South America Forecast Discussion - International Desks
NWS Weather Prediction Center College Park MD
151 PM EST Tue Feb 25 2025

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

South America Forecast Bulletin 25 Feb 2025 at 2000UTC:

In Mid - Latitude South America...

In north - central Argentina, Uruguay, and South Brasil, expect an
active precipitation pattern for the next three days. Through
Tuesday evening, a potent jet streak and upper trough will
continue to favor upper divergence and favor the formation of mid
- level shortwave troughs through Wednesday evening. In the low
levels, moisture convergence will be favorable along and ahead of
a meandering surface trough across the Pampas region, yielding to
a marginal risk for severe weather and a total precipitation
maxima of 40 - 80mm possible from Tuesday morning through
Wednesday morning. Expect the upper trough to exit into the south
Atlantic by Wednesday evening, moisture convergence will decrease
thereafter. From Wednesday morning through Thursday morning, a
total precipitation maxima of 25 - 50mm is possible across central
Argentina, and a total precipitation maxima of 20 - 40mm is
possible across south Uruguay. After Thursday evening, another
trough will begin to move into the Andes mountain range,
increasing upper divergence across the west - central Argentina.
In the low levels, moisture is also anticipated to increase across
east - central Argentina yielding to a total precipitation maxima
of 25 - 50mm from Thursday morning through Friday morning. In Rio
Negro, Argentina, a shortwave upper trough and subtle increase in
moisture will yield to a total precipitation maxima of 20 - 35mm
possible during the same period.

Elsewhere, in south Chile, a series of upper troughs and mid -
level shortwave troughs will continue to traverse this region for
the next three days. In the low levels, starting Tuesday evening
through Wednesday evening, a moisture plume is expected to impact
the region. An increase in low level westerly winds and a subtle
increase in wind speeds will also favor moisture convergence
during this period. Thus, these conditions will yield a daily
total precipitation maxima of 15mm through Thursday morning.

In Tropical South America...

In west Ecuador and Colombia,  two low level troughs have
developed to the north and south of the equator, with centers at
1N 98W and 5S 92W, and will continue to propagate west into the
central Atlantic. Through Tuesday evening, these two low level
features will continue enhancing low level westerlies into the
Ecuadorian and Colombian coasts, increasing moisture convergence.
Moisture convergence will decrease briefly by Wednesday, when a
more northerly low level wind will dominate across this region.
Thus, the greatest precipitation impact will occur for Tuesday
into Wednesday and Thursday into Friday, where a daily total
precipitation maxima of 35 - 70mm is possible.

Elsewhere in tropical south america, the ITCZ, Southern ITCZ, NET,
and surface troughs will continue to favor the development for
precipitation through the next three days. A series of surface
troughs will be affecting the region through the forecast cycle,
increasing the potential for increased precipitation
accumulations, especially in the central Amazon Basin. In the
Amazon delta, total precipitation maxima of 25 - 45mm are possible
daily through Thursday morning. In Peru and Bolivia, an increase
in moisture convergence after Wednesday evening will begin to
favor higher total precipitation maxima for Wednesday into
Thursday.



Morales...(WPC)
Ledesma...(WPC)