednesday. As this feature moves westward
into the central Caribbean and away from the forecast area during
Wednesday afternoon into Wednesday night; a mid to upper level ridge
will slowly build from the east and hold on Thursday. At lower
levels, a broad high pressure will continue to prevail across the
central Atlantic to yield a moderate to locally fresh easterly wind
flow across the isles.
Based on the latest bulletin from the NHC, Tropical Storm Bret which
is well south of the forecast area, will continue to move west-
northwest near 22 mph gradually reducing its forward speed over the
next 48 hours. This feature will move south of the forecast area
throughout the day. For additional information, please refer to
TCPAT2.
Under the aforementioned pattern, expect fair weather conditions
during the morning hours followed by numerous showers and isolated
thunderstorms across west Puerto Rico in the afternoon. Hazy skies
are also possible through the day. Under trofiness aloft and
moisture advection across the offshore Caribbean waters...which is
associated with Bret moving well south of the area...squally weather
is then possible over the Caribbean waters tonight and into
Wednesday morning. As the ridge aloft builds and the low level
moisture erodes, a generally fair weather pattern is expected to
prevail across the local islands on Thursday with locally induced
scattered showers and thunderstorms in the afternoon across west
Puerto Rico.
.LONG TERM...Friday through Wednesday...
Under ridge aloft...diurnally induced afternoon convection is
expected on Friday. However, another tutt low is forecast to move
from the northeast early on Saturday and provide good divergence
aloft for scattered showers and isolated thunderstorm development
over portions of the local waters and over the interior and
western sections of the island. A tropical wave is forecast to
move quickly late on Sunday. This wave will bring a good amount
of tropical moisture through Monday that will increase showers and
thunderstorms across the forecast area. Another tropical wave is
forecast to reach the islands by Wednesday morning.
&&
.AVIATION...VFR conds expected to prevail at all TAF sites with VCSH
possible at the Leeward and USVI terminals as well as JSJ early in
the morning. Aft 20/16z SHRA/TSRA expected in and around JMZ with
MVFR conds likely through 20/22z. Easterly winds 10-15 knots,
increasing 15-20 knots aft 20/13z with higher gusts. Hazy skies
possible through the day, however visibilities are expected to
remain P6SM.
&&
.MARINE...Seas will deteriorate quickly today across the Caribbean
waters and passages as TC Bret continues to move across the
Caribbean Sea. Seas up to 8 feet are expected. Gusty winds and
thunderstorms with heavy showers are possible across the Caribbean
waters through Wednesday afternoon.
Life threatening rip currents and rough surf conditions are
expected late this evening through Wednesday across the southern
coasts of PR and the USVI.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 77 / 20 20 40 30
STT 90 80 88 77 / 40 40 40 30