094
FXSA20 KWBC 301930
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 PM EST MON DEC 30 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 30 DEC 2024 AT 1930 UTC:
AN IMPORTANT FEATURE OVER THE NEXT COUPLE OF DAYS...IS A BROAD SFC
LOW PRESSURE THAT WILL BE PASSING THROUGH THE SOUTHERN CONE OF
SOUTH AMERICA TONIGHT AND TUESDAY. THIS LOW WILL HAVE ASSOCIATED
COLD AND OCCLUDED FRONTS PASSING THROUGH AS WELL. THE LOW WILL
BRING SOME MOISTURE FROM THE SOUTHEAST...INTO THE SANTA CRUZ
PROVINCE...WHICH COULD BE AS MUCH AS TWO STANDARD DEVIATIONS
HIGHER THAN NORMAL. SOUTHERN CHILE WILL HAVE HIGHER THAN NORMAL
MOISTURE...BUT IT IS NOT EXPECTED TO SEE AS SIGNIFICANT OF AN
INCREASE AS ARGENTINA...HOWEVER. THIS LOW PRESSURE WILL MOVE
OFFSHORE INTO THE ATLANTIC BY THURSDAY...BUT A FRONTAL BOUNDARY
WILL APPROACH FROM THE WEST TO CAUSE ANOTHER EQUALLY SIGNIFICANT
INCREASE IN MOISTURE OVER THE SOUTHERN CONE OF SOUTH
AMERICA...THIS TIME INCLUDING CHILE. THAT BEING SAID...ANOTHER
THING TO NOTE IS THAT THE MID LEVELS AND UPPER LEVELS ALSO HAVE
STRONG LOW PRESSURE SYSTEMS...WHICH WILL PROVIDE DIVERGENCE ALOFT
NEAR THE LOW CENTER... INCREASING INSTABILITY OVER THE AREA. THERE
IS ALSO SOME DIFFLUENCE TO THE NORTHEAST OF THE MID AND UPPER
LEVEL LOWS...WHICH WILL HELP THE DEVELOPMENT OF STRONG STORMS
AHEAD OF THE COLD FRONT FURTHER NORTH IN ARGENTINA...MAINLY OVER
LA PAMPA. THE GR02T ALGORITHM ALSO INDICATES THE POSSIBILITY OF
STRONG THUNDERSTORMS WITH A RISK OF SEVERE WEATHER OVER THE AREA
FOR THE NEXT SEVERAL DAYS...NEAR THE CENTER OF THE LOW WITH THE
MOISTURE ADVECTION...AND ALSO AHEAD OF THE COLD FRONT OVER LA
PAMPA TONIGHT INTO TUESDAY...THEN AS FAR NORTH AS URUGUAY ON
WEDNESDAY INTO THURSDAY.
OVER THE NORTHERN HALF OF SOUTH AMERICA...THE RAINFALL AND
THUNDERSTORM DEVELOPMENT WILL BE HEAVILY INFLUENCED BY THE
AVAILABLE MOISTURE...LOW LEVEL CONVERGENCE AND DIURNAL AND LOCAL
EFFECTS. THE BOLIVIAN HIGH IS EXPECTED TO DOMINATE FOR THE NEXT
SEVERAL DAYS...AND THE AVAILABLE MOISTURE WILL BE BELOW NORMAL
ACROSS MANY SECTIONS OF CENTRAL BOLIVIA...SOUTHERN BRASIL AND
PARAGUAY. THE OVERALL RAINFALL FORECAST REFLECTS THAT...WITH
LITTLE RAIN IN THE FORECAST OVER THE NEXT THREE DAYS.
HOWEVER...AREAS IN THE PERIPHERY OF THE BOLIVIAN HIGH...WHICH WILL
ALSO HAVE NEAR NORMAL TO ABOVE NORMAL MOISTURE...ARE FORECAST
SHOWERS AND THUNDERSTORMS EACH DAY INTO MIDWEEK. THE DAILY AMOUNTS
OF RAIN EXPECTED OVER THE TROPICAL SOUTH AMERICA WILL BE GENERALLY
IN THE ORDER OF 05-15MM/DAY WITH MAX VALUES UP TO 35MM. THAT
SAID...SOME AREAS ALONG THE ITCZ/NET ARE FORECAST TO HAVE DAILY
RAINFALL THAT COULD MAX OUT NEAR 45MM EACH DAY. THERE IS A LOW
LEVEL TROUGH ACROSS SOUTHEASTERN BRASIL...THAT WILL HELP SHOWER
AND THUNDERSTORM DEVELOPMENT OVER PORTIONS OF SAO PAULO INTO MINAS
GERAIS OVER THE NEXT FEW DAYS...WITH DAILY RAINFALL TOTALS OF UP
TO 45MM FROM TODAY INTO EARLY WEDNESDAY...THEN NEAR 20-35MM ON
WEDNESDAY INTO THURSDAY MORNING.
ALAMO...(WPC)
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