211
FXSA20 KWBC 242000
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM EST TUE FEB 24 2026
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/DATA/NCCF/COM/GFS/PROD/
FORECAST BULLETIN 24 FEBRUARY 2026 AT 2000 UTC:
ONSHORE LOW-LEVEL FLOW IS EXPECTED TO CONTINUE ADVECTING DEEP
MOISTURE FROM THE PACIFIC INTO ECUADOR AND PORTIONS OF
NORTHWESTERN PERU TODAY THROUGH WEDNESDAY, ENHANCING PRECIPITATION
IN THE AREA. WITH UPPER-LEVEL DIFFLUENCE IN THE REGION,
THUNDERSTORMS AND CONVECTIVE ACTIVITY ARE ANTICIPATED. TOTAL
RAINFALL ACCUMULATION IS EXPECTED TO RANGE AROUND 20-45MM FROM
TODAY THROUGH WEDNESDAY. THE ONSHORE LOW-LEVEL FLOW IS ANTICIPATED
TO BE INTERRUPTED AS A LOW-LEVEL TROUGH DEVELOPS WEST OF THE
PACIFIC COAST ON WEDNESDAY, WHICH WILL RESULT IN LESS
PRECIPITATION OVER THIS REGION, ALTHOUGH THERE IS ENOUGH MOISTURE
TO BRING RAINFALL IN THE REGION WITH DIURNAL HEATING AND LOCAL
EFFECTS.
LOW-LEVEL MOISTURE CONVERGENCE AND UPPER-LEVEL SPEED DIVERGENCE
WILL BRING RAINFALL OVER THE WESTERN AMAZON REGIONS OF PERU AND
BRAZIL STARTING TODAY THROUGH THURSDAY. ACCUMULATIONS ARE EXPECTED
TO RANGE FROM 20-35MM. A DECREASE IN RAINFALL TOTALS IS
ANTICIPATED FROM THURSDAY THROUGH FRIDAY, AS DRY AIR IS ADVECTED
INTO THE REGION. OVER PERU, EXPECT PRECIPITATION OVER THE SELVA
ALTA REGION, WHERE OROGRAPHIC LIFTING WILL LIKELY SUPPORT THE
DEVELOPMENT OF SHOWERS WITH STRONG LOW-LEVEL WINDS AND DEEP
MOISTURE AVAILABLE IN THE REGION THROUGHOUT THE FORECAST PERIOD.
ISOLATED HEAVY THUNDERSTORMS ARE ALSO LIKELY, PARTICULARLY TODAY
WITH THE PRESENCE OF SHORTWAVE MID-LEVEL TROUGHS, RESULTING IN
TOTAL ACCUMULATIONS OF 40MM.
HEAVY PRECIPITATION AND CONVECTIVE ACTIVITY ARE EXPECTED TO AFFECT
BOLIVIA STARTING TODAY THROUGH THURSDAY. THE MAIN DRIVERS OF
PRECIPITATION OVER THE REGION WILL BE THE ADVECTION OF DEEP
MOISTURE, STRONG LOW-LEVEL WINDS, AND THE PRESENCE OF A LOW-LEVEL
TROUGH THAT WILL ENHANCE LOW-LEVEL CONVERGENCE. FURTHER SUPPORT IS
EXPECTED FOR THE DEVELOPMENT OF DEEP CONVECTION WITH THE PRESENCE
OF AN UPPER-LEVEL TROUGH WITH AN AXIS OVER NORTHWESTERN ARGENTINA
THAT WILL INCREASE UPPER-LEVEL DIVERGENCE OVER BOLIVIA.
ACCUMULATIONS WILL LIKELY REACH 50-100MM, WITH ISOLATED HIGHER
TOTALS. RAINFALL ACTIVITY IS ANTICIPATED TO START DECREASING FROM
THURSDAY THROUGH FRIDAY, AS THE UPPER-LEVEL TROUGH WEAKENS AND
PROPAGATES EASTWARD AND THE PRECIPITABLE WATER AVAILABLE DECREASES.
OVER BRAZIL, A PLUME OF MOISTURE AND ENHANCED LOW-LEVEL MOISTURE
CONVERGENCE OVER THE AMAZON DELTA REGION WILL BRING RAIN EACH DAY
OF THE FORECAST PERIOD. IN THE AMAZON REGION, DAILY SHOWERS AND
THUNDERSTORMS DUE TO LOW-LEVEL MOISTURE CONVERGENCE, MOISTURE
ADVECTION AND DIURNAL HEATING ARE EXPECTED EACH DAY. OVER THE
RORAIMA AND PORTIONS OF THE EASTERN AMAZON BASIN, A DRYING TREND
IS EXPECTED WITH THE PRESENCE OF THE NOCTURNAL LOW-LEVEL JET.
LOW-LEVEL TROUGHS OVER SOUTHEASTERN INTO CENTRAL-WEST BRAZIL WILL
INCREASE LOW-LEVEL MOISTURE CONVERGENCE IN THE AREA. THIS, ALONG
WITH MID-LEVEL TROUGHING, WILL BRING HEAVY PRECIPITATION AND
THUNDERSTORMS PARTICULARLY OVER PORTIONS OF ESPIRITO SANTO,
CENTRAL BRAZIL AND PORTIONS OF PANTANAL AND MATO GROSSO, EACH DAY
OF THE FORECAST PERIOD. AT UPPER-LEVELS, THE UPPER-LEVEL TROUGH
CURRENTLY OVER NORTHWESTERN ARGENTINA WILL ENHANCE DIVERGENCE
ACROSS SOUTHEASTERN AND CENTRAL-WEST BRAZIL, PROVIDING INSTABILITY
FOR THE DEVELOPMENT OF DEEP CONVECTION. IN ADDITION TO THIS, A
FRONTAL BOUNDARY IS ANTICIPATED TO APPROACH SOUTHERN BRAZIL,
SUPPORTING THE DEVELOPMENT OF RAIN SHOWERS OVER THE SERRA DO MAR
REGION FROM WEDNESDAY THROUGH FRIDAY.
IN URUGUAY, LIGHT PRECIPITATION IS EXPECTED TODAY THROUGH
WEDNESDAY WITH THE PRESENCE OF A FRONTAL BOUNDARY, BUT STABLE
CONDITIONS ARE ANTICIPATED FOR THE REST OF THE FORECAST PERIOD AS
SOUTHERLY WINDS ADVECT DRY AIR INTO THE REGION.
OVER NORTHWESTERN ARGENTINA, RAINFALL IS LIKELY STARTING TODAY
THROUGH FRIDAY WITH NORTHERLY WINDS ADVECTING MOISTURE INTO THE
REGION. THERE IS SOME UNCERTAINTY IN REGARD TO THE TOTAL
ACCUMULATION, DUE TO DIFFERENCES IN THE PRECIPITABLE WATER
AVAILABILITY FORECASTED BY THE ECMWF AND THE GFS, WITH THE ECMWF
SHOWING HIGHER TOTALS AT UPPER-LEVELS. A SLIGHT RISK FOR SEVERE
WEATHER, STARTING ON THURSDAY AFTERNOON, EXISTS FOR NORTHWESTERN
ARGENTINA AND CORDOBA WITH THE PRESENCE OF AN UPPER-LEVEL
SHORTWAVE TROUGH INCREASING INSTABILITY.
A PLUME OF MOISTURE IS EXPECTED TO REACH SOUTHERN AND CENTRAL
CHILE ON FRIDAY AS A FRONTAL BOUNDARY APPROACHES THE REGION, WHICH
ALONG WITH A MID- TO UPPER-LEVEL TROUGH WILL BRING UNSTABLE
CONDITIONS, INCREASING THE CHANCES OF PRECIPITATION IN THE AREA.
RIVERA-TORRES...(WPC)
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