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South American Synoptic Discussion
 
(Latest Discussion - Issued 1354Z May 22, 2018)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
954 AM EDT TUE MAY 22 2018

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

SYNOPSIS (VALID FROM MAY 22 AT 0000 UTC): AT 200 HPA...A TROUGH
OVER MID SECTIONS OF SOUTH AMERICA IS PRESSING AGAINST A WANING
CELL OF THE SUBTROPICAL RIDGE TO THE NORTH. IN THIS
PATTERN...UPPER LEVEL RIDGE CONFINES TO CONTINENTAL AREA TO THE
NORTH OF 10S. THE RIDGE ALOFT IS VENTING DEEP CONVECTION...WITH
MOST ACTIVE CLUSTERING ACROSS EQUATORIAL SOUTH AMERICA AND THE
NEAR EQUATORIAL TROUGH TO THE NORTH.

AT 250 HPA...THE SOUTHERN POLAR JET FORMS AT 46S 119W ALONG 48S
114W...A 123KT MAXIMA AT 49S 110W...50S 101W...50S 91W...50S
83W...47S 73W...EXITING AT 44S 68W. THE NORTHERN POLAR JET FORMS
AT 42S 78W ALONG 36S 69W...31S 58W...32S 49W...32S 39W...33S
34W...35S 24W...38S 16W...A 148KT MAXIMA AT 41S 10W. THE
SUBTROPICAL JET FORMS A FINGER AT 27S 101W ALONG 28S 96W...EXITING
AT 30S 91W. IT REFORMS AT 33S 79W ALONG 30S 72W...26S 64W...25S
53W...25S 43W...26S 34W...31S 22W...34S 16W...A 113KT MAXIMA AT
37S 10W. THE SUBEQUATORIAL JET EXTENDS ALONG 18S 120W...18S
113W...19S 106W...22S 100W...24S 94W...26S 90W...26S 85W...25S
80W...21S 72W...EXITING AT 18S 66W.

AT 500 HPA...BROAD/LOW AMPLITUDE RIDGE OVER THE EASTERN PACIFIC
EXTENDS BETWEEN 90W-70W AND TO THE NORTH OF 45S. SOUTH OF THIS
RIDGE...IN A TIGHT BELT OF MID LATITUDE WESTERLIES...PROGRESSIVE
SHORT WAVE PERTURBATIONS ARE STREAMING ACROSS THE SOUTHEAST
PACIFIC TO THE DRAKE PASSAGE-TIERRA DEL FUEGO/PATAGONIA IN
ARGENTINA. ON THE NORTHERN STREAM...BROAD TROUGH TO THE EAST
EXTENDS FROM 40S 54W TO PARAGUAY/BOLIVIA. THIS SUSTAINS A LOW
LEVEL CYCLONE OFF THE COAST OF URUGUAY. FARTHER EAST...A HIGH NEAR
52S 36W EXTENDS A RIDGE SOUTH ALONG 60S 30W TO THE POLAR ICECAP.

THE SURFACE ANALYSIS SHOWS A 994 HPA OCCLUDED LOW AT 58S 65W. TO
THE EAST...A 994 HPA OCCLUDED LOW CENTERS AT 58S 59W AND EXTENDS A
FRONT INTO A 994 HPA TRIPLE POINT LOW AT 58S 56W...56S 56W...59S
59W...49S 65W...A 1010 HPA LOW AT 50S 68W...48S 69W...49S 74W...A
1010 HPA LOW AT 51S 79W...50S 81W...A 1010 HPA LOW AT 50S
87W...49S 88W. A 1025 HPA HIGH CENTERS OVER THE EASTERN PACIFIC AT
39S 79W. THIS EXTENDS A RIDGE EAST ACROSS LOS LAGOS/LOS RIOS IN
CHILE INTO CENTRAL ARGENTINA...TO A 1021 HPA HIGH AT 32S 63W. A
1006 HPA OCCLUDED LOW AT 42S 52W EXTENDS A FRONT ALONG A 1010 HPA
TRIPLE POINT LOW AT 43S 55W...43S 52W...A 1010 HPA LOW AT 40S
50W...37S 49W...34S 53W...30S 60W. ANOTHER FRONT EXTENDS ALONG A
1014 HPA AT 37S 46W...33S 46W...29S 54W. A 1017 HPA HIGH CENTERS
AT 28S 52W. A 1021 HPA HIGH CENTERS AT 25S 55W.

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