SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
338 PM EDT TUE JUL 09 2024

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

SOUTH AMERICAN FORECAST BULLETIN FOR 09 JUL 2024 AT 1930 UTC:

A BLOCKING HIGH PRESSURE IN THE UPPER TROPOSPHERE IS CONTINUES TO
SUSTAIN A STRONG SURFACE HIGH PRESSURE...WHICH IS CURRENTLY
CENTERED NEAR 44S 90W. THE SFC HIGH IS FORECAST TO PERSIST IN
PLACE THROUGH THURSDAY...DRIFTING SLOWLY TO THE EAST ON
FRIDAY...BUT GENERALLY REMAINING OVER THE SOUTHEAST PACIFIC
THROUGH THE END OF THE WORKWEEK. THIS HIGH PRESSURE WILL CONTINUE
TO BLOCK A SFC LOW PRESSURE TO ITS WEST FROM MOVING INTO THE
CONTINENT. THAT SAID...THE SFC LOW WILL START TO MOVE EAST AS IT
WEAKENS TOWARDS THE END OF THE WORKWEEK. BASED ON THIS
SETUP...MOST OF CHILE AND ARGENTINA WILL REMAIN FAIRLY DRY THROUGH
FRIDAY. ONLY ALLOWING ONLY LIGHT PRECIPITATION IN THE SOUTHERN
PORTIONS OF CHILE OVER THE NEXT FEW DAYS...AS A PATCH OF HIGHER
BUT LIMITED MOISTURE MOVES OVER THE SOUTHERNMOST PORTIONS OF SOUTH
AMERICA.

AN ACCELERATION OF COLD SOUTHWESTERLY WINDS ACROSS TIERRA DEL
FUEGO/SOUTHERN CONE INTO THE SOUTH ATLANTIC WILL BE OBSERVED OVER
THE NEXT 3 DAYS...MAINLY DUE TO A SOUTHWESTERLY UPPER JET THAT
COULD FAVOR CYCLOGENESIS ON THE SOUTHERN DRAKE PASSAGE.

A STATIONARY FRONT CONTINUES EXTENDING AROUND SAO PAULO...CENTRAL
MATO GROSSO...INTO EAST CENTRAL PERU. THIS STATIONARY FRONT IS
EXPECTED TO REMAIN IN PLACE THROUGH WEDNESDAY...BUT IS EXPECTED TO
TRANSITION TO A COLD FRONT BY THURSDAY INTO FRIDAY. HOWEVER...A
SMALL COLD FRONT OVER SANTA CATARINA WILL DEVELOP ON THURSDAY INTO
FRIDAY...WHILE A SMALL WARM FRONT DEVELOPS TO THE SOUTHEAST. IN
THE UPPER LEVELS...AN UPPER TROUGH AND ASSOCIATED UPPER JET WILL
FAVOR CYCLOGENESIS IN SAO PAULO/PARANA BRASIL TODAY. ALTHOUGH THE
CYCLOGENESIS IS FORECAST TO OCCUR PRIMARILY ON THE COLD...OR SOUTH
SIDE OF THE SURFACE FRONT...ASCENT COULD BE SUFFICIENTLY STRONG TO
TRIGGER MODERATE PRECIPITATION IN SOUTHERN BRASIL EACH DAY THROUGH
THE REST OF THE WORKWEEK. THIS INCLUDES THE INFLUENCE OF THE RIGHT
DIVERGENT ENTRANCE OF AN UPPER JET AND ISENTROPIC LIFT. NOTE THAT
A MARGINAL TO SLIGHT RISK FOR SEVERE CONVECTION EXISTS TODAY AND
TOMORROW INTO EARLY THURSDAY...WHILE A MODERATE RISK OF SEVERE
CONVECTION EXISTS FROM THURSDAY INTO FRIDAY...AS SUGGESTED BY THE
GRO2T FORECAST ALGORITHM. EXPECT AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-45MM FROM MATO GROSSO DO SUL INTO SOUTHERN SAO PAULO AND
PARANA TODAY. LESSER AMOUNTS OF RAIN ARE EXPECTED TOMORROW INTO
THURSDAY WITH MAXIMA NEAR 20-35MM AND HIGHER AMOUNTS OF RAIN ARE
FORECAST ON THURSDAY INTO FRIDAY...ALONG WITH THE DEVELOPING COLD
FRONT...WITH MAXIMA BETWEEN 30-60MM WITH A MODERATE RISK OF SEVERE
CONVECTION.

ACROSS TROPICAL SOUTH AMERICA...GENERALLY MINIMAL RAINFALL
ACCUMULATIONS ARE EXPECTED...WITH THE EXCEPTION OF WESTERN
COLOMBIA...WHERE A RAINFALL MAXIMA OF 25-50MM ARE FORECAST TODAY
AND WEDNESDAY INTO THURSDAY... THE REST OF NORTHERN SOUTH AMERICA
COULD OBSERVE RAINFALL AMOUNTS NEAR 05-10MM/DAY WITH MAX NEAR
15-25MM ACROSS ISOLATED AREAS.

ALAMO...(WPC)
ACOSTA..(WPC)
PALAVECINO (SMN-ARGENTINA)