874
FXSA20 KWBC 201915
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
214 PM EST FRI DEC 20 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 20 DEC 2024 AT 1930 UTC:
A POTENT BOLIVIAN HIGH IS SITUATED OVER NORTHERN SOUTH AMERICA ON
FRIDAY...WHICH IS EXTENDING FROM CENTRAL PERU TO EAST BRASIL...AND
AS SOUTH AS NORTH PARAGUAY. THE UPPER RIDGE IS INTERACTING WITH
THE BASE OF AN UPPER TROUGH THAT IS EXTENDING OVER SOUTH PARAGUAY
AND SOUTH BRASIL. THIS INTERACTION IS FAVORING SHORT WAVE TROUGHS
EMBEDDED IN THE BASE OF THE TROUGH THAT ARE MAKING THEIR WAY OVER
PARAGUAY AND SOUTH BRASIL...FAVORING DEEP CONVECTION IN THE REGION
OVER THE NEXT THREE DAYS. IN THE LOWER LEVELS...MOISTURE IS BEING
TRANSPORTED TO BOLIVIA...PARAGUAY AND SOUTH BRASIL DUE TO THE
PRESENCE OF THE UPPER TROUGH IN THE REGION LOWERING THE PRESSURES
IN THE LOWER LEVELS. ALONG THE TRADE WINDS IN PORTIONS OF NORTH
BRASIL...TROUGHS ARE EMBEDDED IN THE TRADES...WHICH WILL ASSIST IN
TRIGGERING CONVECTION IN THE REGION. WITH THE IMPACT OF THE LATENT
HEATING ASSOCIATED WITH THE BOLIVIAN HIGH...THE POTENTIAL FOR DEEP
CONVECTION AND HEAVY LOCALIZED PRECIPITATION IS POSSIBLE IN
CENTRAL AND NORTHERN PORTIONS OF BRASIL OVER THE NEXT THREE DAYS.
FURTHERMORE...A FRONTAL BOUNDARY IS EXPECTED IN SANTA CATARINA AND
PARANA BRASIL BY FRIDAY EVENING. THIS FRONTAL BOUNDARY WILL BECOME
STATIONARY ON SATURDAY...AND IT WILL BE REPLACED BY A SECOND FRONT
THAT IS EXPECTED IN SOUTH BRASIL AND INTO NORTHERN PARAGUAY BY
SUNDAY EVENING. AS THESE FRONTAL BOUNDARIES INTERACT WITH THE
UPPER LEVEL JET AND SHORTWAVE TROUGHS...THEY WILL FAVOR MODERATE
TO HEAVY PRECIPITATION. AS THE INSTABILITY IN THE REGION INCREASES
WITH THE ARRIVAL OF THE SECOND FRONT...AND MOISTURE IS EXPECTED TO
CONVERGE IN REGIONS OF BOLIVIA AND WEST BRASIL...EXPECT ADDITIONAL
HEAVY PRECIPITATION FOR SUNDAY INTO MONDAY. PRECIPITABLE WATER
LEVELS IN THE REGION COULD EXCEED THE 55-60MM VALUES.
IN TERMS OF PRECIPITATION...ON FRIDAY...EXPECT MAXIMA OF 35-70MM
IN SAO PAULO AND EAST PARANA WITH A SLIGHT RISK OF SEVERE WEATHER.
WHILE A MAXIMA OF 25-50MM ARE EXPECTED FROM SOUTH MATO GROSSO SO
SUL THROUGH WEST PARANA AND NORTH SANTA CATARINA. PORTIONS OF SAO
PAULO...MINAS GERAIS...AND RIO DE JANEIRO CAN EXPECT A MARGINAL
RISK OF SEVERE WEATHER AS A SHORTWAVE TROUGH ADVANCES OVER THE
REGION. PRECIPITATION IS EXPECTED TO REMAIN BELOW 35MM FROM SAO
PAULO TO MINAS GERAIS AND BELOW 15MM IN RIO DE JANEIRO. ELSEWHERE
IN THE REGION EXPECT SCATTERED DEEP CONVECTION WITH POTENTIAL FOR
HEAVY PRECIPITATION IN REGIONS OF BRASIL...WHERE MAXIMA OF 20-45MM
ARE EXPECTED. ON SATURDAY...MINAS GERAIS...RIO DE JANEIRO...AND
SAO PAULO CAN EXPECT MAXIMA OF 30-60MM. WHILE REGIONS IN CENTRAL
BRASIL CAN EXPECT MAXIMA OF 20-45MM WITH LOCALIZED HIGHER AMOUNTS
POSSIBLE. ALONG CENTRAL BOLIVIA...MOISTURE CONVERGENCE IS EXPECTED
IN THE REGION WITH MAXIMA OF 25-50MM. THE ADVANCING FRONTAL
BOUNDARY IN SOUTH SANTA CATARINA AND RIO GRANDE DO SUL WILL FAVOR
MAXIMA OF 25-50MM. ON SUNDAY...THE FRONTAL BOUNDARY IS EXPECTED IN
PARANA WHERE EXPECT MAXIMA OF 20-45MM. SIMILAR AMOUNTS ARE
EXPECTED IN CENTRAL BRASIL. WITH THE INCREASED MOISTURE FROM SOUTH
PERU TO BOLIVIA...EXPECT MAXIMA OF 25-50MM.
IN THE SOUTHERN CONE OF THE CONTINENT...AN UPPER TROUGH IS MAKING
ITS WAY EAST OVER THE REGION...WITH EMBEDDED UPPER SHORT WAVE
TROUGHS ON FRIDAY. ALTHOUGH THE DYNAMICS MAY BE PRESENT OVER THE
REGION FOR VENTILATION FOR HEAVY PRECIPITATION...THE AMOUNT OF
AVAILABLE MOISTURE IS NOT SUFFICIENT FOR LARGE AMOUNTS OF
PRECIPITATION IN THE REGION. BY SATURDAY A RIDGE BEGINS TO ENTER
CENTRAL PORTIONS OF CHILE AND ARGENTINA...DECREASING THE POTENTIAL
FOR HEAVIER PRECIPITATION. IN THE LOWER LEVELS...FRONTAL
BOUNDARIES ARE EXPECTED TO MAKE THEIR WAY THROUGH CHILE AND
ARGENTINA...YET PRECIPITATION IS EXPECTED TO REMAIN LOW. ON
SUNDAY...A FRONTAL BOUNDARY EXTENDS INTO LOS LAGOS-CHILE...WITH A
SLIGHT INCREASE IN MOISTURE...ACCOMPANIED BY AN UPPER SHORT WAVE
TROUGH OVER THE REGION. IN CENTRAL ARGENTINA...A DEVELOPING LOWER
LEVEL BOUNDARY IS EXPECTED TO TRIGGER SOME PRECIPITATION...BUT THE
INSTABILITY WILL FAVOR A SLIGHT RISK OF SEVERE WEATHER. ALTHOUGH
THERE IS A POTENTIAL FOR PRECIPITATION...AMOUNTS ARE NOT EXPECTED
TO BE HEAVY. ON FRIDAY...EXPECT MAXIMA OF 15-25MM IN SOUTH AYSEN
AND MAGALLANES. ON SATURDAY...A SLIGHT DECREASE WITH A MAXIMA OF
15-20MM FROM AYSEN TO MAGALLANES. ON SUNDAY...MAXIMA OF 15-25MM
ARE EXPECTED FROM LOS LAGOS TO MAGALLANES...AND SIMILAR AMOUNTS
ARE EXPECTED IN NORTH LA PAMPA...SOUTH SAN LUIS...AND SOUTH
CORDOBA-ARGENTINA.
CASTELLANOS...(WPC)
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