361  
FXSA20 KWBC 141637  
PMDSA  
 
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1236 PM EDT FRI MAR 14 2025  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/DATA/NCCF/COM/GFS/PROD/  
 
SOUTH AMERICAN FORECAST BULLETIN 14 MARCH 2025 AT 13:00 UTC  
   
..CLIMATE/TELECONNECTIONS CONDITIONS  
 
MJO: AT THIS TIME THE MJO CONTINUES TO BE IN PHASE 2. THE ENHANCED  
CONVECTIVE PHASE IS CURRENTLY CROSSING AFRICA AND ENTERING THE  
INDIAN OCEAN BASIN. THIS PHASE ALSO SHOWS ENHANCED PRECIPITATION  
OVER THE EASTERN PART OF BRASIL ON FRIDAY AND SATURDAY. AS THE MJO  
CONTINUES PROPAGATING, THE LARGE-SCALE UPPER-LEVEL CONVERGENCE  
OVER THE AMERICAS WILL BE INCREASINGLY LIMITING THE COVERAGE OF  
DEEP CONVECTION.  
 
ENSO CONDITIONS: LA NINA ADVISORY PERSISTS, WHILE A TRANSITION TO  
ENSO NEUTRAL IS EXPECTED FROM MARCH TO MAY.  
   
..SYNOPTIC CONDITIONS OVER TROPICAL SOUTH AMERICA  
 
ELEVATED SEA SURFACE TEMPERATURES (SSTS) IN THE EASTERN PACIFIC,  
COUPLED WITH THE PACIFIC INTERTROPICAL CONVERGENCE ZONE (ITCZ) AND  
WEAK ONSHORE WINDS AT LOWER LEVELS, WILL CREATE CONDITIONS  
CONDUCIVE TO MOISTURE MOVEMENT INLAND. THIS, ALONG WITH THE SEA  
BREEZE PROCESS AND UPPER-LEVEL DIVERGENCE, WILL LIKELY PROMOTE  
ISOLATED DIURNAL CONVECTION ALONG THE COAST OF ECUADOR AND  
SOUTHERN COLOMBIA BY SUNDAY. OVERALL, A SLIGHT REDUCTION IN  
MOISTURE INFLUX AND RAINFALL IS ANTICIPATED FROM FRIDAY EVENING  
INTO SATURDAY. HOWEVER, BY SUNDAY, WE EXPECT AN INCREASE IN  
MOISTURE INFLUX, LEADING TO PEAK PRECIPITATION RATES.  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER THE COAST OF ECUADOR:  
FRIDAY: 20 - 45MM  
SATURDAY: 30 - 60MM  
SUNDAY: 30 - 60MM  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER THE SOUTHWEST COAST OF  
COLOMBIA:  
FRIDAY: 20 - 45MM  
SATURDAY: 30 - 60MM  
SUNDAY: 30 - 60MM  
 
THE TRANSPORT OF MOISTURE BY TRADE WINDS AROUND THE INTERTROPICAL  
CONVERGENCE ZONE (ITCZ) IS EXPECTED TO PERSIST, COMBINED WITH  
UPPER-LEVEL DIVERGENCE, WHICH WILL ENHANCE PRECIPITATION ALONG THE  
NORTHERN SEGMENT OF THE NET/ITCZ. THIS WILL PARTICULARLY IMPACT  
NORTHWESTERN BRASIL, AS WELL AS SOUTHERN VENEZUELA AND COLOMBIA,  
OVER THE NEXT THREE DAYS.  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER SOUTHERN VENEZUELA AND  
COLOMBIA:  
FRIDAY: 30 - 60MM  
SATURDAY: 20 - 45MM  
SUNDAY: 20 - 35MM  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER NORTHWESTERN BRASIL:  
FRIDAY: 25 - 35MM  
SATURDAY: 20 -35MM  
SUNDAY: 15 - 25MM  
   
..SYNOPTIC CONDITIONS FOR BRASIL  
 
NORTHEASTERN BRASIL: UPPER-LEVEL DIVERGENCE, IN CONJUNCTION WITH  
THE TRANSPORT OF HUMID AIR BY TRADE WINDS APPROACHING THE  
NORTHEAST COAST OF SOUTH AMERICA FROM GUIANA TO NORTHEASTERN  
BRASIL, WILL PROMOTE CONVERGENCE ALONG THE COAST. FOR THE NEXT  
THREE DAYS, NORTHEASTERN BRASIL WILL CONTINUE TO BE AFFECTED BY  
MOISTURE INFLUX AT LOW LEVELS DUE TO WEAK TROPICAL PERTURBATIONS.  
HOWEVER, THESE CONDITIONS WILL BE LESS PRONOUNCED COMPARED TO  
EARLIER IN THE WEEK. DESPITE THE ONGOING MOISTURE TRANSPORT,  
UPPER-LEVEL CONDITIONS ARE NOT EXPECTED TO ADEQUATELY SUPPORT DEEP  
CONVECTION. AS A RESULT, WHILE SOME ISOLATED PRECIPITATION MAY  
OCCUR, SIGNIFICANT RAINFALL IS UNLIKELY DURING THIS PERIOD.  
 
THE FOLLOWING MAXIMA ARE EXPECTED ALONG THE NORTHEAST COAST OF  
BRASIL:  
FRIDAY: 15 -25MM  
SATURDAY: 20 - 35MM  
SUNDAY: 25 - 50MM  
 
THE FOLLOWING MAXIMA ARE EXPECTED ALONG THE GUINAS:  
SATURDAY: 20 - 35MM  
SUNDAY: 30 - 60MM  
 
SOUTHERN BRASIL: A PERSISTENT AND EXPANSIVE HIGH-PRESSURE SYSTEM  
IN THE LOW TO MID TROPOSPHERE CENTERED BETWEEN PANTANAL AND  
SOUTHEAST BRASIL WILL PROMOTE MOIST EASTERLY TO NORTHEASTERLY  
WINDS IN SOUTHWEST AMAZON AND BOLIVIA, THAT WILL RESULT IN SOME  
SHOWERS AROUND THE PERIPHERY OF THE HIGH PRESSURE DURING FRIDAY  
AND SATURDAY. IN THE SERRA DO MAR, LOCAL EFFECTS SUCH AS SEA  
BREEZES, COMBINED WITH AN APPROACHING FRONTAL BOUNDARY, WILL  
INCREASE THE LIKELIHOOD OF SHOWERS AND THUNDERSTORMS FROM FRIDAY  
(TODAY) THROUGH SUNDAY.  
 
THE FOLLOWING MAXIMA ARE EXPECTED IN SERRA DO MAR:  
FRIDAY: 15 - 25MM  
SATURDAY: 20 - 45MM  
SUNDAY: 20 - 45MM  
 
...SYNOPTIC CONDITIONS FOR BOLIVIA, PARAGUAY, URUGUAY AND  
ARGENTINA AND SOUTHERN BRASIL...  
 
FROM FRIDAY (TODAY) THROUGH SATURDAY, A ZONAL UPPER-LEVEL JET WILL  
BE POSITIONED OVER NORTHERN ARGENTINA AND SOUTHEASTERN BRASIL.  
THIS JET STREAM WILL CONTRIBUTE TO ENHANCED WEATHER ACTIVITY IN  
THE REGION. FROM FRIDAY (TODAY) THROUGH SATURDAY, A MID-LEVEL  
SHORT WAVE WILL BE MOVING OVER NORTHERN ARGENTINA AND PARAGUAY.  
FURTHERMORE, THE FRONTAL BOUNDARY AT THE LOWER LEVELS WILL  
CONTRIBUTE TO THE INSTABILITY OF THE ATMOSPHERE. THIS SYSTEM WILL  
BRING LIMITED POTENTIAL FOR SHOWERS AND LOCALIZED THUNDERSTORMS  
ACROSS PARAGUAY AND THE PARANA BASIN IN BRASIL FROM TODAY (FRIDAY)  
INTO EARLY SATURDAY. AFTER THAT, BY SUNDAY, DRIER AIR AT MID  
LEVELS WILL BE DOMINATING OVER NORTHERN ARGENTINA AND CENTRAL  
PARAGUAY AND AS THE STRONG SURFACE HIGH PRESSURE SYSTEM ADVANCES  
ON FRIDAY, DRY AND STABLE CONDITIONS WILL PREVAIL OVER NORTHERN  
ARGENTINA, URUGUAY, AND PARTLY SOUTHEASTERN PARAGUAY.  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER PARAGUAY:  
FRIDAY: 30 - 60MM  
SATURDAY: 30 - 60MM  
SUNDAY: 15 - 25MM  
 
BY SATURDAY EVENING , A WEAK UPPER-LEVEL TROUGH AND A SHORT WAVE  
AT MID-LEVELS WILL MOVE ACROSS CENTRAL ARGENTINA, INTERACTING WITH  
A SURFACE LOW PRESSURE SYSTEM. THIS COMBINATION WILL CREATE A LINE  
OF CONVERGENCE OVER CENTRAL ARGENTINA PRIMARILY AFFECTING SOUTHERN  
CUYO AND NORTHERN PATAGONIA. THE SEA BREEZE WILL ENHANCE MOISTURE  
CONVERGENCE OVER THE NORTHERN PATAGONIA COAST, PROMOTING INCREASED  
CONVECTION AND HIGHER PRECIPITATION RATES. EXPECT SCATTERED  
SHOWERS AND THUNDERSTORMS, PARTICULARLY IN THE AFTERNOON AND  
EVENING HOURS, WITH THE POTENTIAL FOR LOCALIZED HEAVY RAINFALL  
RATES AND SLIGHT RISK OF SEVERE WEATHER. BY SUNDAY, DRIER AND MORE  
STABLE CONDITIONS ARE ANTICIPATED AS ANOTHER SURFACE HIGH-PRESSURE  
SYSTEM ADVANCES INTO THE REGION. THIS SHIFT WILL LIKELY LEAD TO A  
REDUCTION IN CLOUD COVER AND A DECREASE IN PRECIPITATION,  
RESULTING IN CLEARER SKIES AND MORE SETTLED WEATHER ACROSS THE  
AREA.  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER ARGENTINA (MOSTLY OVER CUYO  
AND NORTHERN PATAGONIA):  
SATURDAY: 15 - 25MM  
 
IN BOLIVIA AND PERU, EASTERLY WINDS AT BOTH THE LOW AND UPPER  
LEVELS WILL ENHANCE MOISTURE INFLUX FROM THE INTERIOR OF THE  
CONTINENT. FURTHER THE BOLIVIAN HIGH WILL BE PROMOTING UPWARD  
MOTION OVER NORTHERN BOLIVIA AND EASTERN PERU. IN THE ALTIPLANO  
AND SOUTHERN PERU DIURNAL CONVECTION WILL BE ENHANCED DUE TO AN  
UPPER TROUGH AND JET DYNAMIC APPROACHING FROM THE SOUTHWEST,  
FAVORING PRECIPITATION MAXIMA ON FRIDAY AND SATURDAY.  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER THE NORTHERN REGION OF  
BOLIVIA:  
FRIDAY: 15 - 25MM  
SUNDAY: 15 - 25MM  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER PERU:  
FRIDAY: 15 - 30MM  
SATURDAY: 20 - 35MM  
SUNDAY: 30 - 60MM  
 
THE FOLLOWING MAXIMA ARE EXPECTED OVER THE COAST OF PERU:  
FRIDAY: 15 -25MM  
SATURDAY: 20 - 35MM  
SUNDAY:15MM  
   
..SYNOPTIC CONDITIONS FOR CHILE  
 
IN CENTRAL AND SOUTHERN CHILE, THE ADVANCING SURFACE HIGH-PRESSURE  
SYSTEM, KNOWN AS THE SOUTH PACIFIC ANTICYCLONE, THIS SYSTEM WILL  
FAVOR SUBSIDENCE, WHICH DAMPENS VERTICAL MOVEMENT AND LIMITS CLOUD  
DEVELOPMENT, THEREFORE STABLE CONDITIONS WILL PREVAIL OVER THE  
NEXT THREE DAYS. [THIS ANTICYCLONE WILL FAVOR SUBSIDENCE AND LIMIT  
THE VERTICAL DEVELOPMENT OF THE CLOUD FORMATION, PROMOTING FAIR  
WEATHER.  
 
IN THE SOUTHERN AND AUSTRAL REGIONS, CONDITIONS WILL ALSO REMAIN  
PREDOMINANTLY STABLE, WITH THE PRESENCE OF STRATIFORM  
CLOUDS BY FRIDAY AND SATURDAY. BY FRIDAY, AN UPPER-LEVEL JET IS  
EXPECTED TO MOVE INTO THE ZONA AUSTRAL, AIDING IN THE DEVELOPMENT  
OF STRATIFORM RAIN. HOWEVER, LOW-LEVEL MOISTURE ADVECTION IS  
ANTICIPATED TO BE LIMITED, WHICH MAY RESTRICT THE INTENSITY OF  
PRECIPITATION. A PRECIPITATION MAXIMUM OF 15MM IS EXPECTED ON  
FRIDAY AND SATURDAY. BY SUNDAY A WEAK MOISTURE PLUME WILL BE  
APPROACHING THE REGION AND IN COMBINATION WITH THE UPPER LEVEL  
THROUGH IT WILL FACILITATE THE VENTILATION AND THE UPWARD MOTION  
TO DEVELOP RAINFALL ACTIVITY.  
 
THE PRECIPITATION MAXIMA OVER THE ZONA AUSTRAL IS EXPECTED TO BE  
AROUND:  
FRIDAY: 15MM  
SATURDAY: 15MM  
SUNDAY: 20 - 45MM  
 
FOR MORE QPF GRAPHICAL INFORMATION:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/INTERNATIONAL/SAM_DAY1-3.SHTML  
 
LEDESMA...(WPC)  
ALAMO...(WPC)  
 
 
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