945
FXSA20 KWBC 201849
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
249 PM EDT FRI SEP 20 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 20 SEP 2024 AT 1830 UTC:
SOME AREAS IN AND AROUND NORTHEASTERN ARGENTINA...SOUTHERN BRAZIL
AND SOUTHERN PARAGUAY ARE FORECAST TO OBSERVE SOME STRONG STORMS
THE REST OF TODAY INTO EARLY SATURDAY MORNING. THE RISK OF STRONG
STORMS INCREASES SIGNIFICANTLY FOR SATURDAY INTO SUNDAY OVER THE
BUENOS AIRES PROVINCE...THEN SUNDAY INTO MONDAY HAS A SLIGHT
CHANCE OF SEVERE WEATHER OVER A SMALL SECTION OF SOUTHERN URUGUAY
INTO THE NEARBY SECTIONS OF ARGENTINA. CENTRAL TO SOUTHERN
CHILE...WILL BE SUBJECT TO HIGHER THAN NORMAL MOISTURE FOR THE
NEXT FEW DAYS...STARTING THIS FRIDAY AFTERNOON...AS AN ATMOSPHERIC
RIVER AFFECTS THE AREA. THROUGH THE WEEKEND...SIGNIFICANT RAIN IS
FORECAST IN THE LOWER ELEVATIONS OF CENTRAL CHILE...WHILE SNOW IS
FORECAST ACROSS THE HIGHER ELEVATIONS OF CENTRAL TO SOUTHERN CHILE.
THE EXPECTED THUNDERSTORMS ARE DUE TO THE COMBINATION OF A WARM
AND NORTHERLY LOW LEVEL JET OVER THE CONTINENT INTO THE
AREA...JUST AHEAD OF A FRONTAL BOUNDARY THAT IS PRESENT OVER THE
AREA. THERE IS ALSO AN UPPER TROUGH TO THE EAST OF THE CONTINENT
THAT IS PROVIDING SOME DIVERGENCE TO THE SOUTHEAST OF THE OF
SOUTHERN BRAZIL AND URUGUAY...WHICH MAY HELP WITH THE PERSISTENT
CONVECTION OVER THE AREA TONIGHT. THE UPPER TROUGH CONTINUES TO
MOVE SOUTHEAST...BUT THE STRONG WINDS ALOFT WILL CONTINUE FOR THE
NEXT SEVERAL DAYS FROM CHILE THROUGH CENTRAL ARGENTINA. THE GRO2T
SEVERITY ALGORITHM DOES INDICATE A SLIGHT RISK FOR SEVERE WEATHER
THROUGH EARLY SATURDAY...THEN MODERATE ON SATURDAY OVER THE BUENOS
AIRES PROVINCE...THEN SLIGHT TO MODERATE RISK OVER
URUGUAY...NEARBY AREAS OF ARGENTINA AND PERHAPS SOME NEARBY
SECTIONS OF SOUTHERN BRAZIL.
ACROSS CENTRAL TO SOUTH CENTRAL CHILE...THE PRECIPITABLE WATER IS
FORECAST TO INCREASE TODAY AND REMAIN ABOVE NORMAL OVER A NARROW
SECTOR INTO THE WEEKEND...AS AN ATMOSPHERIC RIVER MOVES IN AND
AFFECTS THE AREA. THE MODEL GUIDANCE IS SUGGESTING SIGNIFICANT
PRECIPITATION OVER CENTRAL TO SOUTHERN CHILE FOR THE NEXT FEW
DAYS. OUR FORECAST SUGGESTS MAX VALUES NEAR 30-60MM OF TOTAL
PRECIPITATION TODAY AND SATURDAY WITH MOUNTAIN SNOW...WHILE SUNDAY
INTO MONDAY UP TO 25MM OF RAIN IS FORECAST ACROSS THE LOWER
ELEVATIONS...BUT SIGNIFICANT SNOW IS FORECAST ACROSS THE HIGHER
ELEVATIONS OF CHILE EACH DAY. 30-60CM OF SNOW IS FORECAST OVER THE
MOUNTAINS OF CENTRAL CHILE TONIGHT INTO SATURDAY...25-50CM MAX
SNOWFALL FOR SATURDAY INTO SUNDAY...AND 20-40CM MAX SNOW FOR
SUNDAY INTO MONDAY. SOUTHERN CHILE IS ALSO FORECAST SNOW ON SUNDAY
INTO MONDAY...WITH A FORECAST MAX SNOWFALL OF 05-15CM. THERE WILL
BE A MID LEVEL TROUGH MOVING INTO CENTRAL TO SOUTHERN CHILE
TONIGHT INTO EARLY SATURDAY...BUT A STRONGER MID LEVEL TROUGH WILL
MOVE IN LATE SUNDAY. THERE WILL BE STRONG UPPER LEVEL WINDS AS
WELL...WHICH WILL CAUSE AN INCREASE IN INSTABILITY. FOR THAT
REASON...THE PRECIPITATION FORECAST FOR THE REST OF TODAY AND
THROUGH THE WEEKEND IS A BIT MORE AGGRESSIVE THAN IT HAS BEEN OVER
THE PAST FEW DAYS.
AS MENTIONED ABOVE...PORTIONS OF EAST CENTRAL ARGENTINA IN TO
SOUTHERN BRAZIL AND SOUTHERN PARAGUAY ARE AT RISK OF OBSERVING
SEVERE WEATHER THIS EVENING INTO THE WEEKEND. THE PRECIPITATION
FORECAST SUGGESTS A RAINFALL MAXIMA NEAR 30-60MM FOR SOUTHERN
BRAZIL AND SOUTHERN PARAGUAY FOR THE REST OF TODAY INTO EARLY
SATURDAY. FROM SATURDAY INTO SUNDAY...THE PRECIPITATION FORECAST
UP TO 35MM OF RAIN ACROSS THE BUENOS AIRES PROVINCE...THOUGH WITH
THE RISK OF SEVERE WEATHER...WHILE SUNDAY INTO MONDAY ALSO HAS MAX
PRECIPITATION VALUES OF 35MM WITH A RISK OF SEVERE WEATHER OVER
SOUTHERN URUGUAY.
PERU IS FORECAST TO OBSERVE SOME RAINFALL AND ISOLATED
THUNDERSTORMS THROUGH THE WEEKEND...BUT THE AMOUNTS OF RAIN WILL
BE GENERALLY UNDER 25MM...WITH NORTHERN PERU RECEIVING THE HIGHEST
AMOUNTS OF RAIN EXPECTED...WHILE THE SOUTHERN HALF OF PERU IS
FORECAST UNDER 10MM OF RAIN. THE EAST CENTRAL COAST OF
BRAZIL...MAINLY IN THE COAST OF ESPIRITO SANTO AND BAHIA...IS
FORECAST SOME RAIN EACH DAY THROUGH THE WEEKEND DUE TO ONSHORE
FLOW...BUT THE AMOUNTS ARE FORECAST TO BE MAINLY UNDER 10MM EACH
DAY.
ALAMO...(WPC)
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