FXUS20 KWBC 141944
PMDSA

South America Forecast Discussion - International Desks
NWS Weather Prediction Center College Park MD
244 PM EST Wed Jan 14 2026

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

South American Forecast Bulletin for 14 January 2026 at 2000UTC

In the high mid-latitudes...
Two potent upper level troughs will be moving into south-central
Chile for the next three days. The axis of the first trough will
be moving over the continent during the day on Monday and will be
accompanied by a surface cold front and long fetch moisture from
the deep tropics. There will also be mid-level vorticity advection
and upper divergence present in the area. These conditions will
favor a total precipitation maxima of 15 - 20mm from Wednesday
morning through Thursday morning. The second upper level trough
will begin to propagate into the continent on Friday afternoon and
will also be accompanied by a surface cold front. Again, expect an
increase in low level moisture, low level westerly wind speeds,
and upper divergence across southern Chile. Note that this upper
torque will also have a jet streak max embedded within its exit
region, further enhancing upper divergence. These conditions will
yield a total precipitation maxima of 25 - 50mm from Thursday
morning through Friday morning.

In the mid-latitudes...
The aforementioned upper trough moving across Chile on Wednesday
will have its axis east of the Andes by the early morning on
Thursday. Prior to its arrival, there will be an increase in upper
level diffluence in the region and the passage of mid-level
troughs. The decrease in pressure levels in the region will
promote an increase in northerly low level winds that will
transport the moist tropical air mass into the mid-latitudes.
Expect the development of a surface cold front early on Thursday
and a significant increase in moisture convergence along this
boundary. Thus, these conditions will favor a total precipitation
maxima of 20 - 45mm across Cordoba and Santa Fe from Wednesday
morning through Thursday morning, with the greatest chances of
precipitation being confined the late evening on Wednesday and
early morning Thursday. Moisture convergence along the northward
propagating cold front and the mid-to-upper level regime will
still favor increasing precipitation chances across northwest
Argentina, the Chaco region of Argentina, Cordoba, and Santa Fe
from Thursday morning through Friday morning. A total maxima of 40
- 80mm is expected across the Chaco region of Argentina and a
total maxima 30 - 60mm is likely across the Mesopotamia region of
Argentina for the above time period. Note that the interaction
between the upper trough and an upper level ridge to the north,
otherwise known as the Bolivian High, will further enhance upper
level diffluence and divergence. The cold front will lose
definition by Friday evening.

In the subtropics...
An upper level ridge (the Bolivian High) will be centered near
19.8S 67W and will continue to dominate the upper level regime
across the region. Expect an enhancement in upper level divergence
across the southwest and central Amazon fo xt three days, though
the period with the greatest precipitation chances will be on
Wednesday and Friday, when low level troughing and moisture
convergence will be most favorable for convective initiation and
sustenance. From Wednesday morning through Thursday morning,
expect total precipitation maxima of 25 - 50mm across eastern
Peru. From Friday morning through Saturday morning, a total
precipitation maxima of 30 - 60mm will be likely across the
Brasilian state of Amazonas. Across the Serra do Mar region in
Brasil, low level moisture convergence will remain in the region
for the next three days. Upper level divergence also will be
present in the region as well as high precipitable water values.

Another region of interest is the Pacific coasts of Colombia and
Ecuador. The Panamanian trough will continue to dominate the low
level regime and will enhance low level moisture convergence and
cyclonic rotation. However, there will be an increase in mid-level
speed shear after Thursday morning, which will limit the
sustenance of deep convection across the region. Also, there will
be a decrease in low level wind speeds. Thus, expect a decreasing
daily total precipitation maxima for the next three days.
Meanwhile along the Pacific coast of Peru, there will be daily
total precipitation maxima reaching 10mm along the high terrain.
There will be a subtle increase in low level moisture content as
well. The presence of the Bolivian High and mid-level troughing
will further assist in the sustenance of showers in this region.

Elsewhere in tropical South America, expect the most intense total
precipitation maxima to be in the vicinity of low level troughs.
Daily diurnal convection is possible across the entire basin for
the next three days. Meanwhile in the Guianas, a long fetch
moisture plume will continue to be the main driver for
precipitation processes. Daily total precipitation maxima will
reach 30mm for the next three days.



Tinoco-Morales...(WPC)


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