SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 PM EDT MON JUL 08 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 08 JUL 2024 AT 1900 UTC:

A BLOCKING HIGH IN THE UPPER TROPOSPHERE IS HELPING TO SUSTAIN A
STRONG SURFACE HIGH PRESSURE WHICH IS CENTERING NEAR 48S 89W. THE
HIGH IS FORECAST TO PERSIST OVER THESE PORTIONS OF THE SOUTHEAST
PACIFIC FOR THE NEXT SEVERAL DAYS. THIS HIGH PRESSURE WILL BLOCK A
SFC LOW PRESSURE TO ITS WEST FROM MOVING INTO THE
CONTINENT...WHICH WILL KEEP MOST OF CHILE AND ARGENTINA FAIRLY DRY
FOR THE NEXT 3 DAYS...ALLOWING LIGHT PRECIPITATION IN FAR AUSTRAL
TIERRA DEL FUEGO ON MONDAY. ON TUESDAY...A SOUTHWESTERLY UPPER JET
WILL FAVOR CYCLOGENESIS ON THE SOUTHERN DRAKE PASSAGE. THIS WILL
FAVOR AN ACCELERATION OF COLD SOUTHWESTERLY WINDS ACROSS TIERRA
DEL FUEGO/SOUTHERN CONE. NEVERTHELESS...LIMITED AVAILABLE MOISTURE
WILL LEAD TO TRACE ACCUMULATIONS OF SNOW IN SOUTHERN TIERRA DEL
FUEGO.

IN MID PORTIONS OF THE CONTINENT...A STATIONARY FRONT CONTINUES
EXTENDING ACROSS SAO PAULO...CENTRAL MATO GROSSO...RONDONIA INTO
SOUTHERN PERU. THE FRONT IS FORECAST TO REMAIN IN THIS POSITION
THROUGH TUESDAY EVENING...TO THEN LOSE DEFINITION. IN THE UPPER
LEVELS...AN UPPER TROUGH AND ASSOCIATED UPPER JET WILL FAVOR
CYCLOGENESIS IN SAO PAULO/PARANA BRASIL LATE ON MONDAY/TUESDAY.
THIS WILL DEVELOP A FRONTAL WAVE THAT IS FORECAST TO EXIT INTO THE
ATLANTIC DURING TUESDAY. ALTHOUGH THE CYCLOGENESIS IS FORECAST TO
OCCUR PRIMARILY ON THE COLD SIDE OF THE SURFACE FRONT...ASCENT
WILL BE SUFFICIENTLY STRONG TO TRIGGER MODERATE PRECIPITATION IN
SOUTHERN BRASIL. THIS INCLUDES THE INFLUENCE OF THE RIGHT
DIVERGENT ENTRANCE OF AN UPPER JET AND ISENTROPIC LIFT. NOTE THAT
A SLIGHT RISK FOR SEVERE CONVECTION EXISTS. EXPECT AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 25-50MM FROM CENTRAL MATO GROSSO DO SUL
INTO SOUTHERN SAO PAULO THROUGH EARLY TUESDAY. IN THE TAIL OF THE
FRONT...OROGRAPHIC INTERACTIONS IN SOUTHERN PERU WILL FAVOR MAXIMA
OF 20-35MM. ON TUESDAY...CONTINUED PRECIPITATION IN THE POST
FRONTAL AIR-MASS WILL FAVOR ADDITIONAL ACCUMULATION OF 10-15MM/DAY
AND MAXIMA OF 20-40MM IN MATO GROSSO SO DUL-SAO PAULO...WITH A
MARGINAL RISK OF SEVERE CONVECTION. ONSHORE EASTERLY FLOW SOUTH OF
THE OCCLUDED LOW WILL FAVOR MAXIMA OF 15-30MM IN EASTERN PORTIONS
OF RIO GRANDE DO SUL TO PARANA...AIDED BY OROGRAPHIC ENHANCEMENT.
ON WEDNESDAY...A POTENT UPPER TROUGH IS FORECAST TO CROSS THE
ANDES IN CENTRAL SOUTH AMERICA. THIS WILL START A NEW CYCLOGENETIC
PROCESS IN PARAGUAY/SOUTHWEST BRASIL...AND INDUCE THE DEVELOPMENT
OF AN EXTRA-TROPICAL CYCLONE OVER THE CONTINENT ON THURSDAY. IN
THE MEAN TIME...PRECIPITATION IS EXPECTED IN EASTERN
PARAGUAY/SOUTHERN MATO GROSSO DO SUL ON WEDNESDAY THROUGH EARLY
THURSDAY TO SUSTAIN MAXIMA OF 15-30MM.

NORTH OVER THE CONTINENT...IN TROPICAL PORTIONS OF SOUTH
AMERICA...EXPECT COVERAGE OF ACCUMULATING PRECIPITATION AS THE DRY
SEASON CONTINUES. ENHANCED SHOWERS WILL LIKELY CLUSTER IN
NORTHEAST BRASIL AND IN PORTIONS OF THE NORTHERN AND WESTERN
AMAZON ASSOCIATED WITH WEAK PERTURBATIONS PROPAGATING IN THE
TRADES.

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