SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT TUE OCT 29 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 29 OCT 2024 AT 1900 UTC: AN
ATMOSPHERIC RIVER IS ENTERING AUSTRAL CHILE NEAR 50-52S. ENHANCED
MOISTURE CONVERGENCE WILL FAVOR LOCALLY HEAVY RAINFALL IN SOUTHERN
AYSEN THROUGH EARLY WEDNESDAY...WHERE EXPECT MAXIMA OF 35-70MM.
THIS DECREASES THEREAFTER. ON THURSDAY...A MERIDIONALLY ORIENTED
FRONTAL SYSTEM IS FORECAST TO ENTER THE SOUTHERN CONE LATE. THIS
WILL FAVOR AN INCREASE IN PRECIPITATION IN MAGALLANES AND SOUTHERN
AYSEN TO FAVOR 05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM AS WELL
AS AN INCREASE IN MOUNTAIN SNOW. NORTH INTO LOS RIOS EXPECT
SCATTERED SHOWERS AND MAXIMA UNDER 15MM/DAY.

A SHORT WAVE UPPER TROUGH IN THE EASTERN PACIFIC IS FORECAST TO
ENTER CENTRAL AND NORTHERN PATAGONIA ON WEDNESDAY. THIS WILL
INTERACT WITH A BUILDING MOIST POOL IN ARGENTINA...AIDED BY
NORTHERLY LOW-LEVEL JETS. INSTABILITY AND UPPER TROUGH DYNAMICS
WILL BE SUFFICIENT TO FAVOR ISOLATED SEVERE CONVECTION IN
NORTHEAST PATAGONIA WHERE EXPECT 05-10MM AND ISOLATED MAXIMA OF
15-20MM.

A SHORT WAVE UPPER TROUGH IS FORECAST TO CROSS THE ANDES OF
NORTHERN ARGENTINA AND SOUTHERN BOLIVIA EARLY ON THURSDAY. THIS
WILL INTERACT WITH A BUILDING MOIST POOL ACROSS PORTIONS OF
NORTHERN ARGENTINA TO FAVOR THE DEVELOPMENT OF STRONG CONVECTION
AND HEAVY RAINFALL RATES. BY THURSDAY THROUGH EARLY FRIDAY EXPECT
15-20MM/DAY AND MAXIMA OF 40-80MM WITH A RISK FOR SEVERITY AND MCS
FORMATION.

ACTIVE CONVECTION IS EXPECTED TO CONTINUE ACROSS SOUTHERN PORTIONS
OF TROPICAL SOUTH AMERICA. IN THE UPPER LEVELS...THE BOLIVIAN HIGH
IS ORGANIZING WHILE CENTERING OVER SOUTHERN PERU. THIS WILL YIELD
TO THE AMPLIFICATION OF AN UPPER TROUGH IN AREAS EAST OF THE HIGH.
AS THE TROUGH AMPLIFIES...EXPECT AN INCREASE IN UPPER
DIVERGENCE...WHICH WILL CONTINUE TO VENTILATE DIURNAL CONVECTION
IN CENTRAL AND SOUTHEAST BRASIL. IN THE LOWER TROPOSPHERE...A
MOIST POOL OF 50-55MM OF PRECIPITABLE WATER IS BUILDING IN THE
REGION. NOTE THAT THE ECMWF MODEL SEEMS TO BE DOING A BETTER JOB
INITIALIZING THE AMOUNTS OF AVAILABLE MOISTURE...THUS IS HAS A
BETTER HANDLE OF AREAS PRONE TO THE DEVELOPMENT OF DIURNAL. A
SACZ-LIKE FEATURE IS TRYING TO ORGANIZE ACROSS ESPIRITO
SANTO...SOUTHERN GOIAS INTO EASTERN BOLIVIA. NEVERTHELESS...THE
850-700 HPA ORGANIZED TROUGH NORMALLY EXPECTED WITH THE SACZ IS
NOT WELL DEFINED IN NUMERICAL MODELS OR OBSERVATIONS.
FURTHERMORE...THE REGION OF ENHANCED CONVERGENCE IS EXPECTED TO
LAST NO LONGER THAN 48 HRS. ACCORDINGLY...WE ARE NOT REPRESENTING
THE PRESENCE OF THE SACZ IN OUR FORECAST CHARTS. IN TERMS OF
RAINFALL ACCUMULATION...ON TUESDAY...EXPECT MAXIMA OF 30-60MM IN
ESPIRITO SANTO...WHILE IN MINAS GERAIS EXPECT MAXIMA OF 20-45MM.
WEST ACROSS CENTRAL SOUTH AMERICA EXPECT MAXIMA OF 15-30MM. ON
WEDNESDAY...A PEAK IN VENTILATION IN CENTRAL BRASIL WILL FAVOR
MAXIMA OF 30-60MM FROM MATO GROSSO INTOGONIAS/NORTHERN MINAS
GERAIS. IN COASTAL AREAS OF ESPIRITO SANTO EXPECT MAXIMA OF
25-50MM. ON THURSDAY...EXPECT MAXIMA OF 25-50MM IN MATO
GROSSO..WHILE IN GOIAS AND MINAS GERAIS/SOUTHERN BAHIA EXPECT
MAXIMA OF 20-45MM.

ACTIVE DIURNAL CONVECTION IS EXPECTED IN THE BOLIVIAN AND PERUVIAN
ALTIPLANO/ANDES ON A DAILY BASIS. UNDER THE INFLUENCE OF
VENTILATION FROM THE BOLIVIAN HIGH AND SUFFICIENT AVAILABLE
MOISTURE...EXPECT AMOUNTS OF 05-10MM/DAY AND ISOLATED MAXIMA
GENERALLY OF 15MM ON A DAILY BASIS. ON TUESDAY...EXPECT ISOLATED
MAXIMA OF 15-30MM IN PORTIONS OF SOUTHERN PERU.

GALVEZ...(WPC)
ALAMO...(WPC)
LOPEZ...(DMH-PARAGUAY)