819
FXSA20 KWBC 021944
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
343 PM EDT FRI AUG 02 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 02 AUG 2024 AT 1900 UTC:
ON FRIDAY...AN UPPER LEVEL TROUGH IS SITUATED OVER CHILE AND
ENTERING INTO ARGENTINA. THE UPPER LEVEL TROUGH IS EXPECTED TO
CONTINUE PROPAGATING EAST AND EXTEND INTO THE EXTREME NORTH OF
CHILE....AND CENTRAL BOLIVIA BY FRIDAY EVENING. A SHORT WAVE
TROUGH IS EMBEDDED IN THE EASTERN SIDE OF THE WIDE UPPER TROUGH
AND WILL PROVIDE THE UPPER LEVEL DIVERGENT SUPPORT FOR VENTILATION
IN BUENOS AIRES AND INTO URUGUAY BY SATURDAY MORNING. IN THE LOWER
LEVELS...A COLD FRONTAL BOUNDARY EXTENDS OVER CENTRAL ARGENTINA
AND EXITS INTO THE ATLANTIC OCEAN THROUGH BUENOS AIRES. THIS
FRONTAL BOUNDARY WILL ENCOUNTER THE WARMER AND MORE HUMID AIR THAT
IS BEING ADVECTED FROM THE SALLJ AND INCREASE THE INSTABILITY OVER
THE EASTERN PORTION OF ARGENTINA...AND PROPAGATE TO THE EAST INTO
URUGUAY. THESE REGIONS ARE EXPECTED TO SEE MODERATE TO ELEVATED
RISK OF SEVERE WEATHER. IN TERMS OF PRECIPITATION...CENTRAL CHILE
CAN EXPECT MAXIMA OF 30-60MM...WHILE NORTH CENTRAL CHILE...AND
NORTH AYSEN AND LOS LAGOS CAN EXPECT MAXIMA OF 20-40MM. MAXIMA OF
15-30MM ARE EXPECTED FROM LOS RIOS TO BIO BIO. SOUTHERN REGIONS OF
MAGALLANES CAN EXPECT MAXIMA OF 15MM. IN NORTHEASTERN
ARGENTINA...AND EXTREME WEST URUGUAY EXPECT MAXIMA OF 20-40MM. THE
SOUTHERN REGION OF ARGENTINA CAN EXPECT MAXIMA OF 15CM OF
SNOWFALL. OF NOTE ON FRIDAY...A ROSSBY WAVE AND INCOMING DIVERGENT
PHASE OF THE MJO IS ASSISTING WITH THE VENTILATION OVER NORTHERN
SOUTH AMERICA. WITH THE PASSING TROUGHS OVER THE
REGION...PRECIPITATION TOTALS ARE EXPECTED TO BE ABOUT
20-35MM...HOWEVER LOCALIZED MAXIMA ARE EXPECTED.
INTO SATURDAY...THE WIDE UPPER LEVEL TROUGH CONTINUES TO CROSS
OVER THE SOUTHERN PORTION OF THE CONTINENT...WHILE ANOTHER UPPER
SHORTWAVE TROUGH EMBEDDED IN THE TROUGH IS PASSING OVER
NORTH-CENTRAL ARGENTINA BY THE END OF THE DAY. IN THE LOWER
LEVELS...THE FRONTAL BOUNDARY IN NORTHERN ARGENTINA PUSHES
NORTHWARD ON SATURDAY AND EXTENDS FROM SOUTHERN BOLIVIA...INTO
PARAGUAY...AND INTO SOUTHERN BRASIL. WITH THE SUPPORT OF THE UPPER
LEVEL DYNAMICS...THE CHANCE OF SEVERE WEATHER IS POSSIBLE ON THIS
DAY. OVER IN SOUTH-CENTRAL CHILE...A COLD FRONTAL SYSTEM ENTERS
THE REGION AND INCREASES THE MOISTURE...FAVORING MAXIMA
OF...15-30MM WITH MOUNTAIN SNOW IN THE HIGHER ELEVATIONS. IN THE
PATAGONIA...THE ANOTHER FRONTAL BOUNDARY IS EXPECTED TO ENTER THE
REGION AND FAVOR SNOW MAXIMA OF 05-10CM. ALONG THE MOUNTAIN
REGIONS IN CENTRAL PERU AND BOLIVIA...INCREASING MOISTURE BEING
ADVECTED BY THE NORTHERLY FLOW FROM THE TROPICAL REGION OF SOUTH
AMERICA...WITH ENHANCE THE MOISTURE AVAILABILITY. AS THE MOIST
FLOW CONVERGES AGAINST THE MOUNTAIN RANGE...INCREASE MOISTURE
CONVERGENCE IS EXPECTED...WITH GENERALIZED MAXIMA OF
15-20MM...WITH POSSIBILITY FOR LOCALIZED HIGHER AMOUNTS.
ON SUNDAY...A SHORT WAVE TROUGH DEVELOPS ALONG THE UPPER LEVEL
TROUGH AND PROPAGATES OVER NORTHERN CHILE...INTO NORTHERN
ARGENTINA BY SUNDAY EVENING. BEHIND IT THE UPPER JET IS ENHANCED
WITH THE INTERACTION OF THE ZONAL FLOW OVER THE NORTHERN PORTION
OF THE CONTINENT. THIS DYNAMIC WILL ENHANCE THE DIVERGENCE ALOFT
AND CONTINUE TO ASSIST WITH SEVERE WEATHER OVER ARGENTINA...SOUTH
PARAGUAY...AND RIO GRANDE DO SUL. THE FRONTAL BOUNDARY IS EXPECTED
TO REMAIN OVER SOUTHERN PARAGUAY AND INTO RIO GRANDE DO
SUL...MEANING THAT THE UPPER LEVEL CONDITIONS ARE COUPLING WITH
THE CONDITIONS IN THE LOWER LEVELS. IN TERMS OF
PRECIPITATION....SOUTHERN PARAGUAY...AND SOUTHWEST RIO GRANDE DO
SUL AND EAST URUGUAY CAN EXPECT MAXIMA OF 25-50MM WITH MODERATE
RISK OF SEVERE WEATHER. NORTHERN RIO GRANDE DO SUL CAN EXPECT
MAXIMA OF 15-25M WITH A MODERATE RISK OF SEVERE WEATHER.IN CENTRAL
CHILE...EXPECT ANOTHER FRONTAL PASSAGE TO BRING PRECIPITATION FROM
SANTIAGO METROPOLITAN TO LOS LAGOS...WHERE THEY CAN SEE
PRECIPITABLE WATER AMOUNTS COULD REMAIN BELOW 25MM. IN THE MID
LEVELS...THE ADVECTION OF VORTICITY...ASSOCIATED WITH THE ENTRANCE
OF THE A SHORT WAVE TROUGH. THESE CONDITIONS WILL FAVOR MAXIMA OF
15-30MM...WHILE THESE CONDITIONS MOVE INTO ARGENTINA...EXPECT
MAXIMA OF 15MM.
ACOSTA...(WPC)
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