South America Forecast Discussion - International Desks
NWS Weather Prediction Center College Park MD
216 PM EST Fri Feb 14 2025

GFS data at ftpprd.ncep.noaa.gov/data/nccf/com/gfs/prod/

South America Forecast Bulletin 14 Feb 2025 at 2000UTC:

Note: Forecast discussions will be paused for 17 Feb 2025. They
will commence on 18 Feb 2025.

In the upper levels, starting on Saturday evening, expect the
Bolivian High to become more defined. In east Brasil, an upper
level trough will also gain definition after Saturday evening. The
interaction between these two features will sustain upper level
diffluence across north-central Brasil for the next three days.

In Mid-Latitude South America...

In north Argentina and Uruguay, a potent upper jet streak
continues to influence the low-to-mid levels through Sunday
evening across north-central Argentina and Uruguay. Expect a
series of low level troughs to meander in this region through the
next three days. From Friday morning through Saturday morning, a
surface trough will be located across north-central Argentina and
north Uruguay Friday evening, migrating slightly north by Saturday
evening. From Friday through Sunday morning, a combination of
upper level divergence, mid-level shortwave trough passages,
cooling of the mid-levels favoring instability, and moisture
convergence along and ahead of the boundary will enhance the
potential for a marginal risk of severe weather with a maximum
precipitation total of 25 - 50mm likely for the next two days.

By Sunday morning through Monday morning, the trough will be
located across north-east Argentina and south Brasil, where an
increase in moisture convergence across a wider region is
anticipated. Upper level divergence will be favorable during this
period, enhanced by the Bolivian High. These factors will cause
the highest precipitation totals to be located across south
Brasil, with a maxima precipitation totals of 30 - 60mm possible
during this time span.

Elsewhere in Mid-Latitude South America, moisture plumes will
continue to converge across austral Chile through the weekend.
Expect daily maxima precipitation totals of 15 - 20mm for north
austral Chile for Saturday morning through Sunday morning and
Sunday morning through Monday morning. After Monday morning, the
upper level blocking pattern will weaken. An upper trough will
propagate across southern South America thereafter, and an
associated  low level atmospheric river will impact the coast of
Chile after Monday morning.

In Tropical South America...

In Ecuador, upper level diffluence will continue to affect this
region through Saturday afternoon. Greatest precipitation impact
will occur from Saturday morning through Sunday morning, when the
low level flow becomes more favorable for moisture convergence
along the coast, enhancing orographic effects. Expect a total
precipitation maxima of 20 - 45mm for this time period.
Thereafter, a more westerly upper level wind flow will begin to
dominate across Ecuador, which will contribute to a decrease in
daily maximum precipitation totals from Sunday morning through
Monday morning.

In Peru and north Bolivia, expect upper level diffluence and
divergence through the next three days. A main driving force is
the reestablishment of the Bolivian High over this region. In the
lower levels, moisture convergence will prevail through the
forecast cycle. Expect maximum precipitation totals of 20 - 45mm
for Friday morning through Saturday morning and Saturday morning
through Sunday morning. Along the Pacific coast of Peru, an
increase in moisture will yield to maximum precipitation totals of
15 - 20mm for Sunday morning through Monday morning.

In the Amazon Delta, upper level divergence and a series of low
level troughs associated with enhanced moisture convergence will
interact with the ITCZ and help induce heavier  precipitation
totals. From Friday morning through Saturday morning, expect a
maxima precipitation total of 30 - 60mm and decreasing thereafter.

Elsewhere in Tropical South America, the ITCZ, NET, and surface
troughs will continue to enhance diurnal convection through the
next three days. However, as the sub-equatorial jet begins to move
farther east and into the continent, increasing subsidence in the
region. Additionally, the reestablishment of the Bolivian High and
upper trough over east Brasil will also assist in enhancement in
upper level diffluence across parts of the central Amazon basin
towards the end of the forecast cycle. However, available moisture
will decrease as well. Locally heavier maximum precipitation
totals are possible, especially across the west Amazon Basin,
where some moisture convergence may be possible.


Morales...(WPC)
Castellanos...(WPC)