833
FXSA20 KWBC 181905
PMDSA

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 PM EDT FRI OCT 18 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 18 OCT 2024 AT 1900 UTC:

ON FRIDAY...A POTENT RIDGE IS PRESENT OVER THE PACIFIC EAST
PACIFIC...AND TO THE WEST OF PERU AND NORTH CHILE. THIS RIDGE IS
BLOCKING ANY TROUGH TO MOVE TO THE NORTH...BUT IT IS FAVORING THE
EXTENSION OF UPPER TROUGHS OVER PARAGUAY...BOLIVIA...AND SOUTH AND
CENTRAL BRASIL. AN UPPER TROUGH IS LOCATED OVER THIS
REGION...WHICH IS FAVORING THE DEVELOPMENT OF DEEP CONVECTION AND
THE PRESENCE OF A WEAKENING FRONTAL BOUNDARY. THE WEAKENING
FRONTAL BOUNDARY IS EXPECTED TO REMAIN SEMI-STATIONARY OVER SOUTH
AND CENTRAL BRASIL...REACHING PORTIONS OF NORTH BOLIVIA...AND
SOUTH PERU. THE PRESENCE OF THE MID LEVEL TROUGH...THE AMOUNT OF
AVAILABLE MOISTURE IN THE REGION...AND CONVERGENCE OF WINDS OVER
THE AFOREMENTIONED REGION WILL ASSIST IN THE DEVELOPMENT OF HEAVY
PRECIPITATION AND DEEP CONVECTION. EXPECT MAXIMA OF 25-50MM IN
EAST BOLIVIA...AND WEST MATO GROSSO DO SUL. THE REST OF THE
WESTERN BRASIL AND NORTH BOLIVIA REGION CAN EXPECT MAXIMA OF
20-45MM.

ON SATURDAY...THE UPPER RIDGE OVER THE EASTERN PACIFIC IS ENTERING
THE CONTINENT THROUGH NORTH CHILE AND INTERACTING WITH THE UPPER
TROUGH IN SOUTHERN BRASIL...THIS WILL BEGIN TO ISOLATE THE UPPER
TROUGH AND BEGIN TO SEGREGATE IT OVER BRASIL. THE INTERACTION OF
THE ONSHORE FLOW WITH THE OROGRAPHY WILL FAVOR MAXIMA OD 50-100MM
IN RIO DE JANEIRO...ESPIRITO SANTO...AND SOUTH MINAS GERAIS.
GENERALIZED MAXIMA OF 30-60MM ARE EXPECTED IN NORTH GOIAS AND
SOUTH TOCANTINS. ELSEWHERE IN SOUTH AND CENTRAL BRASIL..AND INTO
SOUTH PERU EXPECT GENERALIZED MAXIMA OF 20-45MM. DUE TO THE SAME
INTERACTION OF THE UPPER RIDGE...ANOTHER UPPER LEVEL TROUGH BEGINS
TO ENTER CENTRAL CHILE AND ARGENTINA...AND A STRENGTHENING OF THE
UPPER JETS IS EXPECTED. THE CONCAVE SHAPE OF THE JET IS FAVORING
ENHANCED DIVERGENCE OVER WEST-CENTRAL ARGENTINA...AS WELL AS THE
ACTIVATION OF A LOW PRESSURE SYSTEM IN THE LOWER LEVELS. DUE TO
THE LOW AMOUNT OF AVAILABLE MOISTURE...PRECIPITATION TOTALS ARE
EXPECTED TO REMAIN BELOW 20MM IN RIO NEGRO WITH A SLIGHT RISK OF
SEVERE WEATHER.

ON SUNDAY...THE SOUTH AND CENTRAL PORTIONS OF BRASILCAN
ANTICIPATE TO SEE SIMILARCONDITIONS...WHERE THE UPPER LEVEL
TROUGH IS BEGINNING TO WEAKEN...WHILE MOISTURE CONTINUES TO
CONVERGE OVER THE REGION. MINAS GERAIS AND ESPIRITO SANTO CAN
EXPECT MAXIMA OF 40-80MM. GOIAS AND SOUTH TOCANTINS...AS WELL AS
RIO DE JANEIRO CAN EXPECT GENERALIZED MAXIMA OF 20-45MM. IN THE
SOUTHERN PORTION OF THE CONTINENT...THE UPPER LEVEL TROUGH
CONTINUES TO ENTER THE CONTINENT AND ENHANCES THE DEVELOPMENT OF A
FRONTAL BOUNDARY IN CENTRAL ARGENTINA. WITH THE PASSING OF SEVERAL
MID LEVEL SHORT WAVE TROUGHS...AS WELL AS THE UPPER
DIVERGENCE...THIS REGION CAN EXPECT MODERATE RISK OF SEVERE
WEATHER. HOWEVER...THE CHANCE FOR HEAVY PRECIPITATION IS LOWDUE
TO THE ABSENCE OF HIGHER AMOUNTS OF AVAILABLE MOISTURE. MAXIMA OF
15-30MM ARE EXPECTED IN NORTH MENDOZA AND SOUTH SAN
JUAN-ARGENTINA...AND EAST RIO NEGRO-ARGENTINA. CENTRAL REGIONS OF
ARGENTINA CAN EXPECT MAXIMA OF 15-20MM AS THE EFFECTS OF THE SHORT
WAVE TROUGHS IN THE MID TO UPPER LEVELS ARE EXPECTED TO DECREASE
THERE. SOUTHERN CHILE CAN EXPECT AN INCREASE IN MOISTURE DUE TO
THE ENTRANCE OF AN ATMOSPHERIC RIVER IN THE ZONA AUSTRAL AND SUR
OF CHILE...WHERE EXPECT MAXIMA OF 15-30MM.

CASTELLANOS...(WPC)
$$