397
FXSA20 KWBC 221845
PMDSA

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
144 PM EST WED JAN 22 2025

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

SOUTH AMERICAN FORECAST BULLETIN FOR 22 JAN 2025 AT 1845 UTC:

THE MADDEN-JULIAN OSCILLATION (MJO) CONTINUES IN ITS CONVERGENT
PHASE OVER THE SOUTH AMERICA REGION AND THE IMPACTS WILL FAVOR
MORE ISOLATED HEAVIER PRECIPITATION...WITH A GENERALIZED DECREASE
IN PRECIPITATION OVER THE NEXT SEVERAL DAYS.

IN THE NORTH AND CENTRAL PORTION OF THE CONTINENT...THE BOLIVIAN
HIGH IS CENTERED AT APPROXIMATELY THE SOUTHWESTERN COAST OF
PERU/NORTH CHILE AND EXTENDS FURTHER WEST...WHILE EXTENDING INTO
WESTERN BRASIL. A SMALLER CELL OF AN ASSOCIATED UPPER RIDGE IS
EXTENDING FROM THE BOLIVIAN HIGH FROM PARAGUAY INTO SOUTH BRASIL
ON WEDNESDAY. TO THE NORTHEAST...AN UPPER LEVEL TROUGH IS
RETROGRADING OVER THE REGION AND EXPECTED TO ORGANIZE INTO A
CLOSED LOW BY WEDNESDAY EVENING OVER GOIAS/MINAS GERAIS. THIS WILL
WEAKEN THE BOLIVIAN ON WEDNESDAY INTO THURSDAY...HOWEVER...THE
CUTOFF LOW IS EXPECTED TO WEAKEN BY FRIDAY...WHEN THE BOLIVIAN
HIGH IS EXPECTED TO STRENGTHEN INTO PORTIONS OF CENTRAL AND SOUTH
BRASIL. DUE TO THE IMPACTS OF THE MO...EXPECT HEAVY PRECIPITATION
TO REMAIN LOCALIZED OVER THE NEXT THREE DAYS. ON
WEDNESDAY...EXPECT MAXIMA OF 20-45MM IN CENTRAL BOLIVIA. THE
REGION OF VENTILATION DUE TO PERIPHERY OF THE BOLIVIAN HIGH
LOCATION IS OVER NORTHERN BRASIL...WHERE EXPECT MAXIMA OF 20-45MM
FROM AMAZONAS-BRASIL TO CENTRAL PARA-BRASIL. ON THURSDAY...EXPECT
MAXIMA OF 20-35MM FROM AMAZONAS-BRASIL TO CENTRAL PORTIONS OF
PARA. TO THE NORTH...THE PRESENCE OF THE ITCZ ENTERING THE GUIANAS
WILL FAVOR MAXIMA OF 40-80MM WITH A RISK OF ECHO TRAINING. CENTRAL
BOLIVIA CAN EXPECT MAXIMA OF 20-35MM WITH THE PRESENCE OF MOISTURE
ADVECTED BY THE DEVELOPING SOUTH AMERICAN LOW LEVEL JET
(SALLJ)...CONVERGING ALONG THE ANDES MOUNTAINS. ON FRIDAY...THE
NORTHERN REGIONS OF THE CONTINENT ARE EXPECTED TO RECEIVE
GENERALIZED MAXIMA OF 20-45MM IN NORTH
PERU/ECUADOR...AMAZONAS-BRASIL INTO RORAIMA...AND NORTH AMAPA.
EXPECT DRIER CONDITIONS TO THE EAST IN BRASIL AS ANOTHER UPPER
LEVEL TROUGH BEGINS TO ENTER THE REGION...TENDING TO DRY EAST
BRASIL.

IN THE CENTRAL PORTION OF THE CONTINENT...THE DEVELOPING ADVECTION
OF MOISTURE FROM THE TROPICAL REGIONS OF SOUTH AMERICA IS
STRENGTHENING AS THE PRESSURE IS DROPPING SOUTHWARD INTO
ARGENTINA. TROUGHING IS EXPECTED TO ENHANCE IN THE LOWER LEVELS
OVER NORTHERN ARGENTINA AND PARAGUAY WITH THE PRESENCE OF
SHORTWAVE TROUGHS FAVORING DEEP CONVECTION IN THE REGION. WITH THE
ADVECTION OF MOIST AIR CONVERGING WITH THE COOLER AND DRIER AIR
FROM THE SOUTH...AN INCREASE IN INSTABILITY WILL FAVOR DEEP
CONVECTION IN NORTH ARGENTINA AND INTO PORTIONS OF PARAGUAY AND
URUGUAY. ON WEDNESDAY...EXPECT MAXIMA OF 20-45MM IN THE CHACO
REGION OF ARGENTINA...WHILE SOUTH BRASIL CAN EXPECT MAXIMA OF
20-35MM. ON THURSDAY...THE MOIST AIR PUSHES FURTHER SOUTH FROM
SOUTH PARAGUAY INTO THE SIERRAS OF CORDOBA IN ARGENTINA...WHERE
EXPECT MAXIMA OF 20-35MM WITH A SLIGHT RISK OF SEVERE WEATHER.
SOUTH BRASIL CAN EXPECT MAXIMA OF 20-45MM. ON FRIDAY...THE SALLJ
IS EXPECTED OVER REGION OF SOUTH BOLIVIA INTO NORTH ARGENTINA...A
REGION OF CIRCULATION IS EXPECTED OVER SOUTH BRASIL AND INTO
URUGUAY THAT WILL INTERACT WITH A SHORT WAVE TROUGH IN THE MID TO
UPPER LEVELS. THIS WILL ENHANCE SEVERE WEATHER IN THE REGION.
EXPECT MAXIMA OF 30-60MM FROM SOUTH PARAGUAY TO SOUTH BRASIL WITH
A SLIGHT RISK OF SEVERE WEATHER. URUGUAY CAN EXPECT MAXIMA OF
15-25MM WITH A MARGINAL RISK OF SEVERE WEATHER. BUENOS
AIRES-ARGENTINA CAN EXPECT MAXIMA OF 20-35MM WITH A MARGINAL RISK
OF SEVERE WEATHER.

IN SOUTHERN CHILE...THE FRONTAL BOUNDARIES ENTERING INTO THE
REGION WILL FAVOR PRECIPITATION ALONG THE REGION OVER THE NEXT
THREE DAYS. ASSISTED BY UPPER LEVEL DIVERGENCE FROM TROUGHS
PROPAGATING IN THE REGION...THE EFFECTS WILL BE LIMITED AS THESE
SYSTEMS ARE PASSING QUICKLY. ON WEDNESDAY...EXPECT MAXIMA OF 15MM
IN SOUTH AYSEN INTO NORTH MAGALLANES. ON THURSDAY...EXPECT MAXIMA
OF 15-20MM FROM LOS LAGOS INTO MAGALLANES. ON FRIDAY...EXPECT
ISOLATED MAXIMA OF 20-35MM IN NORTH MAGALLANES WITH INCREASED
MOISTURE CONVERGENCE IN THE REGION.

CASTELLANOS...(WPC)
$$