Prognostic Meteorological Discussion
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
951 AM EDT TUE MAY 23 2017

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

SYNOPSIS (VALID FROM MAY 23 AT 0000 UTC): AT 200 HPA...A CLOSED
HIGH OVER NORTHERN BRASIL ANCHORS A RIDGE OVER THE CONTINENT TO
THE NORTH OF 30S AND WEST OF 50W. SHORT WAVE TROUGH TO THE EAST
EXTENDS NORTH ALONG 40W. THE RIDGE ALOFT IS VENTING DIURNAL
CONVECTION OVER THE CONTINENT TO THE NORTH OF 20S AND WEST OF
50W...WHILE THE TROUGH IS INHIBITING ACTIVITY ON THE NORTHEAST
STATES OF BRASIL.

AT 250 HPA...THE JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS
ALONG 65S 118W...63S 96W...58S 77W...EXITING AT 52S 74W. IT
REFORMS AT 44S 70W...THEN ALONG 48S 52W...55S 42W...AND 65S 21W.
THE NORTHERN POLAR LIES ALONG 60S 119W...A 131KT MAXIMUM AT 59S
96W...56S 84W...49S 84W...EXITING AT 40S 87W. ANOTHER BRANCH TO
THE NORTH LIES ALONG 43S 120W...44S 109W...A 140KT MAXIMUM AT 32S
94W...28S 84W...34S 71W...A 136KT MAXIMUM AT 43S 51W...47S
41W...59S 28W...AND 48S 02W. THE SUBTROPICAL JET HAS ITS ENTRANCE
AT 16S 96W...THEN ALONG 14S 88W...24S 69W...29S 60W...30S
53W...EXITING AT 24S 42W. ANOTHER BRANCH TO THE NORTH HAS ITS
ENTRANCE AT 13S 81W...THEN ALONG 16S 75W...19S 69W...EXITING AT
20S 59W.

AT 500 HPA...A NORTH-TO-SOUTH RIDGE EXTENDS ALONG 110W TO 55S.
THIS IS INDUCING THE NORTHWARD AMPLIFICATION OF A TROUGH BETWEEN
100W-50W AND TO THE SOUTH OF 20S. THE TROUGH IS FOCUSING SHORT
WAVE ENERGY ACROSS CENTRAL/NORTHERN CHILE INTO ARGENTINA. THIS IS
PROVIDING DYNAMICAL SUPPORT TO CONVECTION ACROSS MID SECTIONS OF
SOUTH AMERICA. A SKEWED RIDGE TO THE EAST AND NORTH EXTENDS FROM
SOUTHEAST BRASIL...ALONG 40S 30W...50S 20W...TO 70S 20W.

AT LOW LEVELS...THE SURFACE ANALYSIS SHOWS A BROAD RIDGE OVER THE
SOUTH PACIFIC THAT ANCHORS ON A 1041 HPA HIGH AT 47S 11W.
PROGRESSIVE POLAR FRONT TO THE SOUTH EXTENDS FROM AN OCCLUDED 970
HPA LOW AT 65S 91W...A 970 HPA LOW AT 63S 84W...59S 87W...58S
98W...59S 110W...AND 60S 117W. A WANING FRONT TO THE NORTH EXTENDS
FORM AN OCCLUDED 1010 HPA LOW AT 48S 77W...A 1014 HPA LOW AT 45S
77W...42S 80W...A 1022 HPA LOW AT 41S 85W...39S 91W...AND 41S 97W.
ANOTHER FRONT TO THE NORTH EXTENDS FROM A 990 HPA LOW AT 50S
57W...A 994 HPA LOW AT 51S 53W...48S 48W...43S 50W...A 1016 HPA
LOW AT 42S 58W...38S 66W...AND 36S 72W. THIS IS PHASING WITH A
WANING BOUNDARY TO THE NORTH THAT EXTENDS ALONG A 1002 HPA LOW AT
49S 42W...44S 41W...39S 49W...A 1018 HPA LOW OVER BUENOS AIRES
PROVINCE-MENDOZA IN ARGENTINA...TO A 1018 HPA LOW AT 27S 78W.
FARTHER EAST AND NORTH... AN OLD/ELONGATED FRONT EXTENDS ALONG A
1018 HPA LOW AT 44S 39W...40S 36W...35S 40W...31S 45W...A 1018 HPA
LOW AT 28S 46W...A 1014 HPA LOW AT 25S 42W...23S 38W...20S
40W...MATO GROSSO DO SUL TO PARAGUAY. THIS SUSTAINS LIGHT
CONVECTION ACROSS MID PORTIONS OF SOUTH AMERICA.

ABDEMUR...FAA (ARGENTINA)
ESPINOLA...DNM (PARAGUAY)
DAVISON...WPC (USA)
$$





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