659
FXSA20 KWBC 162004
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 PM EST THU JAN 16 2025
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 16 JAN 2025 AT 2000 UTC:
OVER THE NEXT 3 DAYS...BRASIL WILL RECEIVE SIGNIFICANT RAINFALL ON
A DAILY BASIS. ACCORDING TO THE LATEST GUIDANCE...ALTHOUGH THERE
IS SOME UNCERTAINTY IN THE EXACT LOCATION AND AMOUNTS OF RAIN...IN
GENERAL THERE IS AGREEMENT THAT THE CENTRAL PORTIONS OF BRASIL
WILL OBSERVE SHOWERS AND THUNDERSTORMS...RESULTING IN DAILY
RAINFALL MAXIMA THAT COULD RANGE BETWEEN 30-80MM. THAT BEING
SAID...EAST CENTRAL TO SOUTHEASTERN BRASIL COULD OBSERVE RAINFALL
MAXIMA BETWEEN 30-60MM TODAY INTO FRIDAY. THE GFS MODEL IS MORE
AGGRESSIVE THAN THE ECMWF WITH THE AMOUNTS OF RAIN. GIVEN THE
ABOVE THAN NORMAL MOISTURE OVER EASTERN BRASIL TODAY...AND AN
APPROACHING MID AND UPPER LEVEL LOW...WE LEANED TOWARDS THE WETTER
SOLUTION. ACROSS THE HIGHER ELEVATIONS OF PERU INTO NORTHERN
CHILE...DAILY SHOWERS AND THUNDERSTORMS ARE EXPECTED...RESULTING
IN ACCUMULATIONS THAT WOULD MAX OUT NEAR 20-35MM. SOUTHERN CHILE
WILL ALSO RECEIVE DAILY RAINFALL...THOUGH GENERALLY IN THE ORDER
OF 15-25MM. NORTHEASTERN ARGENTINA WILL HAVE A DAILY RISK OF
SEVERE WEATHER...THOUGH THE RAINFALL AMOUNTS WILL INCREASE WITH
EACH PASSING DAY...UP TO 25MM TODAY...THEN UP TO 35MM ON FRIDAY
INTO EARLY SATURDAY...THEN UP TO 50MM ON SATURDAY INT EARLY
MONDAY.
IN THE UPPER LEVELS...AN UPPER JET EAST OF SOUTHERN ARGENTINA WILL
CONTINUE TO MOVE OUT INTO THE ATLANTIC...WHILE AN UPPER TROUGH
WILL SLOWLY MOVE INTO CHILE FROM THE WEST...REACHING THE REGION ON
SATURDAY INTO SUNDAY. AN UPPER HIGH PRESSURE OVER SOUTHEASTERN
BRASIL WILL MOVE WEST AND WILL CENTER ITSELF TO THE WEST OF THE
PERU AND CHILE BORDER. ANOTHER UPPER LOW PRESSURE IS MOVING INTO
NORTHEASTERN BRASIL...WHICH WILL PROVIDE DIFFLUENCE AND DIVERGENCE
OVER PORTIONS OF CENTRAL BRASIL.
IN THE MID LEVELS...THERE IS ALSO A MID-LEVEL JET TO THE EAST OF
ARGENTINA...ASSOCIATED WITH A MID LEVEL TROUGH. A SOMEWHAT WEAK
MID-LEVEL TROUGH IS EXPECTED TO MOVE INTO SOUTHERN CHILE ON FRIDAY
INTO SATURDAY WHILE STRONGER WINDS REMAIN OVER THE SOUTHERNMOST
TIP OF SOUTH AMERICA. MID LEVEL OW WILL MOVE INTO NORTHEAST
BRASIL...WHICH WILL BE VERTICALLY STACKED WITH THE UPPER LOW
MOVING INTO THE AREA.
IN THE LOWER LEVELS...THE WINDS WILL BE FROM THE NORTH TO
NORTHWEST OVER NORTH CENTRAL TO NORTHWESTERN SOUTH AMERICA...WHICH
CONTINUES TO BRING DRY AIR TO THE AREA. EASTERLY WINDS WILL MOVE
INTO EASTERN BRASIL...WHICH WILL BRING DRIER AIR TO THAT
AREA...AND PUSH THE ABOVE NORMAL MOISTURE INTO CENTRAL BRASIL.
THAT IS WHY CENTRAL BRASIL HAS A GOOD CHANCE OF SIGNIFICANT RAIN
THIS WEEKEND...THE COMBINATION OF THE ABOVE NORMAL MOISTURE WITH
THE DIFFLUENCE AND DIVERGENCE OF THE MID AND UPPER LEVELS BROUGHT
IN BY THE MID AND UPPER LEVEL LOWS. THE NET CONTINUES TO BE
PRESENT OVER NORTHERN BRASIL...THOUGH MOST OF THE SIGNIFICANT
CONVECTION WILL BE OVER NORTH CENTRAL BRASIL...IN AREAS OF HIGHEST
MOISTURE AND BEST UPPER LEVEL DYNAMICS. THE 850 MB WINDS ACROSS
SOUTHERN SOUTH AMERICA...WILL BE RELATIVELY STRONG...WITH THE
MODEL GUIDANCE SUGGESTING AS MUCH AS 40-55 KT WINDS ACROSS
SOUTHERNMOST SOUTH AMERICA.
ALAMO...(WPC)
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