National Weather Service San Juan PR
456 AM AST Fri Oct 14 2022
.SYNOPSIS...
Hazy conditions are expected to linger today. Despite the drier
air, though, local effects will combine with the available
moisture to result in showers and isolated thunderstorms.
Increasing shower activity is expected for the first part of next
week, as a deep-layer polar trough approaches from the northwest,
providing instability over the area. A decrease in activity is
likely by midweek next week.
&&
.SHORT TERM...Today through Sunday...
Slightly below normal moisture with some Saharan dust is expected
today across the local area. Isolated to scattered showers are
forecast across the local waters, USVI and eastern PR in the
morning hours, leaving some accumulations across eastern PR, but
little to no accumulations elsewhere. Showers and thunderstorms
are expected this afternoon across central to western PR. Some
showers could be heavy at times, which could lead to urban and
small stream flooding in some areas.
The Saharan dust is expected to move out of the local area by late
tonight, and the available moisture is expected to increase through
the weekend. The shower activity is also expected to increase this
weekend with the additional moisture. That said, the overall pattern
is expected to be close to normal, just with a bit more coverage,
with scattered showers across the local waters, eastern PR and the
USVI, while afternoon thunderstorms develop across central to
western PR. However, for Sunday, there is the potential for more
persistent thunderstorms over central PR, due to an approaching
upper trough from the northwest, causing an increase in instability
over the local area.
As far as temperatures, daytime high temperatures will be near
normal, with highs in the upper 80s to low 90s across the lower
elevations. The heat index values will continue reaching or
surpassing the 100s degrees Fahrenheit during short term period,
especially across north central Puerto Rico.
&&
.LONG TERM...Monday through Friday...
A deep-layer polar trough is expected to continue to dig into the
tropics through the first part of the week next week. Model guidance
has been backing off somewhat in recent runs on how far it will
stretch over the region, but it is likely to be either over the area
or just north of it on Monday morning. From there, it is forecast to
shift southeastward, making its way northeast of the Windward
Islands by Tuesday. Increased instability is expected for Monday,
but then decrease as the mid- to upper-level ridge re-asserts itself
over the region. Moisture will remain on the low end of normal for
Monday. Beyond that, moisture content is expected to decrease over
the region, especially in the mid-levels, through at least midweek.
Overall, expecting active weather conditions for Monday, maintaining
a typical shower pattern but with enhanced activity. The steering
flow is forecast to be quite weak, likely around 5 to 10 knots out
of the east to east-northeast. Above around 600 hPa, however, the
flow backs quickly with height, becoming more west-northwesterly.
So, on the whole, showers will be slow-moving. Because of this,
locally higher rainfall totals are likely, providing a further
increase to the potential for localized flooding impacts, mostly in
the form of urban and small stream flooding. Decreasing shower
activity is expected through at least Wednesday. That being said,
the light steering flow will persist through the week, and could
lead to isolated areas with high rainfall totals.
A modest increase in moisture over the region starting as early as
late Thursday could result in an increase in shower activity.
&&
.AVIATION...
(06Z TAFS)
VFR conditions will prevail. VCSH expected across the local
terminals in the morning hours. VCTS is expected at TJBQ after
14/17Z, with the possibility of TEMPO TSRA. TJSJ may have brief
VCTS/VCSH at some point between 14/17 and 14/20Z, as SCT SHRA/ with
possibly brief TSRA develops south and west of the terminal. Winds
will be generally easterly at around 10KT with sea breeze variations
developing after 14/13Z. Some HZ will be present due to Saharan
Dust, but VIS should remain P6SM.
&&
.MARINE...
Winds of up to 10 to 15 knots out of the east are expected across
the waters. Seas of 4 feet or less are anticipated. Showers and
isolated thunderstorms are expected, especially near western Puerto
Rico in the afternoon, with which locally deteriorated conditions
are possible. There is a low risk of rip currents.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...None.
VI...None.
&&
$$
SHORT TERM...JA
LONG TERM....CRS
AVIATION...JA