National Weather Service San Juan PR
442 AM AST Sat Oct 29 2016
.SYNOPSIS...Upper level ridge will persist across the region
through the weekend. Ridge is to then erode by Tuesday with the
approach of a polar trough which will become amplified and sink
southward across the region into the central and eastern Caribbean
by Wednesday. The low level pattern is also expected to persist
through the weekend with high pressure ridge north and east of the
region and broad troughiness extending northwards across the area
from the central and eastern Caribbean basin. With this pattern
the easterly trade winds will gradually become more southeasterly
during the rest of the weekend and into early next week. By Tuesday
winds are to become more southerly,as a surface trough is forecast
to develop with a low forming just north of the region by Wednesday.
&&
.DISCUSSION...Sufficient trade wind moisture transport across the
region during the rest of the weekend to support early morning shower
development across the coastal waters. Some showers will continue
to reach portions of the north and east coastal sections of the islands
from time to time but no significant rainfall accumulations is anticipated.
During the afternoons local and diurnally induced afternoon convection
can be expected and the focus of the activity should be across part
of the north central and and northwest sections of Puerto Rico. Parts
of the San Juan metro area may also experience showers and possible
isolated afternoon thunderstorms, as the low level wind flow should
steer some streamer like activity over these areas. Urban and small
stream flooding will again be possible in some areas with the periods
of localized heavy rainfall.
As for the U.S Virgin Islands...mostly isolated passing showers
can be expected over the islands with a mixture of sunshine and
clouds during the day. No significant rainfall accumulations of
flooding situation is expected at this time except for some minor
ponding of water on roadways and poor drainage areas with the moderate
to locally heavy rainfall.
By Tuesday and Wednesday of next week...all model guidance continue
to suggest the deepening of the aformentioned polar trough which
is expected to set up across the region by Wednesday. This trough
is forecast to interact with a developing low and surface trough
which is to extend across the region by mid week. If this pattern
unfolds it should be a very moist and unstable environment and therefore
increased potential for enhanced convection across the region. However,
will continue to monitor and see how things unfold over the next few
days. Regardless of how this expected weather pattern, soil remain fairly
saturated across much of central and northern sections of Puerto Rico
and any locally heavy rainfall may lead to minor urban and small stream
flooding as well mudslides in area of steep terrain.
&&
.AVIATION...Mostly VFR conds expected through 29/16Z across the
local terminals. However,VCSH expected for TJSJ, TJPS, TISX, TIST
and TNCM, TKPK this morning. Winds are expected to increase after
29/13Z from the E-ESE to around 10KT with sea breeze variations.
Afternoon convection across PR could cause at least VCTS for TJSJ,
TJMZ, and TJBQ after 29/16Z with possible TEMPO MVFR conds at those
terminals.
&&
.MARINE...The light to gentle east to southeast trade winds will
become more southerly on Sunday and continue through Monday and Tuesday.
Slowly Fading north swell will continue to affect the local atlantic
waters today based on latest info from the surrounding buoys over the
Atlantic waters. Small craft should therefore exercise caution across
the offshore and nearshore Atlantic waters of northern Puerto Rico.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 90 78 / 20 40 40 30
STT 88 79 87 77 / 50 40 40 30