SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
301 PM EDT FRI JUL 19 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 19 JUL 2024 AT 1900 UTC:

IN THE SOUTHERN PORTION OF SOUTH AMERICA...MULTIPLE FRONTAL
BOUNDARIES ARE EXPECTED INTO THE SOUTHERN CONE AND PROPAGATE
NORTHWARD OVER THE NEXT THREE DAYS. A HIGH PRESSURE SYSTEM IN THE
LOWER LEVELS WILL BLOCK THE FRONTS FROM ENTERING CHILE TOO FAR
NORTH...AND MUCH OF THE PRECIPITATION RELATED TO FRONTAL PASSAGES
IN CHILE ARE EXPECTED TO REMAIN SOUTH 40 DEGREES. THE PATAGONIA
REGION OF ARGENTINA IS NOT EXPECTING MUCH PRECIPITATION AND WILL
LIKELY REMAIN DRY DUE TO LOW AVAILABLE MOISTURE IN THE REGION OVER
THE FORECAST REGION. ON SUNDAY INTO MONDAY...HEAVY PRECIPITATION
IS EXPECTED FROM SOUTHERN AYSEN INTO NORTHERN MAGALLANES IN CHILE
WITH AN ATMOSPHERIC RIVER AND FRONTAL SYSTEM ARRIVING WITH
PRECIPITABLE WATER AMOUNTS FROM 25MM TO HIGHER THAN 30MM IN SOME
AREAS. THE MOISTURE TRANSPORT RELATED TO THIS EVENT IS EXPECTED TO
REMAIN HIGH WITH THE LONG FETCH RELATED TO THE ATMOSPHERIC RIVER.
IN THE UPPER LEVELS...NORTH POLAR JET AND SOUTH POLAR JET WILL
COUPLE OVER THE EASTERN PACIFIC OCEAN AND STRENGTHEN OVER SOUTHERN
CHILE. WINDS IN THE JET STREAK ARE EXCEEDING 200KT ACCORDING TO
MODEL GUIDANCE. THE JET OVER THE REGION WILL ENTER CHILE AS A
CONCAVE JET...HOWEVER BY SUNDAY THE JET IS FORECAST TO BECOME
MOSTLY ZONAL OVER SOUTHERN CHILE AND CAN FAVOR THE HEAVIEST
PRECIPITATION AMOUNTS FROM SUNDAY EVENING INTO MONDAY. THIS EVENT
WILL ALSO AFFECT THE SOUTHWEST SECTOR OF SANTA CRUZ IN
ARGENTINA...WITH PRECIPITATION AMOUNTS IN THE FORM OF RAIN AND
SNOW. IN TERMS OF PRECIPITATION...ON FRIDAY...SOUTHERN CHILE CAN
EXPECT MAXIMA OF 20-35MM WITH MOUNTAIN SNOW. ON SATURDAY...SIMILAR
MAXIMA OF 15-30MM ARE EXPECTED IN THE SAME REGION. ON
SUNDAY...EXPECT MAXIMA OF 40-80MM WITH THE CHANCE OF MOUNTAIN SNOW
FROM SOUTH AYSEN TO NORTH MAGALLANES. FROM CENTRAL LAGOS TO
CENTRAL AYSEN EXPECT MAXIMA OF 20-45MM. FROM MAGALLANES-CHILE TO
THE WESTERN PORTION OF SANTA CRUZ-ARGENTINA CAN EXPECT MAXIMA OF
20-35MM. IN ALL OF THE AFOREMENTIONED REGIONS...EXPECT SNOW IN THE
HIGHER ELEVATIONS.

IN THE CENTRAL PORTION OF THE CONTINENT...A DEEPENING UPPER LEVEL
TROUGH IS LOCATED OVER THE PACIFIC OCEAN JUST WEST OF NORTH CHILE
ON FRIDAY. THE JET TO THE NORTH OF THE TROUGH IS STRENGTHENING AND
WILL FAVOR THE DEEPENING OF THE TROUGH OVER THE WEEKEND AND WILL
LIKELY BECOME A CUTOFF LOW BY SATURDAY. DUE TO THE POSITION OF
THIS TROUGH...IN THE LOWER LEVELS...THE PRESSURES ARE DECREASING
AS FRONTAL PASSAGES MAKE THEIR WAY INTO NORTHERN ARGENTINA. THE
WIND FLOW OVER BOLIVIA...INTO ARGENTINA...IS EXPECTED FROM NORTH
TO SOUTH. WITH THIS...MOISTURE FROM THE TROPICAL REGIONS OF SOUTH
AMERICA WILL BE ADVECTED INTO ARGENTINA OF PRECIPITABLE WATER
MAXIMA RANGING FROM 30-35MM. THIS MOISTURE TRANSPORT IS EXPECTED
THROUGHOUT THE WEEKEND...WITH THE SALLJ DEVELOPING BY SUNDAY. FOR
PRECIPITATION THROUGHOUT THE FORECAST PERIOD...EXPECT LOCALIZED
MAXIMA OF 10-20MM FROM NORTH-CENTRAL ARGENTINA AND INTO SOUTHERN
URUGUAY.

IN THE NORTHERNMOST REGION OF THE CONTINENT...THE PROGRESSION OF
TROPICAL WAVES ALONG THE ITCZ/NET LOCATED FURTHER NORTH INTO THE
CONTINENT WILL FAVOR MOST OF THE HEAVIEST PRECIPITATION TO THE
NORTH OF THE FORECAST REGION. MAXIMA FOR THE FORECAST PERIOD ARE
EXPECTED TO REMAIN BELOW 35MM ON FRIDAY FROM NORTHERN AMAZONAS AND
INTO VENEZUELA. ELSEWHERE EXPECT MAXIMA BELOW 20MM. ON
SATURDAY...MAXIMA OF 15-30MM ARE EXPECTED FROM THE GUIANAS TO
SOUTH-CENTRAL VENEZUELA. AND MAXIMA OF 15-20MM IN COLOMBIA. ON
SUNDAY EXPECT MAXIMA OF 20-45MM IN THE WESTERN COAST OF
COLOMBIA...WHILE AMOUNTS OF 15-20MM ARE EXPECTED FROM EAST
COLOMBIA INTO THE GUIANAS

ACOSTA...(WPC)
SARABIA...(DMC-CHILE)
PALAVECINO...(SMN-ARGENTINA)