666
FXSA20 KWBC 311845
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT WED JUL 31 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 31 JUL 2024 AT 1845 UTC:
BEGINNING ON WEDNESDAY...THE SOUTHERN PORTION OF THE
CONTINENT...PRIMARILY IN CENTRAL CHILE...WILL SEE THE ENTRANCE OF
A POTENT AND WIDE UPPER LEVEL TROUGH...AND THE DIVERGENT UPPER
JET...WHICH WILL BE ASSISTING THE ATMOSPHERIC RIVER IN FAVORING
HEAVY PRECIPITATION ON WEDNESDAY AND INTO THURSDAY. THE
ATMOSPHERIC RIVER IS APPROACHING WITH PRECIPITABLE WATER LEVELS OF
OVER 30-40MM AND IT IS EXPECTED THAT THE VALUES REMAIN AROUND 30MM
BY THE TIME IT REACHES CENTRAL CHILE ON WEDNESDAY. THE FRONTAL
SYSTEM ASSOCIATED WITH THIS SYSTEM ENTERS WESTERN CHILE BY
WEDNESDAY EVENING...EXTENDING FROM NORTHERN AYSEN INTO
O'HIGGINS...WHERE MOST OF THE PRECIPITATION IS EXPECTED ON
WEDNESDAY. FROM THE MOUNTAIN REGIONS OF O'HIGGINS TO NORTHERN LOS
LAGOS CAN EXPECT HEAVY PRECIPITATION OF 35-70MM...WITH MOUNTAIN
SNOW IN THE ELEVATED REGIONS. FROM LOS LAGOS TO NORTH AYSEN EXPECT
MAXIMA OF 20-35MM.
ON THURSDAY...THE UPPER LEVEL TROUGH ADVANCES TO THE EAST AND
ENTERS CHILE...AS WELL AS THE JET IN THE NORTHERN PORTION OF THE
TROUGH EXTENDS INTO THE NORTH AND NORTE CHICO REGIONS OF CHILE. IN
THE LOWER LEVELS...ANOTHER FRONTAL SYSTEM...WITH MUCH COLDER AIR
MASS PROPAGATES INTO THE CENTRAL AND NORTHERN REGIONS...FAVORING
ADDITIONAL HEAVY PRECIPITATION FROM MAULE AND NORTH INTO COQUIMBO.
THE ATMOSPHERIC RIVER IS EXPECTED TO TRANSPORT MORE MOISTURE IN
THE FIRST HALF OF THURSDAY...WITH IVT VALUES EXCEEDING 1000KG(M/S)
FROM MAULE TO COQUIMBO. DUE TO THE UPPER LEVEL JET'S CONVEX
SHAPE...AND THE ENTRANCE OF THE FRONTAL SYSTEM INTO THE CONTINENT
BEING FROM NORTH TO SOUTH...THE ELEVATED AMOUNTS OF MOISTURE IN
THE REGION ARE NOT EXPECTED TO LAST FOR TOO LONG. BY FRIDAY
MORNING...THE PRECIPITATIONS ARE EXPECTED TO DECREASE AND THE
SYSTEM SHOULD BE ENDING BY THE END OF DAY TWO. UNDER THESE
CONDITIONS...THE MAXIMA EXPECTED FROM THE REGIONS OF NORTH LOS
RIOS TO COQUIMBO ARE MAXIMA OF 40-80MM. AN AREA OF SOUTHERN
ATACAMA CAN EXPECT MAXIMA OF 20-4OMM....WHILE AMOUNTS OF 20-45MM
ARE EXPECTED FROM LAGOS TO NORTH AYSEN.
BY FRIDAY...THESE CONDITIONS ARE EXPECTED TO DECREASE...AND SUCH
THE PRECIPITATION TOTALS WILL BE DECREASING. THE WIDE UPPER LEVEL
TROUGH CONTINUES TO ENTER THE CONTINENT...HOWEVER THE UPPER JET
WEAKENS THROUGHOUT THE DAY AND MOVES OVER CENTRAL ARGENTINA AND
URUGUAY. THE MOISTURE AVAILABLE IN THE REGION HAS DECREASED TO
ABOUT 20-25MM...AND WILL BE ASSISTED BY MOISTURE CONVERGENCE FROM
A LOW LEVEL JET FROM THE NORTH. POST FRONTAL CONDITIONS OVER CHILE
WILL FAVOR THE POTENTIAL FOR THUNDERSTORMS IN PORTIONS OF CENTRAL
CHILE. IN TERMS OF PRECIPITATION...MAXIMA OF 25-50MM ARE EXPECTED
THE IN NORTE CHICO REGION....WHILE SIMILAR AMOUNTS ARE EXPECTED IN
THE CENTRAL PORTION OF CHILE....AND THE MOUNTAIN REGION OF AYSEN.
IN PORTIONS OF COQUIMBO AND VALPARAISO...AND COASTAL REGIONS OF
AYSEN...EXPECT MAXIMA OF 20-40MM.
ANOTHER AREA OF INTEREST IS NORTH AND CENTRAL
ARGENTINA...PARAGUAY...URUGUAY...AND SOUTH BRASIL. ON
WEDNESDAY...A WARM FRONT IS PROPAGATING FROM SOUTHERN
PARAGUAY...TO SOUTHERN URUGUAY AND SOUTHERN ENTRE RIOS IN
ARGENTINA. IT WILL QUICKLY PROPAGATE FURTHER SOUTH WITH THE LOW
LEVEL JET DEVELOPING FROM NORTHERN BOLIVIA/SOUTHERN PERU INTO
BUENOS AIRES AND INTO THE ATLANTIC OCEAN BY WEDNESDAY EVENING.
THESE STRONG WINDS WILL ADVECT WARMER AIR INTO THE AFOREMENTIONED
REGIONS IN CENTRAL SOUTH AMERICA. WITH THE ENTERING UPPER LEVEL
TROUGH...THESE CONDITIONS ARE EXPECTED TO CONTINUE INTO THE
WEEKEND. ADDITIONALLY...WITH THE UPPER DIVERGENT
CONDITIONS...SHORT WAVE TROUGHS EMBEDDED IN THE WIDE UPPER TROUGH
ARE EXPECTED TO PROPAGATE ALONG THE PERIPHERY OF THE TROUGH IN THE
MID TO UPPER LEVELS. THESE SHORT WAVE TROUGHS WILL FAVOR THE
INCREASE OF SEVERE WEATHER. FURTHERMORE...A POTENT AND COLD
FRONTAL BOUNDARY CROSSES OVER THE ANDES MOUNTAINS BY FRIDAY
MORNING AND ADVANCES TO THE NORTHEAST OVER CENTRAL ARGENTINA. BY
FRIDAY EVENING THE FRONTAL BOUNDARY ENCOUNTERS THE WARMER AIR IN
THE REGION...INCREASING THE INSTABILITY. WITH THESE CONDITIONS
COMBINING BY FRIDAY...THE REGION OF CENTRAL ARGENTINA...FROM THE
SOUTHERN CHACO REGION TO BUENOS AIRES...CAN EXPECT ELEVATED RISK
OF SEVERE WEATHER. IN TERMS OF PRECIPITATION...MAXIMA ARE EXPECTED
BETWEEN 20-35MM ON FRIDAY.
ELSEWHERE IN THE NORTHERN PORTION OF THE CONTINENT...DRY AIR IS
EXPECTED TO BE ADVECTED INTO THE REGION. OVERALL...THE AMOUNT OF
MAXIMA EXPECTED IN THE TROPICAL PORTION OF THE CONTINENT ARE
EXPECTED TO REMAIN BELOW 25MM OVER THE NEXT SEVERAL DAYS. THE
PASSAGES OF A FEW TROUGHS WILL BE FAVORING THE PRECIPITATION
EXPECTED. HOWEVER...NO SIGNIFICANT AMOUNTS ARE EXPECTED AT THIS
TIME.
ACOSTA...(WPC)
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