THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


SOUTH AMERICAN SYNOPSIS




SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1000 AM EDT TUE APR 24 2018

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

SYNOPSIS (VALID FROM APR 24 AT 0000 UTC): AT 200 HPA...THE
SUBEQUATORIAL RIDGE EXTENDS WEST ACROSS THE TROPICAL ATLANTIC TO
NORTHERN SOUTH AMERICA. THIS FAVOR AN UPPER DIVERGENT PATTERN THAT
IS VENTING DEEP CONVECTION ACROSS EQUATORIAL SOUTH AMERICA...WITH
MOST ACTIVE OVER PARA AND AMAZONAS IN BRASIL BUILDING TO THE NORTH
OF 04S. OTHER CONVECTION WAS BUILDING ON THE SIERRA AND JUNGLE OF
PERU AND CENTRAL PORTIONS OF BOLIVIA. OVER CENTRAL AND SOUTHEAST
BRASIL...MEANWHILE...MID LEVEL CONVERGENCE SUSTAINS A TRADE WINDS
CAP. THIS...IN-TURN...FAVORS EROSION OF AVAILABLE MOISTURE AND
FAIR WEATHER CONDITIONS.

AT 250 HPA...THE SOUTHERN POLAR LIES ALONG 62S 116W...55S
113W...EXITING AT 47S 107W. IT REFORMS AT 45S 107W...THEN ALONG
46S 94W...EXITING AT 50S 79W. ANOTHER BRANCH TO THE EAST HAS ITS
ENTRANCE AT 54S 54W...THEN ALONG 56S 38W...57S 22W...AND 58S 10W.
THE NORTHERN POLAR HAS ITS ENTRANCE AT 40S 113W...THEN ALONG A
121KT MAXIMUM AT 42S 97W...41S 91W...EXITING AT 37S 85W. IT
REFORMS AT 41S 72W...THEN ALONG 45S 52W...49S 39W...A 154KT
MAXIMUM AT 54S 23W...53S 09W...49S 06W...AND A 124KT MAXIMUM AT
39S 10W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT 29S 82W...THEN
ALONG 32S 71W...36S 57W...38S 48W...EXITING AT 41S 38W. AT 200
HPA...THE SUBEQUATORIAL JET HAS ITS ENTRANCE AT 13S 100W...THEN
ALONG 14S 88W...EXITING AT 20S 79W. IT REFORMS AT 15S 26W...THEN
ALONG 15S 18W...18S 10W...EXITING AT 21S 00W.

AT 500 HPA...A RIDGE IS BUILDING TO THE SOUTH-SOUTHEAST FROM A
CLOSED HIGH AT 40S 130W...ALONG 60S 120W...TO 70S 110W.
THIS...IN-TURN...SUSTAINS THE NORTHWARD AMPLIFICATION OF A TROUGH
FROM THE ANTARCTIC PENINSULA/BELLINGSHAUSEN SEA...ALONG 60S
85W...50S 100W...TO 40S 110W. THE AMPLIFYING TROUGH IS PHASING
WITH A SHORT WAVE TROUGH TO THE NORTH THAT EXTENDS ALONG THE
CENTRAL COAST OF CHILE. FARTHER EAST...BROAD/LOW AMPLITUDE TROUGH
OVER THE SOUTH ATLANTIC DOMINATES THE FLOW TO THE SOUTH OF 36S. A
SHORT WAVE TROUGH TO THE NORTH EXTENDS FROM 25S 45W TO BAHIA IN
BRASIL. THIS IS ENHANCING COASTAL CONVECTION BETWEEN RIO DE
JANEIRO AND ESPIRITO SANTO.

AT LOW LEVELS...A RIDGE TRAVERSES THE SOUTHERN CONE WHILE
ANCHORING ON TWO 1025 HPA HIGHS...WITH ONE AT 37S 85W AND THE
OTHER AT 41S 60W. PROGRESSIVE FRONT LIES TO THE SOUTH...WITH AXIS
ALONG A 994 HPA LOW AT 57S 51W...55S 54W...56S 66W...A 990 HPA LOW
AT 58S 72W...57S 72W...55S 77W...A 994 HPA LOW AT 54S 81W...51S
81W...49S 87W...A 1002 HPA LOW AT 48S 92W...45S 98W...AND 45S
108W. ANOTHER FRONT TO THE EAST AND NORTH EXTENDS ALONG A 1010 HPA
LOW AT 44S 42W...38S 45W...A 1014 HPA LOW AT 38S 48W...RIO GRANDE
DO SUL...CORRIENTES IN ARGENTINA TO CORDOBA. THIS FAVORS SCATTERED
DEEP CONVECTION ACROSS MID SECTIONS OF SOUTH AMERICA. A RIDGE ON
THE NORTHERN STREAM EXTENDS OVER THE SOUTH ATLANTIC WHILE
CENTERING ON A 1033 HPA HIGH AT 36S 26W. AN OLD FRONT TO THE NORTH
EXTENDS ALONG 21S 06W...21S 16W...20S 29W...TO 24S 43W.

BALBINO...INMET (BRASIL)
DIAZ...INUMET (URUGUAY)
DAVISON...WPC (USA)




Last Updated: 1000 AM EDT TUE APR 24 2018