446
FXSA20 KWBC 081912
PMDSA
SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
311 PM EDT THU AUG 08 2024
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SOUTH AMERICAN FORECAST BULLETIN FOR 08 AUG 2024 AT 1930 UTC:
THE MID TO UPPER LEVEL TROUGH IS ADVANCING INTO THE NORTH AND
EASTERN PORTION OF THE CONTINENT...WHERE IT IS SITUATED OVER EAST
ARGENTINA...AND EXPANDS INTO PARAGUAY...URUGUAY...AND SOUTH
BRASIL. THE BASE OF THE TROUGH IS LOCATED IN NORTH BOLIVIA AND
SOUTH OF PERU. THIS MID TO UPPER TROUGH HAS A COLD NUCLEUS THAT
WILL FAVOR THE ENTRANCE OF COLD FRONTAL BOUNDARIES IN THE LOWER
LEVELS. THE SUBTROPICAL JET EXPANDS OVER SOUTHERN BOLIVIA...AND
EXTENDS INTO PARAGUAY...AND SOUTHERN BRASIL. WHERE THE DYNAMICS
WILL FAVOR A SLIGHT CHANCE OF SEVERE WEATHER FOR THURSDAY. IN THE
LOWER LEVELS...THE COLD FRONT CONTINUES PROGRESSING
NORTH...EXPECTED OVER SOUTHERN PERU...NORTH BOLIVIA...AND
EXPANDING OVER SOUTH-CENTRAL BRASIL...EXITING BY EAST SAO PAULO ON
THURSDAY EVENING. IN TERMS OF PRECIPITATION...FROM MATO GROSSO DO
SUL...TO SAO PAULO AND PARANA...EXPECT MAXIMA OF 20-35MM...WITH
SLIGHT RISK OF SEVERE WEATHER. FROM SOUTHERN PERU TO CENTRAL
BOLIVIA...EXPECT MAXIMA OF 20-35MM...FAVORED BY THE ENTRANCE ON
THE COLD FRONT AND THE DYNAMICS OF THE UPPER JET. TO THE SOUTH IN
CHILE...AN INCREASE IN PRECIPITABLE WATER DUE TO THE ENTRANCE OF
AT ATMOSPHERIC RIVER AND FRONTAL BOUNDARY...ASSISTED BY AN MID TO
UPPER LEVEL SHORT WAVE TROUGH WILL FAVOR MAXIMA OF 25-50MM IN
SOUTH LOS LAGOS AND NORTH AYSEN...WITH MOUNTAIN SNOW IN THE HIGHER
ELEVATIONS.
ON FRIDAY...THE MID TO UPPER LEVEL TROUGH CONTINUES TO PROGRESS TO
THE EAST...BEING BLOCKED BY AN UPPER LEVEL RIDGE IN THE NORTHERN
PORTION OF THE CONTINENT. AS SUCH...THE FRONTAL BOUNDARY BEINGS TO
ENTER A LESS FAVORABLE REGION UNDER THE RIDGE...AND BEGINS TO LOSE
DEFINITION OVER CENTRAL AND WESTERN PORTIONS OF BRASIL...AND INTO
EAST PERU. POST-FRONTAL HUMIDITY IS EXPECTED TO REMAIN OVER THE
SOUTHERN PORTIONS OF BRASIL...AND INTO SOUTH AND EXTREME NORTHWEST
BOLIVIA. ADDITIONALLY...THE PRECIPITABLE WATER LEVELS ARE
DECREASING AS DRIER AIR IS ADVECTED NORTHWARD OVER SOUTHERN
PERU...ACRE AND AMAZONAS-BRASIL. IN SAO PAULO AND RIO DE JANEIRO
EXPECT MAXIMA OF 25-50MM...WHILE FROM NORTH SOU PAULO INTO SOUTH
MATO GROSSO DO SUL CAN EXPECT MAXIMA OF 15-25MM. TO THE
NORTH...PORTIONS OF NORTH PERU INTO AMAZONAS-BRASIL CAN EXPECT
MAXIMA OF 20-35MM...AND MAXIMA OF 20-45MM ARE EXPECTED INTO EAST
ECUADOR INTO SOUTH COLOMBIA...WITH THE CONVERGENCE OF MOISTURE AND
PASSING TROUGHS IN THE NORTHERN PORTION OF THE CONTINENT. TO THE
SOUTH...CHILE WILL CONTINUE TO SEE THE INCURSION OF THE
ATMOSPHERIC RIVER AND ENTRANCE OF A COLD FRONT INTO THE REGION.
ASSISTED WITH THE SHORT WAVE TROUGH...THE BASE OF THE TROUGH WILL
FAVOR JET DYNAMICS OVER SOUTH-CENTRAL CHILE...WHERE FROM LOS LAGOS
TO AYSEN CAN EXPECT MAXIMA OF 25-50MM. TO THE SOUTH THE MAXIMA OF
15-30MM ARE EXPECTED WITH A CHANCE OF RAIN/SNOW.
ON SATURDAY...THE PRESENCE OF THE POST-FRONTAL DRIER AIR IS
EXPECTED OVER MOST OF THE CONTINENT. THE MID TO UPPER LEVEL RIDGE
IS EXPECTED TO CONTINUE MOVING TO THE EAST INTO THE ATLANTIC
OCEAN...AND UPPER LEVEL JET BECOMES ZONAL EXTREME NORTH CHILE...TO
SOUTH-CENTRAL BRASIL. THE UPPER RIDGE IS BLOCKING THE ENTRANCE OF
THE TROUGH AND WILL CONTINUE TO DISSIPATE THE FRONTAL BOUNDARY IN
THE LOWER LEVELS THAT WAS MAKING ITS WAY INTO CENTRAL PORTIONS OF
BRASIL. THE SHORTER AMPLITUDE UPPER TROUGH OVER THE SOUTHERN CONE
OF THE CONTINENT IS EXPECTED TO INTENSIFY WITH THE PRESENCE OF A
STRONG JET IN THE LEFT SIDE OF THE TROUGH. HOWEVER...DUE TO THE
RIDGE IN THE LOWER LEVELS THAT IS ENTERING THE CONTINENT FROM THE
PACIFIC THROUGH CHILE...A DECREASE IN PRECIPITATION IS EXPECTED.
MAXIMA OF 15-20MM ARE EXPECTED FROM LOS LAGOS TO NORTH MAGALLANES.
TO THE NORTH...THE FRONTAL BOUNDARY IS FAVORING ONSHORE FLOW WITH
INCREASED PRECIPITABLE WATER...YET THE AMOUNTS OF MAXIMA ARE
EXPECTED TO REMAIN LOW...WITH MAXIMA OF 20-35MM FROM SOUTHERN SAO
PAULO TO RIO DE JANEIRO. ESPIRITO SANTO CAN EXPECT MAXIMA OF 15MM.
SIMILAR MAXIMA OF 15-20MM ARE EXPECTED IN NORTHERN PERU WITH THE
DECREASE OF AVAILABLE MOISTURE IN THE REGION.
ACOSTA...(WPC)
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