SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
142 PM EST MON DEC 02 2024

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

SOUTH AMERICAN FORECAST BULLETIN FOR 02 DEC 2024 AT 1730 UTC:
LARGE SCALE CONDITIONS ASSOCIATED WITH THE MJO CONTINUE TO BE
UPPER CONVERGENT. THIS WILL CONTINUE TO LIMIT THE COVERAGE OF
CONVECTION THROUGH THE FORECAST CYCLE...WITH THE EXCEPTION OF
REGIONS EXPOSED TO SUBSTANTIAL SYNOPTIC FORCING.

A BROAD MID-UPPER POLAR TROUGH IS PRESENT OVER THE WEDDELL
SEA/SOUTHWEST ATLANTIC. THIS ASSOCIATES WITH FAST COOL
SOUTHWESTERLY WINDS ALONG THE ENTIRE COAST OF ARGENTINA...AND COLD
AIR CUMULUS AND ASSOCIATED SHOWERS ESPECIALLY IN PORTIONS OF THE
BUENOS AIRES PROVINCE AND NORTHEAST PATAGONIA. EXPECT MAXIMA UNDER
15MM THROUGH EARLY TUESDAY.

A MID-UPPER SHORT WAVE TROUGH EXTENDS SOUTH OF 45S AND NEAR 110W.
THIS TROUGH IS EXPECTED TO INTERACT WITH THE LARGER TROUGH TO ITS
EAST AND PROPAGATE NORTHWEASTWARD WHILE AMPLIFYING. AS THIS TROUGH
STARTS CROSSING THE SOUTHERN ANDES ON WEDNESDAY...IT IS EXPECTED
TO FAVOR CYCLOGENESIS IN CENTRAL PATAGONIA...EAST OF THE ANDES.
THIS WILL FAVOR SCATTERED THUNDERSTORM DEVELOPMENT ON WEDNESDAY
AND POTENTIAL RAINFALL AMOUNTS OF 05-10MM/DAY AND ISOLATED MAXIMA
OF 15-20MM THROUGH EARLY THURSDAY.

IN SUBTROPICAL AND TROPICAL PORTIONS OF THE CONTINENT AND AT UPPER
LEVELS...THE BOLIVIAN HIGH CONTINUES TO BE THE SYSTEM OF INTEREST.
THE CURRENT ANALYSIS SHOWS THE HIGH CENTERING OVER BOLIVIA AND
EXTENDING AN AXIS AS FAR EAST AS SOUTHEAST BRASIL. TO THE
NORTHEAST...A POTENT CAVADO DO NORDESTE IS ORGANIZING WHILE
CENTERING ON A LOW NEAT 12S 28W. IN THE LOWER LEVELS...THE LARGEST
VALUES OF AVAILABLE MOISTURE ARE CLUSTERING IN MID-SECTIONS OF THE
CONTINENT BETWEEN BOLIVIA...NORTHERN PARAGUAY AND SOUTH-CENTRAL
BRASIL...WHERE THE STRONGEST CONVECTION IS FLARING UP IN
ASSOCIATION WITH A SURFACE FRONT. ALTHOUGH THE BOLIVIAN HIGH IS
PRESENT...MOISTURE AVAILABILITY IN THE NORTHERN AND CENTRAL AMAZON
BASIN IS BELOW NORMAL. THIS...COMBINED WITH UPPER CONVERGENT MJO
CONDITIONS IS LIMITING THE COVERAGE OF DIURNAL CONVECTION IN THE
REGION AND LIMITING THE CONTRIBUTIONS OF CONDENSATIONAL WARMING
FOR THE STRENGTHENING OF THE HIGH. REGARDING THE FORECAST...MODELS
SUGGEST A GRADUAL WEAKENING OF THE BOLIVIAN HIGH THROUGH
THURSDAY...WHICH WILL ALLOW A WESTWARD MIGRATION OF THE CAVADO DO
NORDESTE. THIS WILL ENHANCE VENTILATION AND INSTABILITY IN EASTERN
BRASIL...YIELDING TO AN INCREASING TREND IN THE COVERAGE AND
INTENSITY OF CONVECTION.

ON MONDAY...EXPECT DEEP CONVECTION TO FLARE ALONG AND NORTH OF THE
SURFACE FRONT EXPECTED ACROSS PARANA-BRASIL...NORTHERN PARAGUAY
INTO CENTRAL BOLIVIA. UNDER ENHANCED VENTILATION IN THE SOUTHERN
PERIPHERY OF THE BOLIVIAN HIGH...EXPECT 15-20MM/DAY AND MAXIMA OF
30-60MM. SIMILAR AMOUNTS ARE EXPECTED ALONG THE EAST SLOPES OF THE
ANDES OF BOLIVIA AND SOUTHERN PERU. ON TUESDAY...EXPECT THE FRONT
TO PROPAGATE ACROSS SOUTHEAST BRASIL...WHILE LOSING DEFINITION ON
AREAS TO THE WEST. HOWEVER...FRONTAL INTERACTION WITH THE ANDES
WILL FAVOR MAXIMA OF 30-60MM IN CENTRAL BOLIVIA. IN SOUTHEAST
BRASIL...LOW-LEVEL MOISTURE CONVERGENCE AND VENTILATION IN THE
SOUTHEAST PERIPHERY OF THE BOLIVIAN HIGH WILL FAVOR 15-30MM/DAY
AND SCATTERED MAXIMA OF 40-80MM INCLUDING A RISK FOR MCS
FORMATION. IN CENTRAL BRASIL AND NORTHERN BOLIVIA EXPECT MAXIMA OF
20-45MM. ON WEDNESDAY...EXPECT THE DESTABILIZING INFLUENCE OF THE
CAVADO DO NORDESTE TO INCREASE IN EAST AND CENTRAL BRASIL. THIS
WILL STIMULATE THE FORMATION OF A LOW-LEVEL TROUGH FROM MINAS
GERAIS INTO SOUTHEAST PARA. EXPECT SCATTERED DIURNAL CONVECTION
CAPABLE OF PRODUCING MAXIMA OF 25-50MM. OTHER REGIONS OF ACTIVE
CONVECTION INCLUDE SOUTHEAST PERU AND NORTHERN BOLIVIA...WHERE
ENHANCED MOISTURE CONVERGENCE AND A SHORT WAVE UPPER TROUGH WILL
FAVOR MAXIMA OF 20-35MM.

GALVEZ/TINOCO...(WPC)