846
FXSA20 KWBC 152037
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
436 PM EDT TUE OCT 15 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 15 OCT 2024 AT 2030 UTC:
A SERIES OF SHORTWAVE TROUGHS WILL BE IMPACTING THE REGION OVER
THE NEXT FEW DAYS. THE AREAS OF MOST INTEREST INCLUDE CHILE AND
CENTRAL TO NORTHERN ARGENTINA. A FRONTAL BOUNDARY IS MOVING
NORTHWARD FROM NORTHERN ARGENTINA TODAY INTO SOUTHERN BRASIL BY
FRIDAY MORNING. AS WE ARE ENTERING THE ACTIVE PERIOD IN THE AMAZON
BASIN...CONVECTION IS EXPECTED TO BE OBSERVED DAILY...ESPECIALLY
IN THE AFTERNOONS ACROSS CENTRAL BRAZIL (AMAZONIA)...WITH DAILY
MAX VALUES GENERALLY NEAR 20-35MM WITH OCCASIONAL STRONG
THUNDERSTORMS. SOUTHWESTERN COLOMBIA WILL ALSO RECEIVE DAILY
RAINFALL...WITH DAILY TOTALS EXPECTED TO BE BETWEEN
20-50MM...TODAY BEING ON THE LOWER END OF THAT RANGE AND WEDNESDAY
INTO THURSDAY BEING ON THE HIGHER END OF THAT RANGE. ONSHORE FLOW
FROM THE ITCZ WILL BRING AN INFLUX MOISTURE INTO THIS REGION.
FOR TODAY...AN UPPER LEVEL TROUGH WILL BE DIGGING INTO
CHILE...WHICH WILL INFLUENCE THE AMOUNTS OF PRECIPITATION ACROSS
CENTRAL CHILE...WHERE MOUNTAIN SNOW IS ALSO EXPECTED. THERE WILL
ALSO BE AN ATMOSPHERIC RIVER BRINGING IN MOISTURE INTO SOUTHERN
CHILE. A SHORTWAVE TROUGH AND A COLD FRONT WILL COMBINE TO CAUSE A
MARGINAL RISK OF SEVERE WEATHER IN PARTS OF NORTHERN URUGUAY TODAY
INTO WEDNESDAY. HOWEVER...THIS FRONTAL SYSTEM IS EXPECTED TO
WEAKEN BY WEDNESDAY. MEANWHILE...A STATIONARY...OR DRIFTING EVER
SO SLIGHTLY SOUTHWARD...FRONT LOCATED OVER PARAGUAY AND BRASIL
WILL PREVAIL. FOR WEDNESDAY INTO THURSDAY...MOISTURE ADVECTION
WILL DIG FARTHER SOUTH INTO THE CENTRAL REGION OF ARGENTINA. THE
LATEST GRO2T ALGORITHM SUGGESTS A CHANCE FOR SEVERE WEATHER IN
THIS REGION DUE TO THE MOISTURE CONVERGENCE...AND THE UPPER LEVEL
DIVERGENCE MOVING FROM A SHORTWAVE TROUGH THAT WILL BE LOCATED
OVER THE ARGENTINIAN ANDES BY WEDNESDAY NIGHT. BY THURSDAY INTO
FRIDAY MORNING...THE STATIONARY FRONTAL BOUNDARY IN CENTRAL SOUTH
AMERICA OVER NORTHERN ARGENTINA WILL START TO MOVE NORTHWARD AS A
COLD FRONT MOVING INTO BRAZIL. IN ADDITION...AN UPPER LEVEL TROUGH
FURTHER ENHANCED INSTABILITY OVER THIS REGION...WHICH WILL COMBINE
WITH A DEEP LAYER MOISTURE FLOW FROM THE SALLJ. THIS MOISTURE
ADVECTION IS EXPECTED TO POOL...AND COMBINE WITH THE NORTHERLY
SALLJ...ENHANCING THE POTENTIAL FOR HEAVY PRECIPITATION TOTALS
ACROSS NORTHERN ARGENTINA INTO SOUTHERN PARAGUAY...CURRENTLY WITH
A RAINFALL FORECAST OF 15-20MM AND MAX OF 35-70MM. THERE IS A HIGH
RISK FOR MCS FORMATION OVER THIS AREA AS UPPER LEVEL
DIVERGENCE...DEEP LAYER MOISTURE...AND INSTABILITY WILL COMBINE
OVER THE AREA. THERE IS SOME UNCERTAINTY IN THE OVERALL COVERAGE
TO THE NORTH OF PARAGUAY...AS THE DIFFERENT MODEL GUIDANCE ARE NOT
IN AGREEMENT WITH THE OVERALL COVERAGE. HOWEVER...THERE WILL BE
ENOUGH INSTABILITY AND MOISTURE TO CAUSE SIGNIFICANT AMOUNTS OF
RAIN OVER THE AREA. ACROSS SOUTHERN CHILE...ANOTHER ATMOSPHERIC
RIVER COULD BRING MUCH HIGHER THAN NORMAL MOISTURE FOR THAT AREA
ON THURSDAY...AND THEREFORE INCREASING THE AMOUNTS OF RAIN IN THE
FORECAST.
ACROSS THE AMAZON BASIN AND PERU... THE AVAILABLE MOISTURE IS
ACTUALLY FORECAST TO BE NEAR TO BELOW NORMAL...AS THE LATEST
GUIDANCE SUGGESTS LAYER PRECIPITABLE WATER ANOMALIES IN THE AMAZON
WILL BE AT AROUND 60 TO 90 PERCENT OF NORMAL. THAT BEING
SAID...THERE IS STILL PLENTY OF MOISTURE...AND THE PRECIPITABLE
WATER VALUES ARE FORECAST TO BE GENERALLY BETWEEN 40 AND 55MM.
THEREFORE...AS MENTIONED ABOVE...DAILY RAINFALL IS EXPECTED OVER
THE AMAZON AND ALSO INTO THE HIGHER ELEVATIONS OF PERU...BUT THE
MAX RAINFALL AMOUNTS ARE EXPECTED TO BE NEAR 15-25MM OVER
PERU...WITH SLIGHTLY HIGHER AMOUNTS OVER THE AMAZON BASIN AND
OTHER SECTIONS OF BRAZIL.
ALAMO...(WPC)
TINOCO...(WPC)
LOPEZ...(DMH-PARAGUAY)
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