Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center
 
South American Forecast Discussion
 
(Latest Discussion - Issued 1640Z Jul 15, 2019)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product


SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1240 PM EDT MON JUL 15 2019

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

MODEL DISCUSSION FROM JULY 15/00UTC: CONFIDENCE IN THE FORECAST IS
HIGH WITH MODELS FOLLOWING A SIMILAR EVOLUTION THROUGH DAY 06.

NORTH OVER THE CONTINENT...AT 200 HPA...SHORT WAVE TROUGH IS TO
MEANDER EAST ACROSS THE EASTERN PACIFIC...WITH AXIS TO EXTEND FROM
NORTHERN CHILE TO CENTRAL PERU LATER ON TUESDAY. AS IT MEANDERS
EAST...THIS IS TO PRESS AGAINST A WANING CELL OF THE SUBEQUATORIAL
RIDGE OVER NORTHERN BRASIL...TIGHTENING THE GRADIENT WHILE
FAVORING INTENSIFICATION OF A SUBTROPICAL JET MAXIMA ACROSS
SOUTHERN PERU-BOLIVIA. DIVERGENCE ON ITS LEFT ENTRANCE REGION IS
TO THEN VENT DEEP CONVECTION OVER NORTHWEST SOUTH AMERICA. OVER
SOUTHERN COLOMBIA-EASTERN ECUADOR/NORTHERN PERU AND AMAZONAS IN
BRASIL INITIALLY EXPECTING MAXIMA OF 20-35MM. THROUGH WEDNESDAY
THIS DECREASES TO 15-25MM. THIS IS TO ALSO TRIGGER MODERATE TO
HEAVY CONVECTION ACROSS SOUTHERN JUNGLE OF PERU-CENTRAL BOLIVIA ON
MONDAY-TUESDAY...WITH DAILY MAXIMA OF 20-35MM. ALSO ON
TUESDAY...ENVIRONMENTAL CONDITIONS WILL BECOME FAVORABLE FOR SNOW
TO ACCUMULATE ON THE SOUTHERN SIERRA OF PERU/BOLIVIA...WITH
ACCUMULATION OF 05-10CM ON TUESDAY AND WEDNESDAY.

OTHER CONVECTION IS TO CLUSTER ALONG THE NORTH COAST OF BRASIL AS
ENHANCED BY TROPICAL WAVES STREAMING ALONG THE ITCZ TO THE NORTH.
MOST ACTIVE BETWEEN PIAUI AND AMAPA...WITH ACCUMULATION OF 05-10MM
EARLY IN THE CYCLE. ON TUESDAY THIS INCREASES TO 15-25MM WHILE
SPREADING WEST ACROSS AMAPA TO NORTHERN PARA IN BRASIL.

FARTHER SOUTH...AT 500 HPA...A SHORT WAVE TROUGH ON THE NORTHERN
STREAM IS TO PULL ACROSS THE BUENOS AIRES PROVINCE/URUGUAY LATER
THIS AFTERNOON...WITH AXIS TO DEEPEN WHILE MEANDERING EAST ACROSS
THE EASTERN SOUTH ATLANTIC ON TUESDAY-WEDNESDAY. AT LOW LEVELS
THIS IS TO INTERACT WITH A SURFACE FRONT OVER SOUTHEAST
BRASIL-MATO GROSSO DO SUL/PARAGUAY...SUSTAINING CYCLOGENESIS ALONG
THIS BOUNDARY EARLY ON TUESDAY MORNING. THROUGH THE DAY THE LOW IS
FORECAST TO RAPIDLY OCCLUDE. THIS WILL THEN DRIVE THE FRONT NORTH
ACROSS SAO PAULO/RIO DE JANEIRO TO MINAS GERAIS ON
TUESDAY-WEDNESDAY. AS IT ACCELERATES...A PREFRONTAL SHEAR LINE IS
TO DEVELOP OVER NORTHEAST BRASIL ON WEDNESDAY-THURSDAY. OVER SAO
PAULO-MATO GROSSO DO SUL FRONTAL CONVECTION WILL SUSTAIN MAXIMA OF
15-30MM EARLY IN THE CYCLE. OVER EASTERN BAHIA-SERGIPE THIS IS TO
THEN TRIGGER MAXIMA OF 15-25MM ON WEDNESDAY-THURSDAY.

ON THE SOUTHERN STREAM...PROGRESSIVE MID LEVEL TROUGH ENTERS
SOUTHERN CHILE/PATAGONIA IN ARGENTINA LATER TODAY. A BROAD TROUGH
IS TO FOLLOW...TO BECOME THE DOMINANT FEATURE OVER THE SOUTHEAST
PACIFIC/SOUTHERN CONE OF SOUTH AMERICA ON WEDNESDAY-FRIDAY. AT LOW
LEVELS THESE ARE TO SUSTAIN SUCCESSIVE POLAR FRONTS THAT ARE TO
CONFINE TO SOUTHERN CHILE-PATAGONIA N ARGENTINA...MEANWHILE
FAVORING A LOW LEVEL CONVERGENT PATTERN BETWEEN TEMUCO-CONCEPCION.
THIS WILL ENHANCE COASTAL CONVECTION IN THIS AREA TO FAVOR
MODERATE RAINFALL AMOUNTS...WITH ACCUMULATION OF 15-20MM/DAY.
THROUGH WEDNESDAY/THURSDAY THIS INTENSIFIES TO 15-30MM WHILE
BUILDING NORTH OVER CENTRAL CHILE. ON THE SOUTHERN ANDES THIS IS
TO ALSO FAVOR LIGHT SNOWFALL AMOUNTS...WITH ACCUMULATION OF
05-10CM EXPECTED ON MONDAY AND ON WEDNESDAY/THURSDAY.

CORONEL...DMH (PARAGUAY)
JIMENEZ...FAC (COLOMBIA)
MATHIAS...CHM (BRASIL)
DAVISON...WPC (USA)